2026 年 16 巻 4 号 p. 23-30
Introduction: Despite advances in therapeutic strategies, multiple myeloma (MM) remains a clinically challenging hematological malignancy. Elranatamab, a bispecific antibody targeting CD3 and B-cell maturation antigens, exerts antitumor effects by inducing T-cell-mediated cytotoxicity against myeloma cells. However, the association between lymphocyte dynamicsand treatment responses remains unclear. We aimed to characterize the effects of elranatamab on lymphocyte populations and functional states, focusing on CD8+ T-cells, and determine whether CD8+CD11b+ cells serve as markers of CD8+ T-cell-mediated antitumor activity.
Methods: We retrospectively analyzed nine patients with relapsed or refractory MM who initiated elranatamab treatment.
Results: The overall response rate was 66.7%. After a median follow-up of 150 days, median progression-free and overall survival were not achieved. After treatment, lymphocyte counts, particularly CD8+ T-cells, increased in patients who achieved a complete response or very good partial response, but not in those with progressive disease. Higher proportions of CD8+ CD11b+ double-positive cells, associated with a lower recurrence rate after allogeneic hematopoietic stem cell transplantation, tended to correlate with better outcomes, suggesting antitumor activity.
Conclusion: In patients with favorable outcomes, CD8+ T-cell proliferation increased. Overall, elranatamab may exert antitumor effects by activating and expanding cytotoxic CD8+ T-cells.
