Chang De-Kuan, Moniz Raymond J, Xu Zhongyao, Sun Jiusong, Signoretti Sabina, Zhu Quan, Marasco Wayne A
Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA, USA.
Department of Medicine, Harvard Medical School, 25 Shattuck Street, Boston, MA, USA.
Mol Cancer. 2015 Jun 11;14:119. doi: 10.1186/s12943-015-0384-3.
Carbonic anhydrase (CA) IX is a surface-expressed protein that is upregulated by the hypoxia inducible factor (HIF) and represents a prototypic tumor-associated antigen that is overexpressed on renal cell carcinoma (RCC). Therapeutic approaches targeting CAIX have focused on the development of CAIX inhibitors and specific immunotherapies including monoclonal antibodies (mAbs). However, current in vivo mouse models used to characterize the anti-tumor properties of fully human anti-CAIX mAbs have significant limitations since the role of human effector cells in tumor cell killing in vivo is not directly evaluated.
The role of human anti-CAIX mAbs on CAIX(+) RCC tumor cell killing by immunocytes or complement was tested in vitro by antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and antibody-dependent cellular phagocytosis (ADCP) as well as on CAIX(+) RCC cellular motility, wound healing, migration and proliferation. The in vivo therapeutic activity mediated by anti-CAIX mAbs was determined by using a novel orthotopic RCC xenograft humanized animal model and analyzed by histology and FACS staining.
Our studies demonstrate the capacity of human anti-CAIX mAbs that inhibit CA enzymatic activity to result in immune-mediated killing of RCC, including nature killer (NK) cell-mediated ADCC, CDC, and macrophage-mediated ADCP. The killing activity correlated positively with the level of CAIX expression on RCC tumor cell lines. In addition, Fc engineering of anti-CAIX mAbs was shown to enhance the ADCC activity against RCC. We also demonstrate that these anti-CAIX mAbs inhibit migration of RCC cells in vitro. Finally, through the implementation of a novel orthotopic RCC model utilizing allogeneic human peripheral blood mononuclear cells in NOD/SCID/IL2Rγ(-/-) mice, we show that anti-CAIX mAbs are capable of mediating human immune response in vivo including tumor infiltration of NK cells and activation of T cells, resulting in inhibition of CAIX(+) tumor growth.
Our findings demonstrate that these novel human anti-CAIX mAbs have therapeutic potential in the unmet medical need of targeted killing of HIF-driven CAIX(+)RCC. The orthotopic tumor xenografted humanized mouse provides an improved model to evaluate the in vivo anti-tumor capabilities of fully human mAbs for RCC therapy.
碳酸酐酶（CA）IX是一种表面表达蛋白，由缺氧诱导因子（HIF）上调，是一种在肾细胞癌（RCC）上过度表达的典型肿瘤相关抗原。针对CAIX的治疗方法主要集中在开发CAIX抑制剂和特异性免疫疗法，包括单克隆抗体（mAb）。然而，目前用于表征全人源抗CAIX mAb抗肿瘤特性的体内小鼠模型存在显著局限性，因为未直接评估人效应细胞在体内杀伤肿瘤细胞中的作用。
通过抗体依赖性细胞介导的细胞毒性（ADCC）、补体依赖性细胞毒性（CDC）和抗体依赖性细胞吞噬作用（ADCP），在体外测试人抗CAIX mAb对免疫细胞或补体杀伤CAIX(+) RCC肿瘤细胞的作用，以及对CAIX(+) RCC细胞运动性、伤口愈合、迁移和增殖的影响。使用新型原位RCC异种移植人源化动物模型确定抗CAIX mAb介导的体内治疗活性，并通过组织学和流式细胞术染色进行分析。
我们的研究表明，抑制CA酶活性的人抗CAIX mAb能够导致免疫介导的RCC杀伤，包括自然杀伤（NK）细胞介导的ADCC, CDC和巨噬细胞介导的ADCP。杀伤活性与RCC肿瘤细胞系上CAIX的表达水平呈正相关。此外，抗CAIX mAb的Fc工程改造显示可增强对RCC的ADCC活性。我们还证明这些抗CAIX mAb在体外抑制RCC细胞的迁移。最后，通过在NOD/SCID/IL2Rγ(-/-)小鼠中利用同种异体人外周血单核细胞建立新型原位RCC模型，我们表明抗CAIX mAb能够在体内介导人免疫反应，包括NK细胞的肿瘤浸润和T细胞的激活，从而抑制CAIX(+)肿瘤生长。
我们的研究结果表明，这些新型人抗CAIX mAb在满足靶向杀伤HIF驱动的CAIX(+)RCC这一未满足的医疗需求方面具有治疗潜力。原位肿瘤异种移植人源化小鼠为评估全人源mAb在RCC治疗中的体内抗肿瘤能力提供了一个改进的模型。
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