Plant-derived HIV neutralizing mAbs for passive immunotherapy in newborn macaques

 描述(由申请人提供)：针对HIV-1的高度有效的广谱中和抗体(BNAbs)的鉴定，以及在被动注射后成功预防SHIV感染，增加了采用免疫治疗策略预防和治疗HIV-1感染的可能性。然而，尽管广泛而有效的中和活性是必不可少的先决条件，但体内特性，如良好的循环稳定性和无免疫原性，对于开发人类治疗方法同样至关重要。在先前的第一阶段和第二阶段的研究中，已经通过农杆菌介导的瞬时转染法获得了第一代bNAbs和最近有效的高度突变的bNAbs 10-1074、NIH45-46G54W、10E8、PGT121、PGT128、PGT145、PGT135、PG9、PG16、VRC01和B12的糖型，并对猕猴的中和活性和给药后的效果进行了评估。到目前为止的研究结果表明：(I)VL结构域中的N-糖链损害了植物来源bNAbs的血浆稳定性；(Ii)虽然PGT121和B12在猕猴多次注射后没有显示出免疫原性，但令人惊讶的是，VRC01、10-1074和NIH45-46G54W在第二次注射后可诱导高滴度的抗独特型抗体，从而特异性地结合所给药的bNab或近家族成员，并在中和实验中抑制bNab；(Iii)两种鸡尾酒(VRC01、10-1074、B12和10E8)以及单独的PGT121在攻击前后静脉或皮下注射都能保护成年猕猴。这些结果构成了当前IIB阶段提案开发有效bNab鸡尾酒的双重方法的基础，方法是：(I)在猕猴中进行围产期保护研究，以对抗更接近于母婴传播(MTCT)的挑战；(Ii)延长它们的循环保留时间；(Iii)识别这些高度突变的bNAb上的T细胞表位，这些表位有助于它们的免疫原性，并可能损害它们在预防和治疗HIV-1方面的价值。此外，本研究中15种广泛中和植物来源的艾滋病毒单抗的快速生产突出了过渡植物系统在速度和通用性、无病原体性质和低技术要求方面的独特优势；特别是在从“克隆到临床前保护研究”的早期发展阶段。

 DESCRIPTION (provided by applicant): The identification of highly potent broadly neutralizing antibodies (bnAbs) against HIV-1, and success in preventing SHIV infection following their passive administration, have increased the likelihood that immunotherapeutic strategies can be adopted to prevent and treat HIV-1 infection. However, while broad and potent neutralizing activity is an essential prerequisite, in vivo properties such as good circulatory stability and no-immunogenicity are equally critical for developing a human treatment. In the previous Phase I and Phase II studies, glycoforms of both first generation bnAbs and more recent potent highly mutated bnAbs 10-1074, NIH45-46G54W, 10E8, PGT121, PGT128, PGT145, PGT135, PG9, PG16, VRC01 and b12 have been produced by Agrobacterium-mediated transient transfection of Nicotiana benthamiana and assessed neutralizing activity and following admin- istration in macaques. The results to date indicate that (i) N-glycans within the VL domain impair plasma stability of plant-derived bnAbs and (ii) while PGT121 and b12 exhibit no immunogenicity in macaques after multiple injections, surprisingly VRC01, 10-1074 and NIH45-46G54W elicit high titer anti-idiotypic antibodies following a second injection which specifically bind the administered bnAb or a close family member, and inhibit the bnAb in neutralization assays (iii) both cocktails (VRC01, 10-1074, b12 and 10E8) as well as single PGT121 delivered either intravenously or subcutaneously both pre-and post-challenge administration can protect adult macaques. These results form the basis of the current Phase IIB proposal's dual approach to develop an efficacious bnAb cocktail by (i) performing perinatal protection studies in macaques against SHIV challenge which more closely mimic mother-to-child-transmission (MTCT) (ii) to extend their circulatory retention time and (iii) to identify the T cell epitopes on these highly mutated bnAbs which contribute to their immunogenicity and which could potentially compromising their value for prophylaxis and therapy of HIV-1. In addition, the rapid production of 15 broadly neutralizing plant-derived HIV mAbs in the current study highlights the unique advantages of the transient plant system in terms of speed and versatility, pathogen- free nature and low-tech requirements; particularly in the early developmental stages from "cloning to preclinical protection studies".