Therapeutic Targeting of Immune Evasion from the MICA - NKG2D Pathway

项目摘要 云母和MICB（云母/B）是多种类型的人类癌症频繁表达的应激蛋白 这是基因组损伤的结果，但很少被健康细胞表达。云母/B作为配体， 由所有细胞毒性淋巴细胞表达的NKG 2D受体，包括CD 8 T细胞、NK T细胞、NKT细胞和NK 细胞，能够识别和消除应激和转化细胞。云母/B的蛋白水解脱落是 这是许多人类癌症中NKG 2D介导的肿瘤免疫的主要免疫逃避机制。这 脱落过程涉及通过二硫键异构酶ERp 5的作用使云母/B β 3结构域解折叠 其能够通过属于ADAM和MMP家族的蛋白酶切割云母/B。是不可行 用小分子抑制剂抑制体内脱落，因为相关蛋白酶具有广泛的底物 特殊性我们开发了一种抑制云母/B脱落的方法， 云母/B β 3结构域中的脱落位点。这些抗体通过多种途径有效抑制云母/B脱落。 一组人癌细胞系，从而显著增加这些刺激性细胞的细胞表面密度。 NKG 2D配体。因此，云母/B抗体诱导NK细胞对人肿瘤细胞的强烈杀伤。 这些抗体还在转移的小鼠模型中诱导免疫。单细胞RNA-seq数据显示， 云母/B抗体诱导转移浸润NK细胞向活化的细胞毒性NK细胞的显著转变， 状态我们还在人源化小鼠模型中验证了这些抗体，其中人NK细胞靶向 由人类肿瘤细胞形成的转移。 许多人类癌症通过丧失MHC I类而对检查点阻断的免疫疗法具有抗性 表情然而，MHC I类蛋白表达并不是先天性巨噬细胞介导的抗肿瘤免疫所必需的。 T细胞群（NKT细胞、NK细胞）和NK细胞均表达NKG 2D受体。的主要目标 该项目是开发云母/B抗体作为MHC I类缺陷肿瘤细胞的治疗策略， 对常规的CD 8 T细胞有抵抗力。我们开发了一种综合方法来研究这一重要的 在完全免疫活性小鼠模型（Aim 1）以及人源化小鼠模型和人 肿瘤转移（Aim 2）。在目标1中，我们将研究先天性T细胞和NK细胞群体对 云母/B抗体介导针对自发转移的免疫。在目标2中，我们将深入执行 人黑色素瘤中表达NKG 2D先天性T细胞和NK细胞群的单细胞RNA-seq分析 转移我们还将使用人源化小鼠模型来开发与已建立的药物的联合疗法。 增强云母/B表达并因此可与云母/B协同作用的癌症治疗剂 抗体的这些研究将通过开发新的癌症免疫疗法来显著推进癌症免疫疗法领域。 靶向对当前免疫疗法具有抗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.