Recent advancements in the clinical evaluation of plant-derived anticancer compounds

Cancer is a chief global health burden and the leading cause of human death worldwide next to heart diseases. The alarming rise in the mortality rate owing to cancer has driven the chase for anticancer agents to effectively combat this disease. Searching for novel and efficient compounds of natural origin has been a major aspect of concerns because they exhibit less toxic side effects. Numerous secondary metabolites from plants and their semisynthetic analogs have been identified as an excellent, novel lead structures in developing promising anticancer agents. In the current scenario, several successful anticancer drugs and their derivatives have been obtained from plant sources, and many of them are in clinical trials. Phytocompounds such as vinca alkaloids, taxanes, podophyllotoxin, camptothecin, homoharringtonine, and their derivatives have appreciably influenced cancer research on many facets. Likewise, some of the other plant-derived anticancer agents including omacetaxine mepesuccinate, ingenol mebutate, ß-lapachone, flavopiridol, curcumin, etc. are currently being under phase I and II clinical trials, either individually or in concert with other anticancer agents for the treatment of a broad range of tumors like lymphomas, leukemias, and solid tumors. Customary anticancer drug discovery has targeted mainly on the cytotoxic agents that hamper metabolic pathways critical to cell division. However, during recent years, several molecular target-based compounds have been emerged concentrating on other cellular process of cancer cells such as apoptosis, metastasis, angiogenesis, etc. Hence, the present anticancer drug discovery involves high-throughput screening of phytocompounds against a series of such molecular targets. The present chapter discusses the clinical evidences of some important phytocompounds of anticancer plants, overview of their current clinical status, and recent advances in their molecular mechanism of action.