vincristine + methotrexate + mercaptopurine

This is a combination chemotherapy regimen consisting of three antineoplastic agents—vincristine, methotrexate, and mercaptopurine. All three are small molecule drugs with distinct mechanisms of action targeting rapidly dividing cells. Vincristine is a vinca alkaloid that inhibits microtubule formation, thereby arresting cell division in metaphase. Methotrexate is an antimetabolite and antifolate agent that inhibits dihydrofolate reductase, blocking DNA synthesis and repair. Mercaptopurine (6-MP) is a purine analog that interferes with nucleic acid synthesis by incorporating into DNA and RNA or inhibiting purine nucleotide interconversion. This combination is commonly used as part of maintenance therapy for acute lymphoblastic leukemia (ALL), particularly in pediatric patients, but also in adults[2][6][8]. The regimen may be administered orally (methotrexate and mercaptopurine) and intravenously (vincristine). It can be used alone or as part of larger regimens such as POMP when combined with prednisone[2][4][9].