Study details
The phase 3, randomized, double-blind trial was conducted at centers in the United States, Europe, Asia, and Australia. A total of 682 patients with completely resected stage IB, II, or IIIA NSCLC, with or without planned adjuvant chemotherapy, were enrolled.
After stratification by stage, EGFR mutation, and race (Asian vs. non-Asian), patients were randomized on a 1:1 basis to receive either osimertinib at 80 mg once daily or placebo. The planned treatment duration was a maximum of 3 years.
Members of the independent data-monitoring committee held a meeting in April 2020. Although they had not planned an efficacy analysis at that time, they decided the results were clearly in favor of osimertinib. So they recommended unblinding and halting of the trial.
At the time of unblinding, the study had completed enrollment, and all patients had been followed for at least 1 year.
Efficacy and safety
For the primary endpoint of disease-free survival (DFS) in patients with stage II to IIIA disease, the median DFS was not reached for patients assigned to osimertinib, but it was 20.4 months for patients assigned to placebo (hazard ratio, 0.17; P < .0001).
The numbers were similar for the secondary endpoint of DFS in the overall population, including patients with stage IB disease. The median DFS was not reached for patients on osimertinib but was 28.1 months for patients on placebo (HR, 0.21; P < .0001).
DFS was significantly superior with osimertinib across all subgroups in the overall population, including sex, age, smoking status, race, stage, EGFR mutation, and adjuvant chemotherapy (yes or no).
Dr. Herbst said patients tolerated osimertinib well, and the drug’s safety profile was consistent with that already known. There were no adverse events leading to death in the osimertinib arm, and the incidence of grade 3 or 4 adverse events of any kind was low.
In all, 10 patients (3%) in the osimertinib arm were reported to have interstitial lung disease. Prolongation of the QT interval was reported in 22 patients (7%) on osimertinib and 4 patients (1%) in the placebo arm.
The results show that “adjuvant osimertinib provides a highly effective, practice-changing treatment for patients with stage IB, II, IIIA, EGFR mutation-positive non–small cell lung cancer after complete tumor resection,” Dr. Herbst said.
Dr. Herbst disclosed relationships with AstraZeneca, which funded the study, as well as Jun Shi Pharmaceuticals and other companies. Dr. Cascone is the international principal investigator of the NeoCOAST trial evaluating durvalumab, an AstraZeneca product.
SOURCE: Herbst RS et al. ASCO 2020, Abstract LBA5.