PREVENT EFFICACY POOL: PREVENT CANCER PRECLINICAL DRUG DEVELOPMENT PROGRAM

肺癌是世界范围内癌症死亡的主要原因。KRAS是肺腺癌患者中最常见的癌基因，而EGFR突变发生在47.9%的亚太非小细胞肺癌（NSCLC）患者和19.2%的西方患者中。此外，在40-89%的NSCLC中发现EGFR过表达。这些发现表明，针对这些突变进行预防可能对控制这种疾病产生重大影响。肺癌疾病控制的一个关键概念是预防癌前病变患者的肺癌进展，并预防既往接受过治疗的肺癌患者的肺癌复发。 KRAS和EGFR突变都很容易在浸润前肺部病变中发现，致癌KRAS或EGFR突变与发生浸润性和转移性肺癌的风险增加相关。研究表明，Th 1辅助细胞免疫对于免疫疗法介导的癌症根除至关重要。MHC II限制性肽疫苗引发肿瘤抗原特异性Th 1免疫，其协调免疫抑制环境的逆转。针对EGFR和KRAS的MHC II限制性多肽疫苗已经显示，当在诱导癌蛋白活性之前接种时，这些疫苗可以显著（~80%）降低肺癌转基因小鼠模型中癌蛋白驱动的肺肿瘤发生。然而，当在癌蛋白诱导后两周给予疫苗时，观察到效力降低，表明癌基因激活后不久肿瘤微环境中存在免疫抑制机制。类似地，高风险个体可能在明显的肺肿瘤发生之前很久就已经具有活性致癌突变，这可能显著促进免疫抑制微环境，从而阻碍疫苗诱导的免疫应答。因此，测试疫苗与可以抑制免疫抑制微环境的药剂组合的功效是非常关键的。 CA-170是免疫检查点蛋白VISTA（T细胞活化的V结构域IG抑制剂）的新型三肽小分子拮抗剂，具有优异的口服生物利用度、相对短的半衰期，并且由于其抑制VISTA的能力，其可以剂量依赖性地增强T淋巴细胞的增殖。在同基因小鼠肿瘤模型中，CA-170在临床前毒理学研究中也显示出高度有利的毒性特征。在最近对晚期实体瘤或淋巴瘤患者的临床研究中，CA-170具有良好的安全性，半衰期相对较短，并表现出免疫调节作用，伴有肿瘤消退。因此，抗原特异性多肽疫苗接种和免疫检查点阻断的组合应增加抗原特异性T细胞活化。 先前的动物研究已经证明，作为吸入气雾剂直接递送到肺部的癌症预防剂提供增强的预防肺癌的功效，同时由于减少全身暴露而减少不良反应。因此，雾化CA-170可显著增强KRAS或EGFR疫苗抑制KRAS/EGFR驱动的致癌作用的功效。该项目的总体目标是在KRAS或EGFR突变驱动的转基因动物模型中，测试KRAS或EGFR多肽疫苗和雾化CA-170的联合治疗是否会改善KRAS或EGFR疫苗对肺肿瘤进展的免疫预防效力，并评估与疫苗效力相关的免疫应答。

Lung cancer is the leading cause of cancer mortality worldwide. KRAS is the most common oncogene in lung adenocarcinoma patients while EGFR mutations occur in 47.9% of Asia-Pacific patients with non-small cell lung cancer (NSCLC) and 19.2% of Western patients. Furthermore, EGFR over expression has been identified in 40–89% of NSCLC. These findings suggest that targeting these mutations for prevention may have significant impact in controlling this disease. A key concept in lung cancer disease control is to prevent lung cancer progression in patients with pre-malignant lesions and to prevent lung cancer recurrence in those with previously treated lung cancer. Both KRAS and EGFR mutations are readily found in pre-invasive lung lesions, and oncogenic KRAS or EGFR mutations are associated with an increased risk of developing invasive and metastatic lung cancer. Studies have shown that the Th1 helper cellular immunity is critical for immunotherapy-mediated cancer eradication. MHC II-restricted peptide vaccines elicit tumor antigen-specific Th1 immunity that orchestrates the reversal of the immune suppressive environment. MHC II-restricted multi-peptide vaccines against EGFR and KRAS have shown that these vaccines can significantly (~80%) decrease oncoprotein-driven lung tumorigenesis in transgenic murine models of lung cancer when vaccinated before the induction of oncoprotein activity. However, diminished efficacy was observed when the vaccines were given two weeks after the oncoprotein induction, suggesting the presence of immunosuppressive mechanisms in the tumor microenvironment soon after the oncogene activation. Similarly, high-risk individuals may already have active oncogenic mutations long before the onset of overt lung tumorigenesis, which could contribute significantly to the immune suppressive microenvironment, thereby hampering the vaccine-induced immune responses. Therefore, testing efficacy of a vaccine in combination with agents that can inhibit the immune suppressive microenvironment is highly critical. CA-170, a novel tripeptide small molecule antagonist of the immune checkpoint protein VISTA (V-domain Ig suppressor of T-cell activation) has excellent oral bioavailability, a relatively short half-life, and it can dose-dependently enhance the proliferation of T lymphocytes due to its ability to inhibit VISTA In syngeneic murine tumor models, CA-170 also showed a highly favorable toxicity profile in preclinical toxicology studies. In recent clinical studies in patients with advanced solid tumors or lymphomas, CA-170 had a favorable safety profile with a relatively short half-life and demonstrated immune-modulating effects, accompanied by tumor regression. Therefore, a combination of an antigen-specific multi-peptide vaccination and immune checkpoint blockade should increase antigen-specific T cell activation. Previous animal studies have demonstrated that cancer prevention agents delivered directly to the lungs as inhaled aerosols provide enhanced efficacy to prevent lung cancer while reducing adverse effects due to reduced systemic exposure. Thus, aerosolized CA-170 may significantly enhance the efficacy of the KRAS or EGFR vaccine to inhibit KRAS/EGFR driven carcinogenesis. The overall goal of the project is to test whether combination treatment with KRAS or EGFR multi-peptide vaccines and aerosolized CA-170 will improve immunopreventive efficacy of KRAS or EGFR vaccine against lung tumor progression in transgenic animal models driven by KRAS or EGFR mutations, and assess immunologic responses that correlate vaccine efficacy.