Mendez LMG, et al. - Using data from the Lupus Nephritis Assessment with Rituximab (LUNAR) study, researchers described the variability of peripheral blood B cell depletion after rituximab and evaluated its relationship with complete response in patients with lupus nephritis. In patients with lupus nephritis treated with rituximab from the LUNAR trial, substantial variability in peripheral blood B cell depletion was noted. They found that achievement of complete peripheral depletion, and also the rapidity and duration of complete peripheral depletion, were correlated with complete response at week 78.

Methods

• For this investigation, 68 participants treated with rituximab were analyzed.
• Researchers characterized peripheral blood B cell depletion as 0 cells/µl, termed “complete peripheral depletion,” evaluated for more than 78 weeks.
• They used logistic regression to evaluate the relationship between characteristics of complete peripheral depletion and complete response (defined as urine protein-to-creatinine ratio <0.5 mg/mg, and normal serum creatinine or an increase in creatinine <15%, if normal at baseline), assessed at week 78.

Results

• According to the findings obtained, an aggregate of 53 (78%) members achieved complete peripheral depletion (0 cells/µl) in a median time of 182 days (interquartile range, 80–339).
• It was observed that the median duration of complete peripheral depletion was 71 days (interquartile range, 14–158).
• They found that 25 (47%) participants with complete peripheral depletion achieved complete response, compared with two (13%) without.
• Findings suggested an association of complete peripheral depletion with complete response (unadjusted odds ratio [OR], 5.8; 95% confidence interval [95% CI], 1.2 to 28; P=0.03).
• It was noted that longer time to achieving complete peripheral depletion was related to a lower likelihood of complete response (unadjusted OR, 0.89; 95% CI, 0.81 to 0.98; P=0.02).
• They discovered that complete peripheral depletion lasting >71 days (the median) was correlated with complete response (unadjusted OR, 4.1; 95% CI, 1.5 to 11; P=0.008).