Hedgehog fights back: mechanisms of acquired resistance against Smoothened antagonists.

Acquired resistance to targeted therapies threatens the value of these otherwise very promising agents. The recent description of resistance to the Hedgehog pathway inhibitor vismodegib (GDC-0449) in a medulloblastoma patient who had a dramatic initial response has spurred efforts to understand potential mechanisms of drug resistance. Elucidating these mechanisms will play a significant role in informing strategies to overcome this meaningful limitation.