JAK1 and neoplasm: When INCB053914 (100 mg/kg orally BID) was combined with itacitinib (60 mg/kg orally BID), which can inhibit JAK1 or JAK1/2, potent synergistic inhibition of tumor growth was detected after 8 days in INA‐6(MM) xenografts, compared with that of each agent alone (Combination Index = 0.720 [0.256, 0.924]).