Multivalent Antiviral XTEN–Peptide Conjugates with Long in Vivo Half-Life and Enhanced Solubility

Abstract

XTENs are unstructured, nonrepetitive protein polymers designed to prolong the in vivo half-life of pharmaceuticals by introducing a bulking effect similar to that of poly(ethylene glycol). While XTEN can be expressed as a recombinant fusion protein with bioactive proteins and peptides, therapeutic molecules of interest can also be chemically conjugated to XTEN. Such an approach permits precise control over the positioning, spacing, and valency of bioactive moieties along the length of XTEN. We have demonstrated the attachment of T-20, an anti-retroviral peptide indicated for the treatment of HIV-1 patients with multidrug resistance, to XTEN. By reacting maleimide-functionalized T-20 with cysteine-containing XTENs and varying the number and positioning of cysteines in the XTENs, a library of different peptide–polymer combinations were produced. The T-20-XTEN conjugates were tested using an in vitro antiviral assay and were found to be effective in inhibiting HIV-1 entry and preventing cell death, with the copy number and spacing of the T-20 peptides influencing antiviral activity. The peptide–XTEN conjugates were also discovered to have enhanced solubilities in comparison with the native T-20 peptide. The pharmacokinetic profile of the most active T-20-XTEN conjugate was measured in rats, and it was found to exhibit an elimination half-life of 55.7 ± 17.7 h, almost 20 times longer than the reported half-life for T-20 dosed in rats. As the conjugation of T-20 to XTEN greatly improved the in vivo half-life and solubility of the peptide, the XTEN platform has been demonstrated to be a versatile tool for improving the properties of drugs and enabling the development of a class of next-generation therapeutics.

Engineering a long-acting, potent GLP-1 analog for microstructure-based transdermal delivery

“…However, peptide-based drugs generally suffer from short half-lives due to proteolytic degradation and fast renal clearance, rendering higher doses and frequent injections necessary, which negatively affects patient compliance (2). To improve their pharmacological properties, peptides have been chemically modified by conformational restriction (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) to increase potency and reduce proteolysis, and also by lipidation (14)(15)(16), polymer conjugation (17)(18)(19)(20)(21)(22)(23), and protein fusion (24)(25)(26) to decrease renal clearance. Although these latter conjugates can have enhanced circulatory half-lives, they often suffer from reduced potency and, as a result, require injection of relatively large quantities of the modified peptides.…”

Synthesis and Characterization of PVAc‐MMT‐DOAB Exfoliated Nanocomposites: Reducing Polymerization Time and Water in the Synthesis

“…Some studies have reported on the application of MMT and OMMT in PVAc, but they all need other additives or agents as main components that are necessary in their synthesis, such as poly(vinyl pyrrolidone), 18,19 anionic surfactants, 20 polyvinyl alcohol, 21,22 glycidyl methacrylate, 23,24 and high-density polyethylene. 25,26 Adding an additional component means adding one or more procedures that makes the synthesis or preparation more complex and so should be avoided. Furthermore, OMMT has some organic properties that are determined by the organics intercalated into MMT layers, [27][28][29] so it has the advantages of inorganic and organic properties.…”

Half‐Life Extension of Biopharmaceuticals using Chemical Methods: Alternatives to PEGylation

“…The conjugates contain multiple copies of T‐20 attached to a single XTEN polymer, but instead of traditional end‐to‐end fusion, the T‐20 molecules are attached at various positions along the XTEN sequence through the side‐chains of Cys residues. Investigation of the PK properties of the most active conjugate (named T‐20‐XTEN‐4) following s.c. administration to Sprague–Dawley rats revealed an elimination half‐life of 55.7 h, corresponding to a 20‐fold increase relative to the reported half‐life of unmodified T‐20 …”