4-Arylindolines Bearing a Pyrido[3,2- <i>d</i> ]pyrimidine Scaffold as Dual Inhibitors of the PD-1/PD-L1 Interaction and NAMPT for Targeting Tumor Immunoevasion and Metabolism

Targeting both the PD-1/PD-L1 axis and NAMPT represents a promising therapeutic strategy to overcome resistance to the immune checkpoint blockade. Herein, we developed a novel series of 4-arylindolines bearing a pyrido[3,2- d ]pyrimidine scaffold as dual-targeting inhibitors. Among these, compound B14 emerged as the most promising inhibitor, exhibiting IC 50 values of 7.5 and 18.8 nM against the PD-1/PD-L1 interaction and NAMPT, respectively, along with favorable metabolic stability. In vitro investigations revealed that B14 significantly enhanced T cell-mediated tumor cell killing, elevated T cell proliferation and CD8 + T cell proportion, and interfered with intracellular NAD + biosynthesis. In a mouse LLC tumor model overexpressing NAMPT and PD-L1, B14 significantly suppressed tumor progression through dual mechanisms involving tumor metabolism disruption and tumor immune microenvironment activation. These findings highlight B14 as a promising lead compound for the development of next-generation antitumor agents that simultaneously target tumor immunoevasion and metabolism.