title: Synthesis and biological evaluation of antibody conjugates of phosphate prodrugs of cytotoxic DNA alkylators for the targeted treatment of cancer.
abstract: The synthesis and biological evaluation of phosphate prodrugs of analogues of 1 (CC-1065) and their conjugates with antibodies are described. The phosphate group on the 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]indol-4-one (CBI) portion of the compounds confers enhanced solubility and stability in aqueous solutions. In the presence of phosphatases, these compounds convert into active DNA-alkylating agents. The synthesis of the prodrugs was achieved sequentially through coupling of CBI with a bis-indolyl moiety, followed by attachment of a thiol-containing linker, and conversion of the hydroxyl group of CBI into a phosphate prodrug. The linkers incorporated into the prodrugs enable conjugation to an antibody via either a stable disulfide or thioether bond, in aqueous buffer solutions containing as little as 5% organic cosolvent, resulting in exclusively monomeric and stable antibody-cytotoxic prodrug conjugates. Two disulfide-containing linkers differing in the degree of steric hindrance were used in antibody conjugates to test the effect of different rates of intracellular disulfide cleavage and effector release on biological activity. The prodrugs can be converted to the active cytotoxic compounds through the action of endogenous phosphatases. Antibody-prodrug conjugates displayed potent antigen-selective cytotoxic activity in vitro and antitumor activity in vivo.
authors.affiliation: ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States. robert.zhao@immunogen.com
authors.forename: Robert Yongxin
authors.initials: RY
authors.lastname: Zhao
authors.forename: Hans K
authors.initials: HK
authors.lastname: Erickson
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Leece
authors.forename: Emily E
authors.initials: EE
authors.lastname: Reid
authors.forename: Victor S
authors.initials: VS
authors.lastname: Goldmacher
authors.forename: John M
authors.initials: JM
authors.lastname: Lambert
authors.forename: Ravi V J
authors.initials: RV
authors.lastname: Chari
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry*; D018906:Antineoplastic Agents, Alkylating / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor; D004355:Drug Stability; D000080890:Duocarmycins; D005260:Female; D006801:Humans; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011355:Prodrugs / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D012995:Solubility; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014183:Transplantation, Heterologous
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D018906:Antineoplastic Agents, Alkylating; D000080890:Duocarmycins; D007211:Indoles; D009943:Organophosphorus Compounds; D011355:Prodrugs; C018782:CC 1065