Therapeutic Targeting of Immune Evasion from the MICA - NKG2D Pathway

项目摘要 MICA和MICB(MICA/B)是应激蛋白，在不同类型的人类癌症中频繁表达 作为基因组损伤的结果，但很少在健康细胞中表达。云母/B作为配位体 包括CD8T细胞、T细胞、NKT细胞和NK细胞在内的所有细胞毒性淋巴细胞都表达NKG2D受体 细胞，能够识别和消除压力和转化的细胞。MICA/B的蛋白质分解脱落 在许多人类癌症中，NKG2D介导的肿瘤免疫的主要免疫逃避机制。这 脱落过程涉及二硫键异构酶作用下MICA/B ERP3结构域的展开 这使得MICA/B能够被属于ADAM和MMP家族的蛋白酶切割。这是不可行的 用小分子抑制剂抑制体内的脱落，因为相关的蛋白酶具有广泛的底物 具体细节。我们开发了一种通过设计无菌阻断MICA/B的抗体来抑制MICA/B脱落的方法 MICA/B3结构域中的脱落部位。这些抗体通过不同的途径有效地抑制MICA/B的脱落 从而大大增加了这些刺激物的细胞表面密度 NKG2D配体。因此，MICA/B抗体可诱导NK细胞对人类肿瘤细胞的强烈杀伤作用。 这些抗体还可以在转移的小鼠模型中诱导免疫。单细胞rna-seq数据显示 MICA/B抗体诱导侵袭转移的NK细胞向活化的细胞毒作用的显著转变 州政府。我们还在人源化小鼠模型中验证了这些抗体，在该模型中，人NK细胞靶向 由人类肿瘤细胞形成的转移。 许多人类癌症通过失去MHC I类分子而耐受检查点封锁的免疫治疗 表情。然而，天然介导的抗肿瘤免疫不需要MHC-I类蛋白的表达 T细胞群(NKT细胞、T细胞)和NK细胞均表达NKG2D受体。的主要目标是 该项目旨在开发MICA/B抗体作为治疗MHC I类缺陷肿瘤细胞的策略 对传统的CD8 T细胞有抵抗力。我们已经开发了一种综合的方法来研究这一重要的 完全免疫活性小鼠模型中的问题(目标1)以及人源化小鼠模型和人 肿瘤转移(目标2)。在目标1中，我们将检查先天T细胞和NK细胞群体对 MICA/B抗体介导的抗自发转移免疫。在目标2中，我们将进行一次深入的 人黑色素瘤中表达NKG2D的天然T细胞和NK细胞群的单细胞RNA序列分析 转移瘤。我们还将使用人源化的小鼠模型来开发与已建立的 增强MICA/B表达并因此可能与MICA/B协同作用的癌症治疗药物 抗体。这些研究将极大地推动癌症免疫治疗领域的发展 针对对当前免疫疗法具有耐药性的人类癌症的方法。

Project Summary MICA and MICB (MICA/B) are stress proteins that are frequently expressed by diverse types of human cancer as a consequence of genomic damage, but are rarely expressed by healthy cells. MICA/B serve as ligands for the NKG2D receptor expressed by all cytotoxic lymphocytes, including CD8 T cells,  T cells, NKT cells and NK cells, enabling recognition and elimination of stressed and transformed cells. Proteolytic shedding of MICA/B is a major immune evasion mechanism from NKG2D-mediated tumor immunity in many human cancers. This shedding process involves unfolding of the MICA/B 3 domain by the action of the disulfide isomerase ERp5 which enables MICA/B cleavage by proteases belonging to the ADAM and MMP families. It is not feasible to inhibit shedding in vivo with small molecule inhibitors because the relevant proteases have broad substrate specificities. We developed an approach to inhibit MICA/B shedding by designing antibodies that sterically block the shedding site in the MICA/B 3 domain. These antibodies potently inhibit MICA/B shedding by a diverse panel of human cancer cell lines and thereby substantially increase the cell surface density of these stimulatory NKG2D ligands. As a consequence, MICA/B antibodies induce strong killing of human tumor cells by NK cells. These antibodies also induce immunity in mouse models of metastasis. Single-cell RNA-seq data show that a MICA/B antibody induces a striking shift among metastasis-infiltrating NK cells to an activated and cytotoxic state. We have also validated these antibodies in a humanized mouse model in which human NK cells target metastases formed by human tumor cells. Many human cancers are resistant to immunotherapy with checkpoint blockade through loss of MHC class I expression. However, MHC class I protein expression is not required for anti-tumor immunity mediated by innate T cell populations (NKT cells, T cells) and NK cells that all express the NKG2D receptor. The major goal of this project is to develop MICA/B antibodies as a therapeutic strategy for MHC class I deficient tumor cells that are resistant to conventional CD8 T cells. We have developed an integrated approach to study this important question in fully immunocompetent mouse models (Aim 1) as well as humanized mouse models and human tumor metastases (Aim 2). In Aim 1, we will examine the contribution of innate T cell and NK cell populations to MICA/B antibody mediated immunity against spontaneous metastases. In Aim 2, we will perform an in depth single-cell RNA-seq analysis of NKG2D-expressing innate T cell and NK cell population in human melanoma metastases. We will also use a humanized mouse model to develop combination therapies with established cancer therapeutics that enhance MICA/B expression and may therefore act synergistically with MICA/B antibodies. These studies will significantly advance the cancer immunotherapy field by developing novel approaches to target human cancers resistant to current immunotherapies.