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Characterisation of a Novel Anti-CD52 Antibody with Improved Efficacy and Reduced Immunogenicity.

ABSTRACT: Anti-CD52 therapy has been shown to be effective in the treatment of a number of B cell malignancies, hematopoietic disorders and autoimmune diseases (including rheumatoid arthritis and multiple sclerosis); however the current standard of treatment, the humanized monoclonal antibody alemtuzumab, is associated with the development of anti-drug antibodies in a high proportion of patients. In order to address this problem, we have identified a novel murine anti-CD52 antibody which has been humanized using a process that avoids the inclusion within the variable domains of non-human germline MHC class II binding peptides and known CD4+ T cell epitopes, thus reducing its potential for immunogenicity in the clinic. The resultant humanized antibody, ANT1034, was shown to have superior binding to CD52 expressing cells than alemtuzumab and was more effective at directing both antibody dependent and complement dependent cell cytotoxicity. Furthermore, when in the presence of a cross-linking antibody, ANT1034 was more effective at directly inducing apoptosis than alemtuzumab. ANT1034 also showed superior activity in a SCID mouse/human CD52 tumour xenograft model where a single 1 mg/Kg dose of ANT1034 led to increased mouse survival compared to a 10 mg/Kg dose of alemtuzumab. Finally, ANT1034 was compared to alemtuzumab in in vitro T cell assays in order to evaluate its potential to stimulate proliferation of T cells in peripheral blood mononuclear cells derived from a panel of human donors: whereas alemtuzumab stimulated proliferation in a high proportion of the donor cohort, ANT1034 did not stimulate proliferation in any of the donors. Therefore we have developed a candidate therapeutic humanized antibody, ANT1034, that may have the potential to be more efficacious and less immunogenic than the current standard anti-CD52 therapy.

SUBMITTER: Holgate RG

PROVIDER: S-EPMC4570798 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Characterisation of a Novel Anti-CD52 Antibody with Improved Efficacy and Reduced Immunogenicity.

Holgate Robert G E RG Weldon Richard R Jones Timothy D TD Baker Matthew P MP

PloS one 20150915 9

Anti-CD52 therapy has been shown to be effective in the treatment of a number of B cell malignancies, hematopoietic disorders and autoimmune diseases (including rheumatoid arthritis and multiple sclerosis); however the current standard of treatment, the humanized monoclonal antibody alemtuzumab, is associated with the development of anti-drug antibodies in a high proportion of patients. In order to address this problem, we have identified a novel murine anti-CD52 antibody which has been humanize ...[more]

PMID: 26372145

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Project description:The CD52 antigen is a lymphocyte glycoprotein with an extremely short polypeptide backbone and a single N-linked glycan, and it is attached to the cell membrane by a glycosylphosphatidylinositol (GPI) anchor. Treatment of rheumatoid arthritis patients with CAMPATH-1H, a humanized monoclonal antibody against CD52, resulted, in a small number of cases, in the appearance and persistence of CD52-negative T cells. Similarly, CD52-negative B cells emerged following in vitro treatment of a CD52-positive human B cell line with CAMPATH-1H. Both the B and T CD52-negative cells were also found to be defective in surface expression of other GPI-anchored proteins. Biochemical analysis revealed a severe defect in the synthesis of a mature GPI precursor in both the B and T cell lines. Therefore the phenotype of these CD52-negative B and T cells closely resembles that of lymphocytes from patients with paroxysmal nocturnal haemoglobinuria (PNH), in which the first step of the GPI-biosynthetic pathway, i.e. synthesis of GlcNAc-phosphatidylinositol, is blocked. In all cases studied to date, this defect maps to a mutation of the phosphatidylinositolglycan class A (PIG-A) structural gene. We therefore amplified the PIG-A gene from both the GPI-negative B and T cells by PCR and determined the nucleotide sequence. No differences from the wild-type sequence were detected; therefore a classical PNH mutation cannot be responsible for the GPI-biosynthesis defect in these cell lines. Significantly, the GPI-negative phenotype of the B cells was reversible upon separation of the positive and negative cells, resulting in a redistribution to a mixed population with either CD52-positive or -negative cells, whereas populations of 100% CD52-negative T cells were stably maintained during culture. Therefore, whereas the GPI-biosynthesis deficiency in the T cell lines may be due to a mutation in another gene required by the GPI-biosynthetic pathway, the reversible nature of this block in the B cell lines suggests a less direct cause, possibly an alteration in a regulatory factor. Overall, these data demonstrate that the PNH phenotype can be generated without a mutation in the PIG-A structural gene, and thereby identify a novel mechanism for the development of GPI deficiency.

Dataset Information

Characterisation of a Novel Anti-CD52 Antibody with Improved Efficacy and Reduced Immunogenicity.

Publications

Characterisation of a Novel Anti-CD52 Antibody with Improved Efficacy and Reduced Immunogenicity.

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