Design, Optimization and Development of RIPK1 Degraders with Improved Pharmacokinetic and Pharmacodynamic Properties

The pivotal role of receptor-interacting protein kinase 1 (RIPK1) as a scaffold protein in mediating tumor resistance to immune checkpoint inhibitors (ICBs) underscores the significance of pharmacological RIPK1 degradation as a therapeutic strategy to enhance antitumor immunity. In this study, we present the design, synthesis, and evaluation of a novel series of RIPK1 degraders, derived from the optimization of the previously identified compound LD4172 . Through systematic refinement of the linker, exit vector of the RIPK1 warhead, and the VHL ligand portion, we identified compound LD5097 ( 24b ), which exhibited potent RIPK1 degradation activity across various cancer cell lines, with DC ₅₀ values of single digit nanomolar range and inducing more than 95% maximum degradation. Remarkably, LD5097 ( 24b ) induced rapid and complete degradation of RIPK1 within 2 hours of treatment and enhanced TNFα-mediated apoptosis in Jurkat cells. Furthermore, proteomic profiling unveiled the high selectivity of LD5097 ( 24b ) in degrading RIPK1. LD5097 ( 24b ) exhibited excellent metabolic stability and pharmacokinetic properties, characterized by low clearance, an extended half-life, and high plasma drug concentrations. Notably, a single administration of LD5097 ( 24b ) effectively reduced RIPK1 protein levels in Jurkat xenograft tumor tissues in mice at both 6- and 24-hour post-administration. These findings underscore LD5097 ( 24b ) as a promising RIPK1 degrader candidate, offering potent activity, favorable pharmaco-kinetic profiles, and notable pharmacodynamic effects, thereby holding significant promise in cancer immunology therapies.