ATLANTA – Adding abatacept to low-dose intravenous cyclophosphamide did not improve the rate of complete renal response at 1 year, compared with IV cyclophosphamide alone, in patients with class III or IV lupus nephritis in the randomized, controlled ACCESS Trial.
The phase II findings suggested, however, that abatacept reduced the need for maintenance immunosuppression, and they also demonstrated for the first time that low-dose IV cyclophosphamide may have applicability in racially and ethnically diverse patients with lupus nephritis, Dr. Brad H. Rovin reported at Kidney Week 2013.
The overall complete renal response rates were similar at 33% and 31%, respectively, in 134 patients with class III or IV lupus nephritis who were enrolled in the trial, treated with a steroid taper and 500 mg of IV cyclophosphamide every 2 weeks for 6 weeks followed by 2 mg/kg of azathioprine daily. Patients then were randomized to receive abatacept or placebo at week 0, 2, and 4 and then monthly.
Dr. Brad Rovin
Complete plus partial responses occurred in 59% of patients in each arm, Dr. Rovin said at the conference, which was sponsored by the American Society of Nephrology.
Patients in the study had a urine protein-to-creatinine ratio (UPCR) greater than 1. Complete renal response was defined as a UPCR of less than 0.5, serum creatinine at normal or within 25% of baseline, and prednisone dose tapered to 10 mg daily or less. African Americans comprised 39% of the cohort, and Hispanic/Mestizo patients comprised 40%.
Among the African American patients, 33% in the treatment group, compared with 16% in the placebo group, achieved complete renal response. This difference was not statistically significant.
This finding is important, because while low-dose cyclophosphamide – the "Euro-Lupus regimen" – has been shown to be as effective as standard and more toxic higher dosing, studies had primarily included a European Caucasian population. It was unclear whether the low-dose regimen would be as effective in a multiracial and multiethnic population, said Dr. Rovin of Ohio State University Medical Center.
No differences were seen between the treatment and control groups with respect to anti-dsDNA or complement levels and/or the frequency of serious or infectious adverse events or study withdrawals.
Of note, azathioprine was stopped in treatment group patients who achieved complete renal response – but not control group patients who achieved complete renal response. These patients were followed to 52 weeks. At that time, 50% and 62% of the treatment group and control group patients, respectively, who were complete responders at 24 weeks still met the criteria for complete response, Dr. Rovin said.
While abatacept did not increase complete response rates, the treatment was associated with maintenance of complete renal response to 1 year despite discontinuation of maintenance immunosuppression in the treated patients and continued azathioprine treatment in the control group. This suggests that abatacept may reduce the need for maintenance immunosuppression, he said.
While it was disappointing that the addition of abatacept to background induction therapy with low-dose IV cyclophosphamide and corticosteroids did not improve the complete renal response rate in this study – despite murine models suggesting that the use of abatacept and IV cyclophosphamide act synergistically to arrest lupus nephritis progression – the findings offer two very important lessons for clinical practice, he said.
"We can take the low-dose cyclophosphamide regimen and potentially use that with good results in our [multiethnic, multiracial] patient population that we see here in this country, and I think that’s a huge step forward. It gives us another option to use besides mycophenolate mofetil and high-dose cyclophosphamide," he said, adding that the low-dose IV cyclophosphamide regimen is well tolerated and delivers a total dose of only 3 g of the drug – a dose that generally does not predispose to premature ovarian failure.
This is particularly important, because women of childbearing years comprise a majority of the patient population with lupus nephritis, he explained.
"We know from the Euro-Lupus trial that the low-dose regimen, over 10 years, provided the same maintenance of renal function as the high-dose regimen, so we have very good long-term follow-up. We don’t quite have that yet with mycophenolate mofetil, so I think that for those of us who are very frequent users of cyclophosphamide, this is a very good alternative to the high-dose, highly toxic regimen that has for so long been the standard of care," he said.
This study was funded by the National Institute of Allergy and Infectious Diseases via the Immune Tolerance Network. Bristol Myers Squibb provided the study drug. Dr. Rovin reported ties to Genentech, Questcor, TEVA, Biogen-IDEC, HGS, Johnson & Johnson, Roche, BMS, and TG Therapeutics.