Impact of oxaliplatin and trastuzumab combination therapy on tumor markers and T lymphocyte subsets for advanced gastric cancer

BACKGROUND Advanced gastric cancer (AGC) remains a challenging malignancy with poor prognosis. The combination of oxaliplatin and trastuzumab has shown promising results in AGC treatment. This study aimed to investigate the effects of oxaliplatin and trastuzumab combination therapy on serum tumor markers and T lymphocyte subsets in patients with AGC and to explore their potential as predictive biomarkers for treatment response. AIM To investigate the impact of oxaliplatin and trastuzumab combination therapy on serum markers and T cell subsets in patients with AGC. METHODS This prospective study enrolled 60 patients with AGC. All patients received oxaliplatin (130 mg/m2, every 3 weeks) and trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg every 3 weeks) for six cycles. Serum carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), and cancer antigen 72-4 (CA72-4) were measured before and after treatment. T-lymphocyte subsets, including CD3+, CD4+, CD8+, and CD4+ /CD8+ ratios, were also evaluated. The clinical response was assessed using the Response Evaluation Criteria in Solid Tumors version 1.1. RESULTS After six cycles of treatment, the CEA, CA19-9, and CA72-4 serum levels significantly decreased compared to baseline levels (P < 0.001). The percentages of CD3+ and CD4+ T lymphocytes increased significantly (P < 0.05), whereas the percentage of CD8+ T lymphocytes decreased (P < 0.05). The CD4+/CD8+ ratio also significantly increased after treatment (P < 0.05). Patients with a higher decrease in serum tumor markers (≥ 50% reduction) and a higher increase in CD4+/CD8+ ratio (≥ 1.5-fold) showed better clinical response rates (P < 0.05). CONCLUSION Oxaliplatin and trastuzumab combination therapy effectively reduced serum tumor marker levels and modulated T lymphocyte subsets in patients with AGC. Combination therapy not only has a direct antitumor effect, but also enhances the immune response in patients with AGC. Serum tumor markers and T lymphocyte subsets may serve as potential predictive biomarkers for treatment response in patients with AGC receiving combination therapy.