Canadian Consensus Recommendations for Predictive Biomarker Testing in Gastric and Gastroesophageal Junction Adenocarcinoma

Curr Oncol. 2024 Dec 4;31(12):7770-7786. doi: 10.3390/curroncol31120572.

Abstract

Gastric cancer is common globally and has a generally poor prognosis with a low 5-year survival rate. Targeted therapies and immunotherapies have improved the treatment landscape, providing more options for efficacious treatment. The use of these therapies requires predictive biomarker testing to identify patients who can benefit from their use. New therapies on the horizon, such as CLDN18.2 monoclonal antibody therapy, require laboratories to implement new biomarker tests. A multidisciplinary pan-Canadian expert working group was convened to develop guidance for pathologists and oncologists on the implementation of CLDN18.2 IHC testing for gastric and gastroesophageal junction (G/GEJ) adenocarcinoma in Canada, as well as general recommendations to optimize predictive biomarker testing in G/GEJ adenocarcinoma. The expert working group recommendations highlight the importance of reflex testing for HER2, MMR and/or MSI, CLDN18, and PD-L1 in all patients at first diagnosis of G/GEJ adenocarcinoma. Testing for NTRK fusions may also be included in reflex testing or requested by the treating clinician when third-line therapy is being considered. The expert working group also made recommendations for pre-analytic, analytic, and post-analytic considerations for predictive biomarker testing in G/GEJ adenocarcinoma. Implementation of these recommendations will provide medical oncologists with accurate, timely biomarker results to use for treatment decision-making.

Keywords: CLDN18; CLDN18.2; HER2; IHC; MMR; PD-L1; gastric cancer; immunohistochemistry; immunotherapy; targeted therapy.

Publication types

  • Consensus Development Conference
  • Review

MeSH terms

  • Adenocarcinoma* / diagnosis
  • Adenocarcinoma* / therapy
  • Biomarkers, Tumor*
  • Canada
  • Consensus
  • Esophageal Neoplasms* / diagnosis
  • Esophageal Neoplasms* / therapy
  • Esophagogastric Junction* / pathology
  • Humans
  • Stomach Neoplasms* / diagnosis
  • Stomach Neoplasms* / therapy

Substances

  • Biomarkers, Tumor

Supplementary concepts

  • Adenocarcinoma Of Esophagus

Grants and funding

Astellas Canada provided funding for the working group meetings. The members of the working group were selected independently of the funding sponsor, and the recommendations and manuscript content were also developed independently. Astellas Canada also provided funding for medical writing support through Precision Rx-Dx Inc. in accordance with version 3 of the Good Publication Practice guidelines (https://www.ismpp.org/gpp3 accessed on 1 October 2024).