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Atezolizumab Plus Chemotherapy Shows Favorable Survival for Extensive-Stage Small Cell Lung Cancer
Exploratory Results From the Phase 3 IMbrella A Extension Study
Exploratory Results From the Phase 3 IMbrella A Extension Study
According to exploratory results from the IMbrella A extension study, administration of atezolizumab after first-line atezolizumab plus chemotherapy demonstrated promising overall survival (OS) results in a cohort of patients with extensive-stage small-cell lung cancer (SCLC), who rolled over from the phase 3 Impower133 study.
IMpower133 was a phase1/3 trial evaluating first-line atezolizumab plus carboplatin/etoposide among patients with extensive-stage SCLC. In the open-label, nonrandomized IMbrella A study, 18 patients were rolled over from the IMpower133 trial to receive 1200 mg of atezolizumab every 3 weeks if they were continuing to receive atezolizumab at Impower133 trial closure or were in survival follow-up after atezolizumab discontinuation. The primary end points were OS and safety.
At the data cut off point, median follow-up was 59.4 months. OS estimates were 16% at 3 years, 13% at 4 years, and 12% at 5 years. Serious adverse events were observed in 16.7% of patients and 1 adverse event of special interest was reported (grade 2 hypothyroidism). These data represent the first report of 5-year OS among patients with extensive-stage SCLC treated with atezolizumab plus chemotherapy in the first-line setting.
While study authors noted the limitations of small sample size and a lack of long-term data from the control arm of the IMpower133 trial, they noted that these exploratory analyses of patients treated with atezolizumab plus chemotherapy “compared favorably with historical data with chemotherapy alone.”
Source:
Reck M, Dziadziuszko R, Sugawara S, et al. Five-year survival in patients with extensive-stage small cell lung cancer treated with atezolizumab in the phase III IMpower133 study and the phase III IMbrella A extension study. Lung Cancer. Published online: August 10, 2024. doi: 10.1016/j.lungcan.2024.107924
