Developing an inactivated whole cell H. pylori vaccine

描述（由申请人提供）： 目前，还没有疫苗用于预防普遍存在的胃病原体幽门螺杆菌的感染，并且由于患者依从性差、治疗成本高以及对耐药菌株无效，使感染的药物治疗复杂化。很明显，要降低消化性溃疡和胃癌的发病率，需要新的医学进步，这两种疾病是由感染H。幽门。临床前研究表明，接种疫苗不仅可以预防感染，还可以用于解决活动性感染。有效的疫苗还可以防止再次感染，并阻止高危人群的传播。Antex Biologics是H. pylori疫苗的开发，并致力于将H. pylori疫苗上市该公司已经进行了两项福尔马林灭活幽门螺杆菌全细胞（HWC）疫苗的1期临床试验，该疫苗与佐剂mLT（R192 G）（E.大肠杆菌不耐热毒素。临床前结果表明，疫苗有效性需要使用佐剂和HWC。为了将最佳安全、稳定和有效的疫苗推向市场，我们在本申请中提出临床评估疫苗制剂的两个新方面，即1）冻干而不是液体活性成分（HWC），和2）LT的新型双突变形式（dmLT），其与单突变mLT（R192 G）相比具有降低的肠毒性活性，但保留完全的佐剂活性。HWC的冻干工艺将根据产品特性（如含水量和复溶行为）的体外试验以及动物免疫和攻毒实验的体内试验进行选择。选择的最终制剂将用于通过使用CD 4、抗体和IFN-γ敲除小鼠研究以及检查接种疫苗和攻毒小鼠中胃T细胞浸润性质的流式细胞术研究来促进对疫苗作用机制的理解。将生产冻干HWC和dmLT的cGMP批次，并将在未感染和感染的无症状受试者中进行I期剂量递增安全性试验。由于dmLT尚未进行临床评价，因此将首先在两个人群中确定单独dmLT的最大耐受剂量。在dmLT剂量选择后，将再次在两个人群中确定固定剂量dmLT背景下冻干和复溶HWC的最大耐受剂量。腹泻是最可能定义耐受限度的不良事件。将对接受HWC + dmLT完整疫苗接种系列的受试者进行一组免疫学检查，包括HWC和dmLT的血清和粘膜抗体，以及PBMC增殖和响应H.幽门裂解物。还将对接种后感染的受试者进行诊断检测，以评估其定植状态的变化。这项试验将使疫苗进入更高效力的1期或早期2期试验，从而将H。幽门螺杆菌疫苗离成为现实又近了一步。

DESCRIPTION (provided by applicant): Currently there exists no vaccine for the prevention of infection with the ubiquitous gastric pathogen Helicobacter pylori, and drug therapy for the infection is complicated by poor patient compliance, the high cost of treatment, and ineffectiveness against drug resistant strains. Clearly a new medical advancement is required to reduce the incidence of peptic ulcer disease and stomach cancer, two conditions caused by infection with H. pylori. Pre-clinical studies have suggested that vaccination could not only prevent infection, but could also be used to resolve active infections. An effective vaccine may also protect against re-infection as well as be an impediment to transmission in at-risk populations. Antex Biologics is an industry leader in H. pylori vaccine development, and is committed to bringing an H. pylori vaccine to the market. The company has performed two Phase 1 clinical trials with a formalin-inactivated Helicobacter pylori Whole Cell (HWC) vaccine, which was given orally in combination with the adjuvant mLT(R192G), a mutant of E. coli heat-labile toxin. Pre-clinical results suggest that the use of an adjuvant with HWC is required for vaccine efficacy. In an effort to bring to market an optimally safe, stable, and potent vaccine, we propose in this application to evaluate clinically two new aspects of the vaccine formulation, namely 1) a lyophilized rather than liquid active ingredient (HWC), and 2) a novel double mutant form of LT (dmLT) that has reduced enterotoxic activity compared to the single mutant mLT(R192G), yet retains full adjuvant activity. The lyophilization process for HWC will be selected based upon in vitro testing of the product for characteristics such as moisture content and reconstitution behavior, and in vivo based upon animal immunization and challenge experiments. The final formulation selected will be used to advance understanding of the vaccine mechanism of action through the use of CD4, antibody, and IFN-gamma knockout mouse studies, and flow cytometric studies examining the nature of the gastric T cell infiltrate in vaccinated and challenged mice. cGMP lots of lyophilized HWC and dmLT will be produced and a Phase 1 dose escalation safety trial in uninfected and infected, asymptomatic subjects will be performed. Because dmLT has yet to be evaluated clinically, the maximum tolerable dose of dmLT alone will be determined first in both populations. Following dmLT dose selection, the maximum tolerable dose of lyophilized and reconstituted HWC in the context of a fixed dose of dmLT will then be determined, again in both populations. Diarrhea is the most likely adverse event that will define tolerance limits. A panel of immunological tests will be performed on subjects receiving the full vaccination series with HWC + dmLT, including serum and mucosal antibodies to HWC and dmLT, and PBMC proliferation and cytokine production in response to restimulation with H. pylori lysate. Diagnostic testing will also be performed on infected subjects post-vaccination to assess changes in their colonization state. This trial will position the vaccine for more highly powered Phase 1 or early Phase 2 trials, and thus will move H. pylori vaccination one step closer to being a reality.