Significance:
T-cell infiltration, tumor
TUMOR, SOLID TUMORS
PD-1 blockade combined with targeted therapies have demonstrated encouraging preclinical activity. In this phase I study, patients with advanced solid tumors treated with pembrolizumab (PD-1 inhibitor) and either itacitinib (JAK1 inhibitor) or parsaclisib (PI3Kδ inhibitor) experienced limited clinical activity beyond that expected with checkpoint inhibition alone and showed little effect on T-cell infiltration in the tumor. These results do not support continued development of these combinations.