title: Systematic evaluation of antibody-mediated siRNA delivery using an industrial platform of THIOMAB-siRNA conjugates.
abstract: Delivery of siRNA is a key hurdle to realizing the therapeutic promise of RNAi. By targeting internalizing cell surface antigens, antibody-siRNA complexes provide a possible solution. However, initial reports of antibody-siRNA complexes relied on non-specific charged interactions and have not been broadly applicable. To assess and improve this delivery method, we built on an industrial platform of therapeutic antibodies called THIOMABs, engineered to enable precise covalent coupling of siRNAs. We report that such coupling generates monomeric antibody-siRNA conjugates (ARCs) that retain antibody and siRNA activities. To broadly assess this technology, we generated a battery of THIOMABs against seven targets that use multiple internalization routes, enabling systematic manipulation of multiple parameters that impact delivery. We identify ARCs that induce targeted silencing in vitro and extend tests to target prostate carcinoma cells following systemic administration in mouse models. However, optimal silencing was restricted to specific conditions and only observed using a subset of ARCs. Trafficking studies point to ARC entrapment in endocytic compartments as a limiting factor, independent of the route of antigen internalization. Our broad characterization of multiple parameters using therapeutic-grade conjugate technology provides a thorough assessment of this delivery technology, highlighting both examples of success as well as remaining challenges.
authors.affiliation: Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Trinna L
authors.identifier: http://orcid.org/0000-0002-9991-9505
authors.initials: TL
authors.lastname: Cuellar
authors.affiliation: Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Dwight
authors.initials: D
authors.lastname: Barnes
authors.affiliation: Department of Protein Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Nelson
authors.affiliation: Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Tanguay
authors.affiliation: Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Shang-Fan
authors.initials: SF
authors.lastname: Yu
authors.affiliation: Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wen
authors.affiliation: Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Suzie J
authors.initials: SJ
authors.lastname: Scales
authors.affiliation: Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Gesch
authors.affiliation: Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: David
authors.initials: D
authors.lastname: Davis
authors.affiliation: Dharmacon Products, Thermo Fisher Scientific, 2650 Crescent Drive, Suite 100, Lafayette, CO 80026, USA.
authors.forename: Anja
authors.initials: A
authors.lastname: van Brabant Smith
authors.affiliation: Dharmacon Products, Thermo Fisher Scientific, 2650 Crescent Drive, Suite 100, Lafayette, CO 80026, USA.
authors.forename: Devin
authors.initials: D
authors.lastname: Leake
authors.affiliation: Department of Protein Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Vandlen
authors.affiliation: Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-0511, USA Siebel.Christian@gene.com.
authors.forename: Christian W
authors.initials: CW
authors.lastname: Siebel
mesh_terms: D000818:Animals; D000906:Antibodies / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D011992:Endosomes / Q000378:metabolism; D051379:Mice; D009369:Neoplasms / Q000235:genetics; D015202:Protein Engineering; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism
chemical_list: D000906:Antibodies; D034741:RNA, Small Interfering