A Systematic Review and Meta-Analysis: Efficacy and Toxicity Profile of Ixazomib for Treatment of Multiple Myeloma

Background: Ixazomib (Ixa) is the first FDA approved oral proteasome inhibitor to be used for relapsed and refractory multiple myeloma (MM). We conducted a comprehensive systematic review and meta-analysis of all published prospective clinical trials to analyze the efficacy and safety of ixazomib in newly diagnosed multiple myeloma (NDMM) and relapsed/refractory multiple myeloma (RRMM). Method: After review of literature (last updated June 30, 2018) using database searches (Pubmed, Embase, Cochrane Library, Web of Science and Clinical Trials.gov), from a total of 1290 studies, only fifteen clinical trials (n=1387) met the inclusion criteria for RRMM and eight clinical trials (n=537) met criteria for NDMM. CMA software v.3 was used for meta-analysis. Heterogeneity among studies was assessed using the I2 test. A random-effect model was applied. Result: Based on pooled analysis, an overall response rate (ORR) of 40.6% (95% CI:19.4-66.0) with a very good partial response or better (≥VGPR) of 15.7% (95% CI: 6.8-32.1) in RRMM and ORR (CR+VGPR+PR) of 77.5% (95% CI: 73.1-81.4, I2=48.05) in NDMM was observed. Most common grade (G) ≥ 3 adverse events (AE) based on regimen were calculated using pooled analysis in MM patients. Ixazomib Based Regimen in RRMM: Ixazomib as monotherapy: Four studies (n=192) evaluated the efficacy of ixazomib as a single agent. On subgroup pooled analysis on Ixa as monotherapy, an ORR of 22.7% (95% CI: 13.3-35.9, I2=45%) was observed with ≥VGPR of 7.8% (95% CI: 2.7-20.3). Pooled analysis for safety profile on most common G ≥ 3 adverse events (AEs) were thrombocytopenia 32.3% (95% CI: 22.4-44.2), neutropenia 21.5% (95% CI: 12.6-34.1), diarrhea 13.1% (95% CI: 6.8-23.9), fatigue 11.6% (95% CI: 7.4-17.7) and peripheral neuropathy 2.2% (95% CI: 0.7-6.6). Ixazomib in two drug regimen: In RRMM, two clinical trials (n=92) evaluated the efficacy of Ixa weekly with dexamethasone (D). In this subgroup pooled analysis, ORR of 40.7% (95% CI: 22.8-61.5, I2=41.76%) with ≥VGPR of 19.5% (95% CI: 4.6-52) was calculated. One study reported event-free survival (EFS) of 8.4 months(4.5-12.8) with a 1-year overall survival rate of 96% (95% CI: 91-100). In our analysis for safety (n=102), common G≥ 3 AEs calculated was thrombocytopenia in 20% (95% CI: 7.5-43.7), neutropenia in 14.3% (95% CI: 3.7-41.6), fatigue in 9.1% (95% CI: 5.0-16.2), diarrhea in 5.7% (1.1-25.5), nausea in 5.7% (95% CI: 1.4-20.2) and peripheral neuropathy in 5.7% (95% CI: 1.4-20.2). Ixazomib in three drug regimen: In RRMM, the efficacy of Ixa was evaluated inten clinical trials (n=646), an ORR of 56.3% (95% CI: 41.8-65.5, I2=82%) with ≥VGPR of 22.8% (95% CI: 13.2-36.4) was noted. Best response was seen when Ixa was used in combination with lenalidomide (R) and dexamethasone, with reported ORR of 78.3%. Common AEs were neutropenia 23.5% (95% CI: 16-33.1), thrombocytopenia 18.8% (95% CI: 13.4-25.6) anemia 10.5% (95% CI: 8.2-13.2), diarrhea 6.3% (95% CI: 3.4 -11.3), fatigue 4.2% (95% CI:2.7-6.4), nausea 1.8% (95% CI: 0.9-3.5) and peripheral neuropathy 2.3% (95% CI: 1.3-3.9). Ixazomib Based Regimen In NDMM: Pooled analysis of subgroup study for combination regimen of Ixa as IRD, Ixa-Thalidomide (T)-D, Ixa-Cyclophosphamide (C)-D, and with Ixa -melphalan-prednisone (IMP), their estimated ORR was 83.7% (95% CI: 75.6-89.5), 80.8% (95% CI: 72.8-86.9), 75% (95% CI: 66.6-82) and 66% (95% CI: 52.4-77.4) respectively. We also measured the efficacy of Ixa as a maintenance therapy, estimated ORR was 81.5% (95% CI: 36.6-97.1, I2=90.5%). In one phase II maintenance study (n=64), a combination of IR receiving patients (n=34), an ORR of 90.4% with VGPR of 53% was reported. Median progression-free survival (PFS) was not reached after a median follow up of 37.8 months and estimated 2-year PFS was 81%. Common G≥3 AEs in NDMM patients were neutropenia 21.6% (95% CI: 11.2-37.6), thrombocytopenia 15.9% (95% CI: 4.7- 42), infections 15.2% (95% CI: 10.3-21.9) and peripheral neuropathy 7.9% (95% CI: 4.7-13). Conclusion: In our pooled analysis (95%CI), Ixazomib has shown promising efficacy both in NDMM as well as RRMM. Especially in three drug regimen it showed an estimated ORR of 84.8% in NDMM and 56.3% RRMM.Cytopenia was a common side effect.Peripheral neuropathy was noted to be a rare side-effect (2.6%) in RRMM. Further studies are required to evaluate efficacy and safety of ixazomib in combination therapies in NDMM. Disclosures No relevant conflicts of interest to declare.