Outcomes of elranatamab in relapsed/refractory multiple myeloma: prognostic impact of monocyte count, MyCARe, and R2-ISS.

BACKGROUND

Elranatamab, a bispecific antibody targeting B-cell maturation antigen and CD3, has demonstrated efficacy in relapsed/refractory multiple myeloma (RRMM). However, real-world evidence is limited, and prognostic factors have not been sufficiently evaluated.

METHODS

We retrospectively analyzed patients with RRMM receiving elranatamab between June 2024 and July 2025. Responses were assessed using the International Myeloma Working Group criteria. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Prognostic factors were evaluated using univariate log-rank analysis, including R2-ISS at elranatamab initiation (dynamic R2-ISS) and modified MyCARe risk, with positivity defined as any detectable plasma cells in peripheral blood.

RESULTS

Thirty-seven patients were evaluated (median age, 67 years; prior lines, 5). Median follow-up was 7.5 (median PFS, 9.7) months. One-year OS was 66.3%. The overall response rate was 67.6%, and 45.9% achieved at least a very good partial response. Extramedullary disease, plasma cells in the peripheral blood, and high-risk cytogenetics were adverse features. A baseline monocyte count < 300/µL, high-risk classification by modified MyCARe, and dynamic R2-ISS stage IV were significantly associated with shorter PFS and OS.

CONCLUSION

Elranatamab was effective in real-world settings. Baseline monocyte count, modified MyCARe risk, and dynamic R2-ISS may serve as practical prognostic tools.