Testing Requirement: CLDN18.2 positivity is defined as ≥75% of tumor cells showing moderate-to-strong membranous staining (IHC 2+/3+). Patients must test positive for CLDN18.2 and negative for HER2 to be eligible for ZELVARA.

Showing 12 of 12 testing locations

Specimen Requirements

Tissue Type	Formalin-fixed, paraffin-embedded (FFPE) tumor tissue
Source	Biopsy or surgical resection specimen (primary or metastatic)
Sections	4-5 unstained slides (4 µm thickness) + 1 H&E stained slide
Block Option	FFPE tissue block accepted; will return after sectioning
Fixation	10% neutral buffered formalin, 6-72 hours fixation time
Minimum Tissue	≥50 viable tumor cells required for valid assessment

IHC Scoring Criteria

Positivity Threshold

≥75% of tumor cells with moderate-to-strong membranous staining (IHC 2+/3+)

Antibody Clone

43-14A

Staining Intensity Scale

0Negative

No staining or faint/barely perceptible

1+Weak

Faint membranous staining in >10% of tumor cells

2+Moderate

Weak-to-moderate complete membranous staining

Counts toward positivity

3+Strong

Strong, complete membranous staining

Counts toward positivity

Important Safety Information

The most common adverse reactions (≥20%) with ZELVARA plus chemotherapy were nausea, vomiting, decreased appetite, fatigue, diarrhea, and peripheral neuropathy. Severe nausea and vomiting can occur; administer antiemetic prophylaxis prior to and during treatment. See Full Prescribing Information.

Important Safety Information

INDICATIONS AND USAGE

ZELVARA (celdatuzumab-mkrz) is indicated, in combination with fluoropyrimidine- and platinum-containing chemotherapy, for the first-line treatment of adults with locally advanced unresectable or metastatic HER2-negative, claudin 18.2 (CLDN18.2)-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma. CLDN18.2 positivity should be determined by an FDA-approved test.

Warnings and Precautions

Nausea and Vomiting: ZELVARA can cause severe nausea and vomiting. In the BEACON-1 trial, nausea occurred in 70.2% of patients treated with ZELVARA plus chemotherapy, including Grade 3 events in 14.8%. Vomiting occurred in 64.8%, including Grade 3 events in 12.1%. Administer antiemetic prophylaxis prior to and during treatment. Withhold, dose reduce, or permanently discontinue based on severity. Infusion-Related Reactions: Infusion-related reactions have been reported. Monitor patients during and after infusion. Interrupt or slow the rate of infusion for mild to moderate reactions. Permanently discontinue for severe or life-threatening reactions. Embryofetal Toxicity: Based on its mechanism of action and findings from animal studies, ZELVARA can cause fetal harm when administered to a pregnant woman. Advise females of reproductive potential to use effective contraception during treatment and for 3 months after the last dose.

Adverse Reactions

The most common adverse reactions (≥20%) in patients receiving ZELVARA plus chemotherapy were nausea (70.2%), vomiting (64.8%), decreased appetite (42.1%), fatigue (38.4%), diarrhea (28.7%), and peripheral neuropathy (22.5%). Serious adverse reactions occurred in 42% of patients treated with ZELVARA plus chemotherapy, including vomiting (8.2%), nausea (4.1%), dehydration (3.8%), and decreased appetite (2.4%). Fatal adverse reactions occurred in 2.1% of patients.

Drug Interactions

No formal drug interaction studies have been conducted with ZELVARA. No clinically significant pharmacokinetic interactions are expected based on the known elimination pathways of celdatuzumab.

Use in Specific Populations

Pregnancy: ZELVARA can cause fetal harm. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Lactation: Advise women not to breastfeed during treatment and for 3 months after the last dose. Females and Males of Reproductive Potential: Verify pregnancy status prior to initiation. Advise females to use effective contraception during treatment and for 3 months after the last dose. Pediatric Use: The safety and efficacy of ZELVARA have not been established in pediatric patients. Hepatic Impairment: No dose adjustment is recommended for patients with mild hepatic impairment. ZELVARA has not been studied in patients with moderate or severe hepatic impairment.

CLDN18.2 Testing & Site Locator

NeoGenomics Laboratories

Quest Diagnostics — Nichols Institute

Foundation Medicine

Tempus Labs

MD Anderson Cancer Center — Pathology

Memorial Sloan Kettering — Diagnostic Molecular Pathology

Mayo Clinic Laboratories

ARUP Laboratories

Dana-Farber Cancer Institute — Pathology

UCLA Health — Pathology & Laboratory Medicine

Cleveland Clinic — Robert J. Tomsich Pathology

Johns Hopkins — Surgical Pathology

Specimen Requirements

IHC Scoring Criteria

Staining Intensity Scale

Important Safety Information

WARNING: NAUSEA AND VOMITING

Important Safety Information

INDICATIONS AND USAGE

Warnings and Precautions

Adverse Reactions

Drug Interactions

Use in Specific Populations