Using the same dosing as treatment for lymphoma and older age were linked with higher odds of complete remission off therapy.
In 2018, the FDA granted rituximab an indication for the treatment of pemphigus vulgaris (PV), and the antibody has emerged as a first-line treatment for the rare autoimmune disease that affects the skin and mucous membranes with progressive blistering. Despite the fact that rituximab has changed the treatment landscape for PV, questions remain as to prognostic factors linked with remission in PV after treatment.
Recently, researchers from a single center reported on a retrospective study of 112 patients whose PV was treated with rituximab from 2005 to 2016, and they found that using the same dosing as treatment for lymphoma and older age were linked with higher odds of complete remission (CR) off therapy.
In the study, most patients were male, and had a median age of 52.3 years (range, 20.0-89.3 years). Median body mass index (BMI) was 28.6 (range, 18.6-52.5). Dosing was administered at either a lymphoma regimen dose of 375 mg per m2 weekly for 4 weeks or at a rheumatoid arthritis (RA) regimen dose of 1000-mg infusions 14 days apart; of the 244 total rituximab cycles administered, 154 cycles were given at the lymphoma dose, and 90 cycles were given at the RA dose. Median follow-up from the first cycle of rituximab was 37.8 months (range, 12.1-130.7 months).
Following 1 cycle of therapy, 54 patients (48.2%) achieved CR off therapy, 15 patients (13.4%) achieved CR on minimal therapy, 10 patients (8.9%) achieved partial remission (PR) off therapy, 14 patients (12.5%) achieved PR on minimal therapy, and 19 patients (17.0%) were nonresponders.
More patients achieved CR off therapy when they had additional rituximab cycles: 17 patients (15.2%) required 2 cycles, 4 patients (3.6%) required 3 cycles, 4 patients (3.6%) required 4 to 7 cycles, and 33 patients (29.5%) did not achieve CR off therapy.
Of the 79 patients (70.5%) who achieved CR off therapy at any time during the study period, the median time to reaching that outcome was 10.5 months (range, 2.0-49.8 months). Length of follow-up was not a confounding factor for the nonresponders, the authors note.
In univariate and multivariate analyses, no significant difference in the rate of CR off therapy was associated with sex, disease subtype, or disease duration before rituximab.
However, in a univariate analysis, the odds of achieving CR off therapy with 1 cycle of rituximab in patients 65 years or older were higher than the odds for patients aged 45 years or younger (odds ratio [OR], 4.60; 95% CI, 1.42-14.86; P = .01). Additionally, the lymphoma regimen dose was associated with increased odds of achieving CR off therapy compared with the odds for achieving the same with the RA regimen dose (OR, 2.65; 95% CI, 1.16-6.05; P = .02).
BMI of 35 or higher was associated with decreased odds of CR off therapy (OR, 0.25; 95% CI, 0.08-0.82; P = .02).
A multivariate analysis also showed that patients receiving the lymphoma dose were more likely to achieve CR off therapy, and a higher rate of CR was observed with increasing age. BMI of 35 or higher was once again linked with decreased odds of CR.
The study was limited by its retrospective design, single-center setting, and lack of quantitative measures of disease activity, but the study’s authors note that these data, which represent the largest retrospective cohort study of patients with PV treated with rituximab to date, can help guide patient and physician expectations about outcomes with rituximab therapy.
Kushner CJ, Wang S, Tovanabutra N, Tsai DE, Werth VP, Payne AS. Factors associated with complete remission after rituximab therapy for pemphigus [published online October 23, 2019]. JAMA Dermatol. doi: 10.1001/jamadermatol.2019.3236.