Self-reported ethnicity and outcomes of newly diagnosed multiple myeloma (NDMM) in the anti-CD38 monoclonal antibody era: A retrospective cohort study.

e19554 Background: Multiple myeloma has a well known disparity in incidence between non-Hispanic Black (NHB) and non-Hispanic White (NHW) persons, but less is known about differences in clinical course by ethnicity for patients treated with upfront anti-CD38 monoclonal antibody (mAb)-containing regimens. We thus performed a retrospective study of clinical outcomes in a diverse NDMM cohort. Methods: We describe 306 adult patients with self-reported ethnicity seen at Columbia University Medical Center, 5/2016-11/2024. Differences in disease characteristics were assessed with Kruskal-Wallis and Fisher’s Exact tests. Outcomes included measurable residual disease (MRD) negativity by flow cytometry (sensitivity: 10 -5 ) and overall survival (OS), analyzed with cumulative incidence methods and restricted mean survival time (RMST). Univariate and multivariate analyses were conducted. Results: Our cohort was comprised of 114 Hispanic, 9 non-Hispanic White (NHW), 65 non-Hispanic Black (NHB), and 118 “Other” patients. Most were ECOG 0-2 (91.8%). Hispanic patients were more likely to be male (66.7% vs 43.2%, p = 0.001/adjusted p = 0.005) and median hemoglobin was higher than in NHB (10.5g/dL vs 8.7, p < 0.001/0.001). Consensus Genomic Score (CGS) high risk disease incidence did not differ among ethnicities. Hispanic patients had lower-risk disease by ISS (p = 0.021/0.067), RISS (p = 0.016/0.063), and R2ISS (p = 0.038/0.102). Most CGS cytogenetic abnormalities were not enriched in Hispanic patients; t(14;20) was seen in 6.8% and 1.9% of NHB and Hispanic patients, respectively (p = 0.048/0.529). Patients of all ethnicities underwent autologous stem cell transplant at similar rates (overall 37.6%, 111/295). There were no differences in 6-month response or response depth. Median follow-up was 33.9 months; median OS was not reached. Cumulative incidence of MRD negativity was similar by ethnicity. Exploratory MRD negativity estimates (τ = 12 months) for Hispanic patients were numerically similar to those of NHB and of combined NHW + Other patients. Formal equivalence with 25% margin was not established (Hispanic vs NHB p = 0.061/0.063; vs NHW+Other 0.063/0.063). Pairwise 12 and 24 month RMST OS analysis demonstrated survival equivalence across all ethnicities and at 36 months showed equivalence among NHB, Hispanic, and Other patients. Ethnicity was not a prognostic factor in multivariate OS analysis. Conclusions: Despite differences in disease characteristics and limitations due to NHW sample size, MRD negativity outcomes did not differ among NHW, NHB, Hispanic, and Other patients. OS estimates were statistically equivalent in all ethnicities at 12 and 24 months. First line regimens containing anti-CD38 mAb appear effective across ethnicities; their administration may mitigate ethnicity-associated survival disparities. Further study is warranted.