MM-345: Differential Toxicities and Survival Outcomes by Race: Chimeric Antigen Receptor (CAR) T-Cell Therapy for Myeloma

Abstract

Context: CAR-T cell therapies targeting BCMA in RRMM have shown promising outcomes. Differences in immune response and activation by race raises the question of differential toxicities and clinical outcomes by race. Objective: To evaluate if any toxicity or clinical outcome disparity with CART exists by race. Methods: Thirty-one patients received CART therapy from 19 March 2018 until 20 April 2020 (26 patients with RRMM and 5 non-relapsed patients). All patients received ≥ 300 × 106 BCMA targeted CAR+ T cells. For PFS and OS evaluations, patients with RRMM were only included. Results: Among the 29 patients [17 white (W) and 12 black (B) patients], the median age at diagnosis and receipt of CART therapy were 49.94 years (W: 52.23, B:48.75, p=0.71) and 56.05 years (W: 58.87, B:52.26, p=0.26), respectively. Any grade CRS occurred in 66% of patients (W: 76.5% vs B: 50%, p=0.14), grade ≥2 CRS requiring intervention with IL-6 receptor monoclonal antibody occurred in 34.5% patients (W: 47.1% vs B:16.7%, p=0.096). Similarly, any grade neurotoxicity occurred in 31% of patients (W: 35.3% vs B: 25%, p=0.43). Grade ≥2 neurotoxicity occurred in 17.2% patients (W: 23.5% vs B: 8.3%, p=0.29). There were no differences in ORR (W: 73.3% vs B 88.9%, p=0.36) or ≥VGPR rates (W: 66.7% vs B 55.6%, p=0.453) or ≥CR rates (W: 40% vs B 33.3%, p=0.51), by race. The median PFS numerically favored B patients (W: 8.3 m vs B: 18.53, p=0.445, median f/u 10.68 months) as well as PFS2 from the receipt of CAR T therapy (W: 12.29 m vs NR, p=0.44, median f/u 8.3 months). At a median f/u of 12.1 months, the median OS didn't differ between the two groups (1 year OS rate W: 61% vs B:64%, p=0.803). Conclusions: While this is the first analysis reviewing the toxicities and clinical outcomes associated with CAR T therapies, the post-CAR T outcomes for all patients seem promising. Accessibility to CAR T therapy was reemphasized with 39% of our cohort comprising B patients. A statistically non-significant decrease in the CRS and neurotoxicity and improved PFS among B patients is encouraging. Enriched trials for minorities and their focussed accrual for adoptive cellular therapy trials will confirm these findings.