Translational insights into manufacturability and stability of broadly neutralizing antibodies for pediatric HIV prevention: lessons from plant-produced CAP256-VRC26.25

Abstract

Monoclonal antibodies hold significant promise for preventing HIV infection in infants and children. However, global access remains constrained by the high production costs and infrastructure requirements associated with complex mammalian cell manufacturing platforms. Alternative expression systems, including plant-based production, have been proposed as scalable and potentially lower-cost approaches for antibody manufacturing. Here, we evaluated the in vivo performance of plant-produced CAP256-VRC26.25, a potent V2-apex HIV-1 broadly neutralizing antibody originally isolated from an HIV-infected individual in South Africa. Purified, endotoxin-free plant-produced CAP256-VRC26.25 was administered to cynomolgus macaques alongside a mammalian cell-produced CAP256-VRC26.25 control antibody prior to mucosal SHIV challenge. While the mammalian-derived antibody conferred protection, the plant-produced antibody did not. Pharmacokinetic analysis revealed approximately two orders of magnitude lower circulating antibody levels and rapid clearance of the plant-produced antibody, despite preserved in vitro neutralization potency. Electrophoretic analysis indicated evidence of partial proteolytic nicking of the plant-produced antibody, suggesting that structural instability may have contributed to reduced in vivo durability. Previous studies have shown that manufacturability liabilities within the CAP256-VRC26 lineage can occur across multiple expression platforms, highlighting the importance of integrating antibody engineering with manufacturing platform development. These findings have informed ongoing work combining host genome engineering to reduce endogenous plant protease activity with targeted modification of predicted protease-sensitive sites within CAP256-VRC26.25. Overall, this study provides translational insights into the engineering challenges associated with scalable production of broadly neutralizing antibodies and highlights key considerations for developing accessible antibody-based interventions for pediatric HIV prevention.