In three sentences, Incyte Corp. and Merck & Co. Inc. threw the immuno-oncology (I-O) world into a tailspin, revealing that the pivotal phase III ECHO-301/KEYNOTE-252 study evaluating Incyte's epacadostat in combination with Merck's Keytruda (pembrolizumab) in individuals with unresectable or metastatic melanoma failed a review by the external data monitoring committee (DMC).