A human IgGI antibody has been reshaped for serotherapy in humans by introducing the six hypervariable regions from the heavy- and light-chain variable domains of a rat antibody directed against human lymphocytes. The reshaped human antibody is as effective as the rat antibody in complement and is more effective in cell-mediated lysis of human lymphocytes.

Reshaping human antibodies for therapy.

The invention relates to transgenic non-human animals capable of producing heterologous antibodies and methods for producing human sequence antibodies which bind to human antigens with substantial affinity.

Transgenic non-human animals capable of producing heterologous antibodies

The murine monoclonal antibody mumAb4D5, directed against human epidermal growth factor receptor 2 (p185HER2), specifically inhibits proliferation of human tumor cells overexpressing p185HER2. However, the efficacy of mumAb4D5 in human cancer therapy is likely to be limited by a human anti-mouse antibody response and lack of effector functions. A "humanized" antibody, humAb4D5-1, containing only the antigen binding loops from mumAb4D5 and human variable region framework residues plus IgG1 constant domains was constructed. Light- and heavy-chain variable regions were simultaneously humanized in one step by "gene conversion mutagenesis" using 311-mer and 361-mer preassembled oligonucleotides, respectively. The humAb4D5-1 variant does not block the proliferation of human breast carcinoma SK-BR-3 cells, which overexpress p185HER2, despite tight antigen binding (Kd = 25 nM). One of seven additional humanized variants designed by molecular modeling (humAb4D5-8) binds the p185HER2 antigen 250-fold and 3-fold more tightly than humAb4D5-1 and mumAb4D5, respectively. In addition, humAb4D5-8 has potency comparable to the murine antibody in blocking SK-BR-3 cell proliferation. Furthermore, humAb4D5-8 is much more efficient in supporting antibody-dependent cellular cytotoxicity against SK-BR-3 cells than mumAb4D5, but it does not efficiently kill WI-38 cells, which express p185HER2 at lower levels.

https://www.pnas.org/content/pnas/89/10/4285.full.pdf

Humanization of an anti-p185HER2 antibody for human cancer therapy.

Depletion of B cells in vivo by a chimeric mouse human monoclonal antibody to CD20

Nonmyeloablative Stem Cell Transplantation and Cell Therapy as an Alternative to Conventional Bone Marrow Transplantation With Lethal Cytoreduction for the Treatment of Malignant and Nonmalignant Hematologic Diseases

Remission induction in non-hodgkin lymphoma with reshaped human monoclonal antibody campath-1h

Elimination of graft-versus-host disease by in-vitro depletion of alloreactive lymphocytes with a monoclonal rat anti-human lymphocyte antibody (campath-1)

Humanised monoclonal antibody therapy for rheumatoid arthritis.

Humanized antibodies are likely to have a major role in therapy and it is important to define their interaction with physiological effectors. By comparing a matched series of chimeric human mAbs we found that igG1 was most efficient in complement lysis, although IgG3 bound more C1q. To resolve this paradox we compared the ability of human IgG1, IgG2, IgG3, IgG4, and IgE and rat IgG2b to cause C1q binding, C1 binding and activation, C4 activation, C4b binding, and C3b binding. Rat IgG2b was included because this isotype has already successfully been used for therapy. Human IgG1 was less efficient than IgG3 and fixing C1q and C1 on the cell surface, but the number of C4 molecules bound per C1 was 10-fold greater for IgG1 than for IgG3. This difference, amplified through later stages of the complement cascade, can account for the superiority of IgG1 for cell lysis. The efficiency of IgG1 in fixing C4 was not due to a favored binding site on the antibody molecule, since virtually all of the bound C4b was attached to the cells. Rather, it appeared that the activation of C4 by C1s was greatly favored by IgG1 compared with IgG3. It should be possible to combine the optimal properties of IgG1 and IgG3 antibodies to produce an improved therapeutic reagent.

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G. Hale

Papers

Remission induction in non-hodgkin lymphoma with reshaped human monoclonal antibody campath-1h

Elimination of graft-versus-host disease by in-vitro depletion of alloreactive lymphocytes with a monoclonal rat anti-human lymphocyte antibody (campath-1)

Humanised monoclonal antibody therapy for rheumatoid arthritis.

Human monoclonal IgG isotypes differ in complement activating function at the level of C4 as well as C1q.

Long-term remission of intractable systemic vasculitis with monoclonal antibody therapy.