{"entity":{"id":"cldn18-2-expression","kind":"biomarker","name":"Claudin 18.2 expression (>= 75% of tumour cells, moderate to strong)","aka":["CLDN18.2","Claudin 18.2 positive","CLDN18.2-positive","claudin 18.2 expression","CLDN18 IHC","CLDN18.2 >= 75%"],"tldr":"Claudin 18.2 is a tight-junction protein exposed on stomach cancer cells. Zolbetuximab requires at least 75 percent of tumour cells to stain moderately or strongly, the strictest expression threshold in any current label.","summary":"Zolbetuximab (Vyloy) is labelled with fluoropyrimidine and platinum chemotherapy for first-line HER2-negative gastric or GEJ adenocarcinoma whose tumours are CLDN18.2 positive as determined by an FDA-approved test; the SPOTLIGHT and GLOW trials and the VENTANA CLDN18 (43-14A) RxDx Assay define positivity as 75 percent or more of tumour cells with moderate to strong membranous staining. About 38 percent of screened patients met the bar. CLDN18.2 ADCs and CAR-T cells in trials use lower or different cut-offs.","asOf":"2026-09-23","links":[{"label":"VYLOY prescribing information (DailyMed)","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e7695a21-abb6-47ac-93f8-0ece5a9c4409"}],"tags":["biomarker","surface-antigen"],"related":["her2-ihc-3-plus","pd-l1-cps"],"cancers":["gastric","gastric-cldn18-2-positive","pancreatic"],"sections":[],"technologies":[],"targets":[],"drugs":["zolbetuximab"],"companies":[],"institutions":[],"pathways":[],"terms":["ihc"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"target":"cldn18-2","measurement":"ihc-score","scoringRule":{"text":"75 percent or more of viable tumour cells with moderate to strong membranous CLDN18 staining on the VENTANA CLDN18 (43-14A) RxDx Assay.","quote":"CLDN18.2 positivity (defined as ≥75% of tumor cells demonstrating moderate to strong membranous CLDN18 staining) was determined by immunohistochemistry on gastric or GEJ tumor tissue specimens from all patients with the VENTANA CLDN18 (43‑14A) RxDx Assay performed in a central laboratory.","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e7695a21-abb6-47ac-93f8-0ece5a9c4409","sourceLabel":"VYLOY prescribing information"},"thresholds":[{"value":">= 75% of tumour cells with moderate to strong membranous staining","drugId":"zolbetuximab","cancerId":"gastric-cldn18-2-positive","regulator":"FDA","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e7695a21-abb6-47ac-93f8-0ece5a9c4409","quote":"VYLOY is a claudin 18.2-directed cytolytic antibody and is indicated in combination with fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of adults with locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-negative gastric or gastroesophageal junction adenocarcinoma whose tumors are claudin (CLDN) 18.2 positive as determined by an FDA-approved test","status":"current"}],"tests":[],"assays":["cldn18-ventana"],"companionDiagnostics":[{"device":"VENTANA CLDN18 (43-14A) RxDx Assay","maker":"Ventana Medical Systems (Roche)","drugs":["zolbetuximab"],"indication":"Gastric or Gastroesophageal Junction (GEJ) Adenocarcinoma - Tissue","pma":"P230018 (10/18/2024)","source":"https://www.fda.gov/medical-devices/in-vitro-diagnostics/list-cleared-or-approved-companion-diagnostic-devices-in-vitro-and-imaging-tools"}],"forPatient":"If at least three quarters of your stomach cancer cells stain moderately or strongly for claudin 18.2, zolbetuximab can be added to first-line chemotherapy, provided the cancer is HER2-negative. A lower percentage does not qualify under the label, though trials of other claudin 18.2 drugs may accept it. Nausea and vomiting during the first infusions are common and expected."},"route":"/biomarkers/cldn18-2-expression/","neighbours":{"biomarker":[{"id":"her2-ihc-3-plus","kind":"biomarker","name":"HER2 IHC 3+ (HER2-positive by immunohistochemistry)","route":"/biomarkers/her2-ihc-3-plus/"},{"id":"pd-l1-cps","kind":"biomarker","name":"PD-L1 CPS (combined positive score)","route":"/biomarkers/pd-l1-cps/"}],"cancer":[{"id":"gastric-cldn18-2-positive","kind":"cancer","name":"Claudin 18.2-positive gastric cancer","route":"/cancers/gastric-cldn18-2-positive/"},{"id":"gastric","kind":"cancer","name":"Gastric & gastro-oesophageal junction cancer","route":"/cancers/gastric/"},{"id":"pancreatic","kind":"cancer","name":"Pancreatic ductal adenocarcinoma","route":"/cancers/pancreatic/"}],"drug":[{"id":"zolbetuximab","kind":"drug","name":"Zolbetuximab","route":"/drugs/zolbetuximab/"}],"term":[{"id":"ihc","kind":"term","name":"Immunohistochemistry (IHC)","route":"/terms/ihc/"}],"target":[{"id":"cldn18-2","kind":"target","name":"Claudin 18.2","route":"/targets/cldn18-2/"}]}}