Thalidomide Derived Immunomodulatory Drugs (IMiDs) as Potential Therapeutic Agents

Thalidomide is known to be effective in the treatment of a number of conditions, including leprosy and various cancers. The exact mechanisms of action remain unclear although these are known to include antitumour necrosis factor (TNF)-α, T cell costimulatory, anti-angiogenic and anti-tumour activities. However, thalidomide is being superceded by novel structural derivatives which have been designed to have improved immunomodulatory activity and side effect profiles. These are currently being characterised and some are entering the clinic in phase I/II studies. One novel group of structural analogues are classified as the Immunomodulatory Drugs (IMiDs). This review describes the emerging immunological, anti-angiogenic and direct anti-tumour properties of thalidomide and the characterisation and clinical application of its IMiD analogues. We describe the laboratory studies which have led to the characterisation and development of IMiDs into potentially clinically relevant drugs. Early trial data suggests that these compounds may themselves become established therapies, particularly in certain cancers. Furthermore, ongoing studies will determine how best to apply these compounds to the appropriate clinical settings. We will describe the various clinical studies of lead compounds that are in progress and speculate as to the potential and future development of these exciting compounds.