Background: Cohort A of the multicohort phase 2 CARTITUDE-2 (NCT04133636) study is assessing ciltacabtagene autoleucel (cilta-cel), a B-cell maturation antigen (BCMA)-directed chimeric antigen receptor T-cell (CAR-T) therapy, in patients with multiple myeloma (MM) who received 1-3 prior lines of therapy (LOT) and were refractory to lenalidomide (len). This population is difficult to treat and has poor prognosis.
Aims: To present updated results from CARTITUDE-2 Cohort A.
Methods: All patients provided informed consent. Eligible patients had progressive MM after 1-3 prior LOT that included a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD). Patients were len-refractory and had no prior exposure to BCMA-targeting agents. Patients received a single cilta-cel infusion (target dose: 0.75×106 CAR+ viable T cells/kg) after lymphodepletion. Cilta-cel safety and efficacy were assessed. The primary endpoint was minimal residual disease (MRD) negativity at 10-5 by next generation sequencing. Patient management strategies were used to reduce the risk of movement and neurocognitive adverse events (MNTs). Other assessments included pharmacokinetic (PK) analyses (Cmax and Tmax of CAR+ T-cell transgene levels in blood), levels of cytokine release syndrome (CRS)-related cytokines (e.g., IL-6) over time, peak levels of cytokines by response and CRS, association of cytokine levels with immune effector cell-associated neurotoxicity syndrome (ICANS), and CAR+ T cell CD4/CD8 ratio by response, CRS, and ICANS.
Results: As of January 2022 (median follow-up: 17.1 months [range: 3.3-23.1]), cilta-cel was administered to 20 patients (male: 65%; median age: 60 years [range: 38-75]). Median number of prior LOT was 2 (range: 1-3); median time since MM diagnosis was 3.5 years (range: 0.7-8.0). 95% of patients were refractory to their last LOT; 40% were triple-class refractory. Overall response rate was 95%, with 90% of patients achieving ≥complete response and 95% achieving ≥very good partial response. Median time to first response was 1.0 month (range: 0.7-3.3); median time to best response was 2.6 months (range: 0.9-13.6). All MRD-evaluable patients (n=16) achieved MRD negativity at 10-5. Median duration of response was not reached. The 12-month progression-free survival rate was 75% and the 12-month event-free rate was 79%. CRS occurred in 95% of patients (grade 3/4: 10%), with a median time to onset of 7 days (range: 5-9) and median duration of 3 days (range: 2-12). 30% of patients had neurotoxicity (5 grade 1/2 and 1 grade 3/4). ICANS occurred in 3 patients (15%; all grade 1/2); 1 patient had facial paralysis (grade 2). No MNTs were observed. 1 death due to COVID-19 occurred and was assessed as treatment-related by the investigator; 2 deaths due to progressive disease and 1 due to sepsis (not related to treatment) also occurred. Based on preliminary PK analyses of CAR transgene by qPCR, peak expansion of CAR-T cells occurred at day 10.5 (range: 8.7-42.9); median persistence was 153.5 days (range: 57.1-336.8).
Summary/Conclusion: A single cilta-cel infusion led to deepening and durable responses at this longer follow-up (median 17.1 months) in patients with MM who had 1-3 prior LOT and were len-refractory. Follow-up is ongoing. We will present updated and detailed PK, cytokine, and CAR-T subset analyses as well as clinical correlation to provide novel insights into biological correlates of efficacy and safety in this difficult-to-treat patient population, which is being further evaluated in the CARTITUDE-4 study (NCT04181827; enrollment concluded).