An in vivo method for diversifying the functions of therapeutic antibodies

• Published in: Proceedings of the National Academy of Sciences - PNAS 2021-03, Vol.118 (10), p.1-11
• Main Authors: Tian, Ming, Cheng, Hwei-Ling, Kimble, Michael T., McGovern, Kelly, Waddicor, Peyton, Chen, Yiwei, Cantor, Elizabeth, Qiu, Mengting, Tuchel, Marie-Elen, Dao, Mai, Alt, Frederick W.
• Format: Article
• Language: English
• Subjects: Affinity; Animal models; Antibodies; Antigens; Antitumor activity; Autoimmune diseases; B-cell receptor; Binding; Biological Sciences; Chains; Heavy chains; Immunization; Immunoglobulins; In vivo methods and tests; Ligands; Lymphocytes; Lymphocytes B; Lymphocytes T; Maturation; Mutation; PD-1 protein; Somatic hypermutation; V(D)J recombination; Variable region
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2025596118

V(D)J recombination generates mature B cells that express huge repertoires of primary antibodies as diverse immunoglobulin (Ig) heavy chain (IgH) and light chain (IgL) of their B cell antigen receptors (BCRs). Cognate antigen binding to BCR variable region domains activates B cells into the germinal center (GC) reaction in which somatic hypermutation (SHM) modifies primary variable region-encoding sequences, with subsequent selection for mutations that improve antigen-binding affinity, ultimately leading to antibody affinity maturation. Based on these principles, we developed a humanized mouse model approach to diversify an anti-PD1 therapeutic antibody and allow isolation of variants with novel properties. In this approach, component Ig gene segments of the anti-PD1 antibody underwent de novo V(D)J recombination to diversify the anti-PD1 antibody in the primary antibody repertoire in the mouse models. Immunization of these mouse models further modified the anti-PD1 antibodies through SHM. Known anti-PD1 antibodies block interaction of PD1 with its ligands to alleviate PD1-mediated T cell suppression, thereby boosting antitumor T cell responses. By diversifying one such anti-PD1 antibody, we derived many anti-PD1 antibodies, including anti-PD1 antibodies with the opposite activity of enhancing PD1/ligand interaction. Such antibodies theoretically might suppress deleterious T cell activities in autoimmune diseases. The approach we describe should be generally applicable for diversifying other therapeutic antibodies.