Real-world outcomes of isatuximab with pomalidomide and dexamethasone for relapsed and/or refractory multiple myeloma

BACKGROUND: The isatuximab, pomalidomide, and dexamethasone (Isa-Pd) regimen has shown survival benefits for relapsed and/or refractory multiple myeloma (RRMM) in several trials, while evidence of effectiveness and safety among Chinese patients is limited. This study aimed to provide real-world evidence of Isa-Pd in Chinese patients with RRMM. METHODS: In a prospective observational real-world study (IsaFiRsT), we enrolled Chinese RRMM patients who had received ≥2 prior therapies, including lenalidomide and proteasome inhibitors, and received the Isa-Pd regimen at Shanghai Jiaotong University School of Medicine, Ruijin-Hainan Hospital. A historical cohort of patients with RRMM who had received >1 additional line of treatment after ≥2 prior therapies was retrospectively included. The primary endpoint of the Isa-Pd cohort was the overall response rate (ORR). Inverse probability treatment weighting (IPTW) was used to balance confounding factors between the Isa-Pd cohort and historical cohort. RESULTS: The Isa-Pd cohort comprised 24 patients with RRMM and reported an ORR of 82.6% (19/23, 95% confidence interval [CI]: 61.2% to 95.0%), a very good partial response or better rate of 73.9% (17/23) and a complete response or better rate of 43.5% (10/23). The median time to first response was 1.2 months (range: 0.9, 3.1 months). The median duration of response, progression-free survival (PFS), and overall survival (OS) were not reached, with a median follow-up of 8.4 months. The 6-month PFS and OS rates were 87.0% and 91.3%, respectively. The IPTW-adjusted ORR in the Isa-Pd cohort was 85.1% compared to 33.4% in the historical cohort, with a risk ratio of 2.55 (95% CI: 1.73 to 4.12). The most common grade >3 treatment-emergent adverse events in the Isa-Pd cohort were neutrophil count decreased (75.0%, 18/24), white blood cell count decreased (54.2%, 13/24), and anemia (45.8%, 11/24). CONCLUSION: The IsaFiRsT study reported that Isa-Pd provided a high rate of deep and rapid response in heavily pretreated Chinese RRMM patients, with an acceptable safety profile in a real-world setting, consistent with Isa-Pd trials. REGISTRATION: Chinese Clinical Trial Registry (ChiCTR2200062878).