This project aimed to identify transcriptional programs and candidate genes associated with primary resistance to chemotherapy or combined chemo-immunotherapy in patients with advanced gastric cancer. To this end, bulk RNA sequencing was performed on treatment-naïve primary tumor samples collected at diagnosis, prior to any systemic therapy. By using pre-treatment tumor gene expression profiles, the study sought to uncover intrinsic molecular features that may predispose tumors to therapeutic resistance.The generated data provide a resource for the discovery of predictive biomarkers, the stratification of patients according to treatment response, and the investigation of mechanisms underlying resistance to cytotoxic and immunomodulatory therapies in advanced gastric cancer. This dataset contains bulk RNA sequencing (RNA-seq) gene expression profiles from 23 primary tumor samples obtained from patients diagnosed with advanced gastric cancer. All samples were collected prior to any systemic treatment (treatment-naïve). After tumor sampling, patients subsequently received either standard chemotherapy or chemotherapy combined with immunotherapy, allowing this dataset to serve as a baseline transcriptional reference for future comparative and outcome-associated studies