P084 Translating clinical trials into practice: real-life experience using mogamulizumab in the treatment of mycosis fungoides and Sézary syndrome in a single centre of 29 patients

Abstract Mogamulizumab has demonstrated efficacy in targeting malignant cells in Sézary syndrome (SS) and mycosis fungoides (MF). This retrospective real-world evaluation study describes the outcomes of mogamulizumab within a tertiary cutaneous T-cell lymphoma service in the UK. Patients were treated with mogamulizumab for SS or MF. Outcomes were evaluated based on Olsen’s criteria (Olsen EA, Whittaker S, Willemze R et al. Primary cutaneous lymphoma: recommendations for clinical trial design and staging update from the ISCL, USCLC, and EORTC. Blood 2022; 140: 419–37). The primary outcome was the objective response rate lasting ≥ 4 months (ORR4). Secondary outcomes were objective response rate (ORR), progression-free survival (PFS), time to response, and time to next treatment. Adverse drug reactions (ADRs) were reported based on the Common Terminology Criteria for Adverse Events v5.0. In total, 29 patients were analysed (20 with SS and nine with MF). The mean age at treatment initiation was 66 years (SD 12.4); 18 (62%) patients were male and 11 female. The median time from diagnosis to mogamulizumab initiation was 35.3 months (range 3.1–240). All received prior systemic therapy, with a median number of 2 (interquartile range 1.0–4.0). No patients had visceral involvement. Overall, 38% of patients were staged IVA1 (SS n = 10, MF n = 1) and 45% patients had stage IVA2 disease (SS n = 10, MF n = 3). In total, 90% of patients had blood involvement (SS B2, n = 20; MF B1, n = 6). The median treatment period was 7.0 months (range 1.0–55.3). The ORR4 was 27.6%, and ORR was 39.3% [complete response (CR) 14.3%, partial response (PR) 25.0%]. CR was reached in 4 of 19 patients with SS and none with MF, while PR was reached in 6 of 19 with SS and 1 of 9 with MF. The median times to PR and CR were 4.5 months (range 2.3–11.7) and 14.5 months (range 7.5–19.6), respectively. Median PFS was 9.0 months (range 0.5–59.9); median PFS times in SS and MF were 9.7 months (range 0.5–59.9) and 5.1 months (range 1.6–27.9), respectively. The blood ORR was 92.3% (CR 84.6%, PR 7.7%). The skin ORR was 37.9% (CR 20.7%, PR 17.2%); by condition the ORRs were 45.0% in SS (CR 25.0%, PR 20.0%) and 22.2% in MF (CR 11.1%, PR 11.1%). The median time to next treatment (n = 12) was 7.2 months (range 3.3–22.9). The most common ADRs were rash (36%, grade 1) and infusion-related reaction (14%: grade 2 n = 1, grade 3 n = 3). Two ADRs, neutropenia (grade 4, n = 1) and persistent idiopathic headache (n = 1), prompted discontinuation of mogamulizumab treatment. In conclusion, this retrospective evaluation confirms the real-world efficacy of mogamulizumab, with results similar to those reported in clinical trial data.