Proteolysis-targeting chimera against NR4A1 for cancer immunotherapy

Abstract

Modulating tumor-infiltrating immune cells is the key mission for the development of cancer immunotherapy. Based on recent literature and our bioinformatic analysis, nuclear receptor subfamily 4 group A member 1 (NR4A1) is an ideal target for cancer immunotherapy due to its important role in T cell exhaustion, regulatory T (Treg) cell function. Here we targets NR4A1 via proteolysis-targeting chimeric (PROTAC) technology, expecting to achieve immune activation and cancer clearance. We designed and synthesized over 80 NR4A1 PROTACs based on several reported NR4A1 ligands, such as celastrol. We found that several celastrol-based PROTACs achieved effective degradation of target protein NR4A1. We studied the therapeutic efficiency of the lead NR-V04, a celastrol- and von Hippel-Lindau (VHL)-based PROTAC. As expected, we confirmed that the NR-V04-induced NR4A1 degradation is through the uniquitin proteasome system with a tenery complex formation among NR4A1, VHL and NR-V04. The lead NR-V04 exhibits outstanding pharmacokinetics and effectively inhibits tumor growth at a low dose, 1.8mg/kg twice a week, in B16F10, Yummer 1.7, and MC38 mouse tumor models. We proved that NR-V04 significantly enhances anti-tumor immunity with seemingly distinct mechanisms of immune activation in a tumor-dependent manner. For example, NR-V04 induces the expansion of B cells and the reduction in myeloid-derived suppressor cells (MDSC) in B16F10; the reduction of Tregs, and the induction of CD8 effector population in Yummer 1.7 and MC38 tumors. we did not find obvious toxicity at these effective doses for up to 2 months. Therefore, the lead NR-V04 or other better ones under test have the potential for translation as a novel immunotherapeutic strategy. BC200100 - “Developing a Novel PROTAC-Based NR4A1 Degrader for Breast Cancer Therapy” (DEPARTMENT OF THE ARMY)