Merck has signed three separate collaboration agreements with Amgen, Incyte Corp. and Pfizer to evaluate novel combination regimens with MK-3475, its investigational anti-PD-1 immunotherapy. Financial terms were not disclosed.   In Phase I/II studies, Pfizer and Merck will evaluate the safety and efficacy of MK-3475 in combination with Pfizer’s small molecule kinase inhibitor axitinib (INLYTA) in patients with renal cell carcinoma, and another study will evaluate MK-3475 plus PF-2566, an investi...