biostudies-literatureAaen KHMinistry of Health and Care Services | Helse Sør-Øst RHF (Southern and Eastern Norway Regional Health Authority)Norges Forskningsråd (Research Council of Norway)Kreftforeningen (Norwegian Cancer Society)8433https://www.ebi.ac.uk/biostudies/studies/S-EPMC12480940biostudies-literatureUnknown16(1)The efficacy of hemophilia B (HB) replacement therapy is evaluated by coagulation factor IX (FIX) activity in plasma, although FIX bound to extravascular type IV collagen (Col4) also contributes to efficient hemostasis. Here, we investigated the impact of engineering FIX for improved (K5R) or reduced (K5A) Col4 binding on the pharmacokinetic properties of FIX Padua, fused to human serum albumin (HSA_QMP) engineered for favorable neonatal Fc receptor (FcRn) engagement. Hyperactive features and extended plasma half-life in human FcRn expressing mice, attributed to FIX Padua and HSA_QMP engineering, respectively, was confirmed. In HB mice, Padua_KA-HSA_QMP exhibited negligible extravascular distribution and the highest plasma levels at early time points followed by the steepest decay. Conversely, Padua_KR-HSA_QMP showed increased extravascular distribution and a 3-fold longer functional half-life (80 hours). These findings support the use of Padua_KA-HSA_QMP and Padua_KR-HSA_QMP as hyperactive short- or long-term therapeutics, respectively, with opportunities for tailored HB replacement therapy.Nature communicationsTailored collagen binding of albumin-fused hyperactive coagulation factor IX dictates in vivo distribution and functional properties.PMC124809403327272024046287927; 332727274993; 332727223315Valacchi GNyquist-Andersen MAndersen JTBernardi FAaen KHCanepari CNilsen JTesta MFPinotti MCantore ABenjakul SBranchini ASandlie IHerigstad MLTarantino RBenedusi MfalseTailored collagen binding of albumin-fused hyperactive coagulation factor IX dictates in vivo distribution and functional properties.The efficacy of hemophilia B (HB) replacement therapy is evaluated by coagulation factor IX (FIX) activity in plasma, although FIX bound to extravascular type IV collagen (Col4) also contributes to efficient hemostasis. Here, we investigated the impact of engineering FIX for improved (K5R) or reduced (K5A) Col4 binding on the pharmacokinetic properties of FIX Padua, fused to human serum albumin (HSA_QMP) engineered for favorable neonatal Fc receptor (FcRn) engagement. Hyperactive features and extended plasma half-life in human FcRn expressing mice, attributed to FIX Padua and HSA_QMP engineering, respectively, was confirmed. In HB mice, Padua_KA-HSA_QMP exhibited negligible extravascular distribution and the highest plasma levels at early time points followed by the steepest decay. Conversely, Padua_KR-HSA_QMP showed increased extravascular distribution and a 3-fold longer functional half-life (80 hours). These findings support the use of Padua_KA-HSA_QMP and Padua_KR-HSA_QMP as hyperactive short- or long-term therapeutics, respectively, with opportunities for tailored HB replacement therapy.2025-01-01T00:00:00Z2025 Sep2026-07-02T03:18:55.975Z2026-07-02T03:12:11.249ZS-EPMC124809404102269910.1038/s41467-025-62955-9