Effectiveness of third- or later-line therapy in patients with HER2-positive advanced gastric cancer: Results from an observational retrospective study in Japan.

Abstract

277 Background: The real-world effectiveness of third- or later-line (3L+) therapies in patients (pts) with HER2-positive gastric cancer remains unknown. We report a multicenter, retrospective, observational study at 20 centers in Japan to investigate the outcomes of 3L+ therapy in pts with HER2-positive advanced gastric/gastroesophageal junction (G/GEJ) cancer previously receiving trastuzumab (UMIN000040853). Methods: Pts aged ≥20 years with HER2-positive advanced G/GEJ cancer who were previously treated with trastuzumab and newly initiated on nivolumab, irinotecan, or trifluridine/tipiracil monotherapy as 3L+ therapy (Sep 2017 to Mar 2020) were evaluated for overall survival (OS), progression-free survival (PFS), duration of response (DOR), time to treatment failure (TTF), objective response rate (ORR), and disease control rate (DCR). An exploratory analysis for factors affecting OS was conducted using a multivariate Cox regression model, with HER2 status as a covariate. Results: The overall analysis population was 117 pts (median: age, 71 years; number of prior treatment lines, 2; days since the initiation of first-line treatment, 431 days). Median (95% confidence interval) OS, PFS, and TTF were 6.2 months (4.5–8.0), 1.9 months (1.5–2.3), and 1.8 months (1.5–2.2), respectively, at a median follow-up of 150 days. Outcomes by treatment groups are shown in the Table. ORR and DCR in 100 pts with evaluable target lesions were 9.0% and 32.0%, respectively, and median DOR was 8.4 months. A higher neutrophil-lymphocyte ratio (≥2.540), Glasgow prognostic score (≥1), ECOG PS (≥2), and hepatic metastasis significantly impacted OS. Conclusions: The real-world effectiveness of 3L+ therapies was limited in this study. New HER2 treatment agent is expected to improve outcomes in pts with HER2-positive G/GEJ cancer.[Table: see text]