6-thioguanine + capecitabine + celecoxib + lomustine

This is a combination therapy consisting of four distinct anticancer agents with different mechanisms of action: - **6-thioguanine**: A purine analog antimetabolite that interferes with nucleic acid biosynthesis. It is converted intracellularly to 6-thioguanylic acid (TGMP), which inhibits several processes in purine nucleotide synthesis and is eventually incorporated into RNA and DNA, causing cytotoxicity. - **Capecitabine**: A prodrug that is enzymatically converted to 5-fluorouracil in tumor tissue, where it inhibits DNA synthesis and slows growth of tumor tissue, primarily through inhibition of thymidylate synthase and incorporation into DNA and RNA. - **Celecoxib**: A selective COX-2 inhibitor with potential anti-angiogenic and anti-tumor properties, beyond its anti-inflammatory effects. - **Lomustine**: A highly lipophilic nitrosourea compound that undergoes hydrolysis in vivo to form reactive metabolites. These metabolites cause alkylation and cross-linking of DNA and RNA, inducing cytotoxicity.