A Factor VIII Variant With Elimination of the N-glycosylation Site at 2118 Reduced Anti-FVIII Immune Responses in Gene Therapy Treated Hemophilia A Mice
Highlights From the ASGCT 25th Annual Meeting

A Factor VIII Variant With Elimination of the N-glycosylation Site at 2118 Reduced Anti-FVIII Immune Responses in Gene Therapy Treated Hemophilia A Mice

Presented by: Carol H. Miao, MD, Seattle Children’s Research Institute, Seattle, Washington, United States

Carol H. Miao1,4, Meng-Ni Fan1, Shuaishuai Wang2, Junping Zhang3, Xiaohe Cai1, Ting-Yen Chao1, Lei Li2, Weidong Xiao3, Barbara A. Konkle4

1Seattle Children’s Research Institute, Seattle, WA
2Georgia State University, Atlanta, GA
3Indiana University, Indianapolis, IN
4University of Washington, Seattle, WA

Key Data Points

Inhibitor Development After Infusion of WT-BDD-FVIII and Mutated FVIII Variants

Hemophilia A mice were injected hydrodynamically with plasmids encoding mutated FVIII variants and WT BDD-FVIII, respectively. Second challenges were performed via hydrodynamic injection in all groups on Day 86. (A) From left to right, the wild-type (WT)-BDD-FVIII plasmids used for N to Q mutagenesis, the resulting FVIII variant constructs used for in vivo gene therapy, and relative FVIII antibody response. (B) FVIII-specific IgG levels were analyzed by ELISA following first and second plasmid challenges. Anti-FVIII immune responses were significantly reduced in mice treated with the plasmid carrying FVIII N2118Q variant.

CD4+T-cell Proliferation in Response to Overlapping Mannosylated Peptides

(A) Overlapping peptides surrounding the N2118 site, 15 amino acids in length, were synthesized with high mannose glycan Man6GlcNAc2 attachments. (B) CD4+ T-cell proliferation levels were measured in response to mannosylated peptides MP1 (left panel), MP2 (middle panel), and MP3 (right panel) and their non-glycosylated counterparts (NGP1, NGP2, and NGP3). The data are presented as means with standard deviation from three separate experiments (**P < 0.01, ***P < 0.001).

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