cisplatin + durvalumab + S-1

This is a combination regimen consisting of three drugs used in oncology: - **Cisplatin** is a platinum-based chemotherapy agent that forms DNA crosslinks, leading to apoptosis and inhibition of cancer cell proliferation. - **Durvalumab** is a human monoclonal antibody targeting programmed death-ligand 1 (PD-L1), blocking its interaction with PD-1 and CD80, thereby enhancing anti-tumor immune responses by counteracting tumor immune evasion. - **S-1** is an oral fluoropyrimidine derivative composed of tegafur (a prodrug of 5-fluorouracil), gimeracil (an inhibitor of dihydropyrimidine dehydrogenase), and potassium oteracil (an inhibitor reducing gastrointestinal toxicity). S-1 acts as an antimetabolite, inhibiting DNA synthesis in rapidly dividing cells. This combination has been investigated primarily for the treatment of advanced gastric cancer and other gastrointestinal malignancies. Each component brings a distinct mechanism—direct cytotoxicity from cisplatin, immunomodulation from durvalumab, and antimetabolite activity from S-1[7][10].