In the phase II BIRCH trial, atezolizumab (Tecentriq) was found to produce higher response rates as first-line or subsequent therapy in patients with advanced non–small cell lung cancer (NSCLC) with higher levels of programmed cell death ligand 1 (PD-L1) expression. Study findings were reported by Peters et al in the Journal of Clinical Oncology.
The study included 659 evaluable patients with advanced NSCLC and no central nervous system (CNS) metastases who received atezolizumab at 1,200 mg intravenously every 3 weeks as first-line (cohort 1, n = 139), second-line (cohort 2, n = 268), or third- or higher-line therapy (cohort 3, n = 252). Only patients with PD-L1 expression on ≥ 5% of tumor cells (TC; TC2/3) or tumor-infiltrating immune cells (ICs; IC2/3) on the SP142 immunohistochemistry assay were enrolled.
Expression levels ≥ 50% on TCs or ≥ 10% on ICs were defined as TC3 or IC3. Overall, 46% to 47% of patients in each cohort had TC3 or IC3 expression status. The primary endpoint was objective response rate on independent review.
Response Rates and Overall Survival
At a minimum of 12 months of follow-up, the objective response rates were 22%, 19%, and 18% in cohorts 1, 2, and 3 and 31%, 26%, and 27% in the TC3 or IC3 subgroups of the cohorts, respectively. Responses were observed irrespective of EGFR or KRAS mutation status. Median durations of response were 9.8 months, not estimable, and 11.8 months in the 3 cohorts and 10.0 months, not estimable, and 7.2 months in the TC3 or IC3 subgroups, respectively.
In a survival analysis with a minimum follow-up of 20 months, median overall survival was 23.5 months (26.9 months for TC3 or IC3 patients), 15.5 months (16.6 months) , and 13.2 months (17.5 months) in the 3 cohorts, respectively.
The safety profile was similar among the three cohorts and consistent with that observed in previous atezolizumab monotherapy trials.
The investigators concluded: “BIRCH demonstrated responses with atezolizumab monotherapy in patients with PD-L1–selected advanced NSCLC, with good tolerability. PD-L1 status may serve as a predictive biomarker for identifying patients most likely to benefit from atezolizumab.”
The study was supported by a National Institutes of Health grant and Genentech (a member of the Roche Group).
Enriqueta Felip, MD, PhD, of Vall d’Hebron Institute of Oncology, is the corresponding author of the Journal of Clinical Oncology article.
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