Discontinued drugs in 2005: oncology drugs.

This perspective is the second in a series of papers discussing drugs dropped from development in 2005, of which 20 were being developed for cancer. Of these 20, 60% were biological agents and included 3 cancer vaccine (e.g., Canvaxin) and 2 antisense oligonucleotide (e.g., aprinocarsen sodium). Overall, 10 cancer drugs were discontinued in Phase I, 6 in Phase II and 4 at Phase III. This paper surveys drugs discontinued in the oncology arena in 2005 by stage of development and class of compound, suggesting some reasons for their failure.