title: Molecular Basis of Valine-Citrulline-PABC Linker Instability in Site-Specific ADCs and Its Mitigation by Linker Design.
abstract: The degree of stability of antibody-drug linkers in systemic circulation, and the rate of their intracellular processing within target cancer cells are among the key factors determining the efficacy of antibody-drug conjugates (ADC) in vivo Previous studies demonstrated the susceptibility of cleavable linkers, as well as auristatin-based payloads, to enzymatic cleavage in rodent plasma. Here, we identify Carboxylesterase 1C as the enzyme responsible for the extracellular hydrolysis of valine-citrulline-p-aminocarbamate (VC-PABC)-based linkers in mouse plasma. We further show that the activity of Carboxylesterase 1C towards VC-PABC-based linkers, and consequently the stability of ADCs in mouse plasma, can be effectively modulated by small chemical modifications to the linker. While the introduced modifications can protect the VC-PABC-based linkers from extracellular cleavage, they do not significantly alter the intracellular linker processing by the lysosomal protease Cathepsin B. The distinct substrate preference of the serum Carboxylesterase 1C offers the opportunity to modulate the extracellular stability of cleavable ADCs without diminishing the intracellular payload release required for ADC efficacy. Mol Cancer Ther; 15(5); 958-70. ©2016 AACR.
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Dorywalska
authors.affiliation: Worldwide Medicinal Chemistry, Pfizer Inc., Groton, Connecticut.
authors.forename: Russell
authors.initials: R
authors.lastname: Dushin
authors.affiliation: Worldwide Medicinal Chemistry, Pfizer Inc., Groton, Connecticut.
authors.forename: Ludivine
authors.initials: L
authors.lastname: Moine
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Santiago E
authors.initials: SE
authors.lastname: Farias
authors.affiliation: Worldwide Medicinal Chemistry, Pfizer Inc., Groton, Connecticut.
authors.forename: Dahui
authors.initials: D
authors.lastname: Zhou
authors.affiliation: Worldwide Medicinal Chemistry, Pfizer Inc., Groton, Connecticut.
authors.forename: Thayalan
authors.initials: T
authors.lastname: Navaratnam
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Victor
authors.initials: V
authors.lastname: Lui
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Adela
authors.initials: A
authors.lastname: Hasa-Moreno
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Meritxell Galindo
authors.initials: MG
authors.lastname: Casas
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Thomas-Toan
authors.initials: TT
authors.lastname: Tran
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Kathy
authors.initials: K
authors.lastname: Delaria
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Shu-Hui
authors.initials: SH
authors.lastname: Liu
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Davide
authors.initials: D
authors.lastname: Foletti
authors.affiliation: Worldwide Medicinal Chemistry, Pfizer Inc., Groton, Connecticut.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: O'Donnell
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Jaume
authors.initials: J
authors.lastname: Pons
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: David L
authors.initials: DL
authors.lastname: Shelton
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California.
authors.forename: Arvind
authors.initials: A
authors.lastname: Rajpal
authors.affiliation: Rinat Laboratories, Pfizer Inc., South San Francisco, California. pavel.strop@bms.com.
authors.forename: Pavel
authors.initials: P
authors.lastname: Strop
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D015415:Biomarkers; D002219:Carbamates / Q000737:chemistry*; D043182:Carboxylesterase / Q000737:chemistry / Q000378:metabolism; D002956:Citrulline / Q000737:chemistry*; D015195:Drug Design; D004355:Drug Stability; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D011485:Protein Binding; D013329:Structure-Activity Relationship; D014633:Valine / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D015415:Biomarkers; D002219:Carbamates; D018796:Immunoconjugates; D002956:Citrulline; D043182:Carboxylesterase; D014633:Valine