lung cancer

Updated Overall Survival And PD-L1 Subgroup Analysis of Patients with Extensive-Stage Small-Cell Lung Cancer Treated with Atezolizumab, Carboplatin, and Etoposide (Impower133)

Updated Overall Survival And PD-L1 Subgroup Analysis of Patients with Extensive-Stage Small-Cell Lung Cancer Treated with Atezolizumab, Carboplatin, and Etoposide (Impower133)

In the February 20, 2021 issue of Journal of Clinical Oncology, Stephen V. Liu and colleagues report on the results of the Impower133 trial.

PURPOSE:

In the IMpower133 randomized, double-blind, phase I/III study, investigators had initially demonstrated that the addition of atezolizumab to carboplatin plus etoposide (CP/ET) for first-line (1L) treatment of extensive-stage small-cell lung cancer had resulted in significant improvements in overall survival and progression-free survival versus placebo plus the same chemotherapy doublet.  In this location, updated overall survival, safety, exploratory biomarker analysis, and progression patterns were reported.  

PATIENTS AND METHODS:

Patients were randomized in a 1:1 fashion to 4 x 21-day cycles of carboplatinum, AUC = 5 intravenously given on day 1 plus 100 mg/m² of etoposide, administered intravenously on days 1, 2, 3 with atezolizumab, fixed flat dose 1,200 mg intravenously on day 1 or placebo followed by maintenance atezolizumab or placebo until toxicity or disease progression or loss of clinical benefit.  

RESULTS:

Patients who were given atezolizumab plus a chemotherapy doublet, (n = 201 patients) or placebo plus the chemotherapy doublet (n = 202 patients) after a median follow up of 22.9 months; 302 deaths had occurred. the median overall survival was 12.3 and 10.3 months with atezolizumab plus a chemotherapy doublet and placebo plus chemotherapy doublet, respectively (HR, 0.76; 95% CI, 0.60 – 0.95; P = .0154). At 18 months, 34.0% and 21.0% of patients were alive in treatment versus placebo arms, respectively.  The benefit of atezolizumab was not correlated to PD-L1 status or tumor mutation burden.

The authors concluded “Adding atezolizumab to cp/et as 1l treatment for es-sclc continued to demonstrate improved OS and a tolerable safety profile at the updated analysis, confirming the regimen as a new standard of care. Exploratory analyses demonstrated treatment benefit independent of biomarker status.”

https://ascopubs.org/doi/full/10.1200/JCO.20.01055

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