Doxorubicin: an update on anticancer molecular action, toxicity and novel drug delivery systems

Objectives The frontline drug doxorubicin has been used for treating cancer for over 30 years. While providing a cure in select cases, doxorubicin causes toxicity to most major organs, especially life-threatening cardiotoxicity, which forces the treatment to become dose-limiting. Key findings Doxorubicin is known to bind to DNA-associated enzymes, intercalate with DNA base pairs, and target multiple molecular targets to produce a range of cytotoxic effects. For instance, it causes the activation of various molecular signals from AMPK (AMP-activated protein kinase inducing apoptosis) to influence the Bcl-2/Bax apoptosis pathway. By altering the Bcl-2/Bax ratio, downstream activation of different caspases can occur resulting in apoptosis. Doxorubicin also induces apoptosis and necrosis in healthy tissue causing toxicity in the brain, liver, kidney and heart. Over the years, many studies have been conducted to devise a drug delivery system that would eliminate these adverse affects including liposomes, hydrogel and nanoparticulate systems, and we highlight the pros and cons of these drug delivery systems. Summary Overall the future for the continued use of doxorubicin clinically against cancer looks set to be prolonged, provided certain enhancements as listed above are made to its chemistry, delivery and toxicity. Increased efficacy depends on these three aims being met satisfactorily as discussed in turn in this review.