Medicinal plants in tropical medicine. 2. Natural products in cancer treatment from bench to the clinic.

The development of anticancer agents has, in the past, relied heavily on leads derived from screening a wide variety of agents from both synthetic and natural sources. With the development of new techniques of measurement of biochemical changes in cells and the advent of molecular biological techniques, it is becoming clear that many naturally occurring agents, specifically selected for their tumour growth inhibiting activity, are highly complex and novel substances which are potentially promising as anticancer agents in the clinic. The process of getting a drug from the laboratory bench to the clinic is itself often complex due to adverse physical characteristics of the drug. The experience of the Cancer Research Campaign Clinical Trials Committee in developing several natural products, currently in various stages of development for clinical trial, is described. The drugs discussed include the vinca alkaloids, maytansine, combretastatins, bryostatin 1, pancratistatin, phyllanthoside, dolastatin 10, and taxol.