title: Adriamycin(hydrazone)-antibody conjugates require internalization and intracellular acid hydrolysis for antitumor activity.
abstract: Adriamycin hydrazone (ADM-Hzn) immunoconjugates have previously been shown to exhibit antibody-directed antitumor activity in vitro and in vivo. In this report, the biological and biochemical properties of the mAb and linker were investigated. Conjugates prepared with two