Ixazomib vs placebo maintenance for newly diagnosed multiple myeloma (NDMM) patients not undergoing autologous stem cell transplant (ASCT): The phase III TOURMALINE-MM4 trial.

Abstract

8527 Background: Maintenance therapy delays disease progression in non-ASCT NDMM patients. However, in practice, currently used maintenance therapies may be limited to fixed duration due to toxicity and route of administration; additional options are needed. Methods: 706 non-ASCT NDMM patients who received 6–12 months of standard-of-care induction therapy and achieved at least a partial response (≥PR) were randomized 3:2, double-blind, to the oral proteasome inhibitor (PI) ixazomib (n = 425; 3 mg, cycles 1–4, then, if tolerated, 4 mg, cycle 5 onwards) vs placebo (n = 281) on days 1, 8, and 15 of 28-day cycles for ≤2 yrs. Patients were stratified by prior PI exposure (yes vs no), pre-induction International Staging System (ISS) disease stage (I/II vs III), age ( < 75 vs ≥75 yrs), and post-induction best response (complete or very good partial response [CR/VGPR] vs PR). Primary endpoint was progression-free survival (PFS). Results: Baseline characteristics were well balanced. Overall median age was 73 yrs, 38% of patients were aged ≥75 yrs, 35% were ISS stage III, and 22%/40%/38% had CR/VGPR/PR post induction. Overall, 82% of patients received a PI and 33% an immunomodulatory drug as part of their induction regimen. At a median follow-up of 21.1 months, median PFS was 17.4 months with ixazomib vs 9.4 months with placebo (hazard ratio [HR] 0.659, 95% confidence interval [CI] 0.542–0.801, p < 0.001). Significant (p < 0.001) PFS benefit was seen in patients who achieved CR/VGPR post induction (Table). Overall survival data are not yet mature (19% of events); follow-up is ongoing. Treatment-emergent adverse events (TEAEs) were mostly grade 1–2 (37% vs 23% of patients had grade ≥3 TEAEs with ixazomib vs placebo). Common TEAEs for ixazomib vs placebo included nausea (27% vs 8%), vomiting (24% vs 4%), and diarrhea (23% vs 12%); 5% vs 6% of patients had new primary malignancies. No cumulative toxicities were observed. Conclusions: Ixazomib maintenance therapy in non-ASCT NDMM patients showed a clinically meaningful 34% reduction in the risk of progression or death, with a well-tolerated safety profile. Ixazomib is the first oral PI maintenance option for non-ASCT NDMM patients. Clinical trial information: NCT02312258 . [Table: see text]