At NovImmune, they are investigating possible extension of their portfolio of therapeutic antibodies by the introduction of a newly developed kappa-lambda body (κλ-body™). This fully human bispecific antibody format has typical functional and biochemical characteristics of a human IgG. The κλ-body features a common heavy chain but two different light chains (one κ and one λ), giving a different target specificity to each antibody arm.
The benefits of using a fully human format, without mutations or linkers, are numerous. They include PK profiles and Fc effector functions of therapeutic antibodies, robust productivity and stability during manufacturing and storage, and low risk of provoking immunogenicity.
The upstream processing group, headed by L. Di Grazia, further developed the novel tri-cistronic vector system for expression of the κλ-bodies in CHO cells, originally designed by the internal research group. CHO cell lines for two different κλ-body products were established, and the cell lines were observed to be genetically stable and maintain constant high-level productivity. The κλ-bodies were tested and shown to maintain biological function.
“Over the course of our work, we’ve grown these cells for over 50 generations without loss in productivity or κλ-body assembly efficiency,” said Di Grazia.
In order to manufacture batches for preclinical studies, the process has been successfully scaled up to the 100 L level using stirred bioreactors. The aim of the early cell-line screening approach is to minimize the impact of cell-line variability on downstream processing, notably with respect to the impact of varying concentrations of product-related impurities.
“To date we readily achieve multigram/liter titers for different κλ-body products using the platform USP,” noted Di Grazia. “These yields are equivalent to those achieved for our monospecific antibody controls, suggesting that κλ-body assembly is as efficient as that of therapeutic monoclonal antibodies.
“We routinely use a binding assay to verify that the purified products maintain the appropriate binding specificity as well as their ability to co-engage the two targets. This is a critical quality control assay for us. Our κλ-body products have also demonstrated favorable drug characteristics in vivo with PK properties equivalent to monospecific monoclonal antibodies.”
The κλ-body products developed to date by NovImmune have been shown to be readily amenable to a scalable platform manufacturing process. Di Grazia noted that the final product has the benefits of a monoclonal antibody plus the added functionality of multiple specificities: it is stable, has the expected half-life in circulation, a low potential for immunogenicity, and contains essential effector functions necessary for cutting-edge biotherapeutics.