The addition of frontline atezolizumab to carboplatin plus etoposide improved OS and PFS among patients with extensive-stage small cell lung cancer, according to results of a multinational, randomized, placebo-controlled phase 3 trial presented at International Association for the Study of Lung Cancer’s World Conference on Lung Cancer.
IMpower133 is a double-blind study of PD-L1 inhibitor atezolizumab (Tecentriq, Genentech) among 403 treatment-naive patients with extensive-stage small cell lung cancer.
Leora Horn, MD, oncologist at Vanderbilt University Medical Center and clinical director of the thoracic oncology program at Vanderbilt-Ingram Cancer Center, and colleagues assigned patients to carboplatin and etoposide with atezolizumab (n = 201) or with placebo (n = 202) for 21-day cycles during the induction phase. During the maintenance phase, patients received atezolizumab or placebo until unacceptable toxicities, disease progression according to RECIST v1.1, or no additional clinical benefit was observed.
Investigator-assessed PFS and OS in the intention-to-treat population served as coprimary endpoints.
Median follow-up was 13.9 months.
The results — published simultaneously in The New England Journal of Medicine —showed median OS was 12.3 months in the atezolizumab arm compared with 10.3 months in the placebo arm (HR for death = 0.7; 95% CI, 0.54-0.91).
Researchers reported median PFS of 5.2 months with atezolizumab vs. 4.3 months with placebo (HR for disease progression or death = 0.77; 95% CI, 0.62-0.96).
The safety profile for the combination appeared consistent with the known safety profiles of the individual medicines.
“The standard of care for extensive-stage small cell lung cancer has been unchanged for decades, which has contributed to unacceptably poor outcomes,” Stephen V. Liu, MD, associate professor of medicine at Georgetown University, said in a press release. “This is the first study in 30 years to show a significant improvement in survival in the first line treatment of this highly lethal disease.” – by Jennifer Southall
Horn L, et al. Abstract PL02.07. Presented at: International Association for the Study of Lung Cancer’s World Conference on Lung Cancer; Sept. 23-26, 2018; Toronto, Canada.
Horn L, et al. N Eng J Med. 2018;doi:10.1056/NEJMoa1809064.
Disclosures: Horn reports personal fees from AbbVie, AstraZeneca, EMD Serono, Genentech, Incyte, Merck and Xcovery, outside the submitted work. Liu reports personal fees from Roche outside the submitted work. Please see the study for all other authors’ relevant financial disclosures.