Phase II Trial of Atezolizumab As First-Line or Subsequent Therapy for Patients With Programmed Death-Ligand 1–Selected Advanced Non–Small-Cell Lung Cancer (BIRCH)

Abstract

Purpose: BIRCH was designed to examine the efficacy of atezolizumab, a humanized anti–programmed death-ligand 1 (PD-L1) monoclonal antibody, in advanced non–small-cell lung cancer (NSCLC) across lines of therapy. Patients were selected on the basis of PD-L1 expression on tumor cells (TC) or tumor-infiltrating immune cells (IC). Patients and Methods: Eligible patients had advanced-stage NSCLC, no CNS metastases, and zero to two or more lines of prior chemotherapy. Patients whose tumors expressed PD-L1 using the SP142 immunohistochemistry assay on ≥ 5% of TC or IC (TC2/3 or IC2/3 [TC or IC ≥ 5% PD-L1–expressing cells, respectively]) were enrolled. Atezolizumab 1,200 mg was administered intravenously every 3 weeks. Efficacy-evaluable patients (N = 659) comprised three cohorts: first line (cohort 1; n = 139); second line (cohort 2; n = 268); and third line or higher (cohort 3; n = 252). The primary end point was independent review facility–assessed objective response rate (ORR; Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1). Secondary end points included median duration of response, progression-free survival, and overall survival (OS). Results: BIRCH met its primary objective of demonstrating a significant ORR versus historical controls. With a minimum of 12 months of follow-up, the independent review facility–assessed ORR was 18% to 22% for the three cohorts, and 26% to 31% for the TC3 or IC3 subgroup; most responses are ongoing. Responses occurred regardless of EGFR or KRAS mutation status. The median OS from an updated survival analysis (minimum of 20 month follow up) for cohort 1 was 23.5 months (26.9 months for TC3 or IC3 patients); the median OS in cohorts 2 and 3 was 15.5 and 13.2 months, respectively. The safety profile was similar across cohorts and consistent with previous atezolizumab monotherapy trials. Conclusion: 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.