Randomized phase II study of adjuvant afatinib for three months versus two years in patients with resected stage I-III EGFR mutant NSCLC.
8507 Background: EGFR tyrosine kinase inhibitors are superior to chemotherapy in patients with advanced EGFR+ lung cancers. In the adjuvant setting, erlotinib for two years improves recurrence free survival (RFS) compared to historical controls. The optimal duration of adjuvant TKI is unknown. Methods: Patients with completely resected Stage I-III NSCLC with a sensitizing EGFR mutation were enrolled after standard adjuvant therapy. Pts were randomly assigned to 3 months (3m) or 2 years (2y) of adjuvant afatinib. Afatinib was started at 30 mg by mouth daily. Patients without toxicity after 28 days were allowed to escalate to 40 mg daily. Patients were imaged with CT every 6 months for 3 years and then annually or as clinically indicated. RFS was measured from the date of randomization. The primary study endpoint was recurrence rate at 2 years. 60 randomized patients would provide 82.5% power to detect a 26% difference in 2y-recurrence rate. Results: Patient characteristics are in the Table. The study was terminated for slow accrual after 46 of the planned 60 patients. Planned treatment was completed by 92% (22/24) pts in the 3m arm and 41% (9/22) of pt in the 2y arm. 22 patients required ≥1 dose modification due to toxicity including expected GI, mucosal, and skin AEs. With a median follow-up of ≥38 months there were 10 recurrences and 3 deaths in the 3m arm and there were 5 recurrences (2 on treatment) and 2 deaths in the 2y arm. Median RFS has not been reached in either arm, but recurrence was more common in the 3m arm at every landmark. 2y-recurrence rates were 29% for 3m and 15% for 2y. Conclusions: Recurrences at 2 years were 14% less common with 2y versus 3m of adjuvant afatinib. This difference did not meet the primary study endpoint. The RFS curves show a durable and clinically meaningful separation with substantial follow-up. Failure to meet significance was likely influenced by under-accrual and early drug discontinuation on the 2y arm. In the era of TKIs with improved tolerance, duration of adjuvant therapy remains an important question. Clinical trial information: NCT01746251. [Table: see text]