# Claudin-18.2 imaging when one biopsy says negative

Source: https://nuclide.cc/opportunities/opp-cldn18-2-imaging-gastric/  
Nuclide record `opp-cldn18-2-imaging-gastric` (Opportunity). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

Stomach cancer patients now get a drug only if a biopsy shows a protein called claudin-18.2. One biopsy core finds it only about six times in ten when the whole tumour has it, so patients are being refused a treatment on a test that misses.

## Summary

Zolbetuximab is approved in the US, EU, Japan, China and elsewhere for CLDN18.2-positive, HER2-negative gastric and gastro-oesophageal junction adenocarcinoma, with patient selection by the VENTANA CLDN18 (43-14A) RxDx immunohistochemistry assay. Roughly 38% of screened patients in the pooled SPOTLIGHT and GLOW populations were positive at the 75%-of-tumour-cells threshold. In June 2026 China's regulator approved satricabtagene autoleucel, a CLDN18.2 CAR-T, in the same biomarker-defined population, so the number of decisions resting on this one assay is rising.

The assay's weakness is measurable. Against whole-tumour-section ground truth, a single representative biopsy gave 58.8% sensitivity for CLDN18.2, rising to 76.5% with six to eight biopsies, and a minimum of six endoscopic biopsies was needed to keep false negatives down; 18% of tumours were discordant between the primary and the matched nodal metastasis. A multi-laboratory ring trial found a 12% false-negative rate with 91% overall accuracy.

The imaging work is almost entirely Chinese and early: 68Ga-PMD22, 68Ga-NC-BCH and 124I-18B10(10L) each have a published pilot of 11 to 17 patients, and none has entered a multicentre or registration trial. The opportunity is therefore unusually well specified for a crossover case, because the incumbent test's failure rate is published and the decision it gates is binary.

## Fields

- Kind: Opportunity
- Last checked: 2026-09-23
- Also known as: CLDN18.2 PET; claudin 18.2 imaging
- Tags: target crossover; gastric; companion diagnostic; sampling error

## Sources

- Single-biopsy sensitivity for CLDN18.2, Scientific Reports 2025: https://www.nature.com/articles/s41598-025-12337-4
- CLDN18.2 positivity in pooled SPOTLIGHT and GLOW screening: https://link.springer.com/article/10.1007/s10120-024-01518-1
- First-in-human CLDN18.2 PET imaging: https://pmc.ncbi.nlm.nih.gov/articles/PMC11149600/
- Multi-laboratory ring trial of CLDN18.2 immunohistochemistry: https://pmc.ncbi.nlm.nih.gov/articles/PMC12647276/
- Gastric cancer biomarker testing review, naming the approved assay: https://www.cancerbiomed.org/content/22/3/212

## Connected records

- isotopes: [Gallium-68](https://nuclide.cc/isotopes/ga-68/), [Iodine-124](https://nuclide.cc/isotopes/i-124/)
- indications: [Gastric and gastro-oesophageal junction adenocarcinoma](https://nuclide.cc/indications/gastric-oesophageal-cancer/)
- technologies: [Immuno-PET](https://nuclide.cc/technologies/immuno-pet/), [PET/CT](https://nuclide.cc/technologies/pet-ct/)
- targets: [Claudin-18.2](https://nuclide.cc/targets/cldn18-2/)

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