Gerald B. Appel, MD

Our knowledge of the pathogenesis of thrombotic microangiopathies has greatly advanced in the last decade, improving the diagnosis and treatment of these diseases.

Many conditions involve thrombotic microangiopathies (Table 1). This article reviews the most common ones, ie, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, atypical hemolytic uremic syndrome, and antiphospholipid syndrome—their clinical features (focusing on the kidney), course, and management. Of note, although the diseases are similar, their pathogeneses and treatments differ.

DIFFERENT PATHWAYS TO MULTIORGAN THROMBOSIS

The thrombotic microangiopathies are multisystem disorders that can affect children and adults and often present with prominent renal and neurologic involvement. Endothelial injury is likely the inciting factor leading to thrombosis in the kidney and in many other organs. The causes variously include:

• Toxins from bacteria or drugs
• Abnormal complement activation, genetic or autoantibody-induced
• Procoagulant factors, eg, antiphospholipid antibodies
• Loss of anticoagulants, eg, from a defect of ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13); ADAMTS13 is also known as von Willebrand factor-cleaving protease
• Severe hypertension.

The histopathologic features are similar in all the thrombotic microangiopathies. Laboratory findings include thrombocytopenia, microangiopathic hemolytic anemia (with schistocytes on the peripheral blood smear), and high serum lactate dehydrogenase (LDH) levels; these are also markers of treatment progress. Bilirubin may be elevated and haptoglobin absent. Renal biopsy reveals thrombi in the glomeruli and arterioles.

THROMBOTIC THROMBOCYTOPENIC PURPURA

A young woman with fever, bruising, and renal failure, then blindness

A 36-year-old black woman who had been previously healthy presents to her doctor with fever and bruising.

Her hematocrit is 28% (reference range 38%–46%), platelet count 15 x 10⁹/L (150–450), and prothrombin and partial thromboplastin times are normal. Her peripheral blood smear shows microangiopathic hemolytic anemia with schistocytes.

Over the next few days, her urine output declines and she develops sudden blindness followed by decreased mental acuity. Blood is drawn and sent for ADAMTS13 assay. Treatment is started at once with daily therapeutic plasma exchange. The assay results, when they arrive, show marked ADAMTS13 reduction (< 5%). Over the ensuing weeks, her mental acuity improves, her vision returns, and her renal function improves.

ADAMTS13 deficiency is definitive

Thrombotic thrombocytopenic purpura is characterized by:

• Neurologic abnormalities and acute renal failure
• Thrombocytopenia and microangiopathic hemolytic anemia
• Histologic evidence of thrombotic microangiopathy
• Deficiency of von Willebrand factor-cleaving protease (ADAMTS13 < 10%).

von Willebrand factor forms ultralarge multimers in the circulation that interact with platelets; these are normally cleaved by ADAMTS13. With ADAMTS13 deficiency (from either a genetic mutation or autoantibodies), the ultralarge multimers lead to coagulation as blood flows through small vessels.¹

In 2003, Tsai² evaluated 127 patients over age 10 who had thrombocytopenia and microangiopathic hemolysis with no plausible cause or features suggestive of hemolytic uremic syndrome. All were severely deficient in ADAMTS13. Subsequently, thrombotic thrombocytopenic purpura has been defined by a severe actual or effective deficiency of ADAMTS13.

Prompt plasma exchange is critical

Although the ADAMTS13 assay is important for diagnosing thrombotic thrombocytopenic purpura, in suspected cases daily plasma exchange should be started promptly, before test results return. Plasma exchange removes autoantibodies to ADAMTS13 from the blood, removes circulating ultralarge von Willebrand factor multimers, and replaces the missing ADAMTS13. Untreated, the disease is progressive, with irreversible renal failure, neurologic deterioration, and a 90% mortality rate. Plasma exchange reduces the mortality rate to less than 15%. If another diagnosis is confirmed, plasma exchange can be stopped.

Plasma exchange has been shown in clinical trials to be superior to plasma infusion in normalizing platelet counts and reducing mortality.^3,4 Mortality rates were comparable with different replacement fluids vs fresh-frozen plasma, including solvent or detergent-treated plasma, and cryo-poor (cryosupernatant) plasma.⁴ Antiplatelet therapy, platelet transfusions, and splenectomy are ineffective.

Glucocorticoids for early treatment

An appropriate strategy is to add a glucocorticoid to plasma-exchange therapy at once (oral prednisone 1 mg/kg per day or intravenous methylprednisolone 125 mg twice daily) and withdraw it after several days if it is determined that it is not needed. Steroids for suspected thrombotic thrombocytopenic purpura can be justified for several reasons:

• The results of the ADAMTS13 assay are usually delayed, so steroids provide coverage for other diagnoses.
• They are helpful if thrombotic thrombocytopenic purpura is idiopathic (which is true for most cases) and if the patient has a poor response to initial therapy with plasma exchange.
• They are indicated for patients whose platelet counts do not increase with several days of plasma exchange or whose thrombocytopenia recurs as plasma exchange is decreased.

Rituximab improves survival

Rituximab, a chimeric (half murine) monoclonal antibody against CD19 and CD20 B cells, suppresses antibody production by knocking out the precursors of antibody-producing cells.

Anecdotal reports and small studies involving a total of 42 patients have been published on the use of rituximab for thrombotic thrombocytopenic purpura. Courses of rituximab varied greatly, from 1 to 13 weekly doses at 375 mg/m², with 4 doses being the most common. Complete remission occurred in 90% of cases.^5,6 A typical study from 2014 involved 48 patients (30 of whom received rituximab) followed by severe ADAMTS13 deficiency during remission.⁷ Despite the small study size, the investigators found significantly improved relapse-free survival rates with rituximab treatment.

But rituximab can cost $25,000 for 2 doses of 1,000 mg, and this will most likely prohibit its routine use. The cost and insurance coverage vary with location and policies.

Based on such studies, a reasonable strategy is to treat thrombotic thrombocytopenic purpura with:

• Daily plasma exchange
• Steroids, at least until the diagnosis is certain
• Rituximab if warranted.

New targeted therapies

Caplacizumab, a humanized immunoglobulin that inhibits the interaction between ultralarge von Willebrand factor multimers and platelets, has the potential to change this strategy when it receives US Food and Drug Administration approval, which is expected soon.

Peyvandi et al⁸ randomized 75 patients with acquired thrombotic thrombocytopenic purpura to either subcutaneous caplacizumab 10 mg daily for 30 days or placebo. Both groups had daily plasma exchange. The treatment group had a 39% reduction in median time to normalization of platelets vs the placebo group, and 3 of 36 patients had exacerbations, compared with 11 of 39 patients in the placebo group. Although 8 patients relapsed within the first month after stopping caplacizumab, their cases were brought under control. There were also more bleeding episodes with caplacizumab (54% vs 38%), most being mild to moderate. Two patients in the placebo group died, but none in the treatment group.

The fact that platelet normalization occurred significantly faster with caplacizumab, even in some patients who had not yet had plasma exchange therapy initiated, has enormous clinical significance. The low platelet count in thrombotic thrombocytopenic purpura is a marker of susceptibility to rapid damage to the brain and kidneys, so correcting it quickly is critical.

Other strategies for new drug development include replacing the deficient ADAMTS13 with a recombinant molecule and blocking antibody production (the same mode of action as rituximab and glucocorticoids).⁹ Using all 3 strategies to treat thrombotic thrombocytopenic purpura may be the future standard of care.

HEMOLYTIC UREMIC SYNDROME

A child with sudden onset of bloody diarrhea and kidney failure

A 4-year-old girl plays with baby animals at a petting zoo and does not wash her hands immediately afterwards. Three days later, she develops fever, abdominal cramps, nausea, vomiting, and bloody diarrhea. Her pediatrician gives her antibiotics. On day 6, she develops ecchymoses on the extremities and lips, thrombocytopenia, low urine output, and seizures. Her stool tests positive for Escherichia coli O157:H7

Classic presentation: Young patient with bloody diarrhea

The classic presentation of hemolytic uremic syndrome is of a young patient with bloody diarrhea typically lasting 5 to 10 days. Kidney failure may follow, requiring dialysis in about 60% of patients for a mean of 10 days. About one-fourth of patients develop neurologic symptoms, and about the same fraction are left with long-term morbidity, eg, hypertension, proteinuria, and reduced glomerular filtration rate. The mortality rate is typically 4%^10,11 but varies with the outbreak.

Histologically, the kidneys look identical to those in thrombotic thrombocytopenic purpura, with thrombi in glomeruli and small vessels.

E coli is the most common culprit, but other bacteria, including Shigella dysenteriae, and viruses are sometimes the cause. Fewer than 10% of children infected with Shiga toxin-positive E coli, also known as enterohemorrhagic E coli (O157:H7, O104:H4), develop hemolytic uremic syndrome.

Lessons from outbreaks

Petting zoos are a common source of transmission of pathogenic bacteria. Disease can be extremely serious: in 15 cases linked to a Florida petting zoo, 3 children died.

Other outbreaks involving pathogenic E coli have been tied to fresh vegetables and to undercooked hamburger at fast-food chains.

In Germany in 2011, more than 3,000 people acquired Shiga toxin nonhemolytic uremic syndrome due to E coli, and 16 of them died. In addition, 845 acquired hemolytic uremic syndrome, and 36 died. This outbreak was associated with the more virulent and less common O104:H4 strain, which has acquired a Shiga toxin-encoding phage. Patients were treated with quinolone antibiotics, which actually increase toxin production in this strain.¹²

Unusual in the German epidemic was that more adults were affected (88%), especially women (68% of cases).¹³ The source of infection was eventually found to be alfalfa sprouts, the seeds of which had been contaminated by E coli. Women did not harbor any intrinsic factor making them more susceptible; rather, they were more likely to eat salads.¹³

Supportive management

Supportive care is most important. Transfusion with packed red blood cells is indicated for hemoglobin below 6 g/dL. Hypertension should be controlled and dialysis provided. For central nervous system involvement or severe disease, plasma exchange is sometimes used.

Eculizumab was tried for a time as therapy but did not prove to be of benefit. Shiga toxin-binding agents have been developed, but by the time they are given it is too late in the disease process to help.

Antibiotics may harm; it is possible that they kill beneficial bacteria, allowing the Shiga toxin-producing E coli to better proliferate. Antimotility agents also are contraindicated. Other agents not recommended include urokinase, heparin, dipyridamole, and vincristine. Splenectomy is not advised.

The most important way to control hemolytic uremic syndrome is to prevent it by thoroughly cooking meat, cleaning fresh produce, and having children wash their hands after petting animals.

ATYPICAL HEMOLYTIC UREMIC SYNDROME

A young man in renal failure

A 28-year-old man has a history of “thrombotic thrombocytopenic purpura-hemolytic uremic syndrome” at age 12. He slowly progresses to end-stage renal disease and receives a renal transplant from his mother at age 20 that fails after 3 months. The renal transplant biopsy report at the time reads “thrombotic microangiopathy.” The patient’s brother also requires dialysis.

The patient’s complement values are low, especially C3. His father is offering him a kidney at this time, and the patient wants to know whether to proceed.

Normal ADAMTS13, no diarrhea

Hemolytic uremic syndrome without diarrhea is now called atypical hemolytic uremic syndrome. Patients have normal levels of ADAMTS13, do not have diarrhea, and have no evidence of Shiga toxin-producing E coli.

Continuous complement pathway activation

The complement system is part of the innate immune system, which provides immediate defense against infection and does not evolve as does the adaptive immune system. The classic complement pathway is activated by the C1 antibody-antigen complex. The alternative complement pathway leads to the same pathway via C3.¹⁴ Both pathways lead to the formation of C5 through C9 membrane attack complexes, which form channels across the membranes of target cells, leading to cell lysis and death.

The alternate pathway does not require an antibody trigger so is always active at a low level. Inhibitory factors (factor H, factor I, membrane cofactor protein, factor H-related proteins) are naturally present and slow it down at various steps. People who are born with an abnormal factor or, more commonly, develop antibodies against one of the factors, have uninhibited complement activation. If this happens in the blood vessels, massive coagulation and atypical hemolytic uremic syndrome ensues. The endothelial damage and clotting in the brain, kidney, and other organs are identical to that of hemolytic uremic syndrome caused by Shiga toxin.

Treat with eculizumab

Historically, atypical hemolytic uremic syndrome was treated with plasma exchange, which replaces defective complement regulatory proteins and removes inhibitory antibodies.

Understanding the complement pathways is key to developing drugs that target atypical hemolytic uremic syndrome, and about 60 are in the pipeline. The only one currently approved in the United States for atypical hemolytic uremic syndrome is eculizumab, a humanized monoclonal antibody that binds with high affinity to C5, blocking the end of the complement cascade and preventing formation of the membrane attack complex.^15–18

The effects of eculizumab on atypical hemolytic uremic syndrome were studied in 2 prospective trials.¹⁹ Platelet counts rose rapidly within weeks of starting treatment, and kidney function improved. Benefits continued throughout the 64 weeks studied. There were no deaths among the 37 patients enrolled, and although these were single-arm trials, they provide evidence of dramatic benefit considering the high mortality risk of this disease.

Eculizumab is now considered the treatment of choice. It may be used empirically for patients with hemolytic uremic syndrome who test negative for Shiga toxin and antiphospholipid antibody, and who do not have a very low level of ADAMTS13. The big drawback of eculizumab is its high price,^20–22 which varies by amount used, location, and pharmacy negotiation, but can be in the hundreds of thousands of dollars.

For a patient with atypical hemolytic uremic syndrome on dialysis, treatment with eculizumab should continue for 4 to 6 months if there are no extrarenal manifestations. But many patients continue to have the defect in the complement system, so the problem may recur.

Case revisited

For our patient considering a kidney transplant, many experts feel that a transplant can be done as long as platelet counts are monitored and treatment with eculizumab is restarted if needed. One can also make the case for waiting a few years for new oral drugs to become available before offering transplant.

ANTIPHOSPHOLIPID SYNDROME

A young woman with a history of thrombosis and miscarriages

A 27-year-old woman presents with arthralgias, low-grade fever, and malaise. She has a history of 3 spontaneous abortions and Raynaud phenomenon. Two years ago, she had deep vein thrombosis of the right calf after a long automobile trip.

She now has swollen metacarpophalangeal and proximal interphalangeal joints, livedo reticularis (a mottled venous pattern of the skin best seen under fluorescent light) of the legs and arms, and ankle edema (2-cm indentation).

Her blood pressure is 152/92 mm Hg. Laboratory values:

• White blood cell count 3.6 × 10⁹/L (reference range 4.5–11.0)
• Hematocrit 24% (36%–47%)
• Platelet count 89 × 10⁹/L (150–450)
• Urinalysis: protein 4+, heme 3+, red blood cells 8–15 per high-power field (< 3), red blood cell casts present
• Blood urea nitrogen 43 mg/dL (10–20)
• Creatinine 2.6 mg/dL (0.5–1.1).
• Prothrombin time 14.6 s (10–14)
• Partial thromboplastin time 85 s (25–35)
• Antinuclear antibody positive at 1:160
• Anti-double-stranded DNA and serum complement normal
• Syphilis serologic screening (VDRL) positive.

The patient has leukopenia, anemia, thrombocytopenia, hematuria, proteinuria, high blood urea nitrogen, and markedly elevated partial thromboplastin time. Although she has a positive antinuclear antibody test and renal dysfunction, her anti-dsDNA and serum complement tests are normal, making the diagnosis of systemic lupus erythematosus unlikely.

Consider antiphospholipid syndrome

In any patient with multiple pregnancy losses, lupus, or a history of thrombosis, antiphospholipid syndrome should be considered.

