title: Effect of linker variation on the stability, potency, and efficacy of carcinoma-reactive BR64-doxorubicin immunoconjugates.
abstract: The internalizing anti-Le(y) monoclonal antibody (MAb) BR64 was conjugated to the anticancer drug doxorubicin (DOX) using an acid-labile hydrazone bond to the DOX and either a disulfide or thioether bond to the MAb. The resulting disulfide (BR64-SS-DOX) and thioether (BR64-S-DOX) conjugates were evaluated for stability, potency, and antigen-specific activity in both in vitro and in vivo model systems. The BR64-SS-DOX conjugates demonstrated antigen-specific activity both in vitro and when evaluated against antigen-expressing, DOX-sensitive human carcinoma xenografts. However, the stability and potency of disulfide conjugates were poor, and in vivo activity superior to unconjugated DOX was seen only at doses approaching the maximum tolerated dose. Furthermore, BR64-SS-DOX conjugates were not active against antigen-expressing, DOX-insensitive colon tumor xenografts. In contrast, the BR64-S-DOX conjugates demonstrated good stability both in vitro and in vivo. The increased stability of the BR64-S-DOX conjugates resulted in the delivery of more biologically active DOX to tumors with a concomitant increase in potency and efficacy over that which could be achieved with either unconjugated DOX or BR64-SS-DOX conjugates. Delivery of DOX by BR64-SS-DOX conjugates resulted in complete regressions and cures of both DOX-sensitive lung xenografts and DOX-intensitive colon tumor xenografts. These results demonstrate the importance of linker stability when delivering drugs such as DOX to carcinomas via internalizing antibodies and are likely to have direct relevance to the clinical utility of MAb-directed delivery.
authors.affiliation: Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Trail
authors.forename: D
authors.initials: D
authors.lastname: Willner
authors.forename: J
authors.initials: J
authors.lastname: Knipe
authors.forename: A J
authors.initials: AJ
authors.lastname: Henderson
authors.forename: S J
authors.initials: SJ
authors.lastname: Lasch
authors.forename: M E
authors.initials: ME
authors.lastname: Zoeckler
authors.forename: M D
authors.initials: MD
authors.lastname: TrailSmith
authors.forename: T W
authors.initials: TW
authors.lastname: Doyle
authors.forename: H D
authors.initials: HD
authors.lastname: King
authors.forename: A M
authors.initials: AM
authors.lastname: Casazza
authors.forename: G R
authors.initials: GR
authors.lastname: Braslawsky
authors.forename: J
authors.initials: J
authors.lastname: Brown
authors.forename: S J
authors.initials: SJ
authors.lastname: Hofstead
authors.forename: R S
authors.initials: RS
authors.lastname: Greenfield
authors.forename: R A
authors.initials: RA
authors.lastname: Firestone
authors.forename: K
authors.initials: K
authors.lastname: Mosure
authors.forename: K F
authors.initials: KF
authors.lastname: Kadow
authors.forename: M B
authors.initials: MB
authors.lastname: Yang
authors.forename: K E
authors.initials: KE
authors.lastname: Hellström
authors.forename: I
authors.initials: I
authors.lastname: Hellström
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D000951:Antigens, Neoplasm / Q000276:immunology*; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism; D004317:Doxorubicin / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D000903:Antibiotics, Antineoplastic; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000939:Epitopes; D018796:Immunoconjugates; D004317:Doxorubicin