5-fluorouracil + bevacizumab + gamma interferon + leucovorin

This is a combination regimen consisting of four agents: - **5-fluorouracil** (5-FU): A pyrimidine analog antimetabolite that inhibits thymidylate synthase, disrupting DNA synthesis and leading to cell death, primarily used as an antineoplastic agent. - **Bevacizumab**: A recombinant humanized monoclonal antibody targeting vascular endothelial growth factor A (VEGF-A), inhibiting angiogenesis and thereby restricting tumor blood supply. - **Gamma interferon** (interferon gamma): An immunomodulatory cytokine that activates macrophages and enhances antigen presentation, with direct antiproliferative effects on some tumor cells; it is less commonly used in standard colorectal cancer regimens but has been studied for its immunostimulatory properties. - **Leucovorin** (folinic acid): A reduced form of folic acid that enhances the binding of 5-FU to thymidylate synthase, increasing its cytotoxicity against cancer cells. This combination brings together cytotoxic chemotherapy (5-FU), targeted antiangiogenic therapy (bevacizumab), immune modulation (gamma interferon), and a chemosensitizer/antidote for folate antagonists (leucovorin). The primary indication for similar combinations—excluding gamma interferon—is metastatic colorectal cancer. The addition of gamma interferon is investigational or experimental rather than standard-of-care.