In a series of patients with antiphospholipid antibody who underwent kidney biopsy, more than half were men, indicating that, unlike lupus, this is not primarily a disease of young women.

Diagnosis based on specific criteria

Clinical criteria require at least one of the following in the patient’s history²³:

• One or more episodes of arterial, venous, or small-vessel thrombosis
• Unexplained pregnancy morbidity (death of a fetus or neonate with normal morphology or 3 or more spontaneous abortions).

Serologic criteria for any of the following antiphospholipid antibodies require that at least one of the following tests be positive at least twice and at least 12 weeks apart:

• Anticardiolipin antibodies—high-titer immunoglobulin (Ig) G or IgM
• Autoantibodies for beta 2-glycoprotein
• Lupus anticoagulant—autoantibodies that increase clotting time in vitro and target beta 2-glycoprotein I and prothrombin (despite its name and actions in vitro, lupus anticoagulant functions as a coagulant).

As with the other thrombotic microangiopathies, patients with anticardiolipin syndrome have microthrombi in the glomeruli and blood vessels that are evident on kidney biopsy.

Suspect condition in likely groups

Antiphospholipid syndrome is surprisingly common.²⁴ In a case-control study, de Groot et al²⁵ found that 3.1% of patients under age 70 with a first episode of venous thrombosis and no known cancer were positive for lupus anticoagulant vs 0.9% of controls. In another case-control study, Urbanus et al²⁶ found that 17% of women under age 50 with a stroke tested positive for lupus anticoagulant compared with less than 1% of controls. Because of such studies, it has become routine to test for anticardiolipin and lupus anticoagulant in young patients presenting with a stroke.

About 1% of women trying to have children have recurrent miscarriages, and of these, 10% to 15% have antiphospholipid antibody present.^27–30

Pathogenesis

Patients with antiphospholipid syndrome have a much higher proportion of plasma beta 2-glycoprotein in the oxidized form than do healthy controls. The level is also higher than in patients with a different autoimmune disease whether or not they have antibodies against beta 2-glycoprotein 1. Although about 40% of patients with lupus have an anticardiolipin antibody, only a small percentage develop antiphospholipid syndrome with clotting.

It is thought that antiphospholipid syndrome involves initial injury to the endothelium, then potentiation of thrombus formation. Oxidized beta 2-glycoprotein complexes may bind to the endothelial cell surface, causing it to become the target of antibodies. The exact relationships between the factors are not yet understood.

The risk of a thrombotic event in an asymp­tomatic patient positive for all 3 factors—lupus anticoagulant, anticardiolipin antibody, and anti-beta 2-glycoprotein I antibody—is more than 5% per year.³¹

Manage thrombosis with anticoagulation

Khamashta et al,³² in a 1995 study, retrospectively studied patients with antiphospholipid antibodies and a history of thrombosis. Of 147 patients, 66 had idiopathic primary disease, 62 had systemic lupus, and 19 had “lupus-like” disease. Almost 70% (101 patients) had a recurrence of thrombosis, totaling 186 events. The mean time to recurrence was 12 months (range 2 weeks to 12 years). Recurrence rates were 0.01 events per patient per year with high-dose warfarin, 0.23 with low-dose warfarin, and 0.18 with aspirin. But the highest bleeding rates were in the 6 months after warfarin withdrawal; 29 patients had bleeding events, one-fourth of which were severe.

Standard therapy has become anticoagulation, starting with heparin or enoxaparin, then warfarin. There is inadequate evidence for the role of newer oral anticoagulant therapy.

A very high INR is not generally better than a moderately elevated level

For a time, it was thought that the international normalized ratio (INR) should be kept on the very high side to prevent thrombosis.

Crowther et al³³ conducted a randomized, double-blind trial comparing moderate warfarin therapy (INR 2.0–3.0) and high-intensity warfarin therapy (INR 3.1–4.0) in antiphospholipid syndrome. Thrombosis actually recurred more frequently in the high-intensity therapy group (10.7% vs 3.4%), with no significant difference in major bleeding events.

A reasonable strategy is to keep the INR between 2.5 and 3.0, keeping in mind that values fluctuate in any individual patient. A higher goal often leads to excessive anticoagulation and bleeding. If the goal is too low, recurrent thrombosis becomes more likely. There are fewer data on the newer oral anticoagulants, but their role is likely to increase as reversal agents are developed.

Recommendations published in 2003 for treating antiphospholipid syndrome include³⁴:

• Warfarin (INR 2.0–3.0) after the first thrombotic event
• Warfarin (INR 3.0–4.0) if a clot develops despite warfarin
• Warfarin (INR > 3.0) for an arterial event.

For the rare but catastrophic antiphospholipid syndrome in which thrombosis occurs in multiple organs, recommendations are for heparin plus steroids, with or without intravenous immunoglobulin and plasmapheresis. This approach has not always been successful, and the mortality rate is high.

Treatment of asymptomatic carriers is uncertain

Treatment of asymptomatic carriers of the antiphospholipid antibody is controversial. Evidence for management is scarce; some experts recommend aspirin therapy, but benefit has yet to be proven in clinical trials.

Canaud et al³⁵ documented the role of activation of the kinase mammalian target of rapamycin (mTOR) in the vascular changes characteristic of antiphospholipid nephropathy. Postkidney transplant surveillance biopsies of patients with antiphospholipid antibodies showed vascular damage occurring over time (despite patients being asymptomatic) compared with other renal transplant patients. Patients with antiphospholipid antibodies who were treated with the immunosuppressive drug sirolimus were protected from developing these changes. Twelve years after transplant, 70% of patients with antiphospholipid antibodies taking sirolimus still had a functioning graft compared with 11% of untreated patients.

Our knowledge of the pathogenesis of thrombotic microangiopathies has greatly advanced in the last decade, improving the diagnosis and treatment of these diseases.

Many conditions involve thrombotic microangiopathies (Table 1). This article reviews the most common ones, ie, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, atypical hemolytic uremic syndrome, and antiphospholipid syndrome—their clinical features (focusing on the kidney), course, and management. Of note, although the diseases are similar, their pathogeneses and treatments differ.

DIFFERENT PATHWAYS TO MULTIORGAN THROMBOSIS

The thrombotic microangiopathies are multisystem disorders that can affect children and adults and often present with prominent renal and neurologic involvement. Endothelial injury is likely the inciting factor leading to thrombosis in the kidney and in many other organs. The causes variously include:

• Toxins from bacteria or drugs
• Abnormal complement activation, genetic or autoantibody-induced
• Procoagulant factors, eg, antiphospholipid antibodies
• Loss of anticoagulants, eg, from a defect of ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13); ADAMTS13 is also known as von Willebrand factor-cleaving protease
• Severe hypertension.

The histopathologic features are similar in all the thrombotic microangiopathies. Laboratory findings include thrombocytopenia, microangiopathic hemolytic anemia (with schistocytes on the peripheral blood smear), and high serum lactate dehydrogenase (LDH) levels; these are also markers of treatment progress. Bilirubin may be elevated and haptoglobin absent. Renal biopsy reveals thrombi in the glomeruli and arterioles.

THROMBOTIC THROMBOCYTOPENIC PURPURA

A young woman with fever, bruising, and renal failure, then blindness

A 36-year-old black woman who had been previously healthy presents to her doctor with fever and bruising.

Her hematocrit is 28% (reference range 38%–46%), platelet count 15 x 10⁹/L (150–450), and prothrombin and partial thromboplastin times are normal. Her peripheral blood smear shows microangiopathic hemolytic anemia with schistocytes.

Over the next few days, her urine output declines and she develops sudden blindness followed by decreased mental acuity. Blood is drawn and sent for ADAMTS13 assay. Treatment is started at once with daily therapeutic plasma exchange. The assay results, when they arrive, show marked ADAMTS13 reduction (< 5%). Over the ensuing weeks, her mental acuity improves, her vision returns, and her renal function improves.

ADAMTS13 deficiency is definitive

Thrombotic thrombocytopenic purpura is characterized by:

• Neurologic abnormalities and acute renal failure
• Thrombocytopenia and microangiopathic hemolytic anemia
• Histologic evidence of thrombotic microangiopathy
• Deficiency of von Willebrand factor-cleaving protease (ADAMTS13 < 10%).

von Willebrand factor forms ultralarge multimers in the circulation that interact with platelets; these are normally cleaved by ADAMTS13. With ADAMTS13 deficiency (from either a genetic mutation or autoantibodies), the ultralarge multimers lead to coagulation as blood flows through small vessels.¹

In 2003, Tsai² evaluated 127 patients over age 10 who had thrombocytopenia and microangiopathic hemolysis with no plausible cause or features suggestive of hemolytic uremic syndrome. All were severely deficient in ADAMTS13. Subsequently, thrombotic thrombocytopenic purpura has been defined by a severe actual or effective deficiency of ADAMTS13.

Prompt plasma exchange is critical

Although the ADAMTS13 assay is important for diagnosing thrombotic thrombocytopenic purpura, in suspected cases daily plasma exchange should be started promptly, before test results return. Plasma exchange removes autoantibodies to ADAMTS13 from the blood, removes circulating ultralarge von Willebrand factor multimers, and replaces the missing ADAMTS13. Untreated, the disease is progressive, with irreversible renal failure, neurologic deterioration, and a 90% mortality rate. Plasma exchange reduces the mortality rate to less than 15%. If another diagnosis is confirmed, plasma exchange can be stopped.

Plasma exchange has been shown in clinical trials to be superior to plasma infusion in normalizing platelet counts and reducing mortality.^3,4 Mortality rates were comparable with different replacement fluids vs fresh-frozen plasma, including solvent or detergent-treated plasma, and cryo-poor (cryosupernatant) plasma.⁴ Antiplatelet therapy, platelet transfusions, and splenectomy are ineffective.

Glucocorticoids for early treatment

An appropriate strategy is to add a glucocorticoid to plasma-exchange therapy at once (oral prednisone 1 mg/kg per day or intravenous methylprednisolone 125 mg twice daily) and withdraw it after several days if it is determined that it is not needed. Steroids for suspected thrombotic thrombocytopenic purpura can be justified for several reasons:

• The results of the ADAMTS13 assay are usually delayed, so steroids provide coverage for other diagnoses.
• They are helpful if thrombotic thrombocytopenic purpura is idiopathic (which is true for most cases) and if the patient has a poor response to initial therapy with plasma exchange.
• They are indicated for patients whose platelet counts do not increase with several days of plasma exchange or whose thrombocytopenia recurs as plasma exchange is decreased.

Rituximab improves survival

Rituximab, a chimeric (half murine) monoclonal antibody against CD19 and CD20 B cells, suppresses antibody production by knocking out the precursors of antibody-producing cells.

Anecdotal reports and small studies involving a total of 42 patients have been published on the use of rituximab for thrombotic thrombocytopenic purpura. Courses of rituximab varied greatly, from 1 to 13 weekly doses at 375 mg/m², with 4 doses being the most common. Complete remission occurred in 90% of cases.^5,6 A typical study from 2014 involved 48 patients (30 of whom received rituximab) followed by severe ADAMTS13 deficiency during remission.⁷ Despite the small study size, the investigators found significantly improved relapse-free survival rates with rituximab treatment.

But rituximab can cost $25,000 for 2 doses of 1,000 mg, and this will most likely prohibit its routine use. The cost and insurance coverage vary with location and policies.

Based on such studies, a reasonable strategy is to treat thrombotic thrombocytopenic purpura with:

• Daily plasma exchange
• Steroids, at least until the diagnosis is certain
• Rituximab if warranted.

New targeted therapies

Caplacizumab, a humanized immunoglobulin that inhibits the interaction between ultralarge von Willebrand factor multimers and platelets, has the potential to change this strategy when it receives US Food and Drug Administration approval, which is expected soon.

Peyvandi et al⁸ randomized 75 patients with acquired thrombotic thrombocytopenic purpura to either subcutaneous caplacizumab 10 mg daily for 30 days or placebo. Both groups had daily plasma exchange. The treatment group had a 39% reduction in median time to normalization of platelets vs the placebo group, and 3 of 36 patients had exacerbations, compared with 11 of 39 patients in the placebo group. Although 8 patients relapsed within the first month after stopping caplacizumab, their cases were brought under control. There were also more bleeding episodes with caplacizumab (54% vs 38%), most being mild to moderate. Two patients in the placebo group died, but none in the treatment group.

The fact that platelet normalization occurred significantly faster with caplacizumab, even in some patients who had not yet had plasma exchange therapy initiated, has enormous clinical significance. The low platelet count in thrombotic thrombocytopenic purpura is a marker of susceptibility to rapid damage to the brain and kidneys, so correcting it quickly is critical.

Other strategies for new drug development include replacing the deficient ADAMTS13 with a recombinant molecule and blocking antibody production (the same mode of action as rituximab and glucocorticoids).⁹ Using all 3 strategies to treat thrombotic thrombocytopenic purpura may be the future standard of care.

HEMOLYTIC UREMIC SYNDROME

A child with sudden onset of bloody diarrhea and kidney failure

A 4-year-old girl plays with baby animals at a petting zoo and does not wash her hands immediately afterwards. Three days later, she develops fever, abdominal cramps, nausea, vomiting, and bloody diarrhea. Her pediatrician gives her antibiotics. On day 6, she develops ecchymoses on the extremities and lips, thrombocytopenia, low urine output, and seizures. Her stool tests positive for Escherichia coli O157:H7

Classic presentation: Young patient with bloody diarrhea

The classic presentation of hemolytic uremic syndrome is of a young patient with bloody diarrhea typically lasting 5 to 10 days. Kidney failure may follow, requiring dialysis in about 60% of patients for a mean of 10 days. About one-fourth of patients develop neurologic symptoms, and about the same fraction are left with long-term morbidity, eg, hypertension, proteinuria, and reduced glomerular filtration rate. The mortality rate is typically 4%^10,11 but varies with the outbreak.

Histologically, the kidneys look identical to those in thrombotic thrombocytopenic purpura, with thrombi in glomeruli and small vessels.

E coli is the most common culprit, but other bacteria, including Shigella dysenteriae, and viruses are sometimes the cause. Fewer than 10% of children infected with Shiga toxin-positive E coli, also known as enterohemorrhagic E coli (O157:H7, O104:H4), develop hemolytic uremic syndrome.

Lessons from outbreaks

Petting zoos are a common source of transmission of pathogenic bacteria. Disease can be extremely serious: in 15 cases linked to a Florida petting zoo, 3 children died.

Other outbreaks involving pathogenic E coli have been tied to fresh vegetables and to undercooked hamburger at fast-food chains.

In Germany in 2011, more than 3,000 people acquired Shiga toxin nonhemolytic uremic syndrome due to E coli, and 16 of them died. In addition, 845 acquired hemolytic uremic syndrome, and 36 died. This outbreak was associated with the more virulent and less common O104:H4 strain, which has acquired a Shiga toxin-encoding phage. Patients were treated with quinolone antibiotics, which actually increase toxin production in this strain.¹²

Unusual in the German epidemic was that more adults were affected (88%), especially women (68% of cases).¹³ The source of infection was eventually found to be alfalfa sprouts, the seeds of which had been contaminated by E coli. Women did not harbor any intrinsic factor making them more susceptible; rather, they were more likely to eat salads.¹³

Supportive management

Supportive care is most important. Transfusion with packed red blood cells is indicated for hemoglobin below 6 g/dL. Hypertension should be controlled and dialysis provided. For central nervous system involvement or severe disease, plasma exchange is sometimes used.

Eculizumab was tried for a time as therapy but did not prove to be of benefit. Shiga toxin-binding agents have been developed, but by the time they are given it is too late in the disease process to help.

