Targeting EphB4-ephrinB2 to decrease immunosuppression in HNSCC

摘要，项目1 对于高危头颈癌(HNSCC)患者来说，治疗耐药性仍然是一个具有挑战性的问题。 目前免疫检查点抑制剂的试验已经产生了次优的应答率。这可能是由于 在很大程度上调节免疫格局的组成、表型和功能的因素。 优先招募独特的免疫抑制细胞亚型到肿瘤床可能起到重要作用 有助于促进肿瘤的生长和进展。肿瘤内皮细胞可作为选择性血管内皮细胞 调节免疫细胞进入、稳定和激活状态的屏障，但其机制基础 人们对此仍然知之甚少。EphB4受体酪氨酸激酶及其配体EFNB2定义新的分子 目标。尽管它们在早期胚胎发育中的细胞迁移和血管生成方面已经被研究过， 关于它们在调节癌症免疫微环境中的作用，发表的文章很少。我们的初步数据 显示HNSCCs富含调节性T细胞(Tregs)和肿瘤相关巨噬细胞(TAMs)，两者均 这些基因在RT后导致了耐药性。放疗后EFNB2上调肿瘤血管，而EphB4上调 表达在Tregs和TAMs上，在所有免疫细胞中，Tregs和Tam对任何一种免疫细胞都最敏感 RT研究中使用TNYL-RAW或基因敲除内皮细胞EFNB2的药理抑制作用。我们 因此，假设RT上调肿瘤血管内皮细胞上的EFNB2，从而作用于 优先招募表达Tregs和TAMs的EphB4。阻止EphB4-EFNB2信号在 肿瘤内皮屏障将阻碍Tregs和Tams的侵袭和促进癌细胞存活 或抑制TEF函数。在Aim1中，我们将分析免疫之间相互作用的机制结果 细胞EphB4和内皮EFNB2对免疫跨内皮转运、存活、极化和 免疫细胞的分化以及血管内皮细胞对RT的反应正常化。我们会 使用药物抑制剂以及内皮细胞EFNB2缺失或EphB4缺失的GEMM 在Tregs或Tams上。目标2将研究相互作用引发的细胞和分子机制。 内皮细胞表达EFNB2和EphB4的免疫细胞对RT反应的免疫细胞过程 内皮免疫细胞共培养实验。靶向抑制STAT3、AKT和ERK通路 根据我们的初步数据，使用了药物抑制剂。AIM 3将使用来自人类临床试验的组织 使用sEphB4-HSA(一种目前处于I期和II期试验的抑制剂)在单独用药或药物和 单纯的化疗和放射治疗。这将有助于确定驱动抗肿瘤免疫的分子介质。 对这种疗法的反应。这些研究还将共同阐明分子和细胞参数 EphB4-EFNB2抑制剂，并将允许使用EphB4- EFNB2抑制剂。

SUMMARY, Project 1 Treatment resistance remains a challenging problem for high-risk head and neck cancer (HNSCC) patients. Current trials with immune checkpoint inhibitors have yielded sub-optimal response rates. This could be due to TME factors that substantially modulate the immune landscape’s composition, phenotype, and function. Preferential recruitment of unique immunosuppressive cell subtypes to the tumor bed may play an important role in contributing to the promotion of tumor growth and progression. The tumor endothelium can act as a selective barrier that regulates entry, stability, and activation status of immune cells, but the mechanistic underpinnings remain poorly understood. The EphB4 receptor tyrosine kinase and its ligand EFNB2 define novel molecular targets. Although they have been studied in cell migration and angiogenesis in early embryonic development, little has been published on their role in modulating the cancer immune microenvironment. Our preliminary data show that HNSCCs are enriched in regulatory T-cells (Tregs) and tumor associated macrophages (TAMs), both of which contribute to resistance after RT. EFNB2 is upregulated on tumor vasculature after RT whereas EphB4 is expressed on Tregs and TAMs, and among all immune cells, Tregs and TAMs are most sensitive to either pharmacologic inhibition with TNYL-RAW or genetic knockdown of endothelial EFNB2 in the context of RT. We therefore hypothesize that RT upregulates EFNB2 on tumor vascular endothelial cells, which acts preferentially to recruit EphB4 expressing Tregs and TAMs. Blockade of EphB4-EFNB2 signaling at the tumor endothelial barrier will hinder Tregs’ and TAMs’ ability to infiltrate and promote cancer cell survival or suppress Teff function. In Aim1, we will analyze the mechanistic outcome of the interaction between immune cell EphB4 and endothelial EFNB2 on immune trans-endothelial trafficking, survival, polarization, and differentiation of immune cells as well as vascular normalization of endothelial cells in response to RT. We will use pharmacological inhibitors as well as GEMMs with EFNB2 deletion on endothelial cells or EphB4 deletion on Tregs or TAMs. Aim 2 will study the cellular and molecular mechanisms triggered by the interaction between endothelial EFNB2 and EphB4-expressing immune cells on immune cell processes in response to RT using endothelial-immune cells co-culture assays. Targeted inhibition of STAT3, AKT, and Erk pathway will be done with pharmacological inhibitors based on our preliminary data. Aim 3 will use tissue from a human clinical trial with sEphB4-HSA (an inhibitor currently in Phase I and II trials) before and after drug alone or drug and chemoradiation alone. This will serve to identify the molecular mediators that drive the anti-tumor immune response to this therapy. These studies will also collectively elucidate the molecular and cellular parameters of EphB4-EFNB2 inhibitors and will allow for the identification of potential predictive markers for this using EphB4- EFNB2 inhibitors.