Selinexor, daratumumab, bortezomib and dexamethasone for the treatment of patients with relapsed or refractory multiple myeloma: results of the phase II, non-randomized, multicenter GEM-SELIBORDARA study

The treatment landscape for multiple myeloma has significantly evolved in the last decade. Notwithstanding, a large proportion of patients continue to relapse and novel combinations continue to be needed. In this phase 2 study, selinexor, a first-in-class inhibitor of exportin-1 was evaluated in combination with standard daratumumab-bortezomib-dexamethasone (DVd), for the treatment of relapsed and refractory multiple myeloma (RRMM). The aim of the trial was to assess the efficacy and safety of the combination of selinexor with DVd (S-DVd). A total of 57 patients were enrolled in the two parts of the study. Part 1 enrolled a heavily pretreated population with at least 3 prior lines of therapy and part 2 enrolled an early relapse population with at least 1 prior therapy. The primary endpoint was complete response (CR) rate in part 2 and overall response rate (ORR) in part 1. In the latter, 24 patients were treated with a median of 3 prior lines. Overall response rate (ORR) was 50% with 2 CR. Median progressionfree survival (PFS) was 7 months. In part 2, 33 patients were enrolled, with a median of 1 prior lines. ORR was 82% and CR or better was 33%. Median PFS was 24 months. In lenalidomide refractory patients, a median PFS of 22.1 months was observed. Thrombocytopenia was the most common hematological adverse event (69%; grade 3-4: 34%) and nausea, the most frequent nonhematological AE (38%; grade 3-4: 6%). 62% of the patients required dose modifications. In summary, although the primary endpoint of the study was not met, the combination of S-DVd showed encouraging clinical efficacy with a generally manageable safety profile representing a potential option for the treatment of RRMM patients.