Formation of Human IFN-βComplex with the Soluble Type I Interferon Receptor IFNAR-2 Leads to Enhanced IFN Stability, Pharmacokinetics, and Antitumor Activity in Xenografted SCID Mice

Abstract

Interferon-beta (IFN-beta) is biologically unstable under physiologic conditions in vitro and is cleared rapidly from the bloodstream on administration in vivo. In the present study, we demonstrate that a soluble recombinant form of the type I IFN receptor subunit, sIFNAR-2, can neutralize the bioactivity of type I IFNs at high concentrations and, at lower concentrations, causes an enhancement of IFN-beta-mediated antiviral activity. The in vitro enhancement is due to the specific interaction of IFN-beta with sIFNAR-2, followed by dissociation of IFN-beta from the complex over time in culture. In vivo, the serum half-life of IFN-beta is extended from minutes to hours when administered intravenously in mice as a sIFNAR-2-associated complex. Moreover, the antitumor effect of IFN-beta is increased by between 9-fold and 27-fold when injected as an sIFNAR-2-associated complex, as demonstrated by an increase in the mean survival time of immunodeficient mice challenged with human Burkitt lymphoma cell (Daudi) xenografts (sIFNAR-2-complexed vs. free IFN-beta treatment). These results show that on association with sIFNAR-2, IFN-beta is more stable in vitro and exhibits increased efficacy when administered in vivo. Administration as a complex with sIFNAR-2 may, therefore, provide a method of enhancing the delivery and effectiveness of type I IFNs.

IFN-β Is a Highly Potent Inhibitor of Gastroenteropancreatic Neuroendocrine Tumor Cell Growth In vitro

“…The short form is able to bind type I IFNs but does not couple to signal transduction because it lacks the signal-transducing tail of IFNAR-2c (34). The soluble form may act as a regulator of free IFNs and, depending on concentration, lead to the neutralization or enhancement of IFN bioactivity (35,36).…”

“…Translation of these findings into a clinical application is, however, not easy, considering the short half-life of IFN-h. But new promising strategies (PEGylated form, carrier proteins like IFNAR-2a, or gene therapy) can improve pharmacokinetic and pharmacodynamic properties of IFN-h, bringing its real clinical application in cancer closer (36,49,50).…”

Type I Interferon Receptors: Biochemistry and Biological Functions

“…4 Potentiation or agonist actions of soluble IFNAR2a may be mediated by the process of trans-signaling (see below), which is the major method of signal transduction by sIL6R and sIL15R (32,34). Soluble IFNAR2a might also have a carrier function, as IFN␤ bound sIFNAR2a increased the stability of IFN␤ and enhanced the anti-tumor activity in a xenograft tumor model (35).…”

Two Interferons Alpha Influence Each Other during Their Interaction with the Extracellular Domain of Human Type Interferon Receptor Subunit 2

“…The evidence of rebinding was an increase in the rate of interferon dissociation in the presence of the soluble receptor (∼30 and ∼1.2 times for CM3 and IFN-α2c, respectively, data not shown). Since we have shown the absence of mass transport limitation in the first experiment, again, the appearance of a strong rebinding effect for CM3 in the configuration of the second experiment, again, cannot be explained on the basis of a simple bimolecular reaction (even allowing for some degree of size-and chargedependence of the diffusional permeability of the immobilization matrix (34). One hypothetical effect that may cause such a behavior could be preferential immobilization of IFNAR2-EC in a conformational state (due to secondary or tertiary structural changes) that exhibits a higher on-rate constant for CM3, as compared to the conformational state when the receptor is in free solution.)…”