| First Author | Muczynski V | Year | 2018 |
| Journal | Blood | Volume | 132 |
| Issue | 11 | Pages | 1193-1197 |
| PubMed ID | 30064978 | Mgi Jnum | J:265977 |
| Mgi Id | MGI:6201791 | Doi | 10.1182/blood-2018-01-829523 |
| Citation | Muczynski V, et al. (2018) A factor VIII-nanobody fusion protein forming an ultrastable complex with VWF: effect on clearance and antibody formation. Blood 132(11):1193-1197 |
| abstractText | Von Willebrand factor (VWF) modulates factor VIII (FVIII) clearance and the anti-FVIII immune response. Despite the high affinity that defines the FVIII/VWF interaction, association/dissociation kinetics dictates 2% to 5% FVIII being present as free protein. To avoid free FVIII when studying the FVIII-VWF complex in vivo, we designed a FVIII-nanobody fusion protein, with the nanobody part being directed against VWF. This fusion protein, designated FVIII-KB013bv, had a 25-fold higher affinity compared with B-domainless FVIII (BDD-FVIII) for VWF. In vitro analysis revealed full cofactor activity in 1-stage clotting and chromogenic assays (activity/antigen ratio 1.0 +/- 0.3 and 1.1 +/- 0.3, respectively). In vivo, FVIII-013bv displayed a twofold increased mean residence time compared with BDD-FVIII (3.0 hours vs 1.6 hours). In a tail clip-bleeding assay performed 24 hours after FVIII infusion, blood loss was significantly reduced in mice receiving FVIII-KB013bv vs BDD-FVIII (15 +/- 7 muL vs 194 +/- 146 muL; P = .0043). Unexpectedly, when examining anti-FVIII antibody formation in FVIII-deficient mice, the immune-response toward FVIII-KB013bv was significantly reduced compared with BDD-FVIII (1/8 vs 14/16 mice produced anti-FVIII antibodies after treatment with FVIII-KB013bv and BDD-FVIII, respectively). Our data show that a stabilized interaction between FVIII and VWF is associated with a prolonged survival of FVIII and a reduced immune response against FVIII. |
