For
example, the drug thalidomide was originally marketed in Europe and Australia as a sedative
agent for pregnantwomen. However, itwas banned for clinical use in 1962 because of
devastating birth defects that occurred if the drug was ingested during a critical period in
pregnancy. But mechanistic studies over the past several decades have demonstrated that this
drug may have a unique molecular mechanism of action that interferes with the
expression of certain genes responsible for blood vessel formation (angiogenesis). With an
understanding of this mechanism, thalidomide has been “rediscovered” as a valuable
therapeutic agent that may be highly effective in the treatment of certain infectious diseases
(e.g., leprosy and AIDS), a variety of inflammatory diseases, and some types of cancer.