Safety and Efficacy of Combination Maintenance Therapy with Ixazomib and Lenalidomide in Post-Transplant Myeloma Patients

• Published in: Blood 2021-11, Vol.138 (Supplement 1), p.4774-4774
• Main Authors: Patel, Krina K., Shah, Jatin J., Feng, Lei, Lee, Hans C., Manasanch, Elisabet E., Olsem, Jasper B., Morphey, Ashley N., Huo, Xiao Jiao, Bashir, Qaiser, Thomas, Sheeba K, Qazilbash, Muzaffar H., Weber, Donna M., Orlowski, Robert Z.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2021-151950

Backrground: Several randomized controlled clinical trials have demonstrated improved outcomes for newly diagnosed multiple myeloma (NDMM) patients who were treated with lenalidomide as maintenance therapy after autologous stem cell transplant (ASCT). Proteasome inhibitors have demonstrated clinical benefit in myeloma patients when used as part of induction and maintenance regimens, and the combination of proteasome inhibitors and lenalidomide in induction regimens has produced strong clinical responses. In this study, the addition of ixazomib to lenalidomide maintenance post-ASCT in NDMM patients was evaluated. Methods: Patients (n=64) were started on maintenance therapy with lenalidomide and ixazomib within 60-180 days of stem cell infusion. Each cycle was defined as 28 days with lenalidomide starting at 10 mg/day orally for 28 days with the option to increase the dose to 15 mg after 3 cycles. Ixazomib was provided at 3 mg (n=48 patients) or 4 mg (n=16 patients) orally on days 1, 8, and 15 of each 28-day cycle. However, ixazomib dose was reduced to 3 mg in all patients based on toxicity observed in other clinical trials of ixazomib at that time. The primary endpoint measured was progression-free survival (PFS), which was defined as the time between ASCT and disease progression or death, whichever occurred first. Results: A total of 64 patients were enrolled on this study between December 4, 2012, and May 13, 2015. Of these patients, 41 (64.06%) were 60 years of age or older and 42 (65.63%) were male. Fourteen patients had high-risk cytogenetic features (+1q21, Del17p, t(14:16), t(4:14)), 50 patients had standard cytogenetic risk features (t(11:14), t(6:14), hyperdiploidy, normal) and 9 patients had International Staging System stage 3 disease. Median PFS (mPFS) for all patients was 73.3 months and has not been reached for those with ISS stage 1 disease. mPFS for ISS Stage 3 disease and high-risk cytogenetic subgroups was 33.8 and 25.4 months, respectively. Twenty-two patients had progressive disease, while 21 patients continue to receive dual maintenance. Response rates deepened over time from baseline post-ASCT for 39 patients. The complete response (CR)/stringent CR rate was 42.9% and median overall survival was not reached with a median follow-up of 62 months (range 25.4 - 82.1 months). Thirty-one patients (48%) had improvement from their baseline response after maintenance therapy: 6 patients improved from PR to VGPR; 7 from PR to stringent CR (sCR)/