肿瘤免疫治疗已成为近年来的研究热点。为小分子免疫肿瘤学药物开发了多种靶标,包括视黄酸相关孤儿受体γt(RORγt),趋化因子受体,干扰素基因刺激因子(Sting),吲哚胺2,3-双加氧酶(IDO),Toll样受体(TLR),等。其中,近年来,视黄酸受体相关的孤儿受体γt(RORγt)逐渐引起了更多的关注。特别是,LYC-55716(cintirorgon),一种由Lycera开发的小分子RORγt激动剂,已进入II期临床研究。在这项工作中,从化合物7开始,经过4轮化合物设计得到化合物28,合成和SAR研究,其在双荧光共振能量转移(双FRET)测定中的EC50为0.021±0.002μM,在小鼠Th17细胞分化测定中的EC50为0.021±0.002μM。提示化合物28具有优异的RORγt激动活性,有望开发为新型的肿瘤免疫治疗小分子药物。分子动力学模拟显示,激动剂28形成了强烈的HYF三重态分子内相互作用以稳定H12,这有助于RORγt形成蛋白质结合位点,因此使受体准备招募共激活因子。当反向激动剂s27与RORγt结合时,S27和H479之间的空间位阻导致HYF三重态的破坏,导致H12崩溃,因此RORγt的转录功能由于招募共激活分子的失败而中断。RORγt中的三重态HYF以及28和s27的刚性被确定为RORγt功能转换的结构决定因素。
Cancer immunotherapy has become a research hotspot in recent years. A variety of targets were developed for small molecule immuno-oncology agents, including retinoic acid-related orphan receptor gamma t (RORγt), chemokine receptor, stimulator of interferon genes (Sting), indoleamine 2,3-dioxygenase (IDO), toll-like receptors (TLR), etc. Among them, the retinoic acid receptor-related orphan receptor γt (RORγt) has gradually attracted more attention in these years. In particular, LYC-55716 (cintirorgon), a small molecule RORγt agonist developed by Lycera, has entered the phase II clinical study. In this work, starting from compound 7, compound 28 was obtained after 4 rounds of compound design, synthesis and SAR studies, which had an EC50 of 0.021 ± 0.002 μM in dual Fluorescence Resonance Energy Transfer (dual-FRET) assay and an EC50 of 0.021 ± 0.002 μM in mouse Th17 cell differentiation assay. It indicated that compound 28 had excellent RORγt agonistic activity and was expected to be developed as a new type of small molecule drug for cancer immunotherapy. The molecular dynamic simulation revealed that the agonist 28 formed a strong HYF triplet intramolecular interaction to stabilize H12, which helped RORγt to form the protein-binding site and therefore made the receptor ready to recruit coactivator. When the inverse agonist s27 bound with RORγt, the steric hindrance between s27 and H479 caused the destruction of the HYF triplet, leading to the collapse of H12, thus the transcription function of RORγt was interrupted due to the failure of recruiting a coactivator molecule. The triplet HYF in RORγt and the rigidity of 28 and s27 were identified to be the structural determinants for the functional switch of RORγt.