Mary M. Bendig

Construction of reshaped human antibodies with HIV-neutralizing activity

Mouse monoclonal antibody (mAb) 0.5 beta binds to the envelope protein gp120 of human immunodeficiency virus (HIV) and neutralizes infection by HIV in vitro. Mouse mAb 0.5 beta, therefore, has potential as a therapeutic agent for the prevention and treatment of acquired immunodeficiency syndrome (AIDS). Since mouse mAbs are highly immunogenic in humans, efforts are being made to humanize mouse mAbs that are being considered for use in humans. This report describes the design, construction, and expression of reshaped human 0.5 beta antibodies. In these antibodies, the entire constant (C) regions were derived from human sequences. The variable (V) regions were derived from human framework regions (FRs) and mouse 0.5 beta complementarity determining regions (CDRs). One version of reshaped human 0.5 beta light (L) chain and six versions of reshaped human 0.5 beta heavy (H) chain were made and tested. Following transient expression in cos cells, all of the constructions were capable of producing humanlike antibody. Three of the H chain constructions (RHc, RHe, and RHf), when co-expressed with the L chain construction (RL), produced reshaped human antibody capable of binding to the epitope on gp120 recognized by mouse 0.5 beta mAb. The best version (RL + RHe) of reshaped human 0.5 beta antibody had both binding affinity and neutralizing activity that were within twofold that of the mouse or chimeric 0.5 beta antibody.

Humanization of a mouse anti-human interleukin-6 receptor antibody comparing two methods for selecting human framework regions

Mouse monoclonal antibody AUK12-20 binds to human IL-6 receptor and inhibits IL-6 functions. It has been humanized by CDR-grafting for therapeutic use. In the design of reshaped human AUK12-20 VL region, the human framework regions (FRs) from the human Bence-Jones protein REI were used. The reshaped human AUK12-20 light chain, in combination with chimeric AUK12-20 heavy chain, bound to antigen as well as chimeric AUK12-20 antibody. In the design of reshaped human AUK12-20 VH region, two sets of the human FRs were chosen and compared. One set was from the consensus amino acid sequence for human VH regions subgroup (HSG)-I and the other set was from human antibody HAX, the most similar human VH region found in a database of human immunoglobulin sequences. The HSG-I-based and the HAX-based reshaped human AUK12-20 heavy chains in combination with the reshaped human AUK12-20 light chain, showed approximately 90 and 100% antigen-binding and competition-binding activities as compared to the chimeric or mouse AUK12-20 heavy chains. Most importantly, these humanized antibodies inhibited the IL-6-dependent tumor cell growth as well as the original mouse antibody suggesting that these humanized antibodies could be efficacious in human patients. Our results show that both approaches for the design of reshaped human antibodies can be used for successful humanization. The approach based on FRs from the most similar individual human antibody, however, seemed to be best for designing a reshaped human antibody that mimicked as closely as possible the original mouse antibody.