LAUSR

Ixazomib, the first oral proteasome inhibitor (PI), has been approved for the treatment of relapsed refractory multiple myeloma (RRMM) in combination with lenalidomide and dexamethasone, based on the TOURMALINE-MM1 phase 3 trial, which demonstrated the efficacy and safety of this all-oral triplet, compared with lenalidomide-dexamethasone. However, clinical trial outcomes do not always translate into real-world outcomes. The aim of this study was to assess the outcomes of ixazomib-based combination for treatment of patients with RRMM in a real-world setting. All consecutive RRMM patients who received at least one cycle of ixazomib-based treatment combination between June 2013 and June 2018 were identified. Data was extracted from medical charts focusing on demographics, disease characteristics, prior treatment, and responses. Primary endpoint was progression-free survival (PFS); secondary endpoints included overall response rate (ORR), overall survival (OS), safety, and tolerability. A total of 78 patients across 7 sites were retrospectively included. Median follow-up was 22 months. Median age was 68 (range 38–90). Sixty-four percent received ixazomib in 2nd line, 19% in 3rd line. Overall, 89% of patients had been exposed to PIs (bortezomib 87%) prior to IRd, 41% to IMiDs. Twenty-nine (48%, of 60 available) had high ( t (4:14), t (14:16), del17p) or intermediate (+1q21) risk aberrations. Most patients (82%) received ixazomib in combination with lenalidomide and dexamethasone. An exploratory assessment for disease aggressiveness at diagnosis was classified by a treating physician as indolent (rapid control to protect from target organ damage not required) vs aggressive (imminent target organ damage) in 63% vs 37%, respectively. Treatment was well tolerated, with a low discontinuation rate (11%). Median PFS on ixazomib therapy was 24 months (95% CI 17–30). PFS was 77% and 47% at 12 and 24 months, respectively. Median OS was not reached; OS was 91% and 80% at 12 and 24 months, respectively. Higher LDH, older age, and worse clinical aggressiveness were associated with worse PFS, whereas a deeper response to ixazomib (≥ VGPR) and a longer response to first-line bortezomib (≥ 24 m) were associated with an improved PFS on ixazomib. No effect on PFS was found for cytogenetic risk by FISH, ISS/rISS, and prior anti-myeloma treatment. Ixazomib-based combinations are efficacious and safe regimens in RRMM patients in the real-world setting, regardless to cytogenetic risk, with a PFS of 24 months comparable with clinical trial data. This regimen had most favorable outcomes among patients who remained progression-free more than 24 months after a bortezomib induction and for those who have a more indolent disease phenotype.