Dual-isotope SPECT imaging and immunophenotyping of immune cells to determine response to immunotherapy

总结 虽然在过去十年中转移性黑色素瘤的免疫疗法取得了重大进展， 对于肾细胞癌（RCC），并非所有患者都有反应，其他患者随着时间的推移会产生耐药性。百篇小说 目前正在制定治疗方案，以克服原发性和获得性耐药性。一些组合增加了 细胞毒性T细胞在肿瘤中的浸润以杀死癌细胞，而其他细胞调节肿瘤相关的细胞毒性T细胞。 巨噬细胞（TAM）的作用，以增强肿瘤微环境中的T细胞活性。然而，对患者的毒性 是免疫治疗方案的一个重要限制。需要非侵入性成像技术来确定 对联合治疗的反应，以避免潜在的非反应者不必要的毒性。当前成像 这些技术不能同时评估T细胞和TAM水平的动态变化。整体 假设同时成像细胞毒性T细胞和TAM的浸润可以更好地确定 对免疫治疗方案的反应。 该提案的目标是开发用于单光子发射计算的非侵入性成像探头 在一个实施方案中，可以同时对T细胞和TAM进行断层摄影（SPECT）成像以确定对组合疗法的响应。 我们预计SPECT将准确地概括病理，并可能最终取代治疗中的 可能有假性进展的患者的活检。SPECT还可以补充基于组织的分析 为了通过数字空间分析（DSP）进一步询问肿瘤微环境， 保留空间信息的方法。DSP可以同时定量免疫细胞中的多种生物标志物 负责肿瘤对联合治疗的敏感性。在我们的初步工作中，我们开发了工具， 用放射性标记的抗体在体内追踪CD 8 + T细胞和CD 68 + TAM。我们将测试我们的 在具有完整免疫系统的小鼠中建立的黑色素瘤和RCC的鼠肿瘤模型中的SPECT药剂。 我们将在体外表征其与CD8+ T细胞和CD68+ TAM的结合特性（目的1）。我们会想象 在黑色素瘤和RCC的同基因肿瘤模型中通过SPECT成像的体内肿瘤T细胞和TAM浸润 并在小鼠和患者组织中通过DSP评估免疫治疗后免疫细胞的活化状态（目的 2）。这些研究将为双同位素SPECT在免疫治疗中的临床试验奠定基础。 患者

SUMMARY While significant progress has been made in the past decade with immunotherapy for metastatic melanoma and renal cell carcinoma (RCC), not all patients respond, and others develop resistance over time. Hundreds of novel regimens are being developed to overcome primary and acquired resistance. Some combinations increase the infiltration of cytotoxic T cells in the tumor to kill cancer cells, while others modulate tumor-associated macrophages (TAMs) to enhance the T cell activity in the tumor microenvironment. However, toxicity to patients is an important limitation to immunotherapy regimens. Non-invasive imaging techniques are needed to determine response to combination therapy to save potential non-responders from unnecessary toxicity. Current imaging techniques do not assess the dynamic changes in the levels of T cells and TAMs at the same time. The overall hypothesis is that imaging the infiltration of cytotoxic T cells and TAMs concurrently can better determine response to immunotherapy regimens. The goal of this proposal is to develop non-invasive imaging probes for single photon emission computed tomography (SPECT) imaging of T cells and TAMs concurrently to determine response to combination therapy. We anticipate that SPECT will accurately recapitulate pathology and may ultimately replace on-treatment biopsies in patients who might have pseudoprogression. SPECT may also complement tissue-based analyses to further interrogate the tumor microenvironment through digital spatial profiling (DSP), an in situ profiling method that preserves spatial information. DSP can quantify multiple biomarkers simultaneously in immune cells responsible for the tumor’s sensitivity to combination therapy. In our preliminary work we developed the tools to implement the tracking of CD8+ T cells and CD68+ TAMs in vivo with radiolabeled antibodies. We will test our SPECT agents in established murine tumor models of melanoma and RCC in mice with intact immune systems. We will characterize their binding properties to CD8+ T cells and CD68+ TAMs in vitro (Aim 1). We will image tumoral T cell and TAM infiltration in vivo by SPECT imaging in syngeneic tumor models of melanoma and RCC and assess activation status of immune cells by DSP after immunotherapy in murine and patient tissues (Aim 2). These studies will lay the foundations for future clinical trials of dual-isotope SPECT in immunotherapy-treated patients.