Overview
Two immunotherapy drugs—atezolizumab and durvalumab—are both approved first-line treatments for extensive-stage small cell lung cancer based on phase 3 clinical trials (IMpower133 and CASPIAN) that showed similar efficacy. However, real-world evidence comparing these two drugs is limited, making it unclear if their real-world outcomes are truly equivalent.
Researchers used Flatiron Health’s US Small Cell Lung Cancer (SCLC) Panoramic Database, inclusive of more than 27,400 patients with SCLC, to analyze data from 2,063 patients with extensive stage (ES)-SCLC treated with atezolizumab (78%) or durvalumab (22%) in combination with platinum chemotherapy, of whom 1,122 patients received maintenance immunotherapy after initial chemotherapy. Patient characteristics were similar between the two groups. In the first-line setting, median overall survival was 8.7 months with atezolizumab and 8.5 months with durvalumab—not statistically different. In the maintenance setting, median overall survival was 9.3 months and 9.2 months respectively, again showing no significant difference. The study met its pre-specified criterion for "non-inferiority," providing evidence that atezolizumab performed at least as effectively as durvalumab in this treatment setting.
Why this matters
These real-world findings support that atezolizumab and durvalumab have comparable effectiveness in ES-SCLC. Notably, overall survival in the real world (approximately 8.7 months) was shorter than reported in the clinical trials (approximately 12-13 months), reflecting the challenges of applying trial-based evidence to diverse, less-selected patient populations. These results help oncologists understand that both drugs are reasonable options, with treatment selection potentially based on other factors like cost, availability, and individual patient circumstances.