Biomarker Study for Selecting Neoadjuvant Chemotherapy Regimens Based on Prognostic Prediction Using Gastric Cancer Biopsy Specimens from a Phase II Randomized Controlled Trial.

Background/aim: The randomized phase II COMPASS trial revealed that neither the regimen nor the number of courses of preoperative neoadjuvant chemotherapy (NAC) for locally advanced gastric cancer (GC) significantly influence overall survival (OS). However, the impact of NAC regimens on OS may vary from patient to patient. The aim of this study was to identify biomarkers that can predict more appropriate individualized NAC regimens for improved prognosis using biopsy specimens from the COMPASS trial.

Patients and methods: RNA was extracted from endoscopic biopsy specimens of primary tumors obtained prior to NAC and real-time PCR analysis of 127 genes was conducted to identify those significantly affecting survival in the context of specific NAC regimens.

Results: THBS1, MSI1, and IGF2BP3 were identified as significant factors for stratifying survival among different NAC regimens, with statistically significantly interaction p values. Immunohistochemical analysis confirmed that the protein levels of THBS1, MSI1, and IGF2BP3 strongly correlated with their gene expression levels, validating these proteins as reliable biomarkers.

Conclusion: This study effectively identified THBS1, MSI1, and IGF2BP3 as promising biomarkers for personalizing NAC regimens in patients with locally advanced GC. By tailoring NAC based on these biomarkers, it is possible to enhance survival outcomes and advance personalized treatment strategies. The findings underscore the potential for incorporating biomarker-guided approaches into clinical trials, aiming to refine and optimize NAC regimens for improved patient-specific treatment efficacy.