Real-world experience with mogamulizumab for mycosis fungoides and Sézary syndrome

Background Mogamulizumab is an established treatment option for relapsed/refractory mycosis fungoides (MF) and Sézary syndrome (SS); however, large-scale real-world outcome data remain limited. Methods We conducted a retrospective cohort study on patients with MF or SS who received treatment with mogamulizumab using TriNetX. Results A total of 394 patients were included [182 (46.2%) MF, 212 (53.8%) SS]. The median follow-up was 31.5 months. The 1- and 3-year OS rates were 85.7% and 73.4%, respectively. Corresponding rates among MF and SS patients were 82.0% versus 88.2% and 69.3% versus 76.7%. In univariable analyses, SS was associated with improved OS (HR 0.75, 95% CI 0.57–0.98; p=0.032), whereas nodal involvement predicted inferior survival (HR 1.36, 95% CI 1.01–1.93; p=0.043). Following adjustment, both associations were attenuated to non-significant trends (SS: aHR=0.70, p=0.067; nodal involvement: aHR 1.40, 95% CI 0.95–2.06; p=0.089). Overall, 154 patients (39.1%) required subsequent systemic therapy, with the 1- and 3-year cumulative incidence being 31.1% (95% CI: 25.7-35.7%) and 41.0% (95% CI: 35.1-46.9%), respectively. Elevated LDH independently predicted shorter TTNT (acsHR 1.62, 95% CI 1.29–2.03; p<0.001). The 12-month incidences of infection, sepsis, hospitalization, and emergency department visits were 39.8%, 13.5%, 34.3%, and 20.6%, respectively, with similar incidences between MF and SS. Conclusions In this large real-world cohort, mogamulizumab was associated with durable survival, prolonged treatment-free intervals, and the outcomes observed were consistent with the pattern seen in the MAVORIC trial. Micro-Abstract Real-world evidence on mogamulizumab for mycosis fungoides (MF) and Sézary syndrome (SS) remains limited. We conducted a retrospective analysis of 394 patients with MF/SS treated with mogamulizumab within TriNetX. Three-year OS was 73.4%, while the 3-year cumulative incidence of subsequent systemic therapy was 41.0%. Twenty-five (16.2%) patients proceeded to stem cell transplant; the median interval from last mogamulizumab dose was 314 days, with a 48.0% incidence of any-grade graft-versus-host disease. Elevated lactate dehydrogenase independently predicted earlier treatment transition. Overall, mogamulizumab provides favorable real-world outcomes and durable clinical benefit in patients with MF and SS.