Quantitative Hla-Class-Ii/Factor Viii (Fviii) Peptidomic Variation In Dendritic Cells Correlates With The Immunogenic Potential Of Therapeutic Fviii Proteins In Hemophilia A

Background Plasma-derived (pd) or recombinant (r) therapeutic factor VIII proteins (FVIIIs) are infused to arrest/prevent bleeding in patients with hemophilia A (PWHA). However, FVIIIs are neutralized if anti-FVIII-antibodies (inhibitors) develop. Accumulating evidence suggests that pdFVIIIs with von Willebrand factor (VWF) are less immunogenic than rFVIIIs and that distinct rFVIIIs are differentially immunogenic. Since inhibitor development is T-helper-cell-dependent, human leukocyte antigen (HLA)-class-II (HLAcII) molecules constitute an important early determinant. Objectives Use dendritic cell (DC)-protein processing/presentation assays with mass-spectrometric and peptide-proteomic analyses to quantify the DP-bound, DQ-bound, and DR-bound FVIII-derived peptides in individual HLAcII repertoires and compare the immunogenic potential of six distinct FVIIIs based on their measured peptide counts. Patients/Methods Monocyte-derived DCs from normal donors and/or PWHA were cultured with either: Mix-rFVIII, a VWF-free equimolar mixture of a full-length (FL)-rFVIII [Advate (R) (Takeda)] and four distinct B-domain-deleted (BDD)-rFVIIIs [Xyntha (R) (Pfizer), NovoEight (R) (Novo-Nordisk), Nuwiq (R) (Octapharma), and Afstyla (R) (CSL Behring GmBH)]; a pdFVIII + pdVWF [Beriate (R) (CSL Behring GmBH)]; Advate +/- pdVWF; Afstyla +/- pdVWF; and Xyntha + pdVWF. Results We showed that (i) Beriate had a significantly lower immunogenic potential than Advate +/- pdVWF, Afstyla - pdVWF, and Mix-rFVIII; (ii) distinct FVIIIs differed significantly in their immunogenic potential in that, in addition to (i), Afstyla + pdVWF had a significantly lower immunogenic potential than Beriate, while the immunogenic potential of Beriate was not significantly different from that of Xyntha + pdVWF; and (iii) rFVIIIs with pdVWF had significantly lower immunogenic potentials than the same rFVIIIs without pdVWF. Conclusions Our results provide HLAcII peptidomic level explanations for several important clinical observations/issues including the differential immunogenicity of distinct FVIIIs and the role of HLAcII genetics in inhibitor development.