L1 capsomeres as a next generation preventive HPV vaccine

最近开发的预防性疫苗保护对“高风险”的人乳头瘤病毒（HPV）是医学上的一个里程碑。目前的疫苗由主要衣壳蛋白L1的重组病毒样颗粒（VLP）组成，包括高危HPV 16和18型。II/III期临床试验已经显示这些VLP制剂在预防HPV 16、18感染中>95%的功效，并且因此有希望预防与这些类型相关的约70%的宫颈癌的最终发展。尽管 VLP疫苗的这种成功具有高成本（在美国最初的三次免疫为360美元）和需要冷藏的不利属性（即，冷链）。我们以前的特点是VLP亚基，五聚体L1壳粒的免疫原性，并比较这些“亚基”在犬感染模型中的VLP。在该模型中，壳粒在诱导抗感染保护方面似乎与VLP接近。在E.大肠杆菌作为GST-融合蛋白，在水平上表明在制造费用的显着降低。 该蛋白易于纯化，并且可以沉淀、重悬和在室温下储存而不损失免疫原性。在正在进行的NCI RAPID奖的背景下，GST-L1衣壳被提议作为“下一代”HPV疫苗，可能非常适合在宫颈癌特别流行的世界不发达国家生产和使用。我们建议使用GMP生产（由Shantha Biotechnica）、瓶装和毒理学筛选的GST-L1蛋白 在第一阶段人体试验研究的RAPID奖的赞助下。在目标1和2中，我们提出了一种剂量递增方案，在三个剂量水平（10、50、500微克和安慰剂）中的每一个剂量水平下15名受试者，重复三次，同时分析毒性、中和抗体的产生、细胞毒性T细胞应答和GST抗体产生的可能不良反应。在第三个目标中，临床标本的实验室研究和动物实验将测试新的佐剂策略，包括Toll样 受体活化，并通过比较壳粒、交联壳粒和VLP来评估抗原间隔和连接对体液免疫的影响。L1壳粒结构和与先天免疫系统相互作用的知识将用于以更低和更少的剂量产生更长寿命和更广泛的免疫力。该项目的结果将决定GST-LI制剂是否可以进行进一步的第二阶段测试。

The recent development of prophylactic vaccines protective against "high risk" human papillomaviruses (HPV) is a landmark in medicine. The current vaccine is composed of recombinant virus-like particles (VLPs) of the major capsid protein, L1, including the high risk HPV types 16 and 18. Phase ll/lll clinical trials have shown >95% efficacy of these VLP preparations in preventing HPV 16, 18 infection, and thus hopefully preventing the eventual development of about 70% of cervical cancers associated with these types. Despite this success the VLP vaccines have the adverse attributes of high cost ($360 for the initial three immunizations In the USA) and a requirement for refrigeration {i.e., cold chain). We have previously characterized the immunogenic properties of VLP subunits, pentameric L1 capsomeres, and compared these "subunits" to VLPs in a canine infection model. In this model capsomeres appeared near equivalent to VLPs in inducing protection against infection. Capsomeres are purified after recombinant expression of L1 in E. coli as a GST-fusion protein, at levels suggesting a significant reduction in manufacturing expense. The protein is readily purified, and can be precipitated, resuspended, and stored at room temperature without loss of immunogenicity. In the context of an ongoing NCI RAPID award GST-L1 capsomeres have been proposed as a "next generation" HPV vaccine that might be ideally suited for production and use in underdeveloped countries of the world where cervical cancer is particularly prevalent. We propose to use the GST-L1 protein that has been GMP produced (by Shantha Biotechnica), vialed, and toxicology screened under the auspices of a RAPID award for study in a phase I human trial. In aims 1 and 2 we propose a dose escalation scheme of 15 subjects at each of three dose levels (10, 50, 500 micrograms and placebo), repeated three times, with concomitant analysis of toxicity, development of neutralizing antibodies, cytotoxic T-cell responses, and possible adverse effects of GST antibody development. In the third aim, laboratory studies with clinical specimens and animal experiments will test new adjuvant strategies including Toll-like receptor activation, and evaluate the effects on humoral immunity of antigen spacing and linking by comparing capsomeres, cross-linked capsomeres, and VLPs. Knowledge of L1 capsomere structure and interaction with the innate immune system will be utilized to generate longer-lived and broader immunity with lower and fewer doses. The results of this project will determine whether the GST-LI preparation can proceed to further phase II testing.