Exploration of different immunotherapy modalities in osteosarcoma

项目总结/摘要 骨肉瘤（OS）是儿童长骨最常见的原发性骨恶性肿瘤， 最常见于美国的成年人。过去20年的生存率没有变化。OS也是 最常见的恶性骨肿瘤（80%）的狗。OS的治疗选择有限。免疫治疗 嵌合抗原受体（CAR）T细胞是一种有前途的新方法，但尚未在OS中充分探索。 设计用于表达重组受体以靶向特异性肿瘤细胞表面抗原并促进T细胞- 介导的癌细胞死亡。然而，CAR T细胞疗法的最大挑战之一是 免疫抑制肿瘤微环境（TME）。另一种免疫治疗策略是使用免疫抑制剂。 检查点抑制剂，如针对PD-1的单克隆抗体（mAb）。抗PD-1 mAb显示 在治疗多种肿瘤中具有显著的效率，但由于mAb的全身递送而引起副作用。 为了避免系统性递送，可以设计溶瘤病毒以直接产生免疫检查点抑制剂 在TME中增强免疫系统，使T细胞能够杀死肿瘤细胞。连续复制型腺病毒 CRAd仅在肿瘤细胞中复制，裂解它们，并刺激TME和远端部位的抗肿瘤免疫 造成旁观者效应。然而，针对癌抗原的效应T细胞的数量有限， 限制了这种方法的有效性。因此，我们提出了一种联合治疗，以协同这些策略 来对抗肿瘤细胞。我们将结合联合收割机CAR T细胞疗法、溶瘤病毒和PD-1/PD-L1抑制剂， 骨肉瘤肿瘤细胞我们已经开发了一种武装溶瘤腺病毒，在肿瘤细胞中产生抗PD-1抗体。 TME。我们将创造两种更多的武装溶瘤病毒，它们将产生分泌的单域抗体（sdAb）。 PD 1和PDL 1。我们将评估CRAd和CAR T细胞（针对B7-H3）诱导的肿瘤细胞裂解。的 条件复制的溶瘤病毒将在TME中产生抗PD 1和抗PDL 1 sdAb，从而减少TME中的不良反应。 全身给药的效果，增强抗肿瘤免疫力。针对B7-H3的CAR T细胞将启动 在活化的TME中杀死肿瘤细胞。最终，在本提案的范围之外， 在转换为儿科OS患者之前，犬患者的自发OS。

Project Summary/Abstract Osteosarcoma (OS) is the most common primary bone malignancy affecting long bones in children and the third most frequent in adults in the United States. The survival rates over the last 20 years are unchanged. OS is also the most common malignant bone tumor (80%) in dogs. Treatment options for OS are limited. Immunotherapy is a promising new approach that has yet to be fully explored in OS. Chimeric antigen receptor (CAR) T cells are designed to express recombinant receptors to target specific tumor cell surface antigens and promote T cell- mediated cancer cell death. However, one of the biggest challenges in CAR T cell therapy is the immunosuppressive tumor micro-environment (TME). Another immunotherapy strategy is the use of immune checkpoint inhibitors, such as monoclonal antibodies (mAb) against PD-1. Anti-PD-1 mAbs have shown significant efficiency in treating multiple tumors but cause adverse effects due to systemic delivery of the mAb. To avoid systemic delivery, oncolytic viruses can be designed to produce immune checkpoint inhibitors directly in TME to boost the immune system and enable T cells to kill tumor cells. Conditionally replicative adenoviruses (CRAds) replicate only in tumor cells, lyse them, and stimulate anti-tumor immunity in TME and at distant sites of disease, causing a bystander effect. However, the limited number of effector T cells against cancer antigens limits the efficacy of this approach. Therefore, we propose a combination therapy to synergize these strategies to combat tumor cells. We will combine CAR T cell therapy, oncolytic virus, and PD-1/PD-L1 inhibitor to target osteosarcoma tumor cells. We have developed an armed oncolytic adenovirus to produce anti-PD-1 Ab in the TME. We will create two more armed oncolytic viruses that will produce secreted single domain antibodies (sdAb) to PD1 and PDL1. We will evaluate CRAd and CAR T cell (against B7-H3) induced tumor cells lysis. The conditionally replicated oncolytic viruses will produce anti-PD1 and anti-PDL1 sdAb in TME, reducing the adverse effects of systemic administration, and enhancing anti-tumor immunity. CAR T cells against B7-H3 will initiate tumor cell killing in an activated TME. Ultimately, beyond the scope of this proposal, this approach will be tested in spontaneous OS in canine patients, before translation to pediatric OS patients.