Extension of in vivo half-life of biologically active molecules by XTEN protein polymers

Abstract

XTEN™ is a class of unstructured hydrophilic, biodegradable protein polymers designed to increase the half-lives of therapeutic peptides and proteins. XTEN polymers and XTEN fusion proteins are typically expressed in Escherichia coli and purified by conventional protein chromatography as monodisperse polypeptides of exact length and sequence. Unstructured XTEN polypeptides have hydrodynamic volumes significantly larger than typical globular proteins of similar mass, thus imparting a bulking effect to the therapeutic payloads attached to them. Since their invention, XTEN polypeptides have been utilized to extend the half-lives of a variety of peptide- and protein-based therapeutics. Multiple clinical and preclinical studies and related drug discovery and development efforts are in progress. This review details the most current understanding of physicochemical properties and biological behavior of XTEN and XTENylated molecules. Additionally, the development path and status of several advanced drug discovery and development efforts are highlighted.

A long‐acting FGF21 alleviates hepatic steatosis and inflammation in a mouse model of non‐alcoholic steatohepatitis partly through an FGF21‐adiponectin‐IL17A pathway

“…We have syntheiszed a novel recombinant polypeptide, PsTag, that could be useful in the development of bio-drugs with properties comparable to those achievable by PEGylation, but with potentially fewer side effects (Podust et al, 2015;Yin et al, 2016). PsTag600-FGF21 was a fusion protein engineered by fusing PsTag600 polypeptides to human FGF21.…”

Half-life extension and non-human primate pharmacokinetic safety studies of i-body AD-114 targeting human CXCR4

“…AD-114 variants were quantified by monitoring the signature framework peptide LTPNQQR in plasma using liquid chromatography-mass spectrometry (LC-MS)/MS (XBridge BEH300 C18, 50 × 2.1 mm, 3.5 μm reverse phase chromatography column and AB Sciex QTRAP5500 triple quadrupole mass spectrometer), as described previously. 6 Study 2 (Figure 3) AD-114-PA600-6H pharmacokinetic studies in mice and rats AD-114-PA600-6H at 10 mg/kg was administered to mice SC or IP, and blood samples were collected at 15, 30 min, 1,2,3,4,8,12,18,24,36,48 and 72 h post dosing. Plasma samples were diluted 1/10 in 1% (w/v) BSA (Sigma #A7030) in PBS and AD-114-PA600-6H was quantified by enzyme-linked immunosorbent assay (ELISA) as described previously using anti-human NCAM-1 (R&D Systems #MAB2408) to capture i-body and anti-Histidine-HRP (BioRad #MCA1396P) to detect His 6 tagged i-body.…”

“…7 This rapid clearance from the bloodstream is attributable to renal filtration, protease degradation and sometimes overall charge of the therapeutic protein, and is undesirable from the perspective that frequent drug administration is required to sustain steady and effective circulating concentrations in the patient. 8 Of the numerous recombinant therapeutic molecules clinically available, half-life extension has been accomplished by a range of modifications, 8 including: 1) increasing the effective hydrodynamic volume by fusion to PEG, 9,10 fusion to unstructured proteins such as Pro/Ala-rich sequences (PASylation®) 11 or XTEN™, 12 or by glycosylation; 13 and 2) engineering capability for binding to the neonatal Fc receptor (FcRn), which enables recycling of the therapeutic back into the bloodstream, via fusion to Fc, 14 IgG 15 or albumin. 16 The single domain i-body AD-114 binds specifically and with high affinity to the G-protein coupled C-X-C chemokine receptor 4, CXCR4.…”

Bioengineered molecules for the management of haemophilia: Promise and remaining challenges

“…The challenge remains to increase the affinity of the D'D3‐FVIII interaction to reduce redistribution to unmodified VWF in vivo. One strategy to address this is through a covalent linkage between a D'D3/Fc fusion and a rFVIIIFc fusion molecule . The rFVIIIFc fusion molecule was further modified with unstructured hydrophilic, biodegradable polypeptide polymers (XTEN, Amunix, Mountain View, CA, USA).…”