Discovery of an Exceptionally Orally Bioavailable and Potent HPK1 PROTAC with Enhancement of Antitumor Efficacy of Anti-PD-L1 Therapy
Mingfei Wu, Yiquan Wu, Yuyuan Jin, Xinfei Mao, Shenxin Zeng, Hengyuan Yu, Jingyu Zhang, Yuheng Jin, Yizhe Wu, Tengfei Xu, Yong Chen, Yuwei Wang, Xiaojun Yao, Jinxin Che, Wenhai Huang, Xiaowu Dong
Abstract
HPK1, a well-known negative regulator of T cell receptors, can cause T cell dysfunction when abnormally activated. In this study, a PROTAC C3 was designed and synthesized by optimizing the physicochemical properties of the warhead, linker, and CRBN ligand. C3 demonstrated significant HPK1 degradation with a DC 50 of 21.26 nM, excellent oral absorption with a C max of 10,899.92 ng/mL, and a bioavailability ( F %) of 81.7%. C3 also showed degradation selectivity and potent immune activation effects. Proteomic and WB analyses revealed that immune-activating effect of C3 is attributed to the inhibition of SLP76 and NF-κB signaling pathways, as well as the enhancement of MAPK signaling pathway transduction. In vivo efficacy study demonstrated that oral administration of C3 in combination with anti-PDL1 antibody significantly inhibited tumor growth (tumor growth inhibition = 65.58%). These findings suggest that C3, a novel HPK1 PROTAC, holds promise as a therapeutic agent for tumor immunotherapy.