AMSTERDAM – Despite some “encouraging signs” seen in a cross-sectional study, it remains difficult to determine whether a patient with systemic lupus erythematosus (SLE) will respond to off-label rituximab therapy, according to David Isenberg, MD.
The presence of constitutional symptoms, which includes fatigue, at baseline were associated with a favorable response to rituximab at 6 months (odds ratio, 7.35; P = .01). Conversely, having more than one anti–extractable nuclear antigen (anti-ENA) antibody was associated with a worse response to rituximab at 12 months (OR, 0.33; P = .032).
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“It’s not a cure for lupus, that’s obvious, but used at the appropriate time in the right sort of patients, it can be very helpful,” Dr. Isenberg said in an interview at the European Congress of Rheumatology. That’s both in terms of improving disease activity and reducing the use of glucocorticosteroids and immunosuppressive drugs, he noted.
“The great mystery, as with all drugs, is: Are there any markers which might tell us that the disease is going to do better with rituximab than perhaps with another form of medication, or is it just saying to us, ‘Whatever you do, it doesn’t make much difference’?” Dr. Isenberg said. He discussed the results of a study involving the first 121 patients treated with rituximab at his institution, University College London Hospital (UCLH); he noted this is one of the largest single-center cohorts of individuals with SLE who have used rituximab.
The aim of the study, which was presented at the congress by Hiurma Sánchez Pérez, MD, was therefore to try to find demographic, clinical, and serological markers that might help in predicting the response to rituximab in SLE patients.
Sara Freeman/MDedge News
Dr. Hiurma Sánchez Pérez
Response to treatment was determined using the British Isles Lupus Assessment Group (BILAG) Index. Patients who initially had markedly (BILAG A) or moderately (BILAG B) active disease but who no longer fell into these categories at 6 or 12 months were designated as responders. Those who remained were designated as nonresponders. In addition, any person moving into category A or B of the BILAG Index was said to have relapsed because of a flare in disease activity.
At 6 and 12 months, a respective 85% and 70% of patients exhibited a response to rituximab. Just under a quarter (24%) relapsed before 1 year, Dr. Sánchez Pérez reported.
Most of the patients in the cohort were white (n = 50) or Afro-Caribbean (n = 38), but ethnicity did not seem to play a role in predicting whether patients would respond to rituximab treatment.
Aside from constitutional symptoms and having more than one anti-ENA antibody, there were no other biological markers of response that remained significant after multivariate analysis.
The mean time to flare after rituximab was nearly 8 months, Dr. Sánchez Pérez said. Arthritis was the main manifestation seen during relapse (41% of patients), and mucocutaneous symptoms occurred in 21%. Biological markers of flare at 12 months after multivariate analysis were musculoskeletal symptoms at baseline (OR, 0.26; P = .039) and being anti-RNP antibody positive (OR, 10.56; P = .03).
“There were one or two encouraging signs,” said Dr. Isenberg, who was the senior author of the study. “Unfortunately, what I think the data show us, it remains pretty hard to know how any individual patient is going to respond to B-cell depletion using rituximab.”
Dr. Sánchez Pérez reported having no disclosures in relation to the study. Dr. Isenberg was one of the first people to use rituximab to treat patients with lupus but reported having no other competing interests.