Article
作者: Sullivan, Kathleen M C ; Fan, Pingchen ; Ebsworth, Karen ; Zeng, Yibin ; Zhao, Bin N ; Yau, Simon ; Lange, Christopher ; Vilalta, Marta ; Charo, Israel ; Lui, Rebecca ; Easterday, Ashton ; Scamp, Ryan ; Yang, Ju ; Miao, Shichang ; Liu, Shirley ; Wang, Yu ; Ertl, Linda S ; Miao, Zhenhua ; Dang, Ton ; Kumamoto, Alice ; Dunlap, Carolyn ; Mali, Venkat ; Zhang, Penglie ; Chhina, Vicky ; Schall, Thomas J ; Li, Shijie ; McMurtrie, Darren
The interaction of PD-L1 with PD-1 is a major immune checkpoint that limits effector T cell function against cancer cells; monoclonal antibodies that block this pathway have been approved in multiple tumor indications. As a next generation therapy, small molecule inhibitors of PD-L1 have inherent drug properties that may be advantageous for certain patient populations compared to antibody therapies. In this report we present the pharmacology of the orally-available, small molecule PD-L1 inhibitor CCX559 for cancer immunotherapy. CCX559 potently and selectively inhibited PD-L1 binding to PD-1 and CD80 in vitro, and increased activation of primary human T cells in a T cell receptor-dependent fashion. Oral administration of CCX559 demonstrated anti-tumor activity similar to an anti-human PD-L1 antibody in two murine tumor models. Treatment of cells with CCX559 induced PD-L1 dimer formation and internalization, which prevented interaction with PD-1. Cell surface PD-L1 expression recovered in MC38 tumors upon CCX559 clearance post dosing. In a cynomolgus monkey pharmacodynamic study, CCX559 increased plasma levels of soluble PD-L1. These results support the clinical development of CCX559 for solid tumors; CCX559 is currently in a Phase 1, first in patient, multicenter, open-label, dose-escalation study (ACTRN12621001342808).