Immunomodulation of the Tumor Microenvironment with Molecular Targeted Radiotherapy to Facilitate an Adaptive Anti-Tumor Immune Response to Combined Modality Immunotherapies

摘要 我们正在开发一种综合治疗方法，以根除转移性癌症， 免疫学上“冷”，并且不响应免疫检查点抑制（ICI）。使用“原位疫苗” 方案包括12戈伊局灶性外束放射治疗（EBRT）和瘤内（IT）注射 肿瘤特异性抗体（mAb）+IL 2，我们已经根除了小鼠中孤立的、大的、冷的同基因肿瘤。这 原位疫苗将靶向肿瘤转化为增强的肿瘤抗原呈递的病灶， 增加的T细胞浸润和强大的T细胞记忆然而，存在相同但未经处理的 小鼠对侧腹的第二个肿瘤（2°）抑制了这种治疗的效果，阻止了肿瘤的根除。 用EBRT + IT mAb-IL 2治疗的原发性（1°）肿瘤。在这种情况下，未经治疗的2°肿瘤导致肿瘤- 在1°肿瘤处对EBRT + IT mAb-IL 2的特异性免疫无应答性。我们称之为伴随 免疫耐受（CIT）。我们可以克服CIT，并通过给予IT mAb-IL 2到1° C来消除两种肿瘤。 肿瘤和EBRT的1°和2°肿瘤。对2°肿瘤进行低至2戈伊的EBRT可以克服 前引书临床上，EBRT（即使是低剂量）输送到所有转移性疾病部位是有问题的，但这可以 使用分子靶向放射治疗（MTRT）可以有效地实现。MTRT越来越多地进入 临床肿瘤学实践，我们的UW团队领导了一种新型MTRT的临床前和临床试验 使用烷基磷酸胆碱（APCh）类似物，其选择性地将辐射递送至体内癌症。这些表明 在几乎所有哺乳动物肿瘤细胞和测试的肿瘤位置（包括> 90个肿瘤细胞）中的肿瘤选择性摄取 线和在各种临床试验中的患者中）。在同基因小鼠黑色素瘤模型中，我们观察到 使用我们的下一代APC系统给予ICI和MTRT之间的有效协同作用 模拟，90 Y-NM 600。在一个项目，建立在我们的多学科正在进行的合作进展， 团队，我们现在将系统地优化MTRT与免疫疗法相结合的效力，以增强 针对免疫冷肿瘤的免疫反应。在小鼠模型中，我们将：1）扩展 初步数据显示MTRT和ICI组合的有效协同作用，2）评估 MTRT克服CIT并增强多发性肿瘤背景下的全身抗肿瘤免疫应答 其中用原位疫苗（EBRT + IT mAb-IL 2）单独或与ICI组合治疗。因为 鼠模型不能复制人转移癌的大小和空间分布， 因素强烈影响MTRT的剂量测定，我们将在原位测试MTRT +的免疫调节作用 在患有自然发生的转移性黑素瘤的大型伴侣犬（宠物犬）中接种疫苗。的 这些研究中开发的见解和治疗方案应该能够快速转化为临床 在患者中进行测试，并可能用于任何类型的转移性癌症。

ABSTRACT We are developing a combined modality therapeutic approach to eradicating metastatic cancers that are immunologically “cold” and do not respond to immune checkpoint inhibition (ICI). Using an “in situ vaccine” regimen consisting of 12 Gy focal external beam radiation therapy (EBRT) and intratumoral (IT) injection of tumor-specific antibody (mAb) + IL2, we have eradicated solitary, large, cold syngeneic tumors in mice. This in situ vaccine converts the targeted tumor into a focus of enhanced tumor antigen presentation resulting in increased T-cell infiltration and potent T-cell memory. However, the presence of an identical but untreated second tumor (2°) on a mouse’s opposite flank inhibits the effect of this treatment, preventing eradication of the primary (1°) tumor treated with EBRT + IT mAb-IL2. In this setting, the untreated 2° tumor causes tumor- specific immune unresponsiveness to EBRT + IT mAb-IL2 at the 1° tumor. We refer to this as concomitant immune tolerance (CIT). We can overcome CIT, and eliminate both tumors by giving IT mAb-IL2 to the 1° tumor and EBRT to both the 1° and 2° tumors. Delivering as little as 2 Gy EBRT to the 2° tumor can overcome CIT. Clinically, delivery of EBRT (even low dose) to all sites of metastatic disease is problematic, but this can effectively be achieved using molecular targeted radiation therapy (MTRT). MTRT is increasingly entering clinical oncology practice and our UW team has led preclinical and clinical testing of a novel class of MTRT using alkylphosphocholine (APCh) analogs that selectively deliver radiation to cancers in vivo. These show tumor-selective uptake in virtually all mammalian tumor cells and tumor locations tested (including > 90 tumor lines and in patients across various clinical trials). In a syngeneic murine melanoma model, we have observed a potent synergy between systemically administered ICI and MTRT delivered using our next-generation APC analog, 90Y-NM600. In a project that builds upon the ongoing collaborative progress of our multidisciplinary team, we will now systematically optimize the potency of combining MTRT with immunotherapy to enhance the immune response against immunologically cold tumors. In murine models, we will: 1) expand on preliminary data showing potent synergy with the combination of MTRT and ICI, 2) evaluate the capacity of MTRT to overcome CIT and enhance systemic anti-tumor immune response in the setting of multiple tumors where one is treated with in situ vaccine (EBRT + IT mAb-IL2) alone or in combination with ICI. Because murine models do not replicate the size and spatial distribution of human metastatic cancer and because these factors strongly influence the dosimetry of MTRT, we will test the immunomodulatory effects of MTRT + in situ vaccine in large breed companion canines (pet dogs) with naturally occurring metastatic melanoma. The insights and treatment regimens developed in these studies should enable rapid translation to clinical testing in patients and potentially for any type of metastatic cancer.