Antibiotics may harm; it is possible that they kill beneficial bacteria, allowing the Shiga toxin-producing E coli to better proliferate. Antimotility agents also are contraindicated. Other agents not recommended include urokinase, heparin, dipyridamole, and vincristine. Splenectomy is not advised.

The most important way to control hemolytic uremic syndrome is to prevent it by thoroughly cooking meat, cleaning fresh produce, and having children wash their hands after petting animals.

ATYPICAL HEMOLYTIC UREMIC SYNDROME

A young man in renal failure

A 28-year-old man has a history of “thrombotic thrombocytopenic purpura-hemolytic uremic syndrome” at age 12. He slowly progresses to end-stage renal disease and receives a renal transplant from his mother at age 20 that fails after 3 months. The renal transplant biopsy report at the time reads “thrombotic microangiopathy.” The patient’s brother also requires dialysis.

The patient’s complement values are low, especially C3. His father is offering him a kidney at this time, and the patient wants to know whether to proceed.

Normal ADAMTS13, no diarrhea

Hemolytic uremic syndrome without diarrhea is now called atypical hemolytic uremic syndrome. Patients have normal levels of ADAMTS13, do not have diarrhea, and have no evidence of Shiga toxin-producing E coli.

Continuous complement pathway activation

The complement system is part of the innate immune system, which provides immediate defense against infection and does not evolve as does the adaptive immune system. The classic complement pathway is activated by the C1 antibody-antigen complex. The alternative complement pathway leads to the same pathway via C3.¹⁴ Both pathways lead to the formation of C5 through C9 membrane attack complexes, which form channels across the membranes of target cells, leading to cell lysis and death.

The alternate pathway does not require an antibody trigger so is always active at a low level. Inhibitory factors (factor H, factor I, membrane cofactor protein, factor H-related proteins) are naturally present and slow it down at various steps. People who are born with an abnormal factor or, more commonly, develop antibodies against one of the factors, have uninhibited complement activation. If this happens in the blood vessels, massive coagulation and atypical hemolytic uremic syndrome ensues. The endothelial damage and clotting in the brain, kidney, and other organs are identical to that of hemolytic uremic syndrome caused by Shiga toxin.

Treat with eculizumab

Historically, atypical hemolytic uremic syndrome was treated with plasma exchange, which replaces defective complement regulatory proteins and removes inhibitory antibodies.

Understanding the complement pathways is key to developing drugs that target atypical hemolytic uremic syndrome, and about 60 are in the pipeline. The only one currently approved in the United States for atypical hemolytic uremic syndrome is eculizumab, a humanized monoclonal antibody that binds with high affinity to C5, blocking the end of the complement cascade and preventing formation of the membrane attack complex.^15–18

The effects of eculizumab on atypical hemolytic uremic syndrome were studied in 2 prospective trials.¹⁹ Platelet counts rose rapidly within weeks of starting treatment, and kidney function improved. Benefits continued throughout the 64 weeks studied. There were no deaths among the 37 patients enrolled, and although these were single-arm trials, they provide evidence of dramatic benefit considering the high mortality risk of this disease.

Eculizumab is now considered the treatment of choice. It may be used empirically for patients with hemolytic uremic syndrome who test negative for Shiga toxin and antiphospholipid antibody, and who do not have a very low level of ADAMTS13. The big drawback of eculizumab is its high price,^20–22 which varies by amount used, location, and pharmacy negotiation, but can be in the hundreds of thousands of dollars.

For a patient with atypical hemolytic uremic syndrome on dialysis, treatment with eculizumab should continue for 4 to 6 months if there are no extrarenal manifestations. But many patients continue to have the defect in the complement system, so the problem may recur.

Case revisited

For our patient considering a kidney transplant, many experts feel that a transplant can be done as long as platelet counts are monitored and treatment with eculizumab is restarted if needed. One can also make the case for waiting a few years for new oral drugs to become available before offering transplant.

ANTIPHOSPHOLIPID SYNDROME

A young woman with a history of thrombosis and miscarriages

A 27-year-old woman presents with arthralgias, low-grade fever, and malaise. She has a history of 3 spontaneous abortions and Raynaud phenomenon. Two years ago, she had deep vein thrombosis of the right calf after a long automobile trip.

She now has swollen metacarpophalangeal and proximal interphalangeal joints, livedo reticularis (a mottled venous pattern of the skin best seen under fluorescent light) of the legs and arms, and ankle edema (2-cm indentation).

Her blood pressure is 152/92 mm Hg. Laboratory values:

• White blood cell count 3.6 × 10⁹/L (reference range 4.5–11.0)
• Hematocrit 24% (36%–47%)
• Platelet count 89 × 10⁹/L (150–450)
• Urinalysis: protein 4+, heme 3+, red blood cells 8–15 per high-power field (< 3), red blood cell casts present
• Blood urea nitrogen 43 mg/dL (10–20)
• Creatinine 2.6 mg/dL (0.5–1.1).
• Prothrombin time 14.6 s (10–14)
• Partial thromboplastin time 85 s (25–35)
• Antinuclear antibody positive at 1:160
• Anti-double-stranded DNA and serum complement normal
• Syphilis serologic screening (VDRL) positive.

The patient has leukopenia, anemia, thrombocytopenia, hematuria, proteinuria, high blood urea nitrogen, and markedly elevated partial thromboplastin time. Although she has a positive antinuclear antibody test and renal dysfunction, her anti-dsDNA and serum complement tests are normal, making the diagnosis of systemic lupus erythematosus unlikely.

Consider antiphospholipid syndrome

In any patient with multiple pregnancy losses, lupus, or a history of thrombosis, antiphospholipid syndrome should be considered.

In a series of patients with antiphospholipid antibody who underwent kidney biopsy, more than half were men, indicating that, unlike lupus, this is not primarily a disease of young women.

Diagnosis based on specific criteria

Clinical criteria require at least one of the following in the patient’s history²³:

• One or more episodes of arterial, venous, or small-vessel thrombosis
• Unexplained pregnancy morbidity (death of a fetus or neonate with normal morphology or 3 or more spontaneous abortions).

Serologic criteria for any of the following antiphospholipid antibodies require that at least one of the following tests be positive at least twice and at least 12 weeks apart:

• Anticardiolipin antibodies—high-titer immunoglobulin (Ig) G or IgM
• Autoantibodies for beta 2-glycoprotein
• Lupus anticoagulant—autoantibodies that increase clotting time in vitro and target beta 2-glycoprotein I and prothrombin (despite its name and actions in vitro, lupus anticoagulant functions as a coagulant).

As with the other thrombotic microangiopathies, patients with anticardiolipin syndrome have microthrombi in the glomeruli and blood vessels that are evident on kidney biopsy.

Suspect condition in likely groups

Antiphospholipid syndrome is surprisingly common.²⁴ In a case-control study, de Groot et al²⁵ found that 3.1% of patients under age 70 with a first episode of venous thrombosis and no known cancer were positive for lupus anticoagulant vs 0.9% of controls. In another case-control study, Urbanus et al²⁶ found that 17% of women under age 50 with a stroke tested positive for lupus anticoagulant compared with less than 1% of controls. Because of such studies, it has become routine to test for anticardiolipin and lupus anticoagulant in young patients presenting with a stroke.

About 1% of women trying to have children have recurrent miscarriages, and of these, 10% to 15% have antiphospholipid antibody present.^27–30

Pathogenesis

Patients with antiphospholipid syndrome have a much higher proportion of plasma beta 2-glycoprotein in the oxidized form than do healthy controls. The level is also higher than in patients with a different autoimmune disease whether or not they have antibodies against beta 2-glycoprotein 1. Although about 40% of patients with lupus have an anticardiolipin antibody, only a small percentage develop antiphospholipid syndrome with clotting.

It is thought that antiphospholipid syndrome involves initial injury to the endothelium, then potentiation of thrombus formation. Oxidized beta 2-glycoprotein complexes may bind to the endothelial cell surface, causing it to become the target of antibodies. The exact relationships between the factors are not yet understood.

The risk of a thrombotic event in an asymp­tomatic patient positive for all 3 factors—lupus anticoagulant, anticardiolipin antibody, and anti-beta 2-glycoprotein I antibody—is more than 5% per year.³¹

Manage thrombosis with anticoagulation

Khamashta et al,³² in a 1995 study, retrospectively studied patients with antiphospholipid antibodies and a history of thrombosis. Of 147 patients, 66 had idiopathic primary disease, 62 had systemic lupus, and 19 had “lupus-like” disease. Almost 70% (101 patients) had a recurrence of thrombosis, totaling 186 events. The mean time to recurrence was 12 months (range 2 weeks to 12 years). Recurrence rates were 0.01 events per patient per year with high-dose warfarin, 0.23 with low-dose warfarin, and 0.18 with aspirin. But the highest bleeding rates were in the 6 months after warfarin withdrawal; 29 patients had bleeding events, one-fourth of which were severe.

Standard therapy has become anticoagulation, starting with heparin or enoxaparin, then warfarin. There is inadequate evidence for the role of newer oral anticoagulant therapy.

A very high INR is not generally better than a moderately elevated level

For a time, it was thought that the international normalized ratio (INR) should be kept on the very high side to prevent thrombosis.

Crowther et al³³ conducted a randomized, double-blind trial comparing moderate warfarin therapy (INR 2.0–3.0) and high-intensity warfarin therapy (INR 3.1–4.0) in antiphospholipid syndrome. Thrombosis actually recurred more frequently in the high-intensity therapy group (10.7% vs 3.4%), with no significant difference in major bleeding events.

A reasonable strategy is to keep the INR between 2.5 and 3.0, keeping in mind that values fluctuate in any individual patient. A higher goal often leads to excessive anticoagulation and bleeding. If the goal is too low, recurrent thrombosis becomes more likely. There are fewer data on the newer oral anticoagulants, but their role is likely to increase as reversal agents are developed.

Recommendations published in 2003 for treating antiphospholipid syndrome include³⁴:

• Warfarin (INR 2.0–3.0) after the first thrombotic event
• Warfarin (INR 3.0–4.0) if a clot develops despite warfarin
• Warfarin (INR > 3.0) for an arterial event.

For the rare but catastrophic antiphospholipid syndrome in which thrombosis occurs in multiple organs, recommendations are for heparin plus steroids, with or without intravenous immunoglobulin and plasmapheresis. This approach has not always been successful, and the mortality rate is high.

Treatment of asymptomatic carriers is uncertain

Treatment of asymptomatic carriers of the antiphospholipid antibody is controversial. Evidence for management is scarce; some experts recommend aspirin therapy, but benefit has yet to be proven in clinical trials.

Canaud et al³⁵ documented the role of activation of the kinase mammalian target of rapamycin (mTOR) in the vascular changes characteristic of antiphospholipid nephropathy. Postkidney transplant surveillance biopsies of patients with antiphospholipid antibodies showed vascular damage occurring over time (despite patients being asymptomatic) compared with other renal transplant patients. Patients with antiphospholipid antibodies who were treated with the immunosuppressive drug sirolimus were protected from developing these changes. Twelve years after transplant, 70% of patients with antiphospholipid antibodies taking sirolimus still had a functioning graft compared with 11% of untreated patients.

Our knowledge of the pathogenesis of thrombotic microangiopathies has greatly advanced in the last decade, improving the diagnosis and treatment of these diseases.

Many conditions involve thrombotic microangiopathies (Table 1). This article reviews the most common ones, ie, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, atypical hemolytic uremic syndrome, and antiphospholipid syndrome—their clinical features (focusing on the kidney), course, and management. Of note, although the diseases are similar, their pathogeneses and treatments differ.

DIFFERENT PATHWAYS TO MULTIORGAN THROMBOSIS

The thrombotic microangiopathies are multisystem disorders that can affect children and adults and often present with prominent renal and neurologic involvement. Endothelial injury is likely the inciting factor leading to thrombosis in the kidney and in many other organs. The causes variously include:

• Toxins from bacteria or drugs
• Abnormal complement activation, genetic or autoantibody-induced
• Procoagulant factors, eg, antiphospholipid antibodies
• Loss of anticoagulants, eg, from a defect of ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13); ADAMTS13 is also known as von Willebrand factor-cleaving protease
• Severe hypertension.

The histopathologic features are similar in all the thrombotic microangiopathies. Laboratory findings include thrombocytopenia, microangiopathic hemolytic anemia (with schistocytes on the peripheral blood smear), and high serum lactate dehydrogenase (LDH) levels; these are also markers of treatment progress. Bilirubin may be elevated and haptoglobin absent. Renal biopsy reveals thrombi in the glomeruli and arterioles.

THROMBOTIC THROMBOCYTOPENIC PURPURA

A young woman with fever, bruising, and renal failure, then blindness

A 36-year-old black woman who had been previously healthy presents to her doctor with fever and bruising.

Her hematocrit is 28% (reference range 38%–46%), platelet count 15 x 10⁹/L (150–450), and prothrombin and partial thromboplastin times are normal. Her peripheral blood smear shows microangiopathic hemolytic anemia with schistocytes.

Over the next few days, her urine output declines and she develops sudden blindness followed by decreased mental acuity. Blood is drawn and sent for ADAMTS13 assay. Treatment is started at once with daily therapeutic plasma exchange. The assay results, when they arrive, show marked ADAMTS13 reduction (< 5%). Over the ensuing weeks, her mental acuity improves, her vision returns, and her renal function improves.

ADAMTS13 deficiency is definitive

Thrombotic thrombocytopenic purpura is characterized by:

• Neurologic abnormalities and acute renal failure
• Thrombocytopenia and microangiopathic hemolytic anemia
• Histologic evidence of thrombotic microangiopathy
• Deficiency of von Willebrand factor-cleaving protease (ADAMTS13 < 10%).

von Willebrand factor forms ultralarge multimers in the circulation that interact with platelets; these are normally cleaved by ADAMTS13. With ADAMTS13 deficiency (from either a genetic mutation or autoantibodies), the ultralarge multimers lead to coagulation as blood flows through small vessels.¹

In 2003, Tsai² evaluated 127 patients over age 10 who had thrombocytopenia and microangiopathic hemolysis with no plausible cause or features suggestive of hemolytic uremic syndrome. All were severely deficient in ADAMTS13. Subsequently, thrombotic thrombocytopenic purpura has been defined by a severe actual or effective deficiency of ADAMTS13.

Prompt plasma exchange is critical

Although the ADAMTS13 assay is important for diagnosing thrombotic thrombocytopenic purpura, in suspected cases daily plasma exchange should be started promptly, before test results return. Plasma exchange removes autoantibodies to ADAMTS13 from the blood, removes circulating ultralarge von Willebrand factor multimers, and replaces the missing ADAMTS13. Untreated, the disease is progressive, with irreversible renal failure, neurologic deterioration, and a 90% mortality rate. Plasma exchange reduces the mortality rate to less than 15%. If another diagnosis is confirmed, plasma exchange can be stopped.

Plasma exchange has been shown in clinical trials to be superior to plasma infusion in normalizing platelet counts and reducing mortality.^3,4 Mortality rates were comparable with different replacement fluids vs fresh-frozen plasma, including solvent or detergent-treated plasma, and cryo-poor (cryosupernatant) plasma.⁴ Antiplatelet therapy, platelet transfusions, and splenectomy are ineffective.

Glucocorticoids for early treatment

An appropriate strategy is to add a glucocorticoid to plasma-exchange therapy at once (oral prednisone 1 mg/kg per day or intravenous methylprednisolone 125 mg twice daily) and withdraw it after several days if it is determined that it is not needed. Steroids for suspected thrombotic thrombocytopenic purpura can be justified for several reasons:

• The results of the ADAMTS13 assay are usually delayed, so steroids provide coverage for other diagnoses.
• They are helpful if thrombotic thrombocytopenic purpura is idiopathic (which is true for most cases) and if the patient has a poor response to initial therapy with plasma exchange.
• They are indicated for patients whose platelet counts do not increase with several days of plasma exchange or whose thrombocytopenia recurs as plasma exchange is decreased.

