New anticancer agents in clinical development.

A better understanding of the biology and biochemistry of the cancer cell has led to the development of various promising new antineoplastic compounds that are now undergoing phase I, II, and III clinical testing. These drugs include topoisomerase I inhibitors, such as camptothecin and its analogs 9-aminocamptothecin, irinotecan, and topotecan; the paclitaxel analog docetaxel; gemcitabine, an antimetabolite structurally related to cytarabine; and fluorouracil prodrugs and other thymidylate synthase (TS) inhibitors. Another exciting approach to cancer treatment is the use of agents that induce a less malignant state by altering cellular phenotype. Such agents include angiogenesis inhibitors, differentiating agents, signal transduction inhibitors, and gene therapy.