Fc-Fusion Drugs Have FcγR/C1q Binding and Signaling Properties That May Affect Their Immunogenicity
Fusing the human immunoglobulin G1 (IgG1) constant region (Fc-domain) to therapeutic proteins or peptides increases their circulating plasma half-life via neonatal Fc receptor (FcRn) binding and recycling. However, Fc-mediated interactions with other molecules including complement C1q and Fc gamma receptors (FcγRs) can have immunological consequences and the potential to modulate the immunogenicity of Fc-fusion therapeutics. In a comparative study, we carried out a comprehensive assessment of Fc-mediated interactions for five FDA-approved Fc-fusion therapeutics. C1q binding and complement activation were measured by ELISA, while FcγR binding and signaling were evaluated using BW5147:FcγR-ζ reporter cell lines. We demonstrate that FIX-Fc and FVIII-Fc bound C1q as well as activating and inhibitory FcγRs (I, IIA, IIB, IIIA). These coagulation factor Fc-fusions also signaled via FcγRIIIA, and to a lesser extent via FcγRI and FcγRIIB. TNFR-Fc and CTLA4-Fc bound FcγRI, while TNFR-Fc also bound FcγRIIIA, but these interactions did not result in FcγR signaling. Our comprehensive assessment demonstrates that (i) different Fc-fusion drugs have distinct C1q/FcγR binding and signaling properties, (ii) FcγR binding does not predict signaling, and (iii) the fusion partner (effector molecule) can influence Fc-mediated interactions.
KeywordsFc-fusion Immunogenicity Fc gamma receptors Complement C1q
B.G. and Z.E.S. are funded by intramural grants from the US FDA. We thank Biogen for providing the coagulation factor Fc-fusions (FIX-Fc [efmoroctocog alfa] and FVIII-Fc [eftrenonacog alfa]) through a Material Transfer Agreement.
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My comments are an informal communication and represent my own best judgment. These comments do not bind or obligate FDA.
- 4.Ning L, Li Z, Bai Z, Hou S, He B, Huang J, et al. Computational design of antiangiogenic peptibody by fusing human IgG1 Fc fragment and HRH peptide: structural modeling, energetic analysis, and dynamics simulation of its binding potency to VEGF receptor. Int J Biol Sci. 2018;14:930–7.CrossRefGoogle Scholar
- 13.Osslund TDC, C.L, Crampton SL, Bass RB. Crystals of etanercept and methods of making thereof. US Patent 2007, US 7,276,477 B2.Google Scholar
- 15.Pierce GTS, Peters RT, Jiang H. Factor ix polypeptides and methods of use thereof US Patent 2012, US 9,670,475 B2.Google Scholar
- 17.Dumont JALS, Bitonti AJ, Pierce G, Luk A, Jiang H, McKinney B, Ottmer M, Sommer J, Nugent K, Li L, Peters R. Factor VIII-Fc chimeric and hybrid polypeptides, and methods of use thereof. US Patent 2015, US 9,050,318 B2.Google Scholar
- 18.Mossner E, Brunker P, Moser S, Puntener U, Schmidt C, Herter S, et al. Increasing the efficacy of CD20 antibody therapy through the engineering of a new type II anti-CD20 antibody with enhanced direct and immune effector cell-mediated B-cell cytotoxicity. Blood. 2010;115:4393–402.CrossRefGoogle Scholar
- 39.Suzuki T, Ishii-Watabe A, Tada M, Kobayashi T, Kanayasu-Toyoda T, Kawanishi T, et al. Importance of neonatal FcR in regulating the serum half-life of therapeutic proteins containing the Fc domain of human IgG1: a comparative study of the affinity of monoclonal antibodies and Fc-fusion proteins to human neonatal FcR. J Immunol. 2010;184:1968–76.CrossRefGoogle Scholar