Rituximab improves survival

Rituximab, a chimeric (half murine) monoclonal antibody against CD19 and CD20 B cells, suppresses antibody production by knocking out the precursors of antibody-producing cells.

Anecdotal reports and small studies involving a total of 42 patients have been published on the use of rituximab for thrombotic thrombocytopenic purpura. Courses of rituximab varied greatly, from 1 to 13 weekly doses at 375 mg/m², with 4 doses being the most common. Complete remission occurred in 90% of cases.^5,6 A typical study from 2014 involved 48 patients (30 of whom received rituximab) followed by severe ADAMTS13 deficiency during remission.⁷ Despite the small study size, the investigators found significantly improved relapse-free survival rates with rituximab treatment.

But rituximab can cost $25,000 for 2 doses of 1,000 mg, and this will most likely prohibit its routine use. The cost and insurance coverage vary with location and policies.

Based on such studies, a reasonable strategy is to treat thrombotic thrombocytopenic purpura with:

• Daily plasma exchange
• Steroids, at least until the diagnosis is certain
• Rituximab if warranted.

New targeted therapies

Caplacizumab, a humanized immunoglobulin that inhibits the interaction between ultralarge von Willebrand factor multimers and platelets, has the potential to change this strategy when it receives US Food and Drug Administration approval, which is expected soon.

Peyvandi et al⁸ randomized 75 patients with acquired thrombotic thrombocytopenic purpura to either subcutaneous caplacizumab 10 mg daily for 30 days or placebo. Both groups had daily plasma exchange. The treatment group had a 39% reduction in median time to normalization of platelets vs the placebo group, and 3 of 36 patients had exacerbations, compared with 11 of 39 patients in the placebo group. Although 8 patients relapsed within the first month after stopping caplacizumab, their cases were brought under control. There were also more bleeding episodes with caplacizumab (54% vs 38%), most being mild to moderate. Two patients in the placebo group died, but none in the treatment group.

The fact that platelet normalization occurred significantly faster with caplacizumab, even in some patients who had not yet had plasma exchange therapy initiated, has enormous clinical significance. The low platelet count in thrombotic thrombocytopenic purpura is a marker of susceptibility to rapid damage to the brain and kidneys, so correcting it quickly is critical.

Other strategies for new drug development include replacing the deficient ADAMTS13 with a recombinant molecule and blocking antibody production (the same mode of action as rituximab and glucocorticoids).⁹ Using all 3 strategies to treat thrombotic thrombocytopenic purpura may be the future standard of care.

HEMOLYTIC UREMIC SYNDROME

A child with sudden onset of bloody diarrhea and kidney failure

A 4-year-old girl plays with baby animals at a petting zoo and does not wash her hands immediately afterwards. Three days later, she develops fever, abdominal cramps, nausea, vomiting, and bloody diarrhea. Her pediatrician gives her antibiotics. On day 6, she develops ecchymoses on the extremities and lips, thrombocytopenia, low urine output, and seizures. Her stool tests positive for Escherichia coli O157:H7

Classic presentation: Young patient with bloody diarrhea

The classic presentation of hemolytic uremic syndrome is of a young patient with bloody diarrhea typically lasting 5 to 10 days. Kidney failure may follow, requiring dialysis in about 60% of patients for a mean of 10 days. About one-fourth of patients develop neurologic symptoms, and about the same fraction are left with long-term morbidity, eg, hypertension, proteinuria, and reduced glomerular filtration rate. The mortality rate is typically 4%^10,11 but varies with the outbreak.

Histologically, the kidneys look identical to those in thrombotic thrombocytopenic purpura, with thrombi in glomeruli and small vessels.

E coli is the most common culprit, but other bacteria, including Shigella dysenteriae, and viruses are sometimes the cause. Fewer than 10% of children infected with Shiga toxin-positive E coli, also known as enterohemorrhagic E coli (O157:H7, O104:H4), develop hemolytic uremic syndrome.

Lessons from outbreaks

Petting zoos are a common source of transmission of pathogenic bacteria. Disease can be extremely serious: in 15 cases linked to a Florida petting zoo, 3 children died.

Other outbreaks involving pathogenic E coli have been tied to fresh vegetables and to undercooked hamburger at fast-food chains.

In Germany in 2011, more than 3,000 people acquired Shiga toxin nonhemolytic uremic syndrome due to E coli, and 16 of them died. In addition, 845 acquired hemolytic uremic syndrome, and 36 died. This outbreak was associated with the more virulent and less common O104:H4 strain, which has acquired a Shiga toxin-encoding phage. Patients were treated with quinolone antibiotics, which actually increase toxin production in this strain.¹²

Unusual in the German epidemic was that more adults were affected (88%), especially women (68% of cases).¹³ The source of infection was eventually found to be alfalfa sprouts, the seeds of which had been contaminated by E coli. Women did not harbor any intrinsic factor making them more susceptible; rather, they were more likely to eat salads.¹³

Supportive management

Supportive care is most important. Transfusion with packed red blood cells is indicated for hemoglobin below 6 g/dL. Hypertension should be controlled and dialysis provided. For central nervous system involvement or severe disease, plasma exchange is sometimes used.

Eculizumab was tried for a time as therapy but did not prove to be of benefit. Shiga toxin-binding agents have been developed, but by the time they are given it is too late in the disease process to help.

Antibiotics may harm; it is possible that they kill beneficial bacteria, allowing the Shiga toxin-producing E coli to better proliferate. Antimotility agents also are contraindicated. Other agents not recommended include urokinase, heparin, dipyridamole, and vincristine. Splenectomy is not advised.

The most important way to control hemolytic uremic syndrome is to prevent it by thoroughly cooking meat, cleaning fresh produce, and having children wash their hands after petting animals.

ATYPICAL HEMOLYTIC UREMIC SYNDROME

A young man in renal failure

A 28-year-old man has a history of “thrombotic thrombocytopenic purpura-hemolytic uremic syndrome” at age 12. He slowly progresses to end-stage renal disease and receives a renal transplant from his mother at age 20 that fails after 3 months. The renal transplant biopsy report at the time reads “thrombotic microangiopathy.” The patient’s brother also requires dialysis.

The patient’s complement values are low, especially C3. His father is offering him a kidney at this time, and the patient wants to know whether to proceed.

Normal ADAMTS13, no diarrhea

Hemolytic uremic syndrome without diarrhea is now called atypical hemolytic uremic syndrome. Patients have normal levels of ADAMTS13, do not have diarrhea, and have no evidence of Shiga toxin-producing E coli.

Continuous complement pathway activation

The complement system is part of the innate immune system, which provides immediate defense against infection and does not evolve as does the adaptive immune system. The classic complement pathway is activated by the C1 antibody-antigen complex. The alternative complement pathway leads to the same pathway via C3.¹⁴ Both pathways lead to the formation of C5 through C9 membrane attack complexes, which form channels across the membranes of target cells, leading to cell lysis and death.

The alternate pathway does not require an antibody trigger so is always active at a low level. Inhibitory factors (factor H, factor I, membrane cofactor protein, factor H-related proteins) are naturally present and slow it down at various steps. People who are born with an abnormal factor or, more commonly, develop antibodies against one of the factors, have uninhibited complement activation. If this happens in the blood vessels, massive coagulation and atypical hemolytic uremic syndrome ensues. The endothelial damage and clotting in the brain, kidney, and other organs are identical to that of hemolytic uremic syndrome caused by Shiga toxin.

Treat with eculizumab

Historically, atypical hemolytic uremic syndrome was treated with plasma exchange, which replaces defective complement regulatory proteins and removes inhibitory antibodies.

Understanding the complement pathways is key to developing drugs that target atypical hemolytic uremic syndrome, and about 60 are in the pipeline. The only one currently approved in the United States for atypical hemolytic uremic syndrome is eculizumab, a humanized monoclonal antibody that binds with high affinity to C5, blocking the end of the complement cascade and preventing formation of the membrane attack complex.^15–18

The effects of eculizumab on atypical hemolytic uremic syndrome were studied in 2 prospective trials.¹⁹ Platelet counts rose rapidly within weeks of starting treatment, and kidney function improved. Benefits continued throughout the 64 weeks studied. There were no deaths among the 37 patients enrolled, and although these were single-arm trials, they provide evidence of dramatic benefit considering the high mortality risk of this disease.

Eculizumab is now considered the treatment of choice. It may be used empirically for patients with hemolytic uremic syndrome who test negative for Shiga toxin and antiphospholipid antibody, and who do not have a very low level of ADAMTS13. The big drawback of eculizumab is its high price,^20–22 which varies by amount used, location, and pharmacy negotiation, but can be in the hundreds of thousands of dollars.

For a patient with atypical hemolytic uremic syndrome on dialysis, treatment with eculizumab should continue for 4 to 6 months if there are no extrarenal manifestations. But many patients continue to have the defect in the complement system, so the problem may recur.

Case revisited

For our patient considering a kidney transplant, many experts feel that a transplant can be done as long as platelet counts are monitored and treatment with eculizumab is restarted if needed. One can also make the case for waiting a few years for new oral drugs to become available before offering transplant.

ANTIPHOSPHOLIPID SYNDROME

A young woman with a history of thrombosis and miscarriages

A 27-year-old woman presents with arthralgias, low-grade fever, and malaise. She has a history of 3 spontaneous abortions and Raynaud phenomenon. Two years ago, she had deep vein thrombosis of the right calf after a long automobile trip.

She now has swollen metacarpophalangeal and proximal interphalangeal joints, livedo reticularis (a mottled venous pattern of the skin best seen under fluorescent light) of the legs and arms, and ankle edema (2-cm indentation).

Her blood pressure is 152/92 mm Hg. Laboratory values:

• White blood cell count 3.6 × 10⁹/L (reference range 4.5–11.0)
• Hematocrit 24% (36%–47%)
• Platelet count 89 × 10⁹/L (150–450)
• Urinalysis: protein 4+, heme 3+, red blood cells 8–15 per high-power field (< 3), red blood cell casts present
• Blood urea nitrogen 43 mg/dL (10–20)
• Creatinine 2.6 mg/dL (0.5–1.1).
• Prothrombin time 14.6 s (10–14)
• Partial thromboplastin time 85 s (25–35)
• Antinuclear antibody positive at 1:160
• Anti-double-stranded DNA and serum complement normal
• Syphilis serologic screening (VDRL) positive.

The patient has leukopenia, anemia, thrombocytopenia, hematuria, proteinuria, high blood urea nitrogen, and markedly elevated partial thromboplastin time. Although she has a positive antinuclear antibody test and renal dysfunction, her anti-dsDNA and serum complement tests are normal, making the diagnosis of systemic lupus erythematosus unlikely.

Consider antiphospholipid syndrome

In any patient with multiple pregnancy losses, lupus, or a history of thrombosis, antiphospholipid syndrome should be considered.

In a series of patients with antiphospholipid antibody who underwent kidney biopsy, more than half were men, indicating that, unlike lupus, this is not primarily a disease of young women.

Diagnosis based on specific criteria

Clinical criteria require at least one of the following in the patient’s history²³:

• One or more episodes of arterial, venous, or small-vessel thrombosis
• Unexplained pregnancy morbidity (death of a fetus or neonate with normal morphology or 3 or more spontaneous abortions).

Serologic criteria for any of the following antiphospholipid antibodies require that at least one of the following tests be positive at least twice and at least 12 weeks apart:

• Anticardiolipin antibodies—high-titer immunoglobulin (Ig) G or IgM
• Autoantibodies for beta 2-glycoprotein
• Lupus anticoagulant—autoantibodies that increase clotting time in vitro and target beta 2-glycoprotein I and prothrombin (despite its name and actions in vitro, lupus anticoagulant functions as a coagulant).

As with the other thrombotic microangiopathies, patients with anticardiolipin syndrome have microthrombi in the glomeruli and blood vessels that are evident on kidney biopsy.

Suspect condition in likely groups

Antiphospholipid syndrome is surprisingly common.²⁴ In a case-control study, de Groot et al²⁵ found that 3.1% of patients under age 70 with a first episode of venous thrombosis and no known cancer were positive for lupus anticoagulant vs 0.9% of controls. In another case-control study, Urbanus et al²⁶ found that 17% of women under age 50 with a stroke tested positive for lupus anticoagulant compared with less than 1% of controls. Because of such studies, it has become routine to test for anticardiolipin and lupus anticoagulant in young patients presenting with a stroke.

About 1% of women trying to have children have recurrent miscarriages, and of these, 10% to 15% have antiphospholipid antibody present.^27–30

Pathogenesis

Patients with antiphospholipid syndrome have a much higher proportion of plasma beta 2-glycoprotein in the oxidized form than do healthy controls. The level is also higher than in patients with a different autoimmune disease whether or not they have antibodies against beta 2-glycoprotein 1. Although about 40% of patients with lupus have an anticardiolipin antibody, only a small percentage develop antiphospholipid syndrome with clotting.

It is thought that antiphospholipid syndrome involves initial injury to the endothelium, then potentiation of thrombus formation. Oxidized beta 2-glycoprotein complexes may bind to the endothelial cell surface, causing it to become the target of antibodies. The exact relationships between the factors are not yet understood.

The risk of a thrombotic event in an asymp­tomatic patient positive for all 3 factors—lupus anticoagulant, anticardiolipin antibody, and anti-beta 2-glycoprotein I antibody—is more than 5% per year.³¹

Manage thrombosis with anticoagulation

Khamashta et al,³² in a 1995 study, retrospectively studied patients with antiphospholipid antibodies and a history of thrombosis. Of 147 patients, 66 had idiopathic primary disease, 62 had systemic lupus, and 19 had “lupus-like” disease. Almost 70% (101 patients) had a recurrence of thrombosis, totaling 186 events. The mean time to recurrence was 12 months (range 2 weeks to 12 years). Recurrence rates were 0.01 events per patient per year with high-dose warfarin, 0.23 with low-dose warfarin, and 0.18 with aspirin. But the highest bleeding rates were in the 6 months after warfarin withdrawal; 29 patients had bleeding events, one-fourth of which were severe.

Standard therapy has become anticoagulation, starting with heparin or enoxaparin, then warfarin. There is inadequate evidence for the role of newer oral anticoagulant therapy.

A very high INR is not generally better than a moderately elevated level

For a time, it was thought that the international normalized ratio (INR) should be kept on the very high side to prevent thrombosis.

Crowther et al³³ conducted a randomized, double-blind trial comparing moderate warfarin therapy (INR 2.0–3.0) and high-intensity warfarin therapy (INR 3.1–4.0) in antiphospholipid syndrome. Thrombosis actually recurred more frequently in the high-intensity therapy group (10.7% vs 3.4%), with no significant difference in major bleeding events.

A reasonable strategy is to keep the INR between 2.5 and 3.0, keeping in mind that values fluctuate in any individual patient. A higher goal often leads to excessive anticoagulation and bleeding. If the goal is too low, recurrent thrombosis becomes more likely. There are fewer data on the newer oral anticoagulants, but their role is likely to increase as reversal agents are developed.

Recommendations published in 2003 for treating antiphospholipid syndrome include³⁴:

• Warfarin (INR 2.0–3.0) after the first thrombotic event
• Warfarin (INR 3.0–4.0) if a clot develops despite warfarin
• Warfarin (INR > 3.0) for an arterial event.

For the rare but catastrophic antiphospholipid syndrome in which thrombosis occurs in multiple organs, recommendations are for heparin plus steroids, with or without intravenous immunoglobulin and plasmapheresis. This approach has not always been successful, and the mortality rate is high.

