The FDA approved atezolizumab for the first-line treatment of adult patients with metastatic non-small cell lung cancer (NSCLC) whose tumors have high PD-L1 expression (PD-L1 stained ≥ 50 percent of tumor cells [TC ≥ 50%] or PD-L1 stained tumor-infiltrating immune cells [IC] covering ≥ 10 percent of the tumor area [IC ≥ 10%]), with no EGFR or ALK genomic tumor aberrations.
The FDA also approved the VENTANA PD-L1 (SP142) Assay as a companion diagnostic device for selecting patients with NSCLC for treatment with atezolizumab.
Efficacy was evaluated in IMpower110 (NCT02409342), a multicenter, international, randomized, open-label trial in patients with stage IV NSCLC whose tumors express PD-L1 (TC ≥ 1% or IC ≥ 1%), who had received no prior chemotherapy for metastatic disease. Patients were randomized (1:1) to receive atezolizumab 1200 mg every 3 weeks until disease progression or unacceptable toxicity or platinum-based chemotherapy. The main efficacy outcome measure was overall survival (OS).
The trial demonstrated a statistically significant improvement in OS for patients with high PD-L1 tumor expression receiving atezolizumab compared to those treated with platinum-based chemotherapy. Median OS was 20.2 months (95% CI: 16.5, NE) for patients in the atezolizumab arm compared with 13.1 months (95% CI: 7.4, 16.5) in the chemotherapy arm (HR 0.59; 95% CI: 0.40, 0.89; p=0.0106). There was no statistically significant difference in OS for the other two PD-L1 subgroups (TC ≥5% or IC ≥5%; and TC ≥1% or IC ≥1%) at the interim or final analyses.
Median progression-free survival (PFS) per investigator was 8.1 months (95% CI: 6.8, 11.0) in the atezolizumab arm and 5.0 months (95% CI: 4.2, 5.7) in the platinum-based chemotherapy arm (HR 0.63; 95%CI: 0.45, 0.88). Confirmed overall response rate (ORR) per investigator was 38% (95% CI: 29, 48) and 29% (95% CI: 20, 39), respectively.
The most common adverse reaction (≥ 20%) with atezolizumab as a single-agent in IMpower110 was fatigue/asthenia.
The recommended atezolizumab dose for treatment of NSCLC is 840 mg every 2 weeks, 1200 mg every 3 weeks, or 1680 mg every 4 weeks, administered intravenously over 60 minutes.