A 5-Year Follow-up Clinical Study of the B-cell Maturation Antigen Chimeric Antigen Receptor T-cell Therapy HDS269B in Patients with Relapsed or Refractory Multiple Myeloma

Purpose: This study aimed to report the 5-year clinical outcomes of anti-B-cell maturation antigen chimeric antigen receptor (CAR) T-cell (HDS269B) therapy in patients with relapsed/refractory multiple myeloma (RRMM), including those with poor performance status [Eastern Cooperative Oncology Group (ECOG) scores 3 to 4], and to identify factors influencing long-term outcomes.

Patients And Methods: Forty-nine patients with RRMM enrolled from 2016 to 2020 received HDS269B (9 × 106 cells/kg) after receiving a conditioning chemotherapy consisting of cyclophosphamide and fludarabine. The overall response, long-term outcomes, and safety were assessed, as were their associations with clinical and disease characteristics.

Results: With a median follow-up of 59.0 months, the overall response rate was 77.55%. The median progression-free survival (PFS) and overall survival (OS) were 9.5 months [95% confidence interval (CI), 5.01-13.99] and 20.0 months (95% CI, 11.26-28.74), respectively. The 5-year PFS and OS rates were 21.3% (95% CI, 12.3%-36.7%) and 34.1% (95% CI, 22.7%-51.3%), respectively. Patients with ECOG 0 to 2 had marked longer survival, with a median PFS of 11.0 months and a median OS of 41.8 months. Early minimal residual disease negativity, higher and persistent CAR T-cell expansion, and the absence of extramedullary disease were associated with better survival outcomes. No new CAR T-cell therapy-associated toxicities were observed. Importantly, ECOG scores 0 to 2, prior therapy lines <4, and CAR T-cell persistence at ≥6 months were independently associated with longer OS.

Conclusions: HDS269B is effective and safe, especially for patients with ECOG scores 0 to 2. Early CAR T-cell intervention may improve prognosis in patients with RRMM.