The VENTANA Claudin‑18 (43‑14A) RxDx Assay is an FDA‑approved qualitative immunohistochemical (IHC) assay that uses a mouse monoclonal anti‑Claudin‑18 antibody. The assay is intended for the assessment of Claudin‑18 protein expression, encoded by the CLDN18 gene, in formalin‑fixed, paraffin‑embedded (FFPE) gastric cancer tissue and is performed on the VENTANA BenchMark ULTRA instrument.
Claudin‑18 testing is indicated as an aid in identifying patients with Gastric Adenocarcinoma, including Gastroesophageal junction (GEJ) Adenocarcinoma. Tumors demonstrating Claudin‑18 expression in ≥75% of tumor cells with 2+ and/or 3+ staining intensity may be eligible for treatment with VYLOY® (zolbetuximab).
Claudin 18 FDA (VYLOY®) for Gastric/GEJ Adenocarcinoma
- Immunohistochemistry (IHC)
- Epic Aura Integration
Specimen Requirements
Preferred specimen (FFPE block):
A formalin-fixed, paraffin-embedded (FFPE) tissue block is the preferred specimen type. Use 10% NBF fixative; do not use zinc or mercury fixatives.
If submitting slides (instead of a block):
Submit the following. All slides cut at 4–5 microns. Please use positively-charged slides and 10% NBF fixative.
H&E slide: One (1) unbaked, unstained slide for H&E staining (required)
Cut Slides: Two (2) positively charged unstained slides for each IHC test/antibody ordered
Specimen adequacy:
Tissue submitted must have >100 viable tumor cells present.
Specimen identification:
Block and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.
A formalin-fixed, paraffin-embedded (FFPE) tissue block is the preferred specimen type. Use 10% NBF fixative; do not use zinc or mercury fixatives.
If submitting slides (instead of a block):
Submit the following. All slides cut at 4–5 microns. Please use positively-charged slides and 10% NBF fixative.
H&E slide: One (1) unbaked, unstained slide for H&E staining (required)
Cut Slides: Two (2) positively charged unstained slides for each IHC test/antibody ordered
Specimen adequacy:
Tissue submitted must have >100 viable tumor cells present.
Specimen identification:
Block and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.
Storage and Transportation
Slides may be stored at room temperature; transport with cold pack, making sure cold pack is not in direct contact with specimen.
NYS Clients: Please provide Date and Time of Collection.
CPT Code(s)*
88360x1
Turnaround time
1-2 Days
Global: 2 Days
Tech-Only (stain only): 24 Hours
Level of Service
- Global
- Tech Only
Integrations
- Epic Aura
New York Approved: Yes
*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.
Biomarkers
Immunohistochemistry (IHC)
| Expression | |||||
|---|---|---|---|---|---|
| CLDN18 | |||||
Last Updated: March 31, 2026