5-fluorouracil + leucovorin + cetuximab + vemurafenib

This is a **combination therapy** consisting of four drugs: - **5-fluorouracil**: an antimetabolite chemotherapeutic agent that interferes with RNA synthesis and, to a lesser degree, DNA synthesis, resulting in cytotoxicity and cell death, especially effective in gastrointestinal cancers[1][7]. - **Leucovorin (folinic acid)**: a vitamin supplement used to increase the efficacy of 5-fluorouracil by stabilizing its binding to thymidylate synthase, enhancing cytotoxicity and modulating folate metabolism (mechanistic inference based on clinical usage). - **Cetuximab**: a chimeric monoclonal antibody against epidermal growth factor receptor (EGFR), inhibiting downstream signaling pathways critical for cancer cell survival and proliferation (mechanistic inference based on established usage). - **Vemurafenib**: a small molecule BRAF kinase inhibitor that selectively inhibits the activity of mutated BRAF V600E, blocking MAPK/ERK pathway signaling and suppressing cancer cell growth[2][4][6]. This specific combination is designed primarily for colorectal cancers with BRAF V600E mutation and EGFR expression, aiming for multi-pathway targeting—antimetabolic, signal transduction, and receptor inhibition.