HER2-low and gastric cancer: A prognostic biomarker?

• DOI: 10.1200/jco.2021.39.15_suppl.e16086
• Publication Date: 2021-06-02T14:14:26Z
• Authors: Bruno Cezar de Me...; Rafaela Pirolli; Luciana Beatriz M...; Francisca Giselle...; Ana Paula Rondina...; Jose Ecio Batista...; Juliana Rosa Chin...; Tiago Felismino; Victor Hugo Fonse...; Mauro Daniel Spin...; Éverton Melo; Marcelle Goldner ...
• Keywords: 03 medical and health sciences; 0302 clinical medicine; 3. Good health

e16086 Background: The role of HER2 positive (HER2+) as a prognostic biomarker for gastric/gastroesophageal junction cancer (G-GEJC) is controversial. Recently, the HER2-low (HER2l) concept has emerged and proved to predict response trastuzumab deruxtecan in metastatic scenario. Data on HER2l value are missing. Methods: All consecutive patients with G-GEJC, tested primary tumor or tissue before initiating first-line therapy at A.C. Camargo Cancer Center, were retrospectively recruited. objective was compare overall survival (OS: from metastasis diagnosis death by any cause) between negative (HER2-) populations. Secondarily, we aimed progression-free (PFS) HER2-, analyze factors associated OS HER2+ HER2l/HER2-. immunohistochemistry (IHC) tests performed Ventana anti-HER2/neu kit, specialized gastrointestinal pathologists study center, using AJCC scoring criteria gastric cancer. In situ hybridization (ISH) done when IHC 2+ detected. 3+ amplified ISH; HER2l, 1+ non-amplified; HER-, 0+. Kaplan-Meier curves, Log-Rank test Cox regression used analysis. uni multivariate Results: From June, 2008 July, 2020, 398 included (48 HER2+; 103 HER2l; 247 HER2-). median follow-up 31 months (m). Median age 58 years; majority men (62.8%), caucasian (50.8%), (81% vs 19% GEJ), diffuse (50.3%), de novo (57.0%) tumors. comparison HER2l/HER2-, group had superior rates men, GEJC, intestinal subtype non-visceral metastasis. Central nervous system metastases uncommon, proportionally higher tumors (HER2+: 6.2%; HER2l: 2.9%; HER2-: 2.0%; p = 0.27). There no imbalances HER2- groups. similar (13m both; HR 1.0, 95%CI 0.76-1.31; 1.0), it PFS (5m 0.84, 0.65-1.08; 0.18). These results did not vary dependence + (0 1 2+). (17m 13m HER2l/HER2-; 0.70, 0.49-0.99; 0.046). When ungrouping this numerical difference remains, loss statistical significance 13m; 0.87, 0.74-1.02; 0.12). HER2+, > line treatment metastasectomy predictive improved neither nor PFS. Conclusions: Although new cancer, its could be study, an absence impact OS. however, survival.