Treatment of asymptomatic carriers is uncertain

Treatment of asymptomatic carriers of the antiphospholipid antibody is controversial. Evidence for management is scarce; some experts recommend aspirin therapy, but benefit has yet to be proven in clinical trials.

Canaud et al³⁵ documented the role of activation of the kinase mammalian target of rapamycin (mTOR) in the vascular changes characteristic of antiphospholipid nephropathy. Postkidney transplant surveillance biopsies of patients with antiphospholipid antibodies showed vascular damage occurring over time (despite patients being asymptomatic) compared with other renal transplant patients. Patients with antiphospholipid antibodies who were treated with the immunosuppressive drug sirolimus were protected from developing these changes. Twelve years after transplant, 70% of patients with antiphospholipid antibodies taking sirolimus still had a functioning graft compared with 11% of untreated patients.

Treatment for lupus nephritis has changed dramatically in recent years. Only 10 years ago, rheumatologists and nephrologists, whether specializing in adult or pediatric medicine, treated lupus nephritis with a similar regimen of monthly intravenous cyclophosphamide (Cytoxan) and glucocorticoids. Although the regimen is effective, side effects such as infection, hair loss, and infertility were extremely common.

Effective but very toxic therapy is common in autoimmune diseases. In the last decade, clinical trials have shown that less toxic drugs are as effective for treating lupus nephritis. This article will review new developments in therapy for lupus nephritis, which can be viewed as a prototype for other fields of medicine.

DEMOGRAPHICS ARE IMPORTANT

Although numerous factors have prognostic value in lupus nephritis (eg, serum creatinine, proteinuria, renal biopsy findings), the most important to consider when designing and interpreting studies are race and socioeconomic variables.

A retrospective study in Miami, FL,¹ evaluated 213 patients with lupus nephritis, of whom 47% were Hispanic, 44% African American, and 20% white. At baseline, African Americans had higher blood pressure, higher serum creatinine levels, and lower household income. After 6 years, African Americans fared the worst in terms of doubling of serum creatinine, developing end-stage renal disease, and death; whites had the best outcomes, and Hispanics were in between. Low income was found to be a significant risk factor, independent of racial background.

In a similar retrospective study in New York City in 128 patients (43% white, 40% Hispanic, and 17% African American) with proliferative lupus nephritis,² disease was much more likely to progress to renal failure over 10 years in patients living in a poor neighborhood, even after adjustment for race.

We need to keep in mind that racial and socioeconomic factors correlate with disease severity when we design and interpret studies of lupus nephritis. Study groups must be carefully balanced with patients of similar racial and socioeconomic profiles. Study findings must be interpreted with caution; for example, whether results from a study from China are applicable to an African American with lupus nephritis in New York City is unclear.

OLDER STANDARD THERAPY: EFFECTIVE BUT TOXIC

The last large National Institutes of Health study that involved only cyclophosphamide and a glucocorticoid was published in 2001,³ with 21 patients receiving cyclophosphamide alone and 20 patients receiving cyclophosphamide plus methylprednisolone. Although lupus nephritis improved, serious side effects occurred in one-third to one-half of patients in each group and included hypertension, hyperlipidemia, valvular heart disease, avascular necrosis, premature menopause, and major infections, including herpes zoster.

Less cyclophosphamide works just as well

The multicenter, prospective Euro-Lupus Nephritis Trial⁴ randomized 90 patients with proliferative lupus nephritis to receive either standard high-dose intravenous (IV) cyclophosphamide therapy (six monthly pulses and two quarterly pulses, with doses increasing according to the white blood cell count) or low-dose IV cyclophosphamide therapy (six pulses every 2 weeks at a fixed dose of 500 mg). Both regimens were followed by azathioprine (Imuran).

At 4 years, the two treatment groups were not significantly different in terms of treatment failure, remission rates, serum creatinine levels, 24-hour proteinuria, and freedom from renal flares. However, the rates of side effects were significantly different, with more patients in the low-dosage group free of severe infection.

One problem with this study is whether it is applicable to an American lupus nephritis population, since 84% of the patients were white. Since this study, others indicate that this regimen is probably also safe and effective for different racial groups in the United States.

At 10-year follow-up,⁵ both treatment groups still had identical excellent rates of freedom from end-stage renal disease. Serum creatinine and 24-hour proteinuria were also at excellent levels and identical in both groups. Nearly three quarters of patients still needed glucocorticoid therapy and more than half still needed immunosuppressive therapy, but the rates were not statistically significantly different between the treatment groups.

The cumulative dose of cyclophosphamide was 9.5 g in the standard-treatment group and 5.5 g in the low-dose group. This difference in exposure could make a tremendous difference to patients, not only for immediate side effects such as early menopause and infections, but for the risk of cancer in later decades.

This study showed clearly that low-dose cyclophosphamide is an option for induction therapy. Drawbacks of the study were that the population was mostly white and that patients had only moderately severe disease.

Low-dose cyclophosphamide has largely replaced the older National Institutes of Health regimen, although during the last decade drug therapy has undergone more changes.

MYCOPHENOLATE AND AZATHIOPRINE: ALTERNATIVES TO CYCLOPHOSPHAMIDE

In a Chinese study, mycophenolate was better than cyclophosphamide for induction

In a study in Hong Kong, Chan et al⁶ randomized 42 patients with severe lupus nephritis to receive either mycophenolate mofetil (available in the United States as CellCept; 2 g/day for 6 months, then 1 g/day for 6 months) or oral cyclophosphamide (2.5 mg/kg per day for 6 months) followed by azathioprine (1.5–2.0 mg/kg per day) for 6 months. Both groups also received prednisolone during the year.

At the end of the first year, the two groups were not significantly different in their rates of complete remission, partial remission, and relapse. The rate of infection, although not significantly different, was higher in the cyclophosphamide group (33% vs 19%). Two patients (10%) died in the cyclophosphamide group, but the difference in mortality rates was not statistically significant.

Nearly 5 years later,⁷ rates of chronic renal failure and relapse were still statistically the same in the two groups. Infections were fewer in the mycophenolate group (13% vs 40%, P = .013). The rate of amenorrhea was 36% in the cyclophosphamide group and only 4% in the mycophenolate group (P = .004). Four patients in the cyclophosphamide group and none in the mycophenolate group reached the composite end point of end-stage renal failure or death (P = .062).

This study appeared to offer a new option with equal efficacy and fewer side effects than standard therapy. However, its applicability to non-Chinese populations remained to be shown.

In a study in Miami,⁸ 59 patients with lupus nephritis were given standard induction therapy with IV cyclophosphamide plus glucocorticoids for 6 months, then randomly assigned to one of three maintenance therapies for 1 to 3 years: IV injections of cyclophosphamide every 3 months (standard therapy), oral azathioprine, or oral mycophenolate. The population was 93% female, their average age was 33 years, and nearly half were African American, with many of the others being Hispanic. Patients tended to have severe disease, with nearly two-thirds having nephrotic syndrome.

After 6 years, there had been more deaths in the cyclophosphamide group than in the azathioprine group (P = .02) and in the mycophenolate group, although the latter difference was not statistically significant (P = .11). The combined rate of death and chronic renal failure was significantly higher with cyclophosphamide than with either of the oral agents. The cyclophosphamide group also had the highest relapse rate during the maintenance phase.

The differences in side effects were even more dramatic. Amenorrhea affected 32% of patients in the cyclophosphamide group, and only 7% and 6% in the azathioprine and mycophenolate groups, respectively. Rates of infections were 68% in the cyclophosphamide group and 28% and 21% in the azathioprine and mycophenolate groups, respectively. Patients given cyclophosphamide had 13 hospital days per patient per year, while the other groups each had only 1.

This study showed that maintenance therapy with oral azathioprine or mycophenolate was more effective and had fewer adverse effects than standard IV cyclophosphamide therapy. As a result of this study, oral agents for maintenance therapy became the new standard, but the question remained whether oral agents could safely be used for induction.

In a US study, mycophenolate was better than cyclophosphamide for induction

In a noninferiority study, Ginzler et al⁹ randomized 140 patients with severe lupus nephritis to receive either monthly IV cyclophosphamide or oral mycophenolate as induction therapy for 6 months. Adjunctive care with glucocorticoids was given in both groups. The study population was from 18 US academic centers and was predominantly female, and more than half were African American.

After 24 weeks, 22.5% of the mycophenolate patients were in complete remission by very strict criteria vs only 4% of those given cyclophosphamide (P = .005). The trend for partial remissions was also in favor of mycophenolate, although the difference was not statistically significant. The rate of complete and partial remissions, a prespecified end point, was significantly higher in the mycophenolate group. Although the study was trying to evaluate equivalency, it actually showed superiority for mycophenolate induction therapy.

Serum creatinine levels declined in both groups, but more in the mycophenolate group by 24 weeks. Urinary protein levels fell the same amount in both groups. At 3 years, the groups were statistically equivalent in terms of renal flares, renal failures, and deaths. However, the study groups were small, and the mycophenolate group did have a better trend for both renal failure (N = 4 vs 7) and deaths (N = 4 vs 8).

Mycophenolate also had fewer side effects, including infection, although again the numbers were too small to show statistical significance. The exception was diarrhea (N = 15 in the mycophenolate group vs 2 in the cyclophosphamide group).

A drawback of the study is that it was designed as a crossover study: a patient for whom therapy was failing after 3 months could switch to the other group, introducing potential confounding. Other problems involved the small population size and the question of whether results from patients in the United States were applicable to others worldwide.

In a worldwide study, mycophenolate was at least equivalent to cyclophosphamide for induction

The Aspreva Lupus Management Study (ALMS)¹⁰ used a similar design with 370 patients worldwide (United States, China, South America, and Europe) in one of the largest trials ever conducted in lupus nephritis. Patients were randomized to 6 months of induction therapy with either IV cyclophosphamide or oral mycophenolate but could not cross over.

At 6 months, response rates were identical between the two groups, with response defined as a combination of specific improvement in proteinuria, serum creatinine, and hematuria (50%–55%). In terms of individual renal and nonrenal variables, both groups appeared identical.

However, the side effect profiles differed between the two groups. As expected for mycophenolate, diarrhea was the most common side effect (occurring in 28% vs 12% in the cyclophosphamide group). Nausea and vomiting were more common with cyclophosphamide (45% and 37% respectively vs 14% and 13% in the mycophenolate group). Cyclophosphamide also caused hair loss in 35%, vs 10% in the mycophenolate group.

There were 14 deaths overall, which is a very low number considering the patients’ severity of illness, and it indicates the better results now achieved with therapy. The mortality rate was higher in the mycophenolate group (5% vs 3%), but the difference was not statistically significant. Six of the nine deaths with mycophenolate were from the same center in China, and none were from Europe or the United States. In summary, the study did not show that mycophenolate was superior to IV cyclophosphamide for induction therapy, but that they were equivalent in efficacy with different side effect profiles.

Membranous nephropathy: Mycophenolate vs cyclophosphamide

Less evidence is available about treatment for membranous disease, which is characterized by heavy proteinuria and the nephrotic syndrome but usually does not progress to renal failure. Radhakrishnan et al¹¹ combined data from the trial by Ginzler et al⁹ and the ALMS trial¹⁰ and found 84 patients with pure membranous lupus, who were equally divided between the treatment groups receiving IV cyclophosphamide and mycophenolate. Consistent with the larger group’s data, mycophenolate and cyclophosphamide performed similarly in terms of efficacy, but there was a slightly higher rate of side effects with cyclophosphamide.

Maintenance therapy: Mycophenolate superior to azathioprine

The ALMS Maintenance Trial¹² evaluated maintenance therapy in the same worldwide population that was studied for induction therapy. Of the 370 patients involved in the induction phase that compared IV cyclophosphamide and oral mycophenolate, 227 responded sufficiently to be rerandomized in a controlled, double-blinded trial of 36 months of maintenance therapy with corticosteroids and either mycophenolate (1 g twice daily) or azathioprine (2 mg/kg per day).

In intention-to-treat analysis, the time to treatment failure (ie, doubling of the serum creatinine level, progressing to renal failure, or death) was significantly shorter in the azathioprine group (P = .003). Every individual end point—end-stage renal disease, renal flares, doubling of serum creatinine, rescue immunosuppression required—was in favor of mycophenolate maintenance. At 3 years, the completion rate was 63% with mycophenolate and 49% with azathioprine. Serious adverse events and withdrawals because of adverse events were more common in the azathioprine group.

In summary, mycophenolate was superior to azathioprine in maintaining renal response and in preventing relapse in patients with active lupus nephritis who responded to induction therapy with either mycophenolate or IV cyclophosphamide. Mycophenolate was found to be superior regardless of initial induction treatment, race, or region and was confirmed by all key secondary end points.

Only one of the 227 patients died during the 3 years—from an auto accident. Again, this indicates the dramatically improved survival today compared with a decade ago.

RITUXIMAB: PROMISING BUT UNPROVEN

Rituximab (Rituxan) was originally approved to treat tumors, then rheumatoid arthritis, and most recently vasculitis. Evidence thus far is mixed regarding its use as a treatment for lupus nephritis. Although randomized clinical trials have not found it to be superior to standard regimens, there are many signs that it may be effective.

Rituximab in uncontrolled studies

Terrier et al¹³ analyzed prospective data from 136 patients with systemic lupus erythematosus, most of whom had renal disease, from the French Autoimmunity and Rituximab registry. Response occurred in 71% of patients using rituximab, with no difference found between patients receiving rituximab monotherapy and those concomitantly receiving immunosuppressive agents.

Melander et al¹⁴ retrospectively studied 19 women and 1 man who had been treated with rituximab for severe lupus nephritis and followed for at least 1 year. Three patients had concurrent therapy with cyclophosphamide, and 10 patients continued rituximab as maintenance therapy; 12 patients had lupus nephritis that had been refractory to standard treatment, and 6 had relapsing disease.

At a median follow-up of 22 months, 12 patients (60%) had achieved complete or partial renal remission.

Condon et al¹⁵ treated 21 patients who had severe lupus nephritis with two doses of rituximab and IV methylprednisolone 2 weeks apart, then maintenance therapy with mycophenolate without any oral steroids. At a mean follow-up of 35 months ( ± 14 months), 16 (76%) were in complete remission, with a mean time to remission of 12 months. Two (9.5%) achieved partial remission. The rate of toxicity was low.

Thus, rituximab appears promising in uncontrolled studies.

Placebo-controlled trials fail to prove rituximab effective

LUNAR trial. On the other hand, the largest placebo-controlled trial to evaluate rituximab in patients with proliferative lupus nephritis, the Lupus Nephritis Assessment With Rituximab (LUNAR) trial¹⁶ found differences in favor of rituximab, but none reached statistical significance. The trial randomized 140 patients to receive either mycophenolate plus periodic rituximab infusions or mycophenolate plus placebo infusions for 1 year. All patients received the same dosage of glucocorticoids, which was tapered over the year.

At the end of 1 year, the groups were not statistically different in terms of complete renal response and partial renal response. Rituximab appeared less likely to produce no response, but the difference was not statistically significant.

African Americans appeared to have a higher response rate to rituximab (70% in the rituximab group achieved a response vs 45% in the control group), but again, the difference did not reach statistical significance, and the total study population of African Americans was only 40.

Rituximab did have a statistically significant positive effect on two serologic markers at 1 year: levels of anti-dsDNA fell faster and complement rose faster. In addition, rates of adverse and serious adverse events were similar between the two groups, with no new or unexpected “safety signals.”

This study can be interpreted in a number of ways. The number of patients may have been too small to show significance and the follow-up may have been too short. On the other hand, it may simply not be effective to add rituximab to a full dose of mycophenolate and steroids, an already good treatment.

