A genetically modified Plasmodium falciparum sporozoite vaccine attenuated at the late-liver stage

摘要 2020年，疟疾导致2.41亿临床病例和62.7万人死亡，这是自 2012年。在非洲，死于疟疾的人数比死于新冠肺炎的人数还多。有一份紧急的未得到满足的医疗报告 需要一种可预防个人感染和疾病并可大规模部署的疟疾疫苗 消除疟疾的疫苗接种计划。RTS，S疟疾疫苗在试点实施中展示 计划在90万名非洲婴儿中显著减少疟疾住院人数21%，并 严重疟疾减少30%。2021年底，世卫组织建议对5个月大的婴儿进行免疫接种。 然而，它并没有显著降低脑型疟疾、严重疟疾贫血或总死亡率，也没有预防 恶性疟原虫(PF)感染。在开发中的疫苗中，只有Sanaria的PfSPZ疫苗 个人或地域预防肺炎衣原体感染应考虑抗肺炎衣原体感染的效果 重点开展消除疟疾运动。Sanaria的第一代疫苗PfSPZ疫苗由以下成分组成 辐射致弱的PF子孢子(SPZ)，在肝脏阶段早期停止。萨纳里亚的第二代 疫苗是PfSPZ-CVac(化学预防疫苗)。在PfSPZ-CVac中，寄生虫在肝脏中复制， 生物放大免疫原负荷高达50,000倍，然后被抗疟疾药物杀死。 PfSPZ-CVAc与氯喹(CQ)联合使用，对异种病毒有100%的疫苗效力(VE 接种后12周使用PfSPZ所需剂量的22%控制人类疟疾感染(CHMI) 使用PfSPZ疫苗在9-10周内对异种CHMI获得80%的VE。PfSPZ-CVAc(CQ)为 因此，剂量为1/5的PfSPZ疫苗比PfSPZ疫苗具有更好的保护作用。然而，疟疾的短暂症状可能 在第一剂PfSPZ后发生，如果CQ给药不当，寄生虫在血液中繁殖 可能会导致严重的疟疾。在我们的第一阶段拨款中，保留PfSPZ-CVac的增强效力并消除 它的缺点是，我们对PF进行了基因改造，以能够完全复制，但在进入血液之前被卡住了 删除第一个和第二个基因，生产PfSPZ-LARC2疫苗，并产生主细胞库 (MCB)。该疫苗目前正在按照cGMPs生产PfSPZ-LARC2疫苗 并将在2022年下半年的临床试验中进行安全性和有效性评估。在这项第二阶段拨款中，我们 建议1)生产2批这种迟发型、复制能力(LARC)疫苗(PfSPZ-LARC2)， 它是基于一种非洲PF寄生虫，用于扩大临床试验的评估，2)制造一种泰国 监管机构指导的疫苗评估用含亚洲变异抗原的PF株(NHP4026)， 3)生产基于NHP4026的PfSPZ-LARC2疫苗，可与非洲LARC2结合作为 如果需要，泛全球疫苗。该项目旨在生产一种有效、成本效益高的PfSPZ疫苗 在全球范围内防止高度变异的PF寄生虫。

ABSTRACT In 2020 malaria caused 241M clinical cases and 627,000 deaths, the greatest numbers of annual deaths since 2012. There were more deaths in Africa from malaria than from COVID-19. There is an urgent unmet medical need for a malaria vaccine that prevents infection and disease in individuals and can be deployed in mass vaccination programs for malaria elimination. The RTS,S malaria vaccine was shown in a pilot implementation program in >900,000 African infants to significantly reduced hospital admissions for malaria by 21% and severe malaria by 30%. In late 2021 it was recommended by WHO for immunization of 5-month-olds. However, it did not significantly reduce cerebral malaria, severe malaria anemia, or overall mortality, or prevent Plasmodium falciparum (Pf) infection. Of vaccines under development, only Sanaria’s PfSPZ vaccines have the efficacy against Pf infection to be considered for prevention of Pf infection in individuals or geographically focused Pf malaria elimination campaigns. Sanaria’s 1st generation vaccine, PfSPZ Vaccine, is composed of radiation-attenuated Pf sporozoites (SPZ), which arrest early in the liver stage. Sanaria’s 2nd generation vaccine is PfSPZ-CVac (Chemoprophylaxis Vaccine). In PfSPZ-CVac, the parasites replicate in the liver, biologically amplifying the immunogen load by up to 50,000-fold and then are killed by an anti-malarial drug. PfSPZ-CVac co-administered with chloroquine (CQ), gave 100% vaccine efficacy (VE) against heterologous controlled human malaria infection (CHMI) 12 weeks after vaccination using 22% the dose of PfSPZ needed to achieve 80% VE at 9-10 weeks against heterologous CHMI with PfSPZ Vaccine. PfSPZ-CVac (CQ) is therefore more protective than PfSPZ Vaccine at ~1/5 the dose. However, transient symptoms of malaria can occur after 1st dose of PfSPZ, and if CQ is not administered appropriately, parasite multiplication in the blood could cause severe malaria. In our Phase I grant, to retain the enhanced potency of PfSPZ-CVac and eliminate its drawbacks, we genetically altered Pf to be able to fully replicate, but arrest prior to entering the blood by deleting first one and then a 2nd gene to produce PfSPZ-LARC2 Vaccine and produced a master cell bank (MCB). This vaccine is now being manufactured in compliance with cGMPs to produce PfSPZ-LARC2 Vaccine and will be assessed for safety and efficacy in a clinical trial in the 2nd half of 2022. In this Phase II grant, we propose to 1) manufacture 2 lots of this late arresting, replication competent (LARC) vaccine (PfSPZ-LARC2), which is based on an African Pf parasite, for assessment in expanded clinical trials, 2) manufacture a Thai strain of Pf (NHP4026) containing Asian variant antigens for regulatory agency directed vaccine assessment, and 3) produce a PfSPZ-LARC2 vaccine based on NHP4026 that can be combined with African LARC2 as a pan-global vaccine if needed. The project is intended to produce a potent, cost effective PfSPZ vaccine that protects against highly variant Pf parasites worldwide.