Explore chemotherapy drugs classified by cell cycle phase (S, G2, M) and mechanism. Understand antimetabolites, mitotic inhibitors, alkylating agents & more.
Classification of Chemotherapy Drugs by Cell Cycle Phase and Mechanism 1. Cell Cycle-Specific Drugs These drugs act on cells that are actively progressing through specific phases of the cell cycle. Drug Class Targeted Cell Cycle Phase Mechanism of Action Examples ------------------------ ------------------------------- ----------------------------------------------------------------------------------------- ------------------------------------- Antimetabolites S phase (DNA synthesis) Mimic or inhibit nucleotide synthesis, blocking DNA replication Methotrexate, 5-Fluorouracil (5-FU), Cytarabine, Mercaptopurine Topoisomerase Inhibitors S phase (and sometimes G2) Inhibit topoisomerase enzymes, preventing DNA unwinding and replication Etoposide (Topoisomerase II), Irinotecan (Topoisomerase I) Mitotic Inhibitors M phase (mitosis) Disrupt microtubule formation or function, blocking chromosome segregation Vincristine, Vinblastine, Paclitaxel, Docetaxel Bleomycin G2 phase Causes DNA strand breaks by free radical formation Bleomycin --- 2. Cell Cycle-Non-Specific Drugs These drugs can act on cells regardless of their phase, including resting (G0) cells. Drug Class Mechanism of Action Examples ------------------------ ----------------------------------------------------------------------------------------- ------------------------------------- Alkylating Agents Cross-link DNA strands or add alkyl groups, causing DNA damage and preventing replication Cyclophosphamide, Ifosfamide, Melphalan, Busulfan Platinum Compounds Form DNA cross-links, inhibiting DNA synthesis and function Cisplatin, Carboplatin, Oxaliplatin Anthracyclines Intercalate into DNA, inhibit topoisomerase II, and generate free radicals causing DNA damage Doxorubicin, Daunorubicin --- 3. Other Important Classes Drug Class Mechanism Examples ------------------------ ----------------------------------------------------------------------------------------- ------------------------------------- Hormonal Agents Block hormone receptors or hormone synthesis, used mainly in hormone-sensitive cancers Tamoxifen, Anastrozole, Leuprolide Targeted Therapies Target specific molecular pathways or proteins involved in cancer cell growth Imatinib, Trastuzumab, Erlotinib Immunotherapy Stimulate or modulate the immune system to attack cancer cells Checkpoint inhibitors (e.g., Pembrolizumab) --- Summary Table: Chemotherapy Drugs by Cell Cycle Phase Phase Drug Classes Examples ----------- ------------------------------------------ ------------------------------------ G0 (Resting) Cell cycle-nonspecific drugs Alkylating agents, Platinum drugs G1 Some antimetabolites (partial effect) Methotrexate (also S phase) S Antimetabolites, Topoisomerase inhibitors 5-FU, Cytarabine, Etoposide G2 Bleomycin, some topoisomerase inhibitors Bleomycin, Etoposide M Mitotic inhibitors Vincristine, Paclitaxel --- Important Notes:- Phase-specific drugs require cells to be actively cycling in the targeted phase for maximal effect. - Cell cycle-nonspecific drugs can kill both dividing and resting cells, often used in combination with phase-specific drugs. - Combination chemotherapy regimens often combine drugs from different classes/phases to maximize cancer cell kill and minimize resistance. - ---