Chemotherapy Primer:Anthracyclines
July 9, 2009 5:21 am Anthracyclines
Many of the currently effective anti-cancer drugs are developed from natural sources. The drug daunorubicin was isolated from Streptomyces, a soil-dwelling fungus. Doxorubicin, another anthracycline drug, was isolated from a mutated strain of the same fungus. Both of these drugs have a similar mechanism of action, but the latter is more effective in the treatment of solid tumors. This class of chemotherapeutics works by the formation of free oxygen radicals. These radicals result in DNA strand breaks and subsequent inhibition of DNA synthesis and function. Anthracyclines also inhibit the enzyme topoisomerase by forming a complex with the enzyme and DNA. Topoisomerases are a class of enzymes that serve to unwind the DNA double strand helix to allow for DNA repair, replication and transcription. This class of chemotherapeutics is also not cell cycle specific. The most important side effect of this group of drugs is cardiac toxicity. The same free radicals that serve to damage the DNA of the cancer cell may damage the cells of the heart muscle. Oncologists monitor heart function very carefully when patients are on these medications. Other commonly used anthracyclines include Idarubicin, Epirubicin, and Mitoxantrone.