title: Influence of molecular design on biodistribution and targeting properties of an Affibody-fused HER2-recognising anticancer toxin.
abstract: Targeted delivery of toxins is a promising way to treat disseminated cancer. The use of monoclonal antibodies as targeting moiety has provided proof-of-principle for this approach. However, extravasation and tissue penetration rates of antibody-based immunotoxins are limited due to antibody bulkiness. The use of a novel class of targeting probes, Affibody molecules, provides smaller toxin-conjugated constructs, which may improve targeting. Earlier, we have demonstrated that affitoxins containing a HER2-targeting Affibody moiety and a deimmunized and truncated exotoxin A from Pseudomonas aeruginosa, PE38X8, provide highly selective toxicity to HER2-expressing cancer cells. To evaluate the influence of molecular design on targeting and biodistribution properties, a series of novel affitoxins were labelled with the residualizing radionuclide 111In. In this study, we have shown that the novel conjugates are more rapidly internalized compared with the parental affitoxin. The use of a (HE)3 purification tag instead of a hexahistidine tag enabled significant (p<0.05) reduction of the hepatic uptake of the affitoxin in a murine model. Fusion of the affitoxin with an albumin-binding domain (ABD) caused appreciable extension of the residence time in circulation and several-fold reduction of the renal uptake. The best variant, 111In-(HE)3-ZHER2-ABD-PE38X8, demonstrated receptor-specific accumulation in HER2-expressing SKOV-3 xenografts. In conclusion, a careful molecular design of scaffold protein based anticancer targeted toxins can appreciably improve their biodistribution and targeting properties.
authors: Institute of Immunology, Genetic and Pathology, Uppsala University, SE-75185 Uppsala, Sweden.
authors: Mohamed
authors: M
authors: Altai
authors: School of Biotechnology, Division of Protein Technology, KTH - Royal Institute of Technology, SE-10691 Stockholm, Sweden.
authors: Hao
authors: H
authors: Liu
authors: Division of Molecular Imaging, Department of Medicinal Chemistry, Uppsala University, SE-75183 Uppsala, Sweden.
authors: Anna
authors: A
authors: Orlova
authors: Institute of Immunology, Genetic and Pathology, Uppsala University, SE-75185 Uppsala, Sweden.
authors: Vladimir
authors: V
authors: Tolmachev
authors: School of Biotechnology, Division of Protein Technology, KTH - Royal Institute of Technology, SE-10691 Stockholm, Sweden.
authors: Torbjörn
authors: T
authors: Gräslund
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D015195:Drug Design; D006801:Humans; D007155:Immunologic Factors / Q000737:chemistry / Q000494:pharmacology*; D000922:Immunotoxins / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D009369:Neoplasms / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000494:pharmacology; D014018:Tissue Distribution
chemical_list: D007155:Immunologic Factors; D000922:Immunotoxins; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; C568088:HER2 affitoxin; C508053:ERBB2 protein, human