Cohort

Response Evaluation Criteria in Solid Tumors

Clinical trial

Lung cancer

Phases of clinical research

Environmental health

Trastuzumab

Trastuzumab emtansine

Population

Internal medicine

Clinical endpoint

Chemotherapy

Oncology

Medicine

Immunohistochemistry

Breast cancer

Cancer

Clinical Cancer Research

Purpose: HER2-targeted therapy is not standard of care for HER2-positive non–small cell lung cancer (NSCLC). This phase II study investigated efficacy and safety of the HER2-targeted antibody–drug conjugate trastuzumab emtansine (T-DM1) in patients with previously treated advanced HER2-overexpressing NSCLC. Patients and Methods: Eligible patients had HER2-overexpressing NSCLC (centrally tested IHC) and received previous platinum-based chemotherapy and targeted therapy in the case of EGFR mutation or ALK gene rearrangement. Patients were divided into cohorts based on HER2 IHC (2+, 3+). All patients received T-DM1 3.6 mg/kg intravenously every 3 weeks until disease progression or unacceptable toxicity. The primary endpoint was investigator-determined overall response rate (ORR) using RECIST v1.1. Results: Forty-nine patients received T-DM1 (29 IHC 2+, 20 IHC 3+). No treatment responses were observed in the IHC 2+ cohort. Four partial responses were observed in the IHC 3+ cohort (ORR, 20%; 95% confidence interval, 5.7%–43.7%). Clinical benefit rates were 7% and 30% in the IHC 2+ and 3+ cohorts, respectively. Response duration for the responders was 2.9, 7.3, 8.3, and 10.8 months. Median progression-free survival and overall survival were similar between cohorts. Three of 4 responders had HER2 gene amplification. No new safety signals were observed. Conclusions: T-DM1 showed a signal of activity in patients with HER2-overexpressing (IHC 3+) advanced NSCLC. Additional investigation into HER2 pathway alterations is needed to refine the target population for T-DM1 in NSCLC; however, HER2 IHC as a single parameter was an insufficient predictive biomarker.

Trastuzumab Emtansine (T-DM1) in Patients with Previously Treated HER2-Overexpressing Metastatic Non–Small Cell Lung Cancer: Efficacy, Safety, and Biomarkers