Genetically Encoding Albumin Binding into Chemotherapeutic-loaded Polypeptide Nanoparticles Enhances Their Antitumor Efficacy

Abstract

We report the development of drug-encapsulating nanoparticles that bind endogenous albumin upon intravenous injection and evaluate their in vivo performance in a murine as well as canine animal model. The gene encoding a protein-G derived albumin binding domain (ABD) was fused to that of a chimeric polypeptide (CP), and the ABD-CP fusion was recombinantly synthesized by bacterial expression of the gene. Doxorubicin (DOX) was conjugated to the C-terminus of the ABD-CP fusion, and conjugation of multiple copies of the drug to one end of the ABD-CP triggered its self-assembly into ∼100 nm diameter spherical micelles. ABD-decorated micelles exhibited submicromolar binding affinity for albumin and also preserved their spherical morphology in the presence of albumin. In a murine model, albumin-binding micelles exhibited dose-independent pharmacokinetics, whereas naked micelles exhibited dose-dependent pharmacokinetics. In addition, in a canine model, albumin binding micelles resulted in a 3-fold increase in plasma half-life and 6-fold increase in plasma exposure as defined by the area under the curve (AUC) of the drug, compared with naked micelles. Furthermore, in a murine colon carcinoma model, albumin-binding nanoparticles demonstrated lower uptake by the reticuloendothelial system (RES) system organs, the liver and spleen, that are the main target organs of toxicity for nanoparticulate delivery systems and higher uptake by the tumor than naked micelles. The increased uptake by s.c. C26 colon carcinoma tumors in mice translated to a wider therapeutic window of doses ranging from 20 to 60 mg equivalent of DOX per kg body weight (mg DOX equiv•kg −1 BW) for albumin-binding ABD-CP-DOX micelles, as compared to naked micelles that were only effective at their maximum tolerated dose of 40 mg DOX equiv•kg −1 BW.

Recent trends in protein and peptide-based biomaterials for advanced drug delivery

“…Albumin is the most abundant protein in human plasma and has a set of properties that make it a unique molecular carrier for drugs: (i) it is a natural physiological carrier of native ligands and nutrients; (ii) it bypasses systemic clearance and degradation by the body's own innate mechanisms, so that it has an exceptionally long half-life of 19 days in humans, and similarly long half-lives in most animal species [ [123] , [124] , [125] , [126] ]; (iii) it preferentially accumulates at sites of vascular leakiness; (iv) it is highly internalized and metabolized by rapidly growing, nutrient-starved cancer cells; and (v) it is biodegradable and has no known systemic toxicity. Because of these properties especially its extraordinarily long plasma circulation, albumin has attracted a lot interest as a carrier for diverse drugs.…”

“…Chilkoti and colleagues recombinantly fused ABDN and ABDH to the N-terminus of a hydrophilic, thermally responsive chimeric polypeptide (CP) that contained multiple C-terminal cysteine residues [ 126 ]. The recombinant polypeptides formed highly monodisperse micellar nanoparticles upon covalent conjugation of multiple copies of hydrophobic DOX molecules to the.…”

“…(E, F) Pharmacokinetics of ABD-decorated nanoparticles in murine (E) and canine (F) models. Adapted with permission from [ 126 ]. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)…”

Engineering the Architecture of Elastin‐Like Polypeptides: From Unimers to Hierarchical Self‐Assembly

“…In another approach to impart stealth properties to ELP nanoparticles, Yousefpour et al developed a method to spontaneously coat the corona of ELP-doxorubicin nanoparticles with endogenous albumin in vivo. [91] This was achieved by fusing a ≈5 kDa protein-an albumin-binding domain (ABD)-to the N-terminus of a hydrophilic ELP which contains a (CGG) 8 domain at the C-terminus for conjugation of doxorubicin or other hydrophobic drugs. Chemical conjugation of multiple doxorubicin molecules to one end of the ABD-ELP-triggered selfassembly into spherical micelles of ≈100 nm diameter.…”

Trends in the design and use of elastin-like recombinamers as biomaterials

“…For instance, an albumin-binding domain (ABD) was fused to an ELR, and the wellknown antitumor drug doxorubicin (DOX) was conjugated to the resulting ABD-ELR [72]. The whole system was found to self-assemble into spherical micelles, and the delivery of DOX with the ABD-containing particles resulted in a 3-fold increase in plasma half-life compared to the naked ELR micelles.…”