Afatinib monotherapy in patients with metastatic squamous cell carcinoma of the lung progressing after erlotinib/gefitinib (E/G) and chemotherapy: Interim subset analysis from a phase III trial.

Abstract

7558 Background: Patients with squamous NSCLC have limited treatment options. For those deriving benefit from EGFR TKIs, it is unclear whether sustained ErbB family blockade offers benefit upon progression. We evaluated afatinib, an irreversible blocker of EGFR (ErbB1), HER2 (ErbB2) and ErbB4 receptor tyrosine kinases, in patients with metastatic NSCLC who had failed chemotherapy and E/G. Here we describe a pre-specified analysis of those with squamous histology in Part A. Methods: This randomized Phase III, open-label, multi-center trial enrolled patients with pathologically confirmed metastatic NSCLC after failing ≥1 line of cytotoxic chemotherapy and E/G. In Part A, patients received oral afatinib 50 mg until disease progression. Those with clinical benefit (≥12 wks) who progressed were eligible to receive afatinib plus paclitaxel or investigator’s choice chemotherapy (Part B). Primary endpoint was PFS (RECIST 1.1). Following an amendment, an interim analysis of Part A was performed to assess afatinib monotherapy. Results: Patient enrolment into Part A was from April 2010 to May 2011. Of 1154 afatinib-treated patients, 91 (8%) had squamous histology; 18/91 and 40/91 had CR/PR and SD on prior E/G, respectively (by investigator). Median age was 63 yrs, 71% were male, 76% were current/ex-smokers. Median PFS on afatinib was 3.7 mths in the squamous histology subset. Of 91 patients, 42 had PFS ≥3 mths; 13 had PFS of ≥6 mths. In evaluable patients (n=77), 1 CR and 3 PRs were confirmed; 51 and 22 patients had best overall response of SD and PD, respectively. Of the 31 patients with PD on prior E/G with no intervening chemotherapy, 10 achieved confirmed disease control (2 PR; 8 SD) on afatinib. Most commonly reported grade 3/4 adverse events (AEs) in Part A were diarrhea (13%) and rash/acne (12%). The safety profile in the squamous histology subset was similar to that observed for the whole trial. Conclusions: Afatinib monotherapy demonstrated encouraging activity in treatment-refractory NSCLC patients with squamous histology that merits further evaluation.