Chemotherapy: General Concepts

Abstract

There are approximately 80 anti-tumor drugs employed to treat cancer patients today. Many of these drugs were discovered by virtue of animal tumor screening programs, some by rational chemical design, and others by astute clinical observation. An example of a drug developed by rational design is 5-Fluorouracil. Heidelberger created this drug after analyzing many human and animal tumors and discovering that malignant cell growth (in contrast to normal cell growth) was heavily dependent upon uracil as an essential component of DNA. He reasoned that distorting the uracil molecule by attaching a halogen, fluorine, may result in a DNA which is incompatible with tumor cell viability. Methotrexate is an example of a drug discovered by clinical observation. Dr. Sidney Farber was the first to detect that leukemic children developed progressive disease when placed on vitamins which included folic acid. The folic acid antagonist Methotrexate (see Figure 4.1) was just then in the process of development and Farber demonstrated in 1948 that an analogue drug of Methotrexate could induce remission in acute leukemia. The great majority of agents, however, have been incorporated into clinical use because of empiric drug screening. The plant alkaloid derivatives, for example, were identified as active anti-tumor agents in the process of screening any and all plant components of all species for such activity.