DP071 | QUALITY AND DURATION OF RESPONSES TO MOGAMULIZUMAB IN CUTANEOUS T-CELL LYMPHOMA: AN INSIGHT INTO DURABLE OUTCOMES

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common cutaneous T-cell lymphomas. In the phase 3 MAVORIC trial, mogamulizumab showed efficacy in patients who had received at least one systemic therapy, with objective responses in 28% of cases and a median progression-free-survival of 7.7 months (Kim et al, Lancet Oncol 2018). However, little is known about the outcomes of patients who maintain a durable response to mogamulizumab. We collected data from 21 patients treated with mogamulizumab in Italy and achieved at least a partial response (PR). Mogamulizumab was administered at 1 mg/kg on days 1, 8, 15 and 22 of the first cycle, then on days 1 and 15 in subsequent cycles until disease progression or unacceptable toxicity. Disease staging and response categorization were performed according to internationally accepted recommendations (Olsen et al, Blood 2022). Patients with a complete response (CR) or PR at any time during treatment were eligible for this analysis. Sixteen patients had SS and 5 patients had MF, predominantly stage IVA1 (66.7%), IIIB (14.3%), and IIA-IIB (9.5% each). Blood involvement was B2 in 66.7%, B1 in 19.0% and B0 in 14.3%. The median age at mogamulizumab start was 73.6 years (range: 50.2-88.5), and the median time from diagnosis of MF/SS to initiation of treatment was 29.3 months (range: 3.6-185.3). Nearly 62% of patients were 70 years or older (43% were 75 years or older) and had received a median of 3 prior systemic therapies (range: 1-7). After a median of 7 doses of mogamulizumab (range: 2-54), patients achieved CR and PR in 57.1% and 42.9% of cases, respectively, with a median time to response of 7.7 months. Depending on the affected compartment, CRs in skin, blood, and lymph nodes were 57.1%, 88.9%, and 100%, respectively. No patient had visceral (M1) spread. The median duration of response, time to next treatment, and overall survival were 67.0%, 67.9%, and 88.4%, respectively, at a median follow-up of 35.3 months. Nine patients (42.9%) developed mogamulizumab-associated rash, which was the cause of discontinuation in 3 of 9 patients. Five patients (23.8%) required further treatment after mogamulizumab failure. Responses obtained with mogamulizumab can be long-lasting even in highly pretreated patients with MF and SS. Achieving a durable response is a clinically important outcome for patients suffering from these incurable diseases that also severely impact their quality of life.