fluorouracil + irinotecan + leucovorin + simvastatin

This is a four-drug combination regimen consisting of fluorouracil, irinotecan, leucovorin (also known as folinic acid), and simvastatin. Fluorouracil and irinotecan are cytotoxic chemotherapy agents commonly used in the treatment of metastatic colorectal cancer. Leucovorin is not itself a chemotherapy drug but enhances the effectiveness of fluorouracil by stabilizing its binding to thymidylate synthase, thereby increasing cytotoxicity against rapidly dividing tumor cells[1][2][6]. Simvastatin is an HMG-CoA reductase inhibitor primarily used for lowering cholesterol; it has been investigated for potential anticancer effects due to its ability to inhibit cell proliferation and induce apoptosis in some cancer cell types, though it is not standardly included in established colorectal cancer regimens. The combination of fluorouracil, irinotecan, and leucovorin (commonly known as FOLFIRI) is a well-established first-line therapy for metastatic colorectal cancer that improves progression-free survival and overall survival compared to regimens without irinotecan[1][2][4][6]. The addition of simvastatin represents an investigational approach aimed at potentially enhancing antitumor efficacy through statin-mediated mechanisms.