Overcoming DC defects in cancer patients by VEGF trap

描述（由申请人提供）：癌症免疫学的进展已导致鉴定出许多肿瘤相关抗原，这些抗原可被人T淋巴细胞识别并能够激活人T淋巴细胞。此外，了解表面受体和细胞信号对T淋巴细胞活化很重要，提示了许多更有效的癌症疫苗接种策略。然而，这一认识伴随着癌症患者主动特异性免疫治疗的令人失望的临床结果。为了对抗我们增强抗肿瘤免疫力的尝试，越来越多的证据表明，携带癌症的宿主发展了许多抑制癌症免疫力的机制。虽然宿主免疫抑制的存在已经讨论了多年，但直到最近才更好地表征了具体机制（即，肿瘤抗原丧失或MHC丧失、T细胞信号传导功能障碍、APC功能障碍）。我们和其他人已经证明，在癌症患者中，免疫缺陷存在于树突状细胞（DC）谱系中，这是关键的抗原呈递细胞。这表现为DC成熟缺陷和源自造血祖细胞（HPC）的具有强效免疫抑制作用的未成熟髓样细胞（ImC）的扩增。由肿瘤细胞或宿主细胞响应于肿瘤细胞产生的VEGF是这种DC功能障碍的主要介质，并且还可能导致ImC扩增和免疫抑制。这些VEGF介导的缺陷的修复可能是有效的癌症免疫治疗的关键。Regeneron计划在约25例晚期实体瘤和淋巴瘤患者中开展一项多机构I期静脉注射VEGF Trap试验。VEGF Trap似乎是体内VEGF的理想抑制剂，并且提供优于受体抗体（VEGFR1和VEGFR2）或配体抗体（VEGF）或酪氨酸激酶抑制剂的优势。虽然用VEGF Trap抑制VEGF主要目的是阻断肿瘤血管生成，但它也可用于逆转对有效抗肿瘤免疫至关重要的DC功能障碍。作为该I期试验的伴随相关研究，我们计划评估DC表型、成熟状态及其功能（刺激性和ImC抑制性）的变化。VEGF Trap作为VEGF抑制的一种形式提供了克服宿主免疫抑制的方法。因此，本文所述的相关研究可能导致建立VEGF抑制，特别是VEGF Trap，作为与癌症免疫治疗联合收割机组合并增强癌症免疫治疗的方法。

DESCRIPTION (provided by applicant): Progress in cancer immunology has led to the identification of numerous tumor-associated antigens that are recognized by and able to activate human T lymphocytes. Furthermore, understanding the surface receptors and cellular signals important to T lymphocyte activation suggests numerous strategies for more effective cancer vaccination. Nevertheless, this knowledge is accompanied by disappointing clinical results in cancer patients with active specific immunotherapy. To counter our attempts to boost anti-tumor immunity, there is a growing body of evidence that cancer-bearing hosts develop a number of mechanisms to suppress cancer immunity. While the presence of host immunosuppression has been discussed for many years, only recently have the specific mechanisms been better characterized (i.e., tumor antigen loss or MHC loss, T cell signaling dysfunction, APC dysfunction). We and others have demonstrated that in cancer patients, immune defects are present in the dendritic cell (DC) lineage, the critical antigen-presenting cell. This is manifested by defects in DC maturation and an expansion of immature myeloid cells (ImC) with potent immunosuppressive effects that are derived from hematopoietic progenitor cells (HPC). VEGF produced by tumor cells or host cells in response to tumor cells is a major mediator of this DC dysfunction and may also lead to ImC expansion and immunosuppression. Reversal of these VEGF mediated defects may be critical to effective cancer immunotherapy. A multi-institutional phase I trial of intravenous VEGF Trap in approximately 25 patients with advanced solid tumors and lymphomas is being planned under Regeneron. VEGF Trap appears to be an ideal inhibitor of VEGF in vivo and offers advantages over antibody to receptor (VEGFR1 and VEGFR2) or to ligand (VEGF) or tyrosine kinase inhibitors. While VEGF inhibition with VEGF Trap is primarily aimed at blocking tumor angiogenesis, it may also act to reverse DC dysfunction critical to effective anti-tumor immunity. As a companion correlative study to this phase I trial we plan to assess changes in DC phenotype, maturation status, and their function (stimulatory and ImC inhibitory). VEGF Trap as a form of VEGF inhibition provides an approach to overcome host immunosuppression. Thereby, the correlative studies described here may lead to the establishment of VEGF inhibition, VEGF Trap, specifically, as an approach to combine with and enhance cancer immunotherapy.