Real-world outcomes of teclistamab for the treatment of relapsed/refractory multiple myeloma at UC San Diego Health: A single-institution experience.

e19504 Background: Bispecific antibodies (BsAb) are emerging as a promising class of cancer immunotherapy. Teclistamab, a BsAb targeting B-cell maturation antigen (BCMA) expressed on plasma cells, received FDA approval for the treatment of relapsed/refractory (R/R) multiple myeloma (MM) in 2022. Here we describe the real-world experience of teclistamab at a single institution. Methods: We retrospectively reviewed patients with R/R MM who received teclistamab at University of California San Diego and had at least 6 months of follow up. Baseline characteristics, efficacy outcomes, and safety outcomes were collected. Kaplan-Meier method was used to describe survival. Results: A total of 18 patients who received teclistamab between 01/01/2023 and 06/15/2023 were included in this analysis. The median age was 67 years old (range 50-83). Median prior lines of therapy was 6.5 (range 3-11). All patients had triple-refractory disease; all but one had penta-refractory disease. Approximately 44% of patients had extramedullary plasmacytomas at time of BsAb initiation; 39% had received prior BCMA therapy (2 belantamab, 5 ide-cel) before teclistamab. High-risk cytogenetics (t(4;14), t(14;16), t(14;20), Del17p, Gain1q) were characterized for 13 patients with data available. 6 had a single high-risk mutation, 4 had two, and 1 had three. Incidence of cytokine release syndrome (CRS) was 12 (67%); (4 (33%) grade 2, no grade 3-5). 6 (50%) received tocilizumab to treat CRS. Immune effector cell-associated neurotoxicity syndrome (ICANS) incidence was 2 (11%); (1 (50%) grade 2, no grade 3-5). Pain crisis occurred in 11% of patients. The incidence of infection was 67%; the majority were grade ≥ 3. The overall response rate (ORR) by IMWG criteria was 50%. All patients who responded had a very good partial response (VGPR) or better; further response data was not available due to the lack of restaging bone marrow biopsies during treatment. Median duration of response for the entire cohort was not reached. Median progression-free survival (PFS) was 12.5 months (95% CI 1.0 – not reached); median overall survival (OS) was not reached (95% CI 7.8 – not reached).Univariate analyses showed no statistically significant relationship between response and prior BCMA therapy (p=.91), response and presence of extramedullary disease (p=.31), or response and mSMART risk stratification (p=.13). Conclusions: Overall, the incidence and grades of CRS, ICANS, and infection in our cohort were similar to those observed in the phase I/II MajesTEC-1 trial. In contrast, the ORR and PFS in this study were lower compared to the MajesTEC-1 study. This difference may be due to a greater proportion of patients with high-risk cytogenetics and more aggressive disease, as depicted by the higher median prior lines of therapy and higher rates of extra-medullary plasmacytomas and triple-/penta-class refractory disease.