Outcomes of ide-cel in patients with relapsed/refractory multiple myeloma: A single-institution experience.

Abstract

e19500 Background: Idecabtagene vicleucel (ide-cel) is a novel CAR T-cell therapy that targets B-cell maturation antigen (BCMA). This single-center retrospective study reports the real-world clinical outcomes of ide-cel therapy in patients with relapsed/refractory multiple myeloma (RRMM) with the additional goal of investigating host predictive factors for therapy performance. Methods: We conducted a retrospective review of adult patients with RRMM who received ide-cel between 2021 and 2023 at University of California San Diego Health and had at least six months of follow-up data available. Data on baseline characteristics, efficacy responses, and adverse reactions (including CRS and ICANS grading per ASTCT) were obtained. Treatment responses were recorded according to the International Myeloma Working Group criteria. Survival analyses were based on Kaplan-Meier and Cox proportional hazards methods. Results: A total of 25 patients with RRMM were included. The median age was 65 (range, 50-79). 48% of patients were male. Patients received a median of six lines of prior therapy with 12% of patients receiving prior BCMA-targeted therapy. Six patients (24%) had confirmed high-risk cytogenetics while twelve patients (48%) had extramedullary disease. The median follow-up was 11.4 months. The objective response rate was 84%; sCR was seen in 56% of patients, VGPR in 16%, PR in 12%, and PD in 16%. Four patients in sCR have since relapsed. Five deaths were observed (20%), all due to progressive disease. Median PFS for the cohort was 13.9 months (95% CI, 9.21 – NR); among responders, PFS was 20.6 months (95% CI, 11.9 – NR). Median OS was NR (95% CI, 19.3 month – NR). The respective PFS and OS at 12 months was 57% (95% CI, 37% – 86%) and 83% (95% CI, 69% – 100%). Of 11 patients who had relapsed/refractory disease to ide-cel, six were alive at time of last follow-up; three are responding to teclistamab, two to talquetamab, and one to radiation. The incidence of CRS and ICANS was 92% (grade 3-4: 4%) and 12% (grade 3-4: 8%), respectively. Univariate and multivariate analysis did not reveal any significant predictive markers of superior PFS or OS, including age, ECOG, mSMART classification, high-risk cytogenetics, extramedullary disease, median number of lines of prior therapy, prior BCMA-targeted therapy, and triple/penta-class refractory disease. Conclusions: Despite our patients having a high median number of prior lines of therapy, our response and toxicity rates were similar to the findings in the current literature, including those observed in the landmark KarMMa-1 trial. We did not find any significant predictive factors of PFS or OS with the caveat of a small sample size. Further research remains necessary to identify potential predictors that may discriminate responders from non-responders, which will improve the application of CAR T-cell therapy in patients with RRMM.