Comparison of Molecular-Genetic Concordance of the Primary Tumor and Brain Metastases of Gastroesophageal Cancers

Sponsor
Blokhin's Russian Cancer Research Center
Study ID
NCT07464470
Status
Recruiting
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Conditions

Eligibility Criteria

Sex
ALL
Age
18 Years - N/A
Healthy Volunteers
Not accepted

Interventions

  • HER2 Testing — DIAGNOSTIC_TEST
    Assessment of HER2 status by immunohistochemistry (IHC) using SP3 antibody clone (DAKO) on Ventana GX platform with OptiView detection system. Cases with IHC 2+ will undergo confirmatory in situ hybridization (FISH, CISH, or SISH).
  • MSI Testing — DIAGNOSTIC_TEST
    Determination of microsatellite instability status by immunohistochemistry (IHC) for mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) ± PCR-based analysis using five mononucleotide repeat markers (BAT25, BAT26, NR21, NR24, NR27).
  • PD-L1 Testing — DIAGNOSTIC_TEST
    Assessment of PD-L1 expression by immunohistochemistry (IHC) using DAKO 22C3 antibody clone on Dako Link48 platform with EnVision Flex detection system. Results reported as Combined Positive Score (CPS), defined as number of PD-L1-stained cells divided by total viable tumor cells, multiplied by 100.
  • CLDN18.2 Testing — DIAGNOSTIC_TEST
    Assessment of CLDN18.2 expression by immunohistochemistry (IHC) using VENTANA CLDN18 (43-14A) assay on Ventana platform. Positive expression defined as moderate-to-strong (2+/3+) complete, basolateral, or lateral membranous staining in ≥ 75% of viable tumor cells.

Study Details

GENCONCOR-2 is a translational research aimed to compare the molecular profile of primary tumors and their matched brain metastases in gastroesophageal cancers, including cancer of the esophagus, gastroesophageal junction, and stomach. The study is based on the previously established international GASTROBRAIN cohort (ClinicalTrials.gov ID: NCT07448493), which provides comprehensive clinicopathological and treatment data for over 230 patients. It will be conducted by retrospective analysis of paired samples of histological material (primary tumor and corresponding brain metastasis) with determination of HER2 expression status (IHC ± FISH), MSI status (IHC ± PCR), PD-L1 combined positive score (CPS), and CLDN18.2 expression status (IHC)

Key Dates

Start date
Apr 1, 2026
Status verified
Mar 2026
Primary completion
Oct 1, 2028
Completion
Oct 1, 2028

Study Design

Enrollment
30 participants (estimated)

Arms

  • Arm: Gastric Cancer Cohort
    Patients with histologically confirmed gastric adenocarcinoma and paired tissue samples of primary tumor and corresponding brain metastasis.
  • Arm: Esophageal Cancer Cohort
    Patients with histologically confirmed esophageal carcinoma (adenocarcinoma or squamous cell carcinoma) and paired tissue samples of primary tumor and corresponding brain metastasis.
  • Arm: Gastroesophageal Junction Cancer Cohort
    Patients with histologically confirmed adenocarcinoma of the gastroesophageal junction (Siewert types I-III) and paired tissue samples of primary tumor and corresponding brain metastasis.

Primary Outcome Measure

Overall Molecular Discordance Rate (%) [ Time Frame: At time of molecular analysis (samples collected retrospectively; analysis will be completed within 12 months of study initiation) ]

Central Contacts

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