PS1260 EFFICACY OF MOGAMULIZUMAB IN PREVIOUSLY TREATED PATIENTS WITH LESS ADVANCED MYCOSIS FUNGOIDES: RESULTS FROM THE MAVORIC STUDY

Abstract

Background:In the MAVORIC Phase 3 study, patients (pts) with previously treated mycosis fungoides (MF)/Sézary syndrome (SS) stage IB‐IVB who received mogamulizumab (MOGA) had significantly prolonged progression‐free survival and greater overall response rates (ORRs) compared to pts on vorinostat (VORI) (Kim et al. Lancet Oncol 2018). Less advanced MF (stage IB/IIA) is a chronic skin malignancy that can involve blood and lymph nodes and may require many lines of systemic therapy over the disease course.Aims:This post‐hoc analysis specifically examined efficacy and safety of the recently approved MOGA in stage IB/IIA MF pts.Methods:In MAVORIC, stage IB‐IVB MF/SS pts who were treated with ≥1 prior systemic therapy were randomized to MOGA or oral VORI. In the post‐hoc analysis, time to next treatment (TTNT) was defined as time to any therapy excluding topical steroids or focal radiation treatment. ORR was based on global composite response in 4 disease compartments – skin, blood, lymph nodes, and viscera – achieved at 2 consecutive visits at least 8 weeks apart. Individual compartment responses were also assessed.Results:A total of 85 pts with stage IB/IIA CTCL were included (MOGA, IB n = 15, IIA n = 21; VORI, IB n = 27, IIA n = 22). Overall, 24% (10/42) of IB pts and 28% (12/43) of IIA pts had received ≥6 prior therapies. Median TTNT with MOGA in IB pts was 11.5 months (mo) (95% CI, 1.4,16.0) compared to 3.1 mo (95% CI, 2.7, 5.3) with VORI; in IIA pts, median TTNT was 10.1 mo (95% CI, 5.5, 12.6) and 4.9 mo (95% CI, 2.4, 8.0), respectively. ORR in IB pts receiving MOGA and VORI was 20% (3/15) and 18.5% (5/27), respectively; ORR in IIA was 19% (4/21) and 0% (0/22), respectively. For stage IB and IIA, compartmental response rates with MOGA were – skin: 20% (3/15) and 38% (8/21), blood: 0% (0/2) and 75% (6/8), and lymph nodes: 0% (0/0) and 15% (3/20), respectively. Adverse events were generally manageable and consistent with the ITT population.Summary/Conclusion:Though MAVORIC was not powered to determine treatment effect by disease stage, this post‐hoc analysis of TTNT, ORR, and compartmental response in stage IB/IIA demonstrates meaningful clinical benefit with MOGA in previously treated, less advanced MF pts.