TREATMENT LANDSCAPE
After Zolbetuximab: CLDN18.2-Directed Options Being Studied in 2026
Zolbetuximab established CLDN18.2 as a validated target. What happens after progression is much less settled.
October 7, 2026 · Vialen Health
Zolbetuximab changed the first-line treatment landscape for selected HER2-negative, CLDN18.2-positive advanced gastric and gastroesophageal junction cancers. But there is not yet an evidence-based, universal sequence of CLDN18.2-directed therapies after progression. A September 2026 review summarizes a rapidly developing field that includes antibody-drug conjugates, CAR-T cells, bispecific antibodies and T-cell engagers.
WHAT IS ESTABLISHED IN THE UNITED STATES
The FDA approved VYLOY (zolbetuximab-clzb) with fluoropyrimidine- and platinum-containing chemotherapy for first-line treatment of adults with locally advanced unresectable or metastatic HER2-negative gastric or GEJ adenocarcinoma whose tumors are CLDN18.2-positive by an FDA-approved test. The U.S. companion-diagnostic definition uses moderate-to-strong membranous staining in at least 75% of tumor cells.
WHAT IS NOT ESTABLISHED
There is no single evidence-based “next CLDN18.2 drug” after zolbetuximab progression. The 2026 review highlights incomplete primary sensitivity, spatial and temporal heterogeneity, gastrointestinal toxicity and uncertainty about biomarker persistence as reasons sequencing remains unsettled.
EMERGING MODALITIES
Research programs are evaluating CLDN18.2-directed antibody-drug conjugates, including exatecan- and vedotin-based approaches; CAR-T-cell therapy; bispecific antibodies and T-cell engagers; and combinations with chemotherapy or immune checkpoint blockade. Activity in early or selected later-line studies is proof of concept, not evidence that these modalities are interchangeable or available to every patient.
BIOMARKER PERSISTENCE MAY CHANGE AFTER TREATMENT
A small retrospective study evaluated paired tumor samples before zolbetuximab and at disease progression in 15 assessable patients out of 65 treated. At the 75% moderate-to-strong staining threshold, 53.3% of those paired cases became CLDN18.2-negative at progression. Lower-level expression was retained more often at 40% and 25% cutoffs. The sample is small, but it reinforces a practical point: a historical positive result may not answer every later-line treatment question.
TISSUE STILL MATTERS
The September 2026 review concludes that tissue immunohistochemistry remains the reference method for CLDN18.2 treatment selection. Circulating tumor DNA cannot currently reproduce membrane-protein intensity or spatial distribution, and liquid-biopsy reassessment of CLDN18.2 remains investigational.
WHERE SATRI-CEL FITS
China has created a commercial later-line access context for CLDN18.2-directed CAR-T in selected gastric or GEJ cancer cases. That is a different regulatory and treatment setting from U.S. first-line zolbetuximab. The existence of a China treatment route does not create an evidence-based automatic sequence after VYLOY, and a receiving center still controls case review and treatment eligibility.
A PRACTICAL REVIEW SEQUENCE
Before opening an international later-line review, confirm the exact prior treatments, current progression state, original CLDN18.2 assay and percentage, whether newer tissue is available, HER2 status, current performance status and major disease complications. U.S. approved options and executable clinical trials should be reviewed first. Only then should a destination-specific treatment route be assessed.
VIALEN’S BOUNDARY
Vialen does not recommend a CLDN18.2 treatment sequence. We organize current evidence, records and access questions so a treating or receiving institution can decide whether formal review is appropriate.
References
FDA approval: VYLOY (zolbetuximab-clzb) for CLDN18.2-positive gastric/GEJ adenocarcinoma
Educational information only. Testing, diagnosis, clinical eligibility and treatment decisions remain with qualified laboratories, licensed treating physicians and receiving institutions.
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