Multiple Myeloma Coverage from Every Angle

Subgroup Analysis of Isatuximab-Based Therapy for Resistant Myeloma

By: Lauren Harrison, MS
Posted: Tuesday, July 28, 2020

Concurrent therapy using the monoclonal antibody isatuximab, pomalidomide, and dexamethasone led to a significant increase in progression-free survival and overall response rate compared with pomalidomide and dexamethasone in patients with relapsed or refractory multiple myeloma and/or plasmacytomas. Meral Beksac, MD, of Ankara University,Turkey, presented work she completed with colleagues at the virtual edition of the 25th European Hematology Association Annual Congress (EHA25 Virtual; Abstract EP978).

This phase III trial recruited 307 patients with relapsed or refractory multiple myeloma and/or plasmacytomas. Patients were randomly assigned 1:1 to receive either isatuximab/pomalidomide/dexamethasone or pomalidomide/dexamethasone. Patients were administered 10 mg/kg of isatuximab once a week for 4 weeks, decreasing to every other week afterward. The 24 study patients with plasmacytomas at study entry underwent CT or MRI scan at baseline, and images were repeated throughout the study.

The progression-free survival was increased in the group receiving isatuximab (4.57 months) compared with pomalidomide plus dexamethasone alone (1.56 months, hazard ratio = 0.22). The probability of progression-free survival at 12 months was 0.31 and 0.00 in the triplet- and doublet-therapy groups, respectively.

The overall response rate was improved among patients with soft-tissue plasmacytomas receiving isatuximab, with 50% responding compared with 10% in those receiving pomalidomide and dexamethasone. A very good partial response was seen in three patients with plasmacytomas in the isatuximab group and in one patient in the control group. Two of the patients in the isatuximab arm showed complete remission by cycle 3 and a significant reduction in the extramedullary lesions at cycle 4.

Grade 3 or higher adverse events occurred in 85.7% of patients in the triplet-therapy group and 70% of patients in the dual-therapy group. Although no grade 3 or higher infusion reactions were reported, 42.9% of patients in the isatuximab group experienced an infusion reaction.

Disclosure: The study authors reported no conflicts of interest.

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