Abstract CT120: A randomized, open-label, open-platform, Phase II study evaluating the efficacy and safety of novel spartalizumab (PDR001) combinations in previously treated unresectable or metastatic melanoma (PLATforM)

Background: Significant advancements, including development of immune checkpoint inhibitors and targeted therapies, have transformed outcomes in patients (pts) with unresectable or metastatic melanoma. However, pts who do not respond or who progress while receiving these regimens have limited options. Spartalizumab (PDR001) is a high-affinity, humanized monoclonal antibody blocking the programmed cell death 1 (PD-1) receptor. This study is evaluating combinations of spartalizumab with novel compounds to restore antitumor T-cell activity in pts with melanoma progressing after prior PD-1 blockade therapy. Methods: This randomized, open-label, 2-part, multicenter, open-platform, Phase II study (NCT03484923; PLATforM) will evaluate the safety and efficacy of spartalizumab combination treatment in pts with unresectable or metastatic melanoma progressing after prior anti-PD-1/L1 therapy and, if the tumor harbors a BRAF V600 mutation, a BRAF inhibitor. The primary endpoint is objective response rate per RECIST v1.1, with duration of response and assessment of paired tumor biopsies for biomarkers of antitumor T-cell activity as part of the secondary endpoints. Part 1, “selection”, will begin with 3 combination arms: (1) spartalizumab + LAG525 (LAG-3 antibody), (2) spartalizumab + capmatinib (c-MET inhibitor), and (3) spartalizumab + canakinumab (IL-1β antagonist). The PLATforM study will use an adaptive design during the selection part that allows for dropping arms for futility, adding new arms, and selecting 1 or multiple arms for further expansion. Bayesian methodology will be used with specific probability criteria for futility and efficacy assessments at each interim analysis. Pts (≈ 60-85) will be stratified by baseline lactate dehydrogenase level and randomized equally to all open arms during the selection part. Part 2, “expansion”, will further investigate the efficacy and safety of treatment combination(s) selected during part 1. The sample size for part 2 will be adaptive and based on predictive power calculations considering the results from part 1. Previously presented at ESMO 2018, FPN 1304TiP, Weber et al. Reused with permission. Citation Format: Caroline Robert, Reinhard Dummer, Ana Arance, Antoni Ribas, Jeffrey Weber, Georgina V. Long, John Haanen, Paul Nathan, Paolo A. Ascierto, Eduard Gasal, Anthony D'Amelio, Severine Bettinger, Aislyn D. Boran, Dirk Schadendorf. A randomized, open-label, open-platform, Phase II study evaluating the efficacy and safety of novel spartalizumab (PDR001) combinations in previously treated unresectable or metastatic melanoma (PLATforM) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT120.