capecitabine + oxaliplatin + S-1

**Capecitabine** + oxaliplatin + S-1 is a combination chemotherapy regimen that includes three agents:\n- **Capecitabine** is an oral prodrug of 5-fluorouracil (5-FU), which inhibits thymidylate synthase, disrupting DNA synthesis in rapidly dividing cancer cells.\n- **Oxaliplatin** is a platinum-based chemotherapeutic that forms DNA crosslinks, inhibiting DNA replication and transcription.\n- **S-1** is an oral fluoropyrimidine derivative composed of tegafur (a prodrug of 5-FU), gimeracil (an inhibitor of dihydropyrimidine dehydrogenase to increase 5-FU bioavailability), and potassium oteracil (to reduce gastrointestinal toxicity).\nThis triple combination has been investigated for the treatment of advanced or metastatic gastric cancer and colorectal cancer. While both capecitabine plus oxaliplatin (CAPOX/XELOX) and S-1 plus oxaliplatin (SOX) are established regimens for these indications, the use of all three together as a single regimen is not standard but may be explored in clinical research settings. The mechanism involves inhibition of DNA synthesis and function through multiple pathways, enhancing antitumor efficacy.