The novel NAMPT/PAK4 inhibitor, KPT-9274, elicited remarkable antitumor effects in a broad panel of tumor mouse models, including models of renal cell carcinoma [118], B-cell acute lymphoblastic leukemia [194], acute myeloid leukemia [169], melanoma [158], colon cancer [158], triple-negative breast cancer [195], pancreatic ductal adenocarcinoma [161], pancreatic neuroendocrine tumors [160], rhabdomyosarcoma [196], Ewing sarcoma [197], multiple myeloma [198], and Waldenstrom macroglobulinemia [159]. This evidence concerns the gene PAK4 and Ewing sarcoma.