A fully human antibody neutralising biologically active human TGF beta 2 for use in therapy

Phage display provides a methodology for obtaining fully human antibodies d irected against human transforming growth factor-beta (TGF beta) suitable f or the treatment of fibrotic disorders. The strategy employed was to isolat e a human single chain Fv (scFv) fragment that neutralises human TGF beta 2 from a phage display repertoire, convert it into a human IgG4 and then det ermine its TGF beta binding and neutralisation properties and its physical characteristics. Several scFv fragments binding to TGF beta 2 were isolated by panning of an antibody phage display repertoire, and subsequent chain s huffling of the selected VH domains with a library of V-L domains. The thre e most potent neutralising antibodies were chosen for conversion to IgG4 fo rmat. The IgG4 antibodies were ranked for their ability to neutralise TGF b eta 2, and the most potent, 6B1 IgG4, was chosen for further characterisati on. 6B1 IgG4 has a high affinity for TGF beta 2 with a dissociation constan t of 0.89 nM as determined using the BIAcore biosensor and only 9% cross-re activity with TGF beta 3 (dissociation constant, 10 nM). There was no detec table binding to TGF beta 1. 6B1 IgG4 strongly neutralises (IC50 = 2 nM) th e anti-proliferative effect of TGF beta 2 in bioassays using TF1 human eryt hroleukaemia cells. Similarly, there was strong inhibition of binding of TG F beta 2 to cell surface receptors in a radioreceptor assay using A549 cell s. 6B1 IgG4 shows no detectable cross-reactivity with related or unrelated antigens by immunocytochemistry or ELISA. The 6B1 V-L domain has entirely g ermline framework regions and the V-H domain has only three non-germline fr amework amino acids. This, together with its fully human nature: should min imise any potential immunogenicity of 6B1 IgG4 when used in therapy of fibr otic diseases mediated by TGF beta 2. (C) 1999 Elsevier Science B.V. All ri ghts reserved.