Real World Clinical Outcomes Based on Race and Ethnicity for Patients with Relapsed Refractory Multiple Myeloma Undergoing Treatment with Bispecific T cell Engagers

Abstract

Introduction

Bispecific T cell engagers (bsAbs) represent a novel therapeutic strategy in relapsed and refractory multiple myeloma (RRMM). This project analyzes clinical outcomes including safety and efficacy for patients with relapsed/refractory multiple myeloma treated with bispecific T cell engagers at the University of Texas MD Anderson Cancer Center, focusing on differences across racial and ethnic groups. However, data is limited regarding outcomes across racial and ethnic subgroups. Our study aims to identify disparities and inform equitable treatment strategies. Understanding these disparities is essential to guide equitable clinical decision-making.

Methods

We conducted a retrospective cohort analysis of 63 RRMM patients treated with bsAbs. Patients were categorized by self-reported race/ethnicity as non-Hispanic White (NHW), non-Hispanic Black (NHB), Hispanic/Latino (H/L), or Other. Clinical characteristics, treatment responses, and toxicity profiles were compared using Fisher’s exact test and Kruskal-Wallis test. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier estimates and log-rank tests.

Results

Significant differences emerged in baseline characteristics across racial/ethnic groups. H/L patients had the highest median number of prior treatment lines (9 vs. 5.5 in NHW; p=0.0177), and all had received prior autologous stem cell transplant (AutoSCT; p=0.0212). NHB patients had a higher proportion of female patients (71.4%) compared to NHW (30.0%; p=0.0189). H/L patients experienced higher rates of thrombocytopenia (70%) than NHW (51.7%), NHB (19.0%), and Other (50%; p=0.0166). The rate of any grade ICANS was significantly lower in H/L patients (0%) compared to NHW (41.4%) and NHB (26.3%; p=0.0423). Platelet nadir differed significantly across groups (p=0.0106), with the H/L and Other groups experiencing the most profound thrombocytopenia. G-CSF support was more frequently required in the H/L group (70%) and Other (100%) compared to NHW (34.5%) and NHB (25%; p=0.0291). Despite these differences in treatment course and hematologic toxicity, no statistically significant differences in best overall response, 30-day or 90-day response, or minimal residual disease negativity were observed across racial/ethnic groups. Median OS was not reached, with 6- and 12-month OS rates of 79% and 73%, respectively, and no significant survival differences across race/ethnicity groups (p=0.7713). Median PFS was 10.6 months (95% CI: 7.75–22.0), also with no significant racial/ethnic variation (p=0.2115).

Conclusions

Significant racial and ethnic differences were observed in baseline disease characteristics, prior treatment exposure, and toxicity profiles, particularly related to hematologic complications. However, treatment response and survival outcomes were not significantly different across groups. These findings underscore the importance of continued evaluation of equitable access and toxicity mitigation strategies in emerging MM therapies.