HER2-positive gastric/GEJ adenocarcinoma (~15-20%): trastuzumab + chemotherapy is standar...
Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.
| ID | BMA-HER2-AMP-GASTRIC |
|---|---|
| Type | Actionability |
| Status | reviewed 2026-04-27 | pending_clinical_signoff | actionability review required |
| Diseases | DIS-GASTRIC |
| Sources | SRC-CIVIC SRC-ESMO-GASTRIC-2024 SRC-NCCN-GASTRIC-2025 |
Actionability Facts
| Biomarker | BIO-HER2-SOLID |
|---|---|
| Variant | amplification / overexpression — IHC 3+ or (IHC 2+ + ISH amplified, HER2/CEP17 ≥2.0); ~15-20% of gastric/GEJ adenocarcinoma |
| Disease | DIS-GASTRIC |
| ESCAT tier | IA |
| Recommended combinations | trastuzumab + fluoropyrimidine + platinum (1L per SRC-NCCN-GASTRIC-2025, SRC-ESMO-GASTRIC-2024), pembrolizumab + trastuzumab + fluoropyrimidine + platinum (1L HER2+ PD-L1 CPS ≥1 per SRC-NCCN-GASTRIC-2025), trastuzumab deruxtecan (2L+ post-trastuzumab progression per SRC-NCCN-GASTRIC-2025) |
| Contraindicated monotherapy | trastuzumab monotherapy (combination with chemotherapy required for survival benefit) |
| Evidence summary | HER2-positive gastric/GEJ adenocarcinoma (~15-20%): trastuzumab + chemotherapy is standard 1L (ToGA Bang Lancet 2010 — mOS 13.8 vs 11.1 mo, HR 0.74). Pembrolizumab + trastuzumab + chemo is FDA-approved 1L for HER2-positive PD-L1 CPS ≥1 metastatic gastric/GEJ disease per SRC-NCCN-GASTRIC-2025, SRC-ESMO-GASTRIC-2024 (KEYNOTE-811). Trastuzumab deruxtecan (T-DXd) is FDA-approved 2L+ for HER2-positive (IHC 3+ or 2+) advanced gastric/GEJ adenocarcinoma based on DESTINY-Gastric01 (Shitara NEJM 2020 — ORR 51% vs 14% with chemotherapy). |
Notes
ESCAT IA / OncoKB Level 1. Gastric HER2 scoring (Hofmann 2008) differs from breast: basolateral/lateral membranous staining ≥10% qualifies (cf. circumferential criterion in breast). HER2 testing recommended for all metastatic gastric/GEJ adenocarcinoma at diagnosis. Heterogeneity is significant: ≥4 endoscopic biopsies preferred. Source-gap: SRC-TOGA-BANG-2010, SRC-DESTINY-GASTRIC01, SRC-KEYNOTE-811 not yet ingested.
Used By
Actionability
BMA-PDL1-CPS-GASTRIC- PD-L1 CPS is a continuous IHC score used as an eligibility threshold for ICI-containing r...