(PQC4) Imaging CD8 T Cells In Tumor Immunotherapy By Immunopet

描述（由申请人提供）：肿瘤除恶性细胞外由多种细胞类型组成，包括基质细胞、脉管细胞和浸润性免疫细胞。了解这些其他细胞成分的身份、数量和状态对于理解肿瘤生物学及其对治疗的反应显然是重要的，正如NCI煽动性问题C4所概述的那样。最近，免疫调节疗法和过继细胞疗法已经成为癌症强有力的治疗方法，因此迫切需要能够直接监测肿瘤内的免疫反应。正电子发射断层扫描（PET）提供高灵敏度、无创和定量成像，可与基于抗体的探针结合，根据细胞表面表型提供体内组织和细胞的分子成像。此外，工程抗体片段（如cys-diabodies；单链抗体片段的共价二聚体）已经以最佳动力学产生，能够通过免疫pet快速在体内靶向和清除成像应用。在这项工作中，将开发利用工程抗体片段识别CD8（细胞毒性T细胞的经典细胞表面标记物）的免疫pet，以解决肿瘤中免疫细胞亚群直接成像的挑战。特异性目标1将侧重于显像剂的生物惰性需求，并将评估体外和体内用抗CD8囊性糖尿病治疗T细胞的生物效应（激活，细胞因子释放）。特异性目标2将使用放射性标记的抗cd8细胞-糖尿病体进行免疫pet评估正常小鼠和荷瘤小鼠的免疫激活，免疫刺激剂如抗cd137抗体治疗。特异性目标3将重点关注用逆转免疫抑制（如抗pd -1和抗ctla -4）和诱导细胞毒性T细胞浸润的抗体治疗荷瘤小鼠的CD8+T细胞的免疫pet检测和定量。这些研究将验证CD8+ T细胞免疫pet探针在体内研究癌症免疫治疗反应中的作用，提供对生物体免疫反应的更深入了解，并将为临床前模型和最终人类免疫细胞亚群成像和定量的广泛方法打开大门。

DESCRIPTION (provided by applicant): Tumors are comprised of a variety of cell types in addition to the malignant cells, including stroma, vasculature, and infiltrating immune cells. An understanding of the identities, numbers, and states of these other cellular components is clearly important to understanding the biology of tumors, and their responses to therapy, as outlined in the NCI Provocative Question C4. Recently, immune-modulatory therapies and adoptive cell therapies have become established as powerful therapeutic approaches in cancer, raising a critical need to be able to monitor immune responses directly within tumors. Positron emission tomography (PET) provides highly sensitive, non-invasive and quantitative imaging, which can be combined with antibody-based probes to provide molecular imaging of tissues and cells in vivo based on cell surface phenotype. Furthermore, engineered antibody fragments (such as cys-diabodies; covalent dimers of single-chain antibody fragments) have been generated with optimal kinetics enabling rapid in vivo targeting and clearance for imaging applications by immunoPET. In the proposed work, immunoPET using engineered antibody fragments that recognize CD8, a classic cell surface marker on cytotoxic T cells, will be developed to address the challenge of direct imaging of immune cell subsets in tumors. Specific Aim 1 will focus on the need for imaging agents to be biologically inert, and will assess biological effects (activation, cytokine release) of treating T cells with anti- CD8 cys-diabodies,in vitro and in vivo. Specific Aim 2 will employ radiolabeled anti-CD8 cys-diabodies for immunoPET assessment of immune activation in normal mice and tumor-bearing mice treated with immune stimulants such as anti-CD137 antibodies. Specific Aim 3 will focus on immunoPET detection and quantification of CD8+T cells in tumor-bearing mice treated with antibodies that reverse immunosuppression (such as anti-PD-1 and anti-CTLA-4) and induce tumor infiltration by cytotoxic T cells. These studies will validate the role of immunoPET probes for CD8+ T cells to study responses to cancer immunotherapy in vivo, provide a deeper understanding of immune responses in living organisms, and will open the door to broad methods for imaging and quantitating immune cell subsets in preclinical models and eventually humans.