EXPLORER trial. Similarly, for patients with lupus without nephritis, the Exploratory Phase II/III SLE Evaluation of Rituximab (EXPLORER) trial¹⁷ also tested rituximab against a background of an effective therapeutic regimen and found no additional benefit. This study had design problems similar to those of the LUNAR trial.

Rituximab as rescue therapy

The evidence so far indicates that rituximab may have a role as rescue therapy for refractory or relapsing disease. Rituximab must be used with other therapies, but maintenance corticosteroid therapy is not necessary. Its role as a first-line agent in induction therapy for lupus nephritis remains unclear, although it may have an important role for nonwhites. In general, it has been well tolerated. Until a large randomized trial indicates otherwise, it should not be used as a first-line therapy.

The US Food and Drug Administration (FDA) sent out a warning about the danger of progressive multifocal leukoencephalopathy as an adverse effect of rituximab and of mycophenolate, but this does not appear to be a major concern for most patients and is only likely to occur in those who have been over-immunosuppressed for many years.

MULTITARGET THERAPY

The concept of using multiple drugs simultaneously—such as mycophenolate, steroids, and rituximab—is increasingly being tried. Multi-target therapy appears to offer the advantages of combining different modes of action with better results, and it offers fewer side effects because dosages of each individual drug can be lower when combined with other immunosuppressives.

Bao et al¹⁸ in China randomly assigned 40 patients with diffuse proliferative and membranous nephritis to 6 to 9 months of induction treatment with either multitarget therapy (mycophenolate, tacrolimus [Prograf], and glucocorticoids) or IV cyclophosphamide. More complete remissions occurred in the multitarget therapy group, both at 6 months (50% vs 5%) and at 9 months (65% vs 15%). Most adverse events were less frequent in the multitarget therapy group, although three patients (15%) in the multitarget therapy group developed new-onset hypertension vs none in the cyclophosphamide group.

NEW MEDICATIONS

Entirely new classes of drugs are being developed with immunomodulatory effects, including tolerance molecules, cytokine blockers, inhibitors of human B lymphocyte stimulator, and costimulatory blockers.

Belimumab offers small improvement for lupus

Belimumab (Benlysta) is a human monoclonal antibody that inhibits the biologic activity of human B lymphocyte stimulator; it has recently been approved by the FDA for lupus nephritis. In a worldwide study,¹⁹ 867 patients with systemic lupus erythematosus were randomized to receive either belimumab (1 mg/kg or 10 mg/kg) or placebo.

The primary end point was the reduction of disease activity by a scoring system (SELENA-SLEDAI) that incorporated multiple features of lupus, including arthritis, vasculitis, proteinuria, rash, and others. Patients in the belimumab group had better outcomes, but the results were not dramatic. Because the drug is so expensive (about $25,000 per year) and the improvement offered is only incremental, this drug will not likely change the treatment of lupus very much.

Moreover, patients with lupus nephritis were not included in the study, but a new study is being planned to do so. Improvement is harder to demonstrate in lupus nephritis than in rheumatoid arthritis and systemic lupus erythematosus: significant changes in creatinine levels and 24-hour urinary protein must be achieved, rather than more qualitative signs and symptoms of joint pain, rash, and feeling better. Although belimumab is still unproven for lupus nephritis, it might be worth trying for patients failing other therapy.

Laquinimod: A promising experimental drug

Laquinimod is an oral immunomodulatory drug with a number of effects, including down-regulating major histocompatability complex II, chemokines, and adhesion-related molecules related to inflammation. It has been studied in more than 2,500 patients with multiple sclerosis. Pilot studies are now being done for its use for lupus nephritis. If it shows promise, a large randomized, controlled trial will be conducted.

Abatacept is in clinical trials

Abatacept (Orencia), a costimulation blocker, is undergoing clinical trials in lupus nephritis. Results should be available shortly.

INDIVIDUALIZE THERAPY

This past decade has seen such an increase in options to treat lupus nephritis that therapy can now be individualized.

Choosing IV cyclophosphamide vs mycophenolate

As a result of recent trials, doctors in the United States are increasingly using mycophenolate as the first-line drug for lupus nephritis. In Europe, however, many are choosing the shorter regimen of IV cyclophosphamide because of the results of the Euro-Lupus study.

Nowadays, I tend to use IV cyclophosphamide as the first-line drug only for patients with severe crescenteric glomerulonephritis or a very high serum creatinine level. In such cases, there is more experience with cyclophosphamide, and such severe disease does not lend itself to the luxury of trying out different therapies sequentially. If such a severely ill patient insists that a future pregnancy is very important, an alternative therapy of mycophenolate plus rituximab should be considered. I prefer mycophenolate for induction and maintenance therapy in most patients.

Dosing and formulation considerations for mycophenolate

Large dosages of mycophenolate are much better tolerated when broken up throughout the day. A patient who cannot tolerate 1 g twice daily may be able to tolerate 500 mg four times a day. The formulation can also make a difference. Some patients tolerate sustained-release mycophenolate (Myfortic) better than CellCept, and vice versa.

For patients who cannot tolerate mycophenolate, azathioprine is an acceptable alternative. In addition, for a patient who is already doing well on azathioprine, there is no need to change to mycophenolate.

Long maintenance therapy now acceptable

The ALMS Maintenance Trial¹² found 3 years of maintenance therapy to be safe and effective. Such a long maintenance period is increasingly viewed as important, especially for patients in their teens and 20s, as it allows them to live a normal life, ie, to finish their education, get married, and become settled socially. Whether 5 years of maintenance therapy or even 10 years is advisable is still unknown.

Treatment during pregnancy

Neither mycophenolate nor azathioprine is recommended during pregnancy, although their effects are unknown. Because we have much more renal transplant experience with azathioprine during pregnancy, I recommend either switching from mycophenolate to azathioprine or trying to stop medication altogether if the patient has been well controlled.

Treatment for lupus nephritis has changed dramatically in recent years. Only 10 years ago, rheumatologists and nephrologists, whether specializing in adult or pediatric medicine, treated lupus nephritis with a similar regimen of monthly intravenous cyclophosphamide (Cytoxan) and glucocorticoids. Although the regimen is effective, side effects such as infection, hair loss, and infertility were extremely common.

Effective but very toxic therapy is common in autoimmune diseases. In the last decade, clinical trials have shown that less toxic drugs are as effective for treating lupus nephritis. This article will review new developments in therapy for lupus nephritis, which can be viewed as a prototype for other fields of medicine.

DEMOGRAPHICS ARE IMPORTANT

Although numerous factors have prognostic value in lupus nephritis (eg, serum creatinine, proteinuria, renal biopsy findings), the most important to consider when designing and interpreting studies are race and socioeconomic variables.

A retrospective study in Miami, FL,¹ evaluated 213 patients with lupus nephritis, of whom 47% were Hispanic, 44% African American, and 20% white. At baseline, African Americans had higher blood pressure, higher serum creatinine levels, and lower household income. After 6 years, African Americans fared the worst in terms of doubling of serum creatinine, developing end-stage renal disease, and death; whites had the best outcomes, and Hispanics were in between. Low income was found to be a significant risk factor, independent of racial background.

In a similar retrospective study in New York City in 128 patients (43% white, 40% Hispanic, and 17% African American) with proliferative lupus nephritis,² disease was much more likely to progress to renal failure over 10 years in patients living in a poor neighborhood, even after adjustment for race.

We need to keep in mind that racial and socioeconomic factors correlate with disease severity when we design and interpret studies of lupus nephritis. Study groups must be carefully balanced with patients of similar racial and socioeconomic profiles. Study findings must be interpreted with caution; for example, whether results from a study from China are applicable to an African American with lupus nephritis in New York City is unclear.

OLDER STANDARD THERAPY: EFFECTIVE BUT TOXIC

The last large National Institutes of Health study that involved only cyclophosphamide and a glucocorticoid was published in 2001,³ with 21 patients receiving cyclophosphamide alone and 20 patients receiving cyclophosphamide plus methylprednisolone. Although lupus nephritis improved, serious side effects occurred in one-third to one-half of patients in each group and included hypertension, hyperlipidemia, valvular heart disease, avascular necrosis, premature menopause, and major infections, including herpes zoster.

Less cyclophosphamide works just as well

The multicenter, prospective Euro-Lupus Nephritis Trial⁴ randomized 90 patients with proliferative lupus nephritis to receive either standard high-dose intravenous (IV) cyclophosphamide therapy (six monthly pulses and two quarterly pulses, with doses increasing according to the white blood cell count) or low-dose IV cyclophosphamide therapy (six pulses every 2 weeks at a fixed dose of 500 mg). Both regimens were followed by azathioprine (Imuran).

At 4 years, the two treatment groups were not significantly different in terms of treatment failure, remission rates, serum creatinine levels, 24-hour proteinuria, and freedom from renal flares. However, the rates of side effects were significantly different, with more patients in the low-dosage group free of severe infection.

One problem with this study is whether it is applicable to an American lupus nephritis population, since 84% of the patients were white. Since this study, others indicate that this regimen is probably also safe and effective for different racial groups in the United States.

At 10-year follow-up,⁵ both treatment groups still had identical excellent rates of freedom from end-stage renal disease. Serum creatinine and 24-hour proteinuria were also at excellent levels and identical in both groups. Nearly three quarters of patients still needed glucocorticoid therapy and more than half still needed immunosuppressive therapy, but the rates were not statistically significantly different between the treatment groups.

The cumulative dose of cyclophosphamide was 9.5 g in the standard-treatment group and 5.5 g in the low-dose group. This difference in exposure could make a tremendous difference to patients, not only for immediate side effects such as early menopause and infections, but for the risk of cancer in later decades.

This study showed clearly that low-dose cyclophosphamide is an option for induction therapy. Drawbacks of the study were that the population was mostly white and that patients had only moderately severe disease.

Low-dose cyclophosphamide has largely replaced the older National Institutes of Health regimen, although during the last decade drug therapy has undergone more changes.

MYCOPHENOLATE AND AZATHIOPRINE: ALTERNATIVES TO CYCLOPHOSPHAMIDE

In a Chinese study, mycophenolate was better than cyclophosphamide for induction

In a study in Hong Kong, Chan et al⁶ randomized 42 patients with severe lupus nephritis to receive either mycophenolate mofetil (available in the United States as CellCept; 2 g/day for 6 months, then 1 g/day for 6 months) or oral cyclophosphamide (2.5 mg/kg per day for 6 months) followed by azathioprine (1.5–2.0 mg/kg per day) for 6 months. Both groups also received prednisolone during the year.

At the end of the first year, the two groups were not significantly different in their rates of complete remission, partial remission, and relapse. The rate of infection, although not significantly different, was higher in the cyclophosphamide group (33% vs 19%). Two patients (10%) died in the cyclophosphamide group, but the difference in mortality rates was not statistically significant.

Nearly 5 years later,⁷ rates of chronic renal failure and relapse were still statistically the same in the two groups. Infections were fewer in the mycophenolate group (13% vs 40%, P = .013). The rate of amenorrhea was 36% in the cyclophosphamide group and only 4% in the mycophenolate group (P = .004). Four patients in the cyclophosphamide group and none in the mycophenolate group reached the composite end point of end-stage renal failure or death (P = .062).

This study appeared to offer a new option with equal efficacy and fewer side effects than standard therapy. However, its applicability to non-Chinese populations remained to be shown.

In a study in Miami,⁸ 59 patients with lupus nephritis were given standard induction therapy with IV cyclophosphamide plus glucocorticoids for 6 months, then randomly assigned to one of three maintenance therapies for 1 to 3 years: IV injections of cyclophosphamide every 3 months (standard therapy), oral azathioprine, or oral mycophenolate. The population was 93% female, their average age was 33 years, and nearly half were African American, with many of the others being Hispanic. Patients tended to have severe disease, with nearly two-thirds having nephrotic syndrome.

After 6 years, there had been more deaths in the cyclophosphamide group than in the azathioprine group (P = .02) and in the mycophenolate group, although the latter difference was not statistically significant (P = .11). The combined rate of death and chronic renal failure was significantly higher with cyclophosphamide than with either of the oral agents. The cyclophosphamide group also had the highest relapse rate during the maintenance phase.

The differences in side effects were even more dramatic. Amenorrhea affected 32% of patients in the cyclophosphamide group, and only 7% and 6% in the azathioprine and mycophenolate groups, respectively. Rates of infections were 68% in the cyclophosphamide group and 28% and 21% in the azathioprine and mycophenolate groups, respectively. Patients given cyclophosphamide had 13 hospital days per patient per year, while the other groups each had only 1.

This study showed that maintenance therapy with oral azathioprine or mycophenolate was more effective and had fewer adverse effects than standard IV cyclophosphamide therapy. As a result of this study, oral agents for maintenance therapy became the new standard, but the question remained whether oral agents could safely be used for induction.

In a US study, mycophenolate was better than cyclophosphamide for induction

In a noninferiority study, Ginzler et al⁹ randomized 140 patients with severe lupus nephritis to receive either monthly IV cyclophosphamide or oral mycophenolate as induction therapy for 6 months. Adjunctive care with glucocorticoids was given in both groups. The study population was from 18 US academic centers and was predominantly female, and more than half were African American.

After 24 weeks, 22.5% of the mycophenolate patients were in complete remission by very strict criteria vs only 4% of those given cyclophosphamide (P = .005). The trend for partial remissions was also in favor of mycophenolate, although the difference was not statistically significant. The rate of complete and partial remissions, a prespecified end point, was significantly higher in the mycophenolate group. Although the study was trying to evaluate equivalency, it actually showed superiority for mycophenolate induction therapy.

Serum creatinine levels declined in both groups, but more in the mycophenolate group by 24 weeks. Urinary protein levels fell the same amount in both groups. At 3 years, the groups were statistically equivalent in terms of renal flares, renal failures, and deaths. However, the study groups were small, and the mycophenolate group did have a better trend for both renal failure (N = 4 vs 7) and deaths (N = 4 vs 8).

Mycophenolate also had fewer side effects, including infection, although again the numbers were too small to show statistical significance. The exception was diarrhea (N = 15 in the mycophenolate group vs 2 in the cyclophosphamide group).

A drawback of the study is that it was designed as a crossover study: a patient for whom therapy was failing after 3 months could switch to the other group, introducing potential confounding. Other problems involved the small population size and the question of whether results from patients in the United States were applicable to others worldwide.

In a worldwide study, mycophenolate was at least equivalent to cyclophosphamide for induction

The Aspreva Lupus Management Study (ALMS)¹⁰ used a similar design with 370 patients worldwide (United States, China, South America, and Europe) in one of the largest trials ever conducted in lupus nephritis. Patients were randomized to 6 months of induction therapy with either IV cyclophosphamide or oral mycophenolate but could not cross over.

At 6 months, response rates were identical between the two groups, with response defined as a combination of specific improvement in proteinuria, serum creatinine, and hematuria (50%–55%). In terms of individual renal and nonrenal variables, both groups appeared identical.

However, the side effect profiles differed between the two groups. As expected for mycophenolate, diarrhea was the most common side effect (occurring in 28% vs 12% in the cyclophosphamide group). Nausea and vomiting were more common with cyclophosphamide (45% and 37% respectively vs 14% and 13% in the mycophenolate group). Cyclophosphamide also caused hair loss in 35%, vs 10% in the mycophenolate group.

There were 14 deaths overall, which is a very low number considering the patients’ severity of illness, and it indicates the better results now achieved with therapy. The mortality rate was higher in the mycophenolate group (5% vs 3%), but the difference was not statistically significant. Six of the nine deaths with mycophenolate were from the same center in China, and none were from Europe or the United States. In summary, the study did not show that mycophenolate was superior to IV cyclophosphamide for induction therapy, but that they were equivalent in efficacy with different side effect profiles.

