Comparative Efficacy of Ciltacabtagene Autoleucel in CARTITUDE-1 vs Physician’s Choice of Therapy in the Long-Term Follow-Up of POLLUX, CASTOR, and EQUULEUS Clinical Trials for the Treatment of Patients with Relapsed or Refractory Multiple Myeloma

BACKGROUND AND OBJECTIVE: Ciltacabtagene autoleucel (cilta-cel) is a novel agent being investigated in the single-arm CARTITUDE-1 trial (NCT03548207) for patients with relapsed or refractory multiple myeloma who are triple-class exposed to an immunomodulatory drug, proteasome inhibitor, and an anti-CD38 monoclonal antibody. The objective of this study was to evaluate the comparative efficacy of cilta-cel vs physician’s choice of treatment, as no head-to-head trials have been conducted. METHODS: An external control arm for CARTITUDE-1 was created from patients in the long-term follow-up for three clinical trials of daratumumab (POLLUX, CASTOR, and EQUULEUS) who satisfied the eligibility criteria of CARTITUDE-1. These patients received physician’s choice of treatment following the discontinuation of study drugs. Inverse probability of treatment weighting was used to align the external control and CARTITUDE-1 populations on important baseline characteristics. Overall response rate, complete response or better rate, progression-free survival, time to next treatment, and overall survival were assessed. Several sensitivity analyses were conducted. RESULTS: After propensity score weighting, baseline characteristics were comparable between cohorts. Patients showed improved results with cilta-cel vs physician’s choice of treatment: overall response rate (relative risk: 2.95 [95% confidence interval (CI) 2.27, 3.84; p < 0.0001]), complete response or better (relative risk: 111.70 [95% CI 29.08, 429.06; p < 0.0001]), progression-free survival (hazard ratio [HR]: 0.24 [95% CI 0.15, 0.37; p < 0.0001]), time to next treatment (HR: 0.14 [95% CI 0.09, 0.22; p < 0.0001]), and overall survival (HR: 0.21 [95% CI 0.13, 0.35; p < 0.0001]). Results were consistent across all sensitivity analyses. CONCLUSIONS: Cilta-cel showed superior efficacy compared with physician’s choice of treatment, making it a promising new treatment option for patients with triple-class exposed relapsed or refractory multiple myeloma. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40261-021-01100-y.