Combination therapy for management of pemphigus patients with unexpected therapeutic response to rituximab: A report of five cases.

Key Clinical Message: The immunosuppressant agents should be considered earlier in the course of treatment with rituximab, possibly after the unfavorable response at first cycle of treatment, especially in male patients and those with high BMI. Abstract: Rituximab (RTX) has recently been proposed as an alternative first-line therapy for pemphigus patients. However, there are some rare reports of worsening of pemphigus following RTX therapy in the literature. This study aimed to evaluate the efficacy and safety of using a combination treatment of mycophenolate mofetil or dapsone and methotrexate in case of nonresponse, exacerbation or development of allergic reactions following rituximab therapy in pemphigus patients. In this case series, archive files of pemphigus patient in a tertiary care hospital from 2016 to 2021 who were treated with rituximab were reviewed and those with failure in treatment process including nonresponsiveness, exacerbation or development of allergic reactions to rituximab were identified and assessed. The study includes five patients out of 1245 RTX-treated patients, who did not respond to RTX (one patient) or experienced an exacerbation of disease (two patients) or development of allergic reactions (two patients). Male patients with high BMI (BMI > 25) whose response to rituximab was not good at first cycle and happened to receive rituximab later in the course of disease, had highest number of relapses and benefited the most from this combination immunosuppressive treatment as an alternative for repeating rituximab cycles. The lower risk of relapse and a better chance of remission might indicate the efficacy of adjuvant immunosuppressant therapy in patients with no-response, exacerbation, or allergic reaction to rituximab. These therapeutic effects were better observed in patients who received lower doses of rituximab which could suggest that the immunosuppressant agents should be considered earlier in the course of the disease, possibly after the first failed trial of rituximab therapy.