Atezolizumab versus Best Supportive Care After Adjuvant Chemotherapy for Resected NSCLC (IMpower010)
Adjuvant atezolizumab extends disease-free survival after adjuvant chemotherapy compared with best supportive care after adjuvant chemotherapy in patients with resected stage II/IIIA non–small-cell lung cancer (NSCLC).
Platinum-based chemotherapy provides only a modest 5-year survival benefit. At the American Society of Clinical Oncology 2021 meeting, researchers reported disease-free survival (DFS) results from the preplanned interim analysis of IMpower010, a randomized, phase 3, open-label trial of adjuvant atezolizumab (anti–PD-L1) compared with best supportive care (BSC) after adjuvant chemotherapy in patients with early-stage resected NSCLC.1
Patients who were eligible for enrollment in IMpower010 had completely resected (4-12 weeks prior to enrollment) stage IB (≥4 cm) to IIIA NSCLC (based on American Joint Committee on Cancer/International Union for Cancer Control, 7th edition) and Eastern Cooperative Oncology Group performance status 0 or 1. Of the 1280 patients who were enrolled, 1269 patients received up to four 21-day cycles of cisplatin-based chemotherapy plus pemetrexed, docetaxel, gemcitabine, or vinorelbine. Of these 1269 patients, 1005 were subsequently randomized to either 16 cycles of atezolizumab 1200 mg every 3 weeks or BSC.1
The primary end point of IMpower010 was investigator-assessed DFS, while a key secondary end point was overall survival (OS). Efficacy assessments were based on randomized patients. Safety was assessed in the safety-evaluable population, defined as patients who received at least 1 dose of atezolizumab or who had at least 1 post-baseline safety assessment if randomized to the BSC arm.1
At data cutoff January 21, 2021, median follow-up was 32.8 months in the intent-to-treat (ITT) population.1 Baseline characteristics were generally balanced between arms.1 Atezolizumab showed statistically significant DFS benefit compared with BSC in the PD-L1 tumor cell ≥1% stage II to IIIA group and in all randomized stage II to IIIA patients; median DFS was not reached for atezolizumab compared with 35.3 months for BSC (hazard ratio, 0.66; 95% confidence interval, 0.50-0.88, P = .04).1 At this interim analysis, the significance boundary was not crossed for DFS in the ITT population; testing will continue to the final DFS analysis.1 OS data were immature and not formally tested.1
Patients in the atezolizumab arm received a median of 16 doses (range, 1-16) of atezolizumab. Any- grade adverse events occurred in 93% (atezolizumab) and 71% (BSC) of patients.1 Events were grade 3/4 in 22% and 12%, respectively.1 Grade 5 treatment-related adverse events occurred in 0.8% of patients in the atezolizumab arm.1 Adverse events leading to treatment discontinuation occurred in 18% of atezolizumab-treated patients.1
Researchers concluded that IMpower010 met its primary end point: adjuvant atezolizumab showed a DFS benefit compared with BSC after adjuvant chemotherapy in patients with resected stage II/IIIA NSCLC. The benefit was particularly pronounced in the PD-L1 tumor cell ≥1% subgroup. Toxicities seen with atezolizumab were consistent with prior experience of atezolizumab monotherapy across indications and lines of therapy.1Reference
1. Wakelee HA, Altorki NK, Zhou C, et al. IMpower010: primary results of a phase III global study of atezolizumab versus best supportive care after adjuvant chemotherapy in resected stage IB-IIIA non- small cell lung cancer (NSCLC). Presented at: 2021 American Society of Clinical Oncology (ASCO) Annual Meeting; June 4-8, 2021. Abstract 8500.