Incyte/Merck's ECHO-301 Failure Casts More Shadow On IDO Space

The Phase III failure of the combination of Incyte Corp.'s IDO inhibitor epacadostat and Merck & Co. Inc.'s Keytruda in melanoma represents another knock on the new immuno-oncology class, raising uncertainty about prospects for other IDO candidates in development.

Epacadostat is the most advanced inhibitor of indoleamine 2,3-dioxygenase 1 (IDO1), an enzyme on the tumor microenvironment that plays an...