Data from: Advances in neglected tropical disease vaccines: developing relative potency and functional assays for the Na-GST-1/Alhydrogel hookworm vaccine

A new generation of vaccines for the neglected tropical diseases (NTDs) have now advanced into clinical development, with the Na-GST-1/Alhydrogel Hookworm Vaccine already being tested in Phase 1 studies in healthy adults. The current manuscript focuses on the often overlooked critical aspects of NTD vaccine product development, more specifically, vaccine stability testing programs. A key measure of vaccine stability testing is "relative potency" or the immunogenicity of the vaccine during storage. As with most NTD vaccines, the Na-GST-1/Alhydrogel Hookworm Vaccine was not developed by attenuation or inactivation of the pathogen (Necator americanus), so conventional methods for measuring relative potency are not relevant for this investigational product. Herein, we describe a novel relative potency testing program and report for the first time on the clinical lot of this NTD vaccine during its first 60 months of storage at 2–8°C. We also describe the development of a complementary functional assay that measures the ability of IgG from animals or humans immunized with Na-GST-1/Alhydrogel to neutralize this important hookworm enzyme. While 90% inhibition of the catalytic activity of Na-GST-1 was achieved in animals immunized with Na-GST-1/Alhydrogel, lower levels of inhibition were observed in immunized humans. Moreover, anti-Na-GST-1 antibodies from volunteers in non-hookworm endemic areas were better able to inhibit catalytic activity than anti-Na-GST-1 antibodies from volunteers resident in hookworm endemic areas. The results described herein provide the critical tools for the product development of NTD vaccines.针对被忽视热带病（Neglected Tropical Diseases, NTDs）的新一代疫苗现已进入临床开发阶段，其中Na-GST-1/Alhydrogel钩虫疫苗已在健康成人中开展I期临床试验。本手稿聚焦于被忽视热带病疫苗产品开发中常被忽视的关键环节，更具体地说，是疫苗稳定性测试方案。疫苗稳定性测试的一项核心指标为"相对效价"，即疫苗在储存过程中的免疫原性。与多数被忽视热带病疫苗一样，Na-GST-1/Alhydrogel钩虫疫苗并非通过病原体（美洲钩虫*Necator americanus*）的减毒或灭活工艺开发而成，因此常规的相对效价检测方法并不适用于这款在研产品。本文描述了一种新型相对效价检测方案，并首次报告了这款被忽视热带病疫苗在2–8℃条件下储存首60个月的临床批次数据。此外，本文还介绍了一种配套功能学检测方法的开发过程，该方法可检测经Na-GST-1/Alhydrogel免疫的动物或人类体内IgG中和该重要钩虫酶的能力。经Na-GST-1/Alhydrogel免疫的动物可实现Na-GST-1催化活性90%的抑制率，但在免疫人群中仅观察到较低水平的抑制效果。此外，来自非钩虫流行区志愿者的抗Na-GST-1抗体，其催化活性抑制能力优于来自钩虫流行区常驻志愿者的抗Na-GST-1抗体。本文所述研究结果为被忽视热带病疫苗的产品开发提供了关键工具支撑。