A phase 1 study of LJM716 in patients with esophageal squamous cell carcinoma, head and neck cancer, or HER2-overexpressing metastatic breast or gastric cancer.

2517 Background: The HER3 receptor is important for maintenance of EGFR- and HER2-driven cancers and targeted therapy resistance. LJM716 is a fully human HER3 monoclonal antibody active in ligand-dependent and -independent preclinical models. Methods: This phase 1, first-in-human study is evaluating LJM716 in patients (pts) with squamous cell carcinoma of the head and neck (SCCHN) or esophagus (ESCC) and HER2-overexpressing metastatic breast cancer (MBC) or gastric/gastroesophageal junction cancer (MGC) for which no effective treatment exists. The objective for the dose-escalation part of the study, guided by a Bayesian model with overdose control, was to identify the maximum tolerated dose (MTD), recommended dose for expansion (RDE), and preferred dosing schedule. MTD was based on cycle 1 dose-limiting toxicity (DLT). Results: As of October 4, 2013, 54 pts (escalation, n = 24; expansion, n = 30) were enrolled (SCCHN, n = 21; ESCC, n = 15; MBC, n = 10; MGC, n = 8) and treated intravenously for 2 hr at dos...