Natural Anticancer Compounds and Their Derivatives in Clinical Trials

Abstract

Cancer continues to be a global challenge to both clinicians and researchers with an increasing mortality rate. Despite the enormous progress made in the anticancer drug discovery, there is a constant demand for novel therapeutic agents, because of the development of resistance to the existing chemotherapeutic drugs and their adverse side effects. The anticancer drugs derived from the natural sources have shown to be effective and safe in the treatment of cancers. Secondary metabolite compounds from plants such as alkaloids, flavonoids, and carotenoids are known for their cancer prevention and antitumor properties. Peptides produced from marine organisms and anthracyclines synthesized by microbes as secondary metabolites are also known for their anticancer properties. Some of these natural compounds are widely used in cancer therapy, and some are under clinical or preclinical trials. Some of the potential anticancer agents from plants (paclitaxel, vincristine, vinblastine, irinotecan, etoposide, topotecan, and camptothecin), marines (dolastatin 10, cytarabine, and aplidine), and microorganisms (bleomycin, doxorubicin, and dactinomycin) have been used in cancer therapy. Cancers are characterized by the alterations in the cell signaling pathways. Most of the current anticancer therapies involve the modulation of altered signaling targets in cancers. The advantage of using natural compounds with antitumor properties for cancer therapy is that the compounds have well-defined signaling targets with a minimal toxicity. Natural anticancer drugs have been categorized based on their target-specific signaling pathways, which include DNA-damaging drugs, methyltransferase inhibitors, mitotic disrupters, and histone deacetylase inhibitors. Thus, the present chapter highlights the natural anticancer compounds and their derivatives which are under clinical trials and their mechanism of action in cancer therapy.