在免疫细胞中特异性表达的核受体RORγt已成为小分子癌症免疫治疗新靶点。RORγt激动剂刺激Th17细胞分化和IL-17A分泌，促进CD8+T细胞激活，发挥抗癌免疫作用。我们在苄基哌嗪类RORγt抑制剂的构效关系研究中意外发现，芳磺酰氨基上的取代位点是调控抑制-激动功能活性的关键位点，磺酰氨基上的氢原子被取代后功能由抑制反转为激动，激动剂的结合模式很可能发生了空间取向的翻转，使原先结合于非活性功能域的芳磺酰氨基转而结合于活性功能域2（AF2）。本项目将通过对苄基哌嗪类化合物左侧芳磺酰氨基、中间苄基哌嗪骨架和右侧烷基甲酰基等部位的结构改造，探索苄基哌嗪类RORγt激动剂的构效关系，利用复合物晶体结构解析、分子对接和动力学模拟等揭示激动剂与RORγt配体结合域（LBD）的作用模式，并指导新一轮化合物的活性与成药性优化，以期发现高效低毒、性质优化的新型癌症免疫治疗小分子药物先导物。

Retinoic acid receptor-related orphan receptor-gamma-t (RORγt), a nuclear receptor subtype specifically expressed in immune cells, has been regarded as a novel target for small molecule cancer immunotherapy. RORγt agonists stimulates Th17 cell differentiation and IL-17A secretion, which has potential to exercise immunotherapeutic efficacy by eliciting remarkable activation of CD8+T cells. In our recent study on structure-activity relationship of benzylpiperazine RORγt inhibitors, it was found that substitutions on arylsulfonylamino group are key to the regulation of inhibition and activation functions. Replacement of the hydrogen atom on sulfonylamino group caused unexpected functional reversion from inhibition to activation. It was hypothesized that binding mode of the agonists were reversed in terms of orientations. As a result, the arylsulfonylamino group, which was previously bound to non-activation function region, now binds to the activation function 2 (AF2) region. In this proposal, benzylpiperazine compounds will be modified on the left-hand side arylsulfonylamino group, the middle benzylpiperazine skeleton and the right-hand side alkylcarbonyl group to explore the structure-activity relationship of benzylpiperazine RORγt agonists. Complex crystal structure determination, molecular docking and dynamics simulation will be employed to reveal the mode of action of these agonists with RORγt ligand binding domain (LBD). New rounds of design and synthesis followed by optimizations on efficacy and properties will lead to the identification of novel small molecule lead compounds with high potency, low toxicity and good developability for cancer immunotherapy.