Attenuation of Liquid Formulation for PfSPZ Vaccine by X-Ray

项目总结： 由国际PfSPZ联盟支持的PfSPZ疫苗在临床开发中有望成为 美国FDA批准的首个针对疟疾或任何人类寄生虫病的疫苗。疫苗是安全的， 对同源(同一菌株)和异源(不同菌株)具有良好的耐受性和保护性 恶性疟原虫在11个国家进行了19项临床试验。到目前为止，疫苗有效率(VE)为80%-100% 已经被证明可以对抗受控的人类疟疾感染(CHMI)，VE已经被证明是在 对异种病毒至少8个月，对CHMI至少14个月，对持续VE至少18个月 用三剂疗法在布基纳法索对抗异质性肺炎毒株的强烈传播。在中国进行试验 马里、赤道几内亚和德国已经建立了优化的方案，为第三阶段临床做准备 试验将于2021年第一季度开始，这将支持2022年向FDA提出的生物制品许可证申请。PfSPZ 疫苗是由辐射减毒、无菌、纯化、冷冻保存的肺炎子孢子(SPZ)组成。这个 PfSPZ在蚊子中产生，并在蚊子体内通过60Co源的照射而减弱。 唾液腺。我们的目标是将提取的、纯化的、PfSPZ在一种名为 疫苗原料药(VBP)，并将PfSPZ的衰减过程从辐射转换为X辐射。 将引入实时电离室剂量测量，以监测剂量给药并确保 衰减。衰减过程的这三个主要变化将提高制造效率 并通过以下方式降低疫苗成本：1)允许较少的PfSPZ数量较多的照射事件 体积更小，2)将辐照过程带入洁净室设施中；3)消除昂贵的60Co- 相关费用、培训和安全考虑，以及4)为大规模疫苗提供更具可扩展性的流程 制作。它还将建立一种适合于减弱体外产生的PfSPZ的方法，该方法计划 在未来4年内取代蚊子生产的PfSPZ。X射线照射是1967年用于证明 原理研究表明，减毒的啮齿动物疟疾SPZ可以保护小鼠免受疟疾的侵害。 后来的研究采用辐射进行衰减，因为这种方法在当时更准确 而且可复制。然而，X射线技术已经有了极大的进步，X射线衰减的好处使 该方法明显优于照射。随着Sanaria进一步扩大GMP制造规模，计划建立 在非洲和亚洲的制造工厂，目标是将体外生产的PfSPZ整合到PfSPZ疫苗中， 以液体悬浮液中的PfSPZ作为VBP进行辐照是最佳的。从本质上讲，X射线辐射远远不止 效率高，易于放大，比60Co辐射更具成本效益。三个具体目标概述了这项工作 进行：1)确定辐照疫苗原料液悬浮液的参数；2)确定 完全衰减PfSPZ所需的最小X射线剂量；3)发展电离的使用 用于实时监测辐射剂量的室剂量计。

PROJECT SUMMARY: PfSPZ Vaccine, supported in clinical development by the International PfSPZ Consortium, is on track to be the first US FDA-licensed vaccine against malaria or any human parasitic disease. The vaccine has been safe, well tolerated, and protective against homologous (same strain) and heterologous (different strains) of Plasmodium falciparum (Pf) malaria in 19 clinical trials in 11 countries. To date, 80–100% vaccine efficacy (VE) has been shown against controlled human malaria infection (CHMI), VE that has been demonstrated for at least 8 months against heterologous and 14 months against CHMI, and at least 18 months sustained VE against intense transmission of heterogeneous strains of Pf in Burkina Faso with a 3-dose regimen. Trials in Mali, Equatorial Guinea, and Germany have established optimized regimens in preparation for Phase 3 clinical trials starting in Q1 2021, which will support a Biologics License Application to the FDA in 2022. PfSPZ Vaccine is composed of radiation-attenuated, aseptic, purified, cryopreserved Pf sporozoites (SPZ). The PfSPZ are produced in mosquitoes, and attenuated by -irradiation from a 60Co source while in the mosquitoes’ salivary glands. Our goals are to convert to irradiation of extracted, purified, PfSPZ in a suspension termed vaccine bulk product (VBP) and to convert the PfSPZ attenuation process from -irradiation to X-irradiation. Real-time ionization chamber dosimetry will be introduced to monitor dose administration and to ensure attenuation. These three major changes to the process of attenuation will increase efficiency of manufacturing and decrease the vaccine cost by: 1) allowing for fewer irradiation events of higher numbers of PfSPZ in smaller volumes, 2) bringing the irradiation process inside the clean room facility; 3) eliminating costly 60Co- related expenses, training, and security concerns, and 4) provide a more scalable process for mass vaccine production. It will also establish a method suitable for attenuating in vitro-generated PfSPZ that are planned to replace mosquito-produced PfSPZ in the next 4 years. X-irradiation was the method used in the 1967 proof of principle studies demonstrating that attenuated rodent malaria SPZ could protect mice against malaria. Subsequent studies adopted -irradiation for attenuation because this method was, at the time more accurate and replicable. However, X-ray technology has vastly improved, and the benefits of X-ray attenuation make this approach much superior to -irradiation. As Sanaria further scales up GMP manufacturing, plans to build manufacturing plants in Africa and Asia, and aims to integrate in vitro-produced PfSPZ into PfSPZ Vaccine, irradiation will optimally occur with the PfSPZ in liquid suspension as VBP. Inherently, X-irradiation is far more efficient, amenable to scale up and cost effective than 60Co-irradiation. Three Specific Aims outline the work to be performed: 1) Define the parameters to irradiate Vaccine Bulk Product liquid suspensions; 2) Determine the minimal dose of X-irradiation required to completely attenuate PfSPZ; 3) Develop the use of ionization chamber dosimetry for real-time monitoring of irradiation dose.