Immunotherapy with checkpoint inhibitors demonstrates impressive improvements in the treatment of several types of cancer. Unfortunately, not all patients respond to therapy while severe immune-related adverse effects are prevalent. Currently, patient stratification is based on immunotherapy marker expression through immunohistochemical analysis on biopsied material. However, expression can be heterogeneous within and between tumor lesions, amplifying the sampling limitations of biopsies. Analysis of immunotherapy target expression by non-invasive quantitative molecular imaging with PET or SPECT may overcome this issue. In this review, an overview of tracers that have been developed for preclinical and clinical imaging of key immunotherapy targets, such as programmed cell death-1, programmed cell death ligand-1, IDO1 and cytotoxic T lymphocyte-associated antigen-4 is presented. We discuss important aspects to consider when developing such tracers and outline the future perspectives of molecular imaging of immunotherapy markers. Current techniques in immune checkpoint imaging and its potential for future applications

中文翻译：

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癌症免疫检查点表达的无创放射性核素示踪剂。

使用检查点抑制剂的免疫疗法在多种类型的癌症的治疗中显示出令人印象深刻的改善。不幸的是，虽然严重的免疫相关不良反应普遍存在，但并非所有患者都对治疗产生反应。目前，患者分层是基于对活检材料进行免疫组织化学分析的免疫治疗标志物表达。但是，表达在肿瘤病变内和之间可能是异质的，从而扩大了活检样本的局限性。通过PET或SPECT的无创定量分子成像技术对免疫治疗靶标表达进行分析可以克服这一问题。在本综述中，对示踪剂的概述进行了概述，这些示踪剂已用于关键免疫治疗靶标的临床前和临床成像，例如程序性细胞死亡-1，程序性细胞死亡配体-1，介绍了IDO1和细胞毒性T淋巴细胞相关抗原4。我们讨论了开发此类示踪剂时要考虑的重要方面，并概述了免疫疗法标记物分子成像的未来观点。免疫检查点成像的当前技术及其在未来应用中的潜力