Real-world outcomes of mogamulizumab retreatment in cutaneous T-cell lymphoma: A single-center retrospective study.

Abstract

7096 Background: Mogamulizumab, monoclonal antibody against CCR4, is approved for relapsed/refractory cutaneous T cell lymphoma (CTCL), with an overall response rate of 28%in CTCL. The most common toxicity is mogamulizumab-associated rash (MAR), occurring in ~24% of patients and reported in up to 88% of responders, frequently leading to treatment discontinuation. Given the limited therapeutic options in CTCL, retreatment with mogamulizumab is clinically appealing but not well described. We report a single center experience with mogamulizumab retreatment in patients with CTCL. Methods: We conducted a single-center retrospective study of all adult patients with CTCL treated with mogamulizumab from 2013 to 2025. Retreatment was defined as reinitiation after a >90-day treatment-free interval. Disease status, patient characteristics, response and toxicity to therapy was collected. Results: Among 54 CTCL patients treated with mogamulizumab, 13 (24%) (MF=7, SS=6) underwent retreatment. Median age at diagnosis was 67 years (range, 44 - 84) and mostly male (69%). Patients had a median of 5 prior systemic therapy lines (range, 3–9). The median interval from initial mogamulizumab discontinuation to retreatment was 11.4 months (range 3.1- 40.2). During initial mogamulizumab exposure, ORR 92.3% (12/13, 8 CR, 4 PR).11 discontinued mogamulizumab due to rash, 1 due to clinical response and 1 with PD. Retreatment dosing schedules included weekly administration in 2 patients (15%), every-2-week dosing in 8 (62%), and every-4-week dosing in 3 (23%). On retreatment, ORR was 38.5% (5/13) with CR in 2 patients and PR in 3, SD in 3 and progressive disease (PD) in 5. Median number of doses on retreatment was 5 (range 1-44). Among retreatment responders (CR/PR; n=5), median DOR was 15.0 months (range, 6.2–28.0). Median PFS from retreatment initiation was 4.0 months (range, 0.0–40.7) and estimated 2 -year OS was 84.6%. Both deaths were unrelated to CTCL progression or mogamulizumab-related toxicity. MAR occurred in 10/13 (76.9%) patients on retreatment. Rechallenge strategies included temporary treatment interruption until resolution of MAR (n=7) and increasing dosing intervals (n=3). Rash was predominantly maculopapular or morbilliform, most commonly involving the trunk and extremities. All MAR events were CTCAE grade 1-2. MAR was managed with topical steroids (n=9), oral steroids (n=1), and cessation of mogamulizumab (n=9). Conclusions: In this real-world, heavily pretreated CTCL cohort, mogamulizumab retreatment demonstrated meaningful clinical activity with durable responses in patients despite prior exposure. Although rash was common, it was most often low to moderate grade, responsive to standard management, and retreatment or rechallenge after resolution was feasible.