A single-arm phase II trial of afatinib in pretreated patients with advanced NSCLC harboring a HER2 mutation: The ETOP NICHE trial.

Abstract

9070 Background: HER2mutations are identified in about 2% of lung adenocarcinomas and are critical for lung carcinogenesis. Afatinib is a selective and irreversible erbB family blocker with a manageable toxicity profile and promising results in small retrospective studies targeting HER2 in NSCLC. Methods: NICHE is a single-arm phase II trial exploring the potential of afatinib to control disease (complete or partial response or disease stabilization for ≥12 weeks) in pre-treated patients with advanced NSCLC harboring HER2 exon 20 mutations. Patients were treated with afatinib 40 mg/day p.o. until tumor progression or lack of tolerability. A Simon’s two stage phase II design was adopted, to explore whether afatinib can achieve a DCR of 75%, as opposed to a DCR of 50% under the current treatment options. For a 1-sided type I error of 10% and power of 80%, a total of 22 patients were needed. Results: As of 24 November 2016, 13 patients were recruited into the trial. Median age was 60 years, 69% female and 62% never smokers. The overall toxicity profile was in the expected range, with 5 patients experiencing serious adverse events (dyspnea, diarrhea, dehydration, epistaxis, pleural, pericardial and renal insufficiency). The median follow-up was 23 weeks (IQR 12 – 39). Three patients died and 10 were still on follow-up, among them five were still on treatment. Total of 7 patients (54%) achieved DC at 12-weeks, 3 patients had PD before and 3 at 12-weeks. The 12-week PFS was 51% (95% CI: 22 - 75) and the median PFS 13 weeks (95% CI 6 - NE). In the 1st stage analysis of the Simon’s design, with 9 patients included, the stopping boundary was crossed. Therefore and upon recommendations of the ETOP IDMC, recruitment into the trial was stopped prematurely in December 2016. Treatment and follow-up of the enrolled patients continues as planned. Conclusions: Based on the interim results, afatinib did not show the expected potential to control disease in this patient population. However in the full analysis set with 13 patients, clear signs of activity were seen. A comprehensive biomolecular analysis of the tumors is currently ongoing in order to identify a subgroup of patients who might still derive benefit from afatinib treatment. Clinical trial information: NCT02369484.