Patients with resected early-stage non–small cell lung cancer (NSCLC) who received the PD-L1 inhibitor atezolizumab following cisplatin-based chemotherapy had a 34% reduction in the risk of disease recurrence compared with best supportive care, according to the results from the phase III IMpower010 study. The benefit was most pronounced in the subgroup of patients with stage II to IIIA disease whose tumors expressed PD-L1. The study by Heather A. Wakelee, MD, FASCO, and colleagues was presented in a presscast in advance of the 2021 ASCO Annual Meeting (Abstract 8500).

Heather A. Wakelee, MD, FASCO

Study Methodology

The researchers sought to determine whether atezolizumab, which has demonstrated benefit in advanced-stage NSCLC, could also be beneficial for patients with earlier-stage disease who may be at risk for disease recurrence following surgery.

The researchers enrolled 1,280 patients with completely resected stage IB to IIIA NSCLC in this randomized phase III open-label clinical trial. Following cisplatin-based chemotherapy, plus pemetrexed, docetaxel, gemcitabine, or vinorelbine, 1,005 patients were randomly assigned to receive either atezolizumab or best supportive care.

The primary endpoint of investigator-assessed disease-free survival and secondary endpoint of overall survival were tested hierarchically: first, disease-free survival in the PD-L1 tumor cell ≥ 1% (SP263) subgroup with stage II to IIIA disease; then, disease-free survival in all randomly assigned patients with stage II to IIIA disease; then, disease-free survival in the intent-to-treat population stage IB to IIIA; and finally, overall survival in the intent-to-treat population. Efficacy assessments were based on randomly assigned patients. Safety was assessed in the safety-evaluable population, defined as patients who received one or more doses of atezolizumab or who had one or more post-baseline safety assessments if assigned to the best supportive care arm.

Results

At data cutoff on January 21, 2021, median follow-up was 32.2 months in the intent-to-treat population. Baseline characteristics were generally balanced between the study arms. Atezolizumab showed a statistically significant disease-free survival benefit vs best supportive care in the PD-L1 tumor cells ≥ 1% stage II to IIIA and in all randomly assigned stage II to IIIA populations; the significance boundary was not crossed for disease-free survival in the intent-to-treat population. Overall survival data were immature and not formally tested.

Patients in the atezolizumab arm received a median of 16 doses. Any-grade adverse events occurred in 92.7% of patient in the atezolizumab arm and 70.7% of those receiving best supportive care; events were grade 3 in 21.8% and grade 4 in 11.5%. Grade 5 treatment-related adverse events occurred in 0.8% of patients in the atezolizumab arm. Adverse events leading to discontinuation of atezolizumab occurred in 18.2% of the atezolizumab-treated patients.

“IMpower010 met its primary endpoint, showing a disease-free survival benefit with adjuvant atezolizumab vs best supportive care after adjuvant chemotherapy in patients with resected stage II to IIIA NSCLC, with pronounced benefit in the PD-L1 tumor cell ≥ 1% subgroup. The safety profile of atezolizumab was consistent with prior experience of atezolizumab across indications and lines of therapy,” concluded the study authors.

Clinical Relevance

Julie R. Gralow, MD, FACP, FASCO

““[The results from IMpower010 show that atezolizumab] is effective in treating early-stage NSCLC,” said ASCO Chief Medical Officer and Executive Vice President Julie R. Gralow, MD, FACP, FASCO, during a media press briefing highlighting this study abstract. “This is an important advance in understanding the role of [atezolizumab] in earlier-stage lung cancer, [and] potentially a step forward for many patients with lung cancer.”

Disclosure: Funding for this study was provided by Hoffman-LaRoche. For full disclosures of the study authors, visit coi.ascopubs.org.