Multivalent Poly(ethylene glycol)-Containing Conjugates for In Vivo\nAntibody Suppression

Abstract

Poly(ethylene glycol) (PEG) was incorporated into multivalent conjugates of the N-terminal domain\nof β₂GPI (domain 1). PEG was incorporated to reduce the rate of elimination of the conjugates from\nplasma and to putatively improve their efficacy as toleragens for the suppression of anti-β₂GPI\nantibodies and the treatment of antiphospholipid syndrome (APS). Three structurally distinct types\nof multivalent platforms were constructed by incorporating PEG into the platform structures in\ndifferent ways. The amount of PEG incorporated ranged from about 5000 g per mole to about 30000\ng per mole. The platforms were functionalized with either four or eight aminooxy groups. The conjugates\nwere prepared by forming oxime linkages between the aminooxy groups and N-terminally glyoxylated\ndomain 1 polypeptide. The plasma half-life of each conjugate, labeled with ¹²⁵I, was measured in both\nmice and rats. The half-lives of the conjugates ranged from less than 10 min to about 1 h in mice, and\nfrom less than 3 h to about 19 h in rats. The ability of five tetravalent conjugates to suppress anti-domain 1 antibodies in immunized rats was also measured. Incorporation of PEG in the conjugates\nsignificantly reduced the doses required for suppression, and the amount of reduction correlated with\nthe amount of PEG incorporated.