Membranous nephropathy: Mycophenolate vs cyclophosphamide

Less evidence is available about treatment for membranous disease, which is characterized by heavy proteinuria and the nephrotic syndrome but usually does not progress to renal failure. Radhakrishnan et al¹¹ combined data from the trial by Ginzler et al⁹ and the ALMS trial¹⁰ and found 84 patients with pure membranous lupus, who were equally divided between the treatment groups receiving IV cyclophosphamide and mycophenolate. Consistent with the larger group’s data, mycophenolate and cyclophosphamide performed similarly in terms of efficacy, but there was a slightly higher rate of side effects with cyclophosphamide.

Maintenance therapy: Mycophenolate superior to azathioprine

The ALMS Maintenance Trial¹² evaluated maintenance therapy in the same worldwide population that was studied for induction therapy. Of the 370 patients involved in the induction phase that compared IV cyclophosphamide and oral mycophenolate, 227 responded sufficiently to be rerandomized in a controlled, double-blinded trial of 36 months of maintenance therapy with corticosteroids and either mycophenolate (1 g twice daily) or azathioprine (2 mg/kg per day).

In intention-to-treat analysis, the time to treatment failure (ie, doubling of the serum creatinine level, progressing to renal failure, or death) was significantly shorter in the azathioprine group (P = .003). Every individual end point—end-stage renal disease, renal flares, doubling of serum creatinine, rescue immunosuppression required—was in favor of mycophenolate maintenance. At 3 years, the completion rate was 63% with mycophenolate and 49% with azathioprine. Serious adverse events and withdrawals because of adverse events were more common in the azathioprine group.

In summary, mycophenolate was superior to azathioprine in maintaining renal response and in preventing relapse in patients with active lupus nephritis who responded to induction therapy with either mycophenolate or IV cyclophosphamide. Mycophenolate was found to be superior regardless of initial induction treatment, race, or region and was confirmed by all key secondary end points.

Only one of the 227 patients died during the 3 years—from an auto accident. Again, this indicates the dramatically improved survival today compared with a decade ago.

RITUXIMAB: PROMISING BUT UNPROVEN

Rituximab (Rituxan) was originally approved to treat tumors, then rheumatoid arthritis, and most recently vasculitis. Evidence thus far is mixed regarding its use as a treatment for lupus nephritis. Although randomized clinical trials have not found it to be superior to standard regimens, there are many signs that it may be effective.

Rituximab in uncontrolled studies

Terrier et al¹³ analyzed prospective data from 136 patients with systemic lupus erythematosus, most of whom had renal disease, from the French Autoimmunity and Rituximab registry. Response occurred in 71% of patients using rituximab, with no difference found between patients receiving rituximab monotherapy and those concomitantly receiving immunosuppressive agents.

Melander et al¹⁴ retrospectively studied 19 women and 1 man who had been treated with rituximab for severe lupus nephritis and followed for at least 1 year. Three patients had concurrent therapy with cyclophosphamide, and 10 patients continued rituximab as maintenance therapy; 12 patients had lupus nephritis that had been refractory to standard treatment, and 6 had relapsing disease.

At a median follow-up of 22 months, 12 patients (60%) had achieved complete or partial renal remission.

Condon et al¹⁵ treated 21 patients who had severe lupus nephritis with two doses of rituximab and IV methylprednisolone 2 weeks apart, then maintenance therapy with mycophenolate without any oral steroids. At a mean follow-up of 35 months ( ± 14 months), 16 (76%) were in complete remission, with a mean time to remission of 12 months. Two (9.5%) achieved partial remission. The rate of toxicity was low.

Thus, rituximab appears promising in uncontrolled studies.

Placebo-controlled trials fail to prove rituximab effective

LUNAR trial. On the other hand, the largest placebo-controlled trial to evaluate rituximab in patients with proliferative lupus nephritis, the Lupus Nephritis Assessment With Rituximab (LUNAR) trial¹⁶ found differences in favor of rituximab, but none reached statistical significance. The trial randomized 140 patients to receive either mycophenolate plus periodic rituximab infusions or mycophenolate plus placebo infusions for 1 year. All patients received the same dosage of glucocorticoids, which was tapered over the year.

At the end of 1 year, the groups were not statistically different in terms of complete renal response and partial renal response. Rituximab appeared less likely to produce no response, but the difference was not statistically significant.

African Americans appeared to have a higher response rate to rituximab (70% in the rituximab group achieved a response vs 45% in the control group), but again, the difference did not reach statistical significance, and the total study population of African Americans was only 40.

Rituximab did have a statistically significant positive effect on two serologic markers at 1 year: levels of anti-dsDNA fell faster and complement rose faster. In addition, rates of adverse and serious adverse events were similar between the two groups, with no new or unexpected “safety signals.”

This study can be interpreted in a number of ways. The number of patients may have been too small to show significance and the follow-up may have been too short. On the other hand, it may simply not be effective to add rituximab to a full dose of mycophenolate and steroids, an already good treatment.

EXPLORER trial. Similarly, for patients with lupus without nephritis, the Exploratory Phase II/III SLE Evaluation of Rituximab (EXPLORER) trial¹⁷ also tested rituximab against a background of an effective therapeutic regimen and found no additional benefit. This study had design problems similar to those of the LUNAR trial.

Rituximab as rescue therapy

The evidence so far indicates that rituximab may have a role as rescue therapy for refractory or relapsing disease. Rituximab must be used with other therapies, but maintenance corticosteroid therapy is not necessary. Its role as a first-line agent in induction therapy for lupus nephritis remains unclear, although it may have an important role for nonwhites. In general, it has been well tolerated. Until a large randomized trial indicates otherwise, it should not be used as a first-line therapy.

The US Food and Drug Administration (FDA) sent out a warning about the danger of progressive multifocal leukoencephalopathy as an adverse effect of rituximab and of mycophenolate, but this does not appear to be a major concern for most patients and is only likely to occur in those who have been over-immunosuppressed for many years.

MULTITARGET THERAPY

The concept of using multiple drugs simultaneously—such as mycophenolate, steroids, and rituximab—is increasingly being tried. Multi-target therapy appears to offer the advantages of combining different modes of action with better results, and it offers fewer side effects because dosages of each individual drug can be lower when combined with other immunosuppressives.

Bao et al¹⁸ in China randomly assigned 40 patients with diffuse proliferative and membranous nephritis to 6 to 9 months of induction treatment with either multitarget therapy (mycophenolate, tacrolimus [Prograf], and glucocorticoids) or IV cyclophosphamide. More complete remissions occurred in the multitarget therapy group, both at 6 months (50% vs 5%) and at 9 months (65% vs 15%). Most adverse events were less frequent in the multitarget therapy group, although three patients (15%) in the multitarget therapy group developed new-onset hypertension vs none in the cyclophosphamide group.

NEW MEDICATIONS

Entirely new classes of drugs are being developed with immunomodulatory effects, including tolerance molecules, cytokine blockers, inhibitors of human B lymphocyte stimulator, and costimulatory blockers.

Belimumab offers small improvement for lupus

Belimumab (Benlysta) is a human monoclonal antibody that inhibits the biologic activity of human B lymphocyte stimulator; it has recently been approved by the FDA for lupus nephritis. In a worldwide study,¹⁹ 867 patients with systemic lupus erythematosus were randomized to receive either belimumab (1 mg/kg or 10 mg/kg) or placebo.

The primary end point was the reduction of disease activity by a scoring system (SELENA-SLEDAI) that incorporated multiple features of lupus, including arthritis, vasculitis, proteinuria, rash, and others. Patients in the belimumab group had better outcomes, but the results were not dramatic. Because the drug is so expensive (about $25,000 per year) and the improvement offered is only incremental, this drug will not likely change the treatment of lupus very much.

Moreover, patients with lupus nephritis were not included in the study, but a new study is being planned to do so. Improvement is harder to demonstrate in lupus nephritis than in rheumatoid arthritis and systemic lupus erythematosus: significant changes in creatinine levels and 24-hour urinary protein must be achieved, rather than more qualitative signs and symptoms of joint pain, rash, and feeling better. Although belimumab is still unproven for lupus nephritis, it might be worth trying for patients failing other therapy.

Laquinimod: A promising experimental drug

Laquinimod is an oral immunomodulatory drug with a number of effects, including down-regulating major histocompatability complex II, chemokines, and adhesion-related molecules related to inflammation. It has been studied in more than 2,500 patients with multiple sclerosis. Pilot studies are now being done for its use for lupus nephritis. If it shows promise, a large randomized, controlled trial will be conducted.

Abatacept is in clinical trials

Abatacept (Orencia), a costimulation blocker, is undergoing clinical trials in lupus nephritis. Results should be available shortly.

INDIVIDUALIZE THERAPY

This past decade has seen such an increase in options to treat lupus nephritis that therapy can now be individualized.

Choosing IV cyclophosphamide vs mycophenolate

As a result of recent trials, doctors in the United States are increasingly using mycophenolate as the first-line drug for lupus nephritis. In Europe, however, many are choosing the shorter regimen of IV cyclophosphamide because of the results of the Euro-Lupus study.

Nowadays, I tend to use IV cyclophosphamide as the first-line drug only for patients with severe crescenteric glomerulonephritis or a very high serum creatinine level. In such cases, there is more experience with cyclophosphamide, and such severe disease does not lend itself to the luxury of trying out different therapies sequentially. If such a severely ill patient insists that a future pregnancy is very important, an alternative therapy of mycophenolate plus rituximab should be considered. I prefer mycophenolate for induction and maintenance therapy in most patients.

Dosing and formulation considerations for mycophenolate

Large dosages of mycophenolate are much better tolerated when broken up throughout the day. A patient who cannot tolerate 1 g twice daily may be able to tolerate 500 mg four times a day. The formulation can also make a difference. Some patients tolerate sustained-release mycophenolate (Myfortic) better than CellCept, and vice versa.

For patients who cannot tolerate mycophenolate, azathioprine is an acceptable alternative. In addition, for a patient who is already doing well on azathioprine, there is no need to change to mycophenolate.

Long maintenance therapy now acceptable

The ALMS Maintenance Trial¹² found 3 years of maintenance therapy to be safe and effective. Such a long maintenance period is increasingly viewed as important, especially for patients in their teens and 20s, as it allows them to live a normal life, ie, to finish their education, get married, and become settled socially. Whether 5 years of maintenance therapy or even 10 years is advisable is still unknown.

Treatment during pregnancy

Neither mycophenolate nor azathioprine is recommended during pregnancy, although their effects are unknown. Because we have much more renal transplant experience with azathioprine during pregnancy, I recommend either switching from mycophenolate to azathioprine or trying to stop medication altogether if the patient has been well controlled.

Treatment for lupus nephritis has changed dramatically in recent years. Only 10 years ago, rheumatologists and nephrologists, whether specializing in adult or pediatric medicine, treated lupus nephritis with a similar regimen of monthly intravenous cyclophosphamide (Cytoxan) and glucocorticoids. Although the regimen is effective, side effects such as infection, hair loss, and infertility were extremely common.

Effective but very toxic therapy is common in autoimmune diseases. In the last decade, clinical trials have shown that less toxic drugs are as effective for treating lupus nephritis. This article will review new developments in therapy for lupus nephritis, which can be viewed as a prototype for other fields of medicine.

DEMOGRAPHICS ARE IMPORTANT

Although numerous factors have prognostic value in lupus nephritis (eg, serum creatinine, proteinuria, renal biopsy findings), the most important to consider when designing and interpreting studies are race and socioeconomic variables.

A retrospective study in Miami, FL,¹ evaluated 213 patients with lupus nephritis, of whom 47% were Hispanic, 44% African American, and 20% white. At baseline, African Americans had higher blood pressure, higher serum creatinine levels, and lower household income. After 6 years, African Americans fared the worst in terms of doubling of serum creatinine, developing end-stage renal disease, and death; whites had the best outcomes, and Hispanics were in between. Low income was found to be a significant risk factor, independent of racial background.

In a similar retrospective study in New York City in 128 patients (43% white, 40% Hispanic, and 17% African American) with proliferative lupus nephritis,² disease was much more likely to progress to renal failure over 10 years in patients living in a poor neighborhood, even after adjustment for race.

We need to keep in mind that racial and socioeconomic factors correlate with disease severity when we design and interpret studies of lupus nephritis. Study groups must be carefully balanced with patients of similar racial and socioeconomic profiles. Study findings must be interpreted with caution; for example, whether results from a study from China are applicable to an African American with lupus nephritis in New York City is unclear.

OLDER STANDARD THERAPY: EFFECTIVE BUT TOXIC

The last large National Institutes of Health study that involved only cyclophosphamide and a glucocorticoid was published in 2001,³ with 21 patients receiving cyclophosphamide alone and 20 patients receiving cyclophosphamide plus methylprednisolone. Although lupus nephritis improved, serious side effects occurred in one-third to one-half of patients in each group and included hypertension, hyperlipidemia, valvular heart disease, avascular necrosis, premature menopause, and major infections, including herpes zoster.

Less cyclophosphamide works just as well

The multicenter, prospective Euro-Lupus Nephritis Trial⁴ randomized 90 patients with proliferative lupus nephritis to receive either standard high-dose intravenous (IV) cyclophosphamide therapy (six monthly pulses and two quarterly pulses, with doses increasing according to the white blood cell count) or low-dose IV cyclophosphamide therapy (six pulses every 2 weeks at a fixed dose of 500 mg). Both regimens were followed by azathioprine (Imuran).

At 4 years, the two treatment groups were not significantly different in terms of treatment failure, remission rates, serum creatinine levels, 24-hour proteinuria, and freedom from renal flares. However, the rates of side effects were significantly different, with more patients in the low-dosage group free of severe infection.

One problem with this study is whether it is applicable to an American lupus nephritis population, since 84% of the patients were white. Since this study, others indicate that this regimen is probably also safe and effective for different racial groups in the United States.

At 10-year follow-up,⁵ both treatment groups still had identical excellent rates of freedom from end-stage renal disease. Serum creatinine and 24-hour proteinuria were also at excellent levels and identical in both groups. Nearly three quarters of patients still needed glucocorticoid therapy and more than half still needed immunosuppressive therapy, but the rates were not statistically significantly different between the treatment groups.

The cumulative dose of cyclophosphamide was 9.5 g in the standard-treatment group and 5.5 g in the low-dose group. This difference in exposure could make a tremendous difference to patients, not only for immediate side effects such as early menopause and infections, but for the risk of cancer in later decades.

This study showed clearly that low-dose cyclophosphamide is an option for induction therapy. Drawbacks of the study were that the population was mostly white and that patients had only moderately severe disease.

Low-dose cyclophosphamide has largely replaced the older National Institutes of Health regimen, although during the last decade drug therapy has undergone more changes.

MYCOPHENOLATE AND AZATHIOPRINE: ALTERNATIVES TO CYCLOPHOSPHAMIDE

In a Chinese study, mycophenolate was better than cyclophosphamide for induction

In a study in Hong Kong, Chan et al⁶ randomized 42 patients with severe lupus nephritis to receive either mycophenolate mofetil (available in the United States as CellCept; 2 g/day for 6 months, then 1 g/day for 6 months) or oral cyclophosphamide (2.5 mg/kg per day for 6 months) followed by azathioprine (1.5–2.0 mg/kg per day) for 6 months. Both groups also received prednisolone during the year.

At the end of the first year, the two groups were not significantly different in their rates of complete remission, partial remission, and relapse. The rate of infection, although not significantly different, was higher in the cyclophosphamide group (33% vs 19%). Two patients (10%) died in the cyclophosphamide group, but the difference in mortality rates was not statistically significant.

