JAK1 and neoplasm: In addition, specific combinations increased the number of intratumoral effector cells or activation phenotype of immune cells.5 In preclinical melanoma models, IDO1 inhibition synergizes with either anti-CTLA-4 or anti-PD-(L)1 in delaying tumor growth and increasing survival.14 15 Based on preclinical findings, JAK1 combined with IDO1 or PI3Kδ inhibition may result in greater immunomodulatory effects than either agent alone.