Some categories of chemotherapy drugs include:
- Plant Alkaloids: These are chemotherapy drugs that are derived from
certain species of plants. The periwinkle plant (for example) falls
into the group known as vinca alkaloids, which are the biological basis
for the widely used cytotoxic drugs vinorelbine, vinblastine, and vincristine.
Another group of plant alkaloids are known as Taxanes, which
are obtained from the bark of the Pacific Yew tree and serve as
the biological blueprint for the cancer-fighting drugs paclitaxel and
docetaxal.
The May apple plant contains what are known as podophyllotoxins that provide the basis for the cancer-fighting agents eloposide and tenisopide. Another plant alkaloid comes from the Asian “Happy Tree”, which provides the campothecan analogues irinotecan and topotecan. It should be noted that cytotoxic plant alkaloids are known as cell-cycle specific biological agents, which means they attack cancer cells during various phases of mitosis (cell division).
- Alkylating Agents: This class of biological substances is characterized by cell-cycle non-specific agents, which means they are most active against cancer during the malignant cell’s resting period. Some of the more common alkylating agent cytotoxic drugs are the mustard gas derivatives ifosamide, melphalan, and chlorambucil. Also in the alkylating agent group are the widely used metal salt-based drugs carboplatin, cisplatin, and oxaliplatin.
- Topoisomerase Inhibitors: These are chemotherapy drugs that interfere with the production of topoisomerase enzymes, which can facilitate cancer promoting changes in DNA structure. Cancer chemotherapies can include use of the topoisomerase inhibitors amsacrine, etoposide, etoposide phosphate, and teniposide.
- Antimetabolites: These biological agents are very similar to substances that exist normally within cells, but, when incorporated in cellular metabolism, they prevent or greatly inhibit mitosis. Commonly used antimetabolite chemotherapies include methotrexate, 5-flouricil, foxuridine, cytarabine, and capecitabine.
- Anthracyclines: Considered to be more effective than any other class
of cancer-fighting agents, anthracyclines
are derived from the Streptomyces bacteria, and are widely used
to combat leukemias, lymphomas (blood borne cancers), breast, lung,
uterine, ovarian and other types of cancer. The first anthracycline
to be discovered was daunorubicin (trade name Daunomycin), which was
followed by the similar cytotoxic drugs liposomal, adriamycin and others.