Chemo-immunotherapy strategy for pediatric high grade glioma

摘要 在美国，儿童脑肿瘤是儿童癌症死亡的主要原因。 高级别神经胶质瘤（pHGG）是脑癌中最常见和最具侵袭性的形式之一， 存活9-15个月。1 -3在大脑半球中出现的pHGG的一个突出亚群 编码组蛋白H3 F3 A中的G34 R/V取代，沿着ATRX和TP 53失活突变。 目前的标准治疗，包括肿瘤切除术，然后是放疗和化疗，仅1-4次 导致中位生存期的适度增加。治疗效果有限的原因之一是 肿瘤复发，由pHGG细胞扩散浸润大脑引起。1 -4治疗效果 由于血脑屏障（BBB）5，pHGG也受到限制，血脑屏障阻碍了pHGG的有效递送。 将化疗化合物施用于肿瘤块。涉及局部递送的治疗策略 化疗剂对肿瘤的治疗正在成为有吸引力的方法。探索新的治疗方法 我们开发了一种携带G34 R/V pHGG亚型遗传病变的从头小鼠模型， 使用睡美人（SB）转座酶介导系统。6 -8我们的初步数据表明， H3.3G34R突变降低了与DNA修复相关的基因的表达，使细胞变得更加脆弱。 易受体内电离辐射和DNA损伤敏化剂如奥拉帕尼（一种PARP抑制剂）的影响。在 在这一应用中，我们提出使用高密度脂蛋白（HDL）模拟将奥拉帕尼递送到TME中。 纳米盘（ND）可以通过清道夫受体B-1类（SR-1）特异性内化到肿瘤细胞中， 我们观察到SR-B1在H3.3G34R pHGG中表达， 在来源于SB模型的神经球（NS）中，以及在H3.3G34R pHGG患者来源的细胞中。在这 研究中，我们将开发基于sHDL ND的化学免疫治疗运载工具，该运载工具装载有CpG，一种Toll- Like受体9（TLR 9）激动剂与Olaparib（一种化疗剂）一起用于靶向H3.3G34R pHGG我们证明，局部递送载有化学免疫治疗剂的sHDL NDs， 颅内同基因小鼠胶质瘤模型，引发肿瘤消退和抗肿瘤CD 8 + T细胞应答 在脑肿瘤微环境（TME）中没有明显的脱靶效应。10这些数据表明，sHDL ND是一种有吸引力的pHGG药物递送平台，我们假设这将导致肿瘤消退 和长期生存。所提出的输送系统具有显著的临床转化潜力。

Abstract Pediatric brain tumors are the leading cause of death in children with cancer in the U.S. Among them, pediatric high-grade gliomas (pHGGs) are one of the most common and aggressive forms of brain cancer, with a median survival of 9-15 months.1-3 One of the prominent subgroups of pHGG that arises in cerebral hemispheres encodes for G34R/V substitutions in the histone H3F3A, along with ATRX and TP53 inactivating mutations. The current standard of care, consisting of tumor resection followed by radiation and chemotherapy,1-4 only leads to a modest increase in median survival. One of the reasons for the limited therapeutic outcomes is tumor recurrence, caused by the spread of pHGG cells that infiltrate the brain.1-4 Treatment effectiveness for pHGG has also been limited due to the blood-brain barrier (BBB),5 which precludes the efficient delivery of chemotherapeutic compounds to the tumor mass. Therapeutic strategies involving local delivery of chemotherapeutic agents to the tumor are emerging as attractive approaches. To explore novel therapeutic modalities for the G34R/V pHGG subtype, we developed a de novo mouse model harboring the genetic lesions using the Sleeping Beauty (SB) transposase-mediated system.6-8 Our preliminary data demonstrate that the H3.3G34R mutation reduces the expression of genes involved with DNA repair, rendering the cells more susceptible to ionizing radiation in vivo and to DNA damage sensitizers such as Olaparib, a PARP inhibitor. In this application, we propose to deliver Olaparib into the TME using high-density lipoprotein (HDL)-mimicking nanodiscs (NDs) that can be specifically internalized into tumor cells via scavenger receptor class B-1 (SR- B1) and caveolae lipid rafts endocytosis.9 We observed that SR-B1 is expressed in H3.3G34R pHGG neurospheres (NS) derived from the SB model, as well as in H3.3G34R pHGG patient-derived cells. In this study, we will develop chemo-immunotherapy delivery vehicles based on sHDL NDs loaded with CpG, a Toll- like receptor 9 (TLR9) agonist, together with Olaparib, a chemotherapeutic agent, for targeting H3.3G34R pHGG. We demonstrated that local delivery of sHDL NDs loaded with chemo-immunotherapeutics, in an intracranial syngeneic mouse glioma model, elicited tumor regression and anti-tumor CD8+ T cell responses in the brain tumor microenvironment (TME) without overt off-target effects.10 These data indicate that sHDL NDs are an attractive drug delivery platform for pHGG, which we hypothesize will result in tumor regression and long-term survival. The proposed delivery system has significant potential for clinical translation.