A randomized, open-label phase II study evaluating emibetuzumab plus erlotinib and emibetuzumab monotherapy in MET immunohistochemistry positive NSCLC patients with acquired resistance to erlotinib

Abstract

This open-label Phase II study conducted prior to routine EGFR mutation testing, assessed whether acquired resistance to erlotinib in NSCLC patients with a given MET protein expression level enriched for EGFRmt could be overcome by emibetuzumab, an antibody against MET. Although some responses were seen, the trial did not meet its primary endpoint.Introduction: The hepatocyte growth factor receptor MET represents a resistance mechanism to epidermal growth factor receptor (EGFR) inhibition in EGFR mutant (mt) non-small cell lung cancer (NSCLC). This Phase 2 study tested whether acquired resistance to erlotinib in MET protein positive NSCLC patients enriched for EGFRmt can be overcome by emibetuzumab plus erlotinib. Patient and Methods: Patients with Stage IV NSCLC with acquired resistance to erlotinib and MET diagnostic (+) (>= 10% of cells expressing MET at >= 2+ IHC staining intensity at any time) were randomized (3:1) to receive emibetuzumab 750 mg every 2 weeks with or without erlotinib 150 mg once daily. The primary objective was to evaluate the overall response rate (ORR) relative to historic control, with a co-primary objective of ORR in patients with MET expression in >= 60% of cells >= 2+ (MET > 60%). Results: One hundred and eleven MET+ patients received emibetuzumab plus erlotinib (N = 83) or emibetuzumab monotherapy (N = 28). 89 of 111 MET+ samples were post-erlotinib. ORR was 3.0% for emibetuzumab plus erlotinib (95% CI: 0.4, 10.5) and 4.3% for emibetuzumab (95% CI: 0.1, 21.9), in patients with post-erlotinib progression biopsies available (n = 89). Similar results were observed in patients with MET >= 60% expression (n = 74). Disease control rate and progression-free survival were higher for emibetuzumab plus erlotinib (50%/3.3 months) than for emibetuzumab (26%/1.6 months). No unexpected safety signals emerged. Partial responses were observed in patients with and without EGFRmt or MET amplification. EGFR sensitizing mutations were identified retrospectively in 84.2% of those with available tissue (85/101). Conclusion: Acquired resistance to erlotinib in MET diagnostic (+) patients was not reversed by emibetuzumab plus erlotinib or emibetuzumab monotherapy, although a subset of patients obtained clinical benefit. (C) 2022 Elsevier Inc. All rights reserved.