Adjuvant atezolizumab after adjuvant chemotherapy in resected stage IB-IIIA non-small-cell lung cancer (IMpower010): a randomised, multicentre, open-label, phase 3 trial

Background: Novel adjuvant strategies are needed to optimise outcomes after complete surgical resection in patients with early-stage non-small-cell lung cancer (NSCLC). We aimed to evaluate adjuvant atezolizumab versus best supportive care after adjuvant platinum-based chemotherapy in these patients.

Methods: IMpower010 was a randomised, multicentre, open-label, phase 3 study done at 227 sites in 22 countries and regions. Eligible patients were 18 years or older with completely resected stage IB (tumours ≥4 cm) to IIIA NSCLC per the Union Internationale Contre le Cancer and American Joint Committee on Cancer staging system (7th edition). Patients were randomly assigned (1:1) by a permuted-block method (block size of four) to receive adjuvant atezolizumab (1200 mg every 21 days; for 16 cycles or 1 year) or best supportive care (observation and regular scans for disease recurrence) after adjuvant platinum-based chemotherapy (one to four cycles). The primary endpoint, investigator-assessed disease-free survival, was tested hierarchically first in the stage II-IIIA population subgroup whose tumours expressed PD-L1 on 1% or more of tumour cells (SP263), then all patients in the stage II-IIIA population, and finally the intention-to-treat (ITT) population (stage IB-IIIA). Safety was evaluated in all patients who were randomly assigned and received atezolizumab or best supportive care. IMpower010 is registered with ClinicalTrials.gov, NCT02486718 (active, not recruiting).

Findings: Between Oct 7, 2015, and Sept 19, 2018, 1280 patients were enrolled after complete resection. 1269 received adjuvant chemotherapy, of whom 1005 patients were eligible for randomisation to atezolizumab (n=507) or best supportive care (n=498); 495 in each group received treatment. After a median follow-up of 32·2 months (IQR 27·4-38·3) in the stage II-IIIA population, atezolizumab treatment improved disease-free survival compared with best supportive care in patients in the stage II-IIIA population whose tumours expressed PD-L1 on 1% or more of tumour cells (HR 0·66; 95% CI 0·50-0·88; p=0·0039) and in all patients in the stage II-IIIA population (0·79; 0·64-0·96; p=0·020). In the ITT population, HR for disease-free survival was 0·81 (0·67-0·99; p=0·040). Atezolizumab-related grade 3 and 4 adverse events occurred in 53 (11%) of 495 patients and grade 5 events in four patients (1%).

Interpretation: IMpower010 showed a disease-free survival benefit with atezolizumab versus best supportive care after adjuvant chemotherapy in patients with resected stage II-IIIA NSCLC, with pronounced benefit in the subgroup whose tumours expressed PD-L1 on 1% or more of tumour cells, and no new safety signals. Atezolizumab after adjuvant chemotherapy offers a promising treatment option for patients with resected early-stage NSCLC.

Funding: F Hoffmann-La Roche and Genentech.