HER2-Mutant Advanced and/or Metastatic Non-Small-Cell Lung Cancer: A US Electronic Health Records Database Analysis of Clinical Characteristics, Treatment Practice Patterns, and Outcomes.

BACKGROUND: Real-world data for advanced/metastatic non-small-cell lung cancer (NSCLC) with mutations in human epidermal growth factor 2 (HER2) are scarce. We aimed to assess treatment patterns and outcomes among patients with HER2-mutant advanced/metastatic NSCLC.

PATIENTS AND METHODS: This retrospective nationwide electronic health record study evaluated patient characteristics, treatment patterns, treatment duration, and overall survival for adults with HER2-mutant advanced/metastatic NSCLC without epidermal growth factor receptor mutation.

RESULTS: Of 55 included patients, median (quartile 1 [Q1]-quartile 3 [Q3]) age was 63.0 (58.0-72.0) years, 42 (76%) were women, and 39 (71%) were current/former smokers. In first-line therapy, 14 regimens were used for median (Q1-Q3) duration of 3.1 (2.4-6.2) months, with most patients (n = 39, 71%) receiving platinum-based chemotherapy alone or in combination with other agents. Median (95% CI) overall survival from first-line treatment initiation was 19.0 (12.2-not estimable) months, with no significant association with age, sex, or smoking status. Thirty-five (64%) patients received second-line therapy for median (Q1-Q3) duration of 3.3 (2.0-5.2) months. Fourteen second-line regimens were used; most commonly immunotherapy alone or in combination with other agents (n = 16, 46%). Sixteen (46%) patients received third-line therapy for median (Q1-Q3) duration of 1.9 (1.3-2.7) months. Nine third-line regimens were used, with 7 (44%) patients receiving HER2-directed agents.

CONCLUSION: First- and second-line treatments for HER2-mutant NSCLC varied widely and treatment duration was short. The approval of trastuzumab deruxtecan for NSCLC supports wider HER2 testing to identify eligible patients for HER2-directed therapy.