TRAIL-expressing Recombinant Adenovirus Based Immunotherapy for RCC

描述（由申请人提供）：今年在美国约有40000例新的肾细胞癌（RCC）将被诊断出来，预计将有13000例死于RCC。转移性肾细胞癌的中位生存期为8个月，约30%的肾细胞癌患者被诊断为晚期转移性疾病。局部RCC通过手术切除治疗；然而，目前尚无有效的治疗转移性疾病的方法。RCC的适应性免疫在肿瘤监测中起着关键作用，CD8+和CD4+ T细胞都有助于肿瘤的消退。肺是RCC转移的主要部位之一，即使在没有肿瘤生长的情况下，肺也是一个已知的免疫抑制环境。因此，如果针对转移性RCC的新型免疫疗法要进入临床试验，与原发肿瘤部位相比，必须了解肺环境对保护性T细胞反应的产生和维持的影响。我们之前描述了一种重组腺病毒载体的开发，该载体编码人类tnf相关的凋亡诱导配体（TRAIL; Ad5-TRAIL） cDNA。最近，我们的研究集中在使用类似的重组腺病毒编码全长小鼠TRAIL （Ad5-mTRAIL）在携带实验性肾细胞癌（Renca）肿瘤的免疫活性小鼠中。来自Ad5-mTRAIL杀死的Renca细胞的抗原可以在体外交叉呈递给CD8+ T细胞，并且单独使用Ad5-mTRAIL在体内最低限度地延长存活时间并诱导低水平的CTL活性。为了提高DC效率，我们将Ad5-mTRAIL与CpG寡核苷酸（CpG）联合使用，显著增强了Renca肿瘤小鼠体内抗原特异性T细胞增殖和CTL活性，并延长了存活时间。有趣的是，治疗前CD4+或CD25+细胞耗尽进一步提高了生存率和体内CTL活性，CD4+细胞耗尽的无肿瘤小鼠也拒绝了Renca细胞的后续攻击，但不拒绝mhc匹配的前列腺肿瘤细胞，这表明存在肿瘤特异性免疫记忆。虽然CD4+细胞耗竭的影响是显著的，但生存率并没有达到100%，这表明存在额外的免疫抑制机制。在这项更新申请中，我们提出了以下具体目标，以研究局部Ad5-TRAIL给药与旨在克服肿瘤源性免疫抑制的疗法联合使用时，将导致实验性转移性RCC小鼠肺部的保护性抗肿瘤免疫：目的1)确定原发性RCC肿瘤部位瘤内Ad5-mTRAIL/CpG给药对实验性肺转移CD8+效应T细胞反应的影响程度；目的2)研究CD4+ T细胞亚群，特别是CD4+CD25+ Treg和Th17对CD8+ T细胞介导的抗RCC肺转移肿瘤反应的质量和数量的影响；3)研究肿瘤浸润性骨髓细胞群对Ad5-mTRAIL/CpG免疫治疗期间肺抗肿瘤免疫反应的影响，重点关注这些细胞的刺激与抑制能力。目前的提案反映了我们致力于开发新的RCC免疫疗法，可以消除原发性肿瘤和远端转移，从而延长晚期RCC患者的生存期。

DESCRIPTION (provided by applicant): This year in the U.S. ~40,000 new cases of renal cell carcinoma (RCC) will be diagnosed and >13,000 deaths are expected from RCC. Metastatic RCC carries a median survival of 8 months and ~30% of RCC patients are diagnosed with advanced metastatic disease. Localized RCC is treated surgically through resection; however, there is no efficacious therapy currently available for metastatic disease. Adaptive immunity to RCC plays a critical role in tumor surveillance, with both CD8+ and CD4+ T cells contributing to tumor regression. One of the major sites of RCC metastasis is the lung, an environment that is known to be immunosuppressive even in the absence of tumor outgrowth. Therefore, if novel immunotherapies against metastatic RCC are to move forward into clinical trials, the effect of the lung environment on the generation and maintenance of protective T cell responses, compared to the primary tumor site, must be understood. We previously described the development of a recombinant adenoviral vector encoding the human TNF-related apoptosis-inducing ligand (TRAIL; Ad5-TRAIL) cDNA. More recently, our studies have focused on using a similar recombinant adenovirus encoding full-length murine TRAIL (Ad5-mTRAIL) in immunocompetent mice bearing experimental renal cell carcinoma (Renca) tumors. Antigens derived from Ad5-mTRAIL-killed Renca cells could be cross- presented to CD8+ T cells in vitro, and Ad5-mTRAIL used alone minimally prolonged survival and induced a low level of CTL activity in vivo. To enhance DC efficiency we combined Ad5-mTRAIL with CpG oligonucleotides (CpG), which significantly augmented in vivo antigen-specific T cell proliferation and CTL activity, as well as prolonged survival of Renca tumor-bearing mice. Interestingly, CD4+ or CD25+ cell depletion prior to therapy further enhanced survival and in vivo CTL activity, and CD4+ cell-depleted, tumor-free mice also rejected a subsequent challenge of Renca cells, but not MHC-matched prostate tumor cells, showing the existence of tumor-specific immunologic memory. While the effects of CD4+ cell depletion were striking, survival did not reach 100%, suggesting the presence of additional immunosuppressive mechanisms. In this renewal application, we propose the following specific aims to investigate the hypothesis that localized Ad5-TRAIL administration, when used in conjunction with therapies designed to overcome tumor- derived immunosuppression, will lead to protective antitumor immunity in the lungs of mice with experimental metastatic RCC: Aim 1) Ascertain the extent to which intratumoral Ad5-mTRAIL/CpG administration at the primary RCC tumor site impacts the magnitude of CD8+ effector T cell responses against experimental lung metastases; Aim 2) Examine the effect of CD4+ T cell subsets, specifically CD4+CD25+ Treg and Th17, on the quality and quantity of the CD8+ T cell-mediated antitumor response against RCC lung metastases; and Aim 3) Examine the impact of tumor-infiltrating myeloid cell populations on the lung antitumor immune response during Ad5-mTRAIL/CpG immunotherapy - focusing on the stimulatory versus suppressive capacities of these cells. The current proposal reflects our commitment to develop novel immunotherapies for RCC that can eliminate both primary tumors and distal metastases, thereby prolonging the survival of patients with advanced RCC.