Nearly 5 years later,⁷ rates of chronic renal failure and relapse were still statistically the same in the two groups. Infections were fewer in the mycophenolate group (13% vs 40%, P = .013). The rate of amenorrhea was 36% in the cyclophosphamide group and only 4% in the mycophenolate group (P = .004). Four patients in the cyclophosphamide group and none in the mycophenolate group reached the composite end point of end-stage renal failure or death (P = .062).

This study appeared to offer a new option with equal efficacy and fewer side effects than standard therapy. However, its applicability to non-Chinese populations remained to be shown.

In a study in Miami,⁸ 59 patients with lupus nephritis were given standard induction therapy with IV cyclophosphamide plus glucocorticoids for 6 months, then randomly assigned to one of three maintenance therapies for 1 to 3 years: IV injections of cyclophosphamide every 3 months (standard therapy), oral azathioprine, or oral mycophenolate. The population was 93% female, their average age was 33 years, and nearly half were African American, with many of the others being Hispanic. Patients tended to have severe disease, with nearly two-thirds having nephrotic syndrome.

After 6 years, there had been more deaths in the cyclophosphamide group than in the azathioprine group (P = .02) and in the mycophenolate group, although the latter difference was not statistically significant (P = .11). The combined rate of death and chronic renal failure was significantly higher with cyclophosphamide than with either of the oral agents. The cyclophosphamide group also had the highest relapse rate during the maintenance phase.

The differences in side effects were even more dramatic. Amenorrhea affected 32% of patients in the cyclophosphamide group, and only 7% and 6% in the azathioprine and mycophenolate groups, respectively. Rates of infections were 68% in the cyclophosphamide group and 28% and 21% in the azathioprine and mycophenolate groups, respectively. Patients given cyclophosphamide had 13 hospital days per patient per year, while the other groups each had only 1.

This study showed that maintenance therapy with oral azathioprine or mycophenolate was more effective and had fewer adverse effects than standard IV cyclophosphamide therapy. As a result of this study, oral agents for maintenance therapy became the new standard, but the question remained whether oral agents could safely be used for induction.

In a US study, mycophenolate was better than cyclophosphamide for induction

In a noninferiority study, Ginzler et al⁹ randomized 140 patients with severe lupus nephritis to receive either monthly IV cyclophosphamide or oral mycophenolate as induction therapy for 6 months. Adjunctive care with glucocorticoids was given in both groups. The study population was from 18 US academic centers and was predominantly female, and more than half were African American.

After 24 weeks, 22.5% of the mycophenolate patients were in complete remission by very strict criteria vs only 4% of those given cyclophosphamide (P = .005). The trend for partial remissions was also in favor of mycophenolate, although the difference was not statistically significant. The rate of complete and partial remissions, a prespecified end point, was significantly higher in the mycophenolate group. Although the study was trying to evaluate equivalency, it actually showed superiority for mycophenolate induction therapy.

Serum creatinine levels declined in both groups, but more in the mycophenolate group by 24 weeks. Urinary protein levels fell the same amount in both groups. At 3 years, the groups were statistically equivalent in terms of renal flares, renal failures, and deaths. However, the study groups were small, and the mycophenolate group did have a better trend for both renal failure (N = 4 vs 7) and deaths (N = 4 vs 8).

Mycophenolate also had fewer side effects, including infection, although again the numbers were too small to show statistical significance. The exception was diarrhea (N = 15 in the mycophenolate group vs 2 in the cyclophosphamide group).

A drawback of the study is that it was designed as a crossover study: a patient for whom therapy was failing after 3 months could switch to the other group, introducing potential confounding. Other problems involved the small population size and the question of whether results from patients in the United States were applicable to others worldwide.

In a worldwide study, mycophenolate was at least equivalent to cyclophosphamide for induction

The Aspreva Lupus Management Study (ALMS)¹⁰ used a similar design with 370 patients worldwide (United States, China, South America, and Europe) in one of the largest trials ever conducted in lupus nephritis. Patients were randomized to 6 months of induction therapy with either IV cyclophosphamide or oral mycophenolate but could not cross over.

At 6 months, response rates were identical between the two groups, with response defined as a combination of specific improvement in proteinuria, serum creatinine, and hematuria (50%–55%). In terms of individual renal and nonrenal variables, both groups appeared identical.

However, the side effect profiles differed between the two groups. As expected for mycophenolate, diarrhea was the most common side effect (occurring in 28% vs 12% in the cyclophosphamide group). Nausea and vomiting were more common with cyclophosphamide (45% and 37% respectively vs 14% and 13% in the mycophenolate group). Cyclophosphamide also caused hair loss in 35%, vs 10% in the mycophenolate group.

There were 14 deaths overall, which is a very low number considering the patients’ severity of illness, and it indicates the better results now achieved with therapy. The mortality rate was higher in the mycophenolate group (5% vs 3%), but the difference was not statistically significant. Six of the nine deaths with mycophenolate were from the same center in China, and none were from Europe or the United States. In summary, the study did not show that mycophenolate was superior to IV cyclophosphamide for induction therapy, but that they were equivalent in efficacy with different side effect profiles.

Membranous nephropathy: Mycophenolate vs cyclophosphamide

Less evidence is available about treatment for membranous disease, which is characterized by heavy proteinuria and the nephrotic syndrome but usually does not progress to renal failure. Radhakrishnan et al¹¹ combined data from the trial by Ginzler et al⁹ and the ALMS trial¹⁰ and found 84 patients with pure membranous lupus, who were equally divided between the treatment groups receiving IV cyclophosphamide and mycophenolate. Consistent with the larger group’s data, mycophenolate and cyclophosphamide performed similarly in terms of efficacy, but there was a slightly higher rate of side effects with cyclophosphamide.

Maintenance therapy: Mycophenolate superior to azathioprine

The ALMS Maintenance Trial¹² evaluated maintenance therapy in the same worldwide population that was studied for induction therapy. Of the 370 patients involved in the induction phase that compared IV cyclophosphamide and oral mycophenolate, 227 responded sufficiently to be rerandomized in a controlled, double-blinded trial of 36 months of maintenance therapy with corticosteroids and either mycophenolate (1 g twice daily) or azathioprine (2 mg/kg per day).

In intention-to-treat analysis, the time to treatment failure (ie, doubling of the serum creatinine level, progressing to renal failure, or death) was significantly shorter in the azathioprine group (P = .003). Every individual end point—end-stage renal disease, renal flares, doubling of serum creatinine, rescue immunosuppression required—was in favor of mycophenolate maintenance. At 3 years, the completion rate was 63% with mycophenolate and 49% with azathioprine. Serious adverse events and withdrawals because of adverse events were more common in the azathioprine group.

In summary, mycophenolate was superior to azathioprine in maintaining renal response and in preventing relapse in patients with active lupus nephritis who responded to induction therapy with either mycophenolate or IV cyclophosphamide. Mycophenolate was found to be superior regardless of initial induction treatment, race, or region and was confirmed by all key secondary end points.

Only one of the 227 patients died during the 3 years—from an auto accident. Again, this indicates the dramatically improved survival today compared with a decade ago.

RITUXIMAB: PROMISING BUT UNPROVEN

Rituximab (Rituxan) was originally approved to treat tumors, then rheumatoid arthritis, and most recently vasculitis. Evidence thus far is mixed regarding its use as a treatment for lupus nephritis. Although randomized clinical trials have not found it to be superior to standard regimens, there are many signs that it may be effective.

Rituximab in uncontrolled studies

Terrier et al¹³ analyzed prospective data from 136 patients with systemic lupus erythematosus, most of whom had renal disease, from the French Autoimmunity and Rituximab registry. Response occurred in 71% of patients using rituximab, with no difference found between patients receiving rituximab monotherapy and those concomitantly receiving immunosuppressive agents.

Melander et al¹⁴ retrospectively studied 19 women and 1 man who had been treated with rituximab for severe lupus nephritis and followed for at least 1 year. Three patients had concurrent therapy with cyclophosphamide, and 10 patients continued rituximab as maintenance therapy; 12 patients had lupus nephritis that had been refractory to standard treatment, and 6 had relapsing disease.

At a median follow-up of 22 months, 12 patients (60%) had achieved complete or partial renal remission.

Condon et al¹⁵ treated 21 patients who had severe lupus nephritis with two doses of rituximab and IV methylprednisolone 2 weeks apart, then maintenance therapy with mycophenolate without any oral steroids. At a mean follow-up of 35 months ( ± 14 months), 16 (76%) were in complete remission, with a mean time to remission of 12 months. Two (9.5%) achieved partial remission. The rate of toxicity was low.

Thus, rituximab appears promising in uncontrolled studies.

Placebo-controlled trials fail to prove rituximab effective

LUNAR trial. On the other hand, the largest placebo-controlled trial to evaluate rituximab in patients with proliferative lupus nephritis, the Lupus Nephritis Assessment With Rituximab (LUNAR) trial¹⁶ found differences in favor of rituximab, but none reached statistical significance. The trial randomized 140 patients to receive either mycophenolate plus periodic rituximab infusions or mycophenolate plus placebo infusions for 1 year. All patients received the same dosage of glucocorticoids, which was tapered over the year.

At the end of 1 year, the groups were not statistically different in terms of complete renal response and partial renal response. Rituximab appeared less likely to produce no response, but the difference was not statistically significant.

African Americans appeared to have a higher response rate to rituximab (70% in the rituximab group achieved a response vs 45% in the control group), but again, the difference did not reach statistical significance, and the total study population of African Americans was only 40.

Rituximab did have a statistically significant positive effect on two serologic markers at 1 year: levels of anti-dsDNA fell faster and complement rose faster. In addition, rates of adverse and serious adverse events were similar between the two groups, with no new or unexpected “safety signals.”

This study can be interpreted in a number of ways. The number of patients may have been too small to show significance and the follow-up may have been too short. On the other hand, it may simply not be effective to add rituximab to a full dose of mycophenolate and steroids, an already good treatment.

EXPLORER trial. Similarly, for patients with lupus without nephritis, the Exploratory Phase II/III SLE Evaluation of Rituximab (EXPLORER) trial¹⁷ also tested rituximab against a background of an effective therapeutic regimen and found no additional benefit. This study had design problems similar to those of the LUNAR trial.

Rituximab as rescue therapy

The evidence so far indicates that rituximab may have a role as rescue therapy for refractory or relapsing disease. Rituximab must be used with other therapies, but maintenance corticosteroid therapy is not necessary. Its role as a first-line agent in induction therapy for lupus nephritis remains unclear, although it may have an important role for nonwhites. In general, it has been well tolerated. Until a large randomized trial indicates otherwise, it should not be used as a first-line therapy.

The US Food and Drug Administration (FDA) sent out a warning about the danger of progressive multifocal leukoencephalopathy as an adverse effect of rituximab and of mycophenolate, but this does not appear to be a major concern for most patients and is only likely to occur in those who have been over-immunosuppressed for many years.

MULTITARGET THERAPY

The concept of using multiple drugs simultaneously—such as mycophenolate, steroids, and rituximab—is increasingly being tried. Multi-target therapy appears to offer the advantages of combining different modes of action with better results, and it offers fewer side effects because dosages of each individual drug can be lower when combined with other immunosuppressives.

Bao et al¹⁸ in China randomly assigned 40 patients with diffuse proliferative and membranous nephritis to 6 to 9 months of induction treatment with either multitarget therapy (mycophenolate, tacrolimus [Prograf], and glucocorticoids) or IV cyclophosphamide. More complete remissions occurred in the multitarget therapy group, both at 6 months (50% vs 5%) and at 9 months (65% vs 15%). Most adverse events were less frequent in the multitarget therapy group, although three patients (15%) in the multitarget therapy group developed new-onset hypertension vs none in the cyclophosphamide group.

NEW MEDICATIONS

Entirely new classes of drugs are being developed with immunomodulatory effects, including tolerance molecules, cytokine blockers, inhibitors of human B lymphocyte stimulator, and costimulatory blockers.

Belimumab offers small improvement for lupus

Belimumab (Benlysta) is a human monoclonal antibody that inhibits the biologic activity of human B lymphocyte stimulator; it has recently been approved by the FDA for lupus nephritis. In a worldwide study,¹⁹ 867 patients with systemic lupus erythematosus were randomized to receive either belimumab (1 mg/kg or 10 mg/kg) or placebo.

The primary end point was the reduction of disease activity by a scoring system (SELENA-SLEDAI) that incorporated multiple features of lupus, including arthritis, vasculitis, proteinuria, rash, and others. Patients in the belimumab group had better outcomes, but the results were not dramatic. Because the drug is so expensive (about $25,000 per year) and the improvement offered is only incremental, this drug will not likely change the treatment of lupus very much.

Moreover, patients with lupus nephritis were not included in the study, but a new study is being planned to do so. Improvement is harder to demonstrate in lupus nephritis than in rheumatoid arthritis and systemic lupus erythematosus: significant changes in creatinine levels and 24-hour urinary protein must be achieved, rather than more qualitative signs and symptoms of joint pain, rash, and feeling better. Although belimumab is still unproven for lupus nephritis, it might be worth trying for patients failing other therapy.

Laquinimod: A promising experimental drug

Laquinimod is an oral immunomodulatory drug with a number of effects, including down-regulating major histocompatability complex II, chemokines, and adhesion-related molecules related to inflammation. It has been studied in more than 2,500 patients with multiple sclerosis. Pilot studies are now being done for its use for lupus nephritis. If it shows promise, a large randomized, controlled trial will be conducted.

Abatacept is in clinical trials

Abatacept (Orencia), a costimulation blocker, is undergoing clinical trials in lupus nephritis. Results should be available shortly.

INDIVIDUALIZE THERAPY

This past decade has seen such an increase in options to treat lupus nephritis that therapy can now be individualized.

Choosing IV cyclophosphamide vs mycophenolate

As a result of recent trials, doctors in the United States are increasingly using mycophenolate as the first-line drug for lupus nephritis. In Europe, however, many are choosing the shorter regimen of IV cyclophosphamide because of the results of the Euro-Lupus study.

Nowadays, I tend to use IV cyclophosphamide as the first-line drug only for patients with severe crescenteric glomerulonephritis or a very high serum creatinine level. In such cases, there is more experience with cyclophosphamide, and such severe disease does not lend itself to the luxury of trying out different therapies sequentially. If such a severely ill patient insists that a future pregnancy is very important, an alternative therapy of mycophenolate plus rituximab should be considered. I prefer mycophenolate for induction and maintenance therapy in most patients.

Dosing and formulation considerations for mycophenolate

Large dosages of mycophenolate are much better tolerated when broken up throughout the day. A patient who cannot tolerate 1 g twice daily may be able to tolerate 500 mg four times a day. The formulation can also make a difference. Some patients tolerate sustained-release mycophenolate (Myfortic) better than CellCept, and vice versa.

For patients who cannot tolerate mycophenolate, azathioprine is an acceptable alternative. In addition, for a patient who is already doing well on azathioprine, there is no need to change to mycophenolate.

Long maintenance therapy now acceptable

The ALMS Maintenance Trial¹² found 3 years of maintenance therapy to be safe and effective. Such a long maintenance period is increasingly viewed as important, especially for patients in their teens and 20s, as it allows them to live a normal life, ie, to finish their education, get married, and become settled socially. Whether 5 years of maintenance therapy or even 10 years is advisable is still unknown.

Treatment during pregnancy

Neither mycophenolate nor azathioprine is recommended during pregnancy, although their effects are unknown. Because we have much more renal transplant experience with azathioprine during pregnancy, I recommend either switching from mycophenolate to azathioprine or trying to stop medication altogether if the patient has been well controlled.