Benefit of Ixazomib Unclear in Post-Transplant Maintenance Therapy for High-Risk Myeloma

By Cecilia Brown - Last Updated: November 22, 2022

The benefit of maintenance therapy with ixazomib after allogenic hematopoietic stem cell transplantation (HSCT) in high-risk multiple myeloma (MM) patients “could not be firmly established” in a clinical trial, investigators reported.

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The multicenter, double-blind, placebo-controlled, phase II trial evaluated maintenance ixazomib after allogeneic HSCT for high-risk MM patients. The study was led by Qaiser Bashir, MD, of the University of Texas MD Anderson Center, and Taiga Nishihori, MD, of the Moffitt Cancer Center, and the results were published in Transplantation and Cellular Therapy.

Patients with high-risk MM (defined as those with poor-risk cytogenetics, plasma cell leukemia, or relapse within 24 months after autologous transplant) were randomized to receive treatment with ixazomib 3 mg or placebo after allogeneic HSCT. The trial enrolled 57 patients, with 52 receiving allogeneic HSCT and 43 patients receiving treatment with ixazomib (n=21) or placebo (n=22) after allogeneic HCT.

The trial’s primary endpoint was progression-free survival (PFS) post-randomization.

There was no significant difference in PFS rates reported at 21 months post-randomization between the ixazomib and placebo arms (55.3% and 59.1%, respectively; P=1.00). Overall survival (OS) was similar between the ixazomib and placebo arms at the same time point (94.7% vs 86.4%, respectively; P=.17).

PFS was 52% and OS was 82% at 24 months post-allogeneic HSCT in an analysis of all patients from both arms who received transplants.

“The study failed to meet the primary objective of PFS improvement with ixazomib; however, the results are confounded by premature study closure, thus preventing definite conclusions,” the authors wrote. “The question of ideal post-allogeneic [HSCT] maintenance in MM, therefore, remains largely unanswered.”

Despite the study’s limitations and the remaining avenues for investigation, its results “show safety and durable disease control with allogeneic HSCT in high-risk myeloma patients,” the investigators concluded.

Bashir Q, Nishihori T, Pasquini MC, et al. Multicenter phase II, double-blind placebo-controlled trial of maintenance ixazomib after allogeneic transplantation for high-risk multiple myeloma: results of the BMT CTN 1302 Trial. Transplant Cell Ther. 2022. doi:10.1016/j.jtct.2022.07.007

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