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. MATERIALS AND 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 (Hazard ratio [HR] 0.75, 95% confidence interval [CI] 0.57-0.98; P = .032), whereas nodal involvement predicted inferior survival (HR 1.36, 95% CI 1.01-1.93; P = .043). Following adjustment, both associations were attenuated to non-significant trends (SS: aHR = 0.70, 95% CI: 0.47-1.03, P = .067; nodal involvement: aHR 1.40, 95% CI 0.95-2.06; P = .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 < .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.