Biomarker Analysis of HIPEC Combined With PD1/PDL1 Inhibitor for Gastric Cancer With Peritoneal Metastasis

Integrated Biomarker Analysis for Hyperthermic Intraperitoneal Chemotherapy(HIPEC) Combined PD1/PDL1 Inhibitor Treatment in Patients of Advanced Gastric Cancer With Peritoneal Metastasis

A single-center, observational study, integrated biomarker analysis of HIPEC combined Programmed cell death 1 /Programmed cell death 1 ligand 1(PD1/PDL1)inhibitor in previously treated patients of advanced gastric cancer with peritoneal metastasis. Tests will be performed on tumor tissue and blood samples, and imaging assessments will be reviewed in order to monitor how well each patient responds to treatment. This is an observational study, so participants will not receive cancer treatment, other than the treatment received as standard of care.

To analyze the correlation between genomic alterations, gene expression characteristics and the efficacy of HIPEC combined with PD1/PDL1 inhibitor conversion therapy in patients with peritoneal metastasis of gastric cancer. Circulating tumor DNA(ctDNA) in plasma samples and DNA, RNA in tumor tissue sample were obtained over the course of HIPEC combined PD1/PDL1 inhibitor conversion treatment will be assessed by high-intensity, next-generation sequencing(NGS) to identify genomic alterations. The assay will performed used AmoyDx® Master Panel(Amoy Diagnostics Co., Xiamen, China), which contains 559 genes for DNA mutation detection and 1813 genes for RNA expression and fusion detection. Data acquired will be analyzed to characterize the association between these genetic elements, clinical response, and durability of responses. There will be prospective groups for the study. Samples will be collected from patients in the prospective cohort who have been treated with HIPEC combined PD1/PDL1 inhibitor at Affiliated Cancer Hospital & Institute of Guangzhou Medical University under standard of conversion treatment.

Inclusion Criteria:

1. Advanced gastric (gastroesophageal junction) adenocarcinoma confirmed by histology;
2. Age 18-75 years, Male or Non-pregnant female
3. Eastern Cooperative Oncology Group(ECOG): 0~1；
4. Negative for human epidermal growth factor receptor 2(HER-2) by immunocytochemistry or fluorescence in situ hybridization；
5. The presence of gastric cancer peritoneal metastasis is confirmed by laparoscopic exploration, and the PCI≤20；
6. Patients had received HIPEC combined with PD1/PDL1 inhibitor conversion therapy.
7. Signed the Informed Consent Form, and blood and tissue samples can be obtained;

Exclusion Criteria:

1. Other distal metastases besides peritoneal metastases (e.g., liver, lung, pleural, brain, bone metastases, etc.);
2. Other patients who were considered unsuitable for inclusion by the researchers;