OA03.02 Atezolizumab as 1L Therapy for Advanced NSCLC in PD-L1–Selected Patients: Updated ORR, PFS and OS Data from the BIRCH Study

Abstract

Atezolizumab, a humanized anti-PDL1 mAb, inhibits the PD-L1/PD-1 pathway to restore tumor-specific T-cell immunity, resulting in durable anti-tumor effects. BIRCH (NCT02031458) is a single-arm Phase II study of atezolizumab monotherapy in PD-L1–selected advanced NSCLC patients, across multiple therapy lines. Primary analyses (median follow-up, 8.5 months) demonstrated a meaningful ORR with durable response in chemotherapy-naive 1L and 2L+ PD-L1–selected patients. Here we report updated efficacy data in 1L patients. 1L eligibility criteria included PD-L1–selected, advanced-stage NSCLC with no CNS metastases or prior chemotherapy. PD-L1 was centrally evaluated (VENTANA SP142 IHC assay). Patients expressing PD-L1 on ≥5% of tumor cells (TC) or tumor-infiltrating immune cells (IC), ie, TC2/3 or IC2/3, were enrolled. Patients with EGFR mutation or ALK rearrangement must have had prior TKI treatment. Atezolizumab 1200mg was administered IV q3w until radiographic disease progression or unacceptable toxicity. The primary endpoint was independent review facility(IRF)-assessed ORR. Secondary endpoints included investigator(INV)-assessed ORR, DOR, PFS (RECIST v1.1) and OS. With a median follow-up of 14.6 months, median OS was not reached in TC3 or IC3 patients and was 20.1 months in TC2/3 or IC2/3 (ITT) patients; INV-assessed ORR was 32% and 24%, respectively (Table). Furthermore, ORR was 31% for mutant EGFR (n=13) vs 20% for wild-type EGFR patients (n=104), and 27% for mutant KRAS (n=33) vs 21% for wild-type KRAS patients (n=67). No new safety signals were observed. Updated efficacy (including IRF ORR), safety and exploratory biomarker analyses will be presented. With longer follow-up, atezolizumab continued to demonstrate promising efficacy in 1L NSCLC. These results indicate that atezolizumab has durable efficacy in the 1L setting, in EGFR and KRAS mutant and wild-type tumors, and support ongoing Phase III trials evaluating atezolizumab vs chemotherapy in 1L NSCLC.Tabled 1Endpoint (95% CI)TC3 or IC3a (n=65)TC2/3 or IC2/3b (n=139)INV ORR, %32% (21.2–45.1)24% (16.9–31.7)EGFR mutant/wild-type, %25%/29%31%/20%KRAS mutant/wild-type, %38%/27%27%/21%mDOR, mo13.1 (8.5–NE)13.1 (9.9–17.5)mOS, moNE (12.0–NE)20.1 (20.1–NE)12-mo OS rate, %61% (48.8–73.8)66% (57.9–74.5)mPFS, mo7.3 (4.9–12.0)7.3 (5.6–9.1)12-mo PFS rate, %36% (23.8–48.8)32% (24.0–40.7)NE, not estimable.a TC ≥50% or IC ≥10% PD-L1–expressing cells.b TC or IC ≥5% PD-L1–expressing cells. Open table in a new tab