(PA-082) Real-world Outcomes of Patients with Multiple Myeloma Who Received BCMA-targeted Bispecific Antibodies in British-Columbia

Teclistamab and Elranatamab are bispecific antibodies targeting B-cell maturation antigen (BCMA), demonstrating high overall response rates (ORR) and durable responses in patients with relapsed and/or refractory multiple myeloma (RRMM), including those with triple-class exposure.

Methods:

We retrospectively analyzed clinical outcomes in 58 patients with RRMM who received compassionate access single-agent BCMA bispecific antibody in British-Columbia between May 2023 and April 2025, as per standard indication. Eligible patients had at least one month of follow-up post-therapy initiation.

Results: Among the 58 patients, 56 (97%) received Teclistamab and 2 (3.4%) received Elranatamab. Two patients had prior BCMA-directed therapies (Cilta-Cel and/or Belantamab Mafodotin). Median number of prior lines was 4 (range:2–10). All patients were triple-class refractory and 43% were penta-refractory. 57 patients (98%) were refractory to their last line of treatment and 24% had failed to achieve at least a stable disease at any time. The median age was 67 years (range:41-84), 41% aged ≥70. High-risk cytogenetics. (IMWG 2009) were present in 26%, and 33% had extramedullary disease. With a median follow-up of 4.5 months (range:0.6–23.8), the ORR was 53%, including complete responses (CR) in 34%, very good partial responses (VGPR) in 9%, and partial responses (PR) in 10%. The estimated 12-month PFS for all patients was 37% (95%CI, 26-53%), with a median of 4.1 months (2.3-NR). The estimated 12-month OS was 53% (95%CI, 40-68%) with the median not reached (5.1-NR).  The median duration of response (DOR) was not reached, with an estimated 12-month DOR rate of 69% (95% CI, 52–90%). Responders (≥PR) had significantly better outcomes than non-responders with median PFS not reached vs. 1.05 months (p< 0.001) and median OS not reached vs. 2.4 months(p< 0.0001). Patients who were exclusively triple-class refractory (n=33) had higher ORR (67% vs. 36%, p=0.02), longer mPFS (7.9 vs. 2.2 months, p=0.04), and superior mOS (NR vs. 3.8 months, p=0.01) compared to penta-refractory patients (n=25). In responders, DOR was similar in both groups (estimated 12-month DOR of 72% vs. 63%, p=0.66). Cytokine-release syndrome occurred in 68% (all ≤ grade 2). Immune effector cell associated neurotoxicity syndrome occurred in 9% (one grade 3). 48% had an infection.

Conclusions:

This data demonstrates the real-world effectiveness of BCMA-targeted bispecific therapy. In this heavily pretreated RRMM cohort, triple-class refractory patients derived significantly improved outcomes compared to those with penta-refractory disease, showing higher response rates and improved survival endpoints. However, when responses were achieved the disease control was comparable. These results highlight the importance of refractory status in predicting treatment outcome. Further, it supports the use of these therapies earlier in the treatment course to increase the proportion of responding patients and maximize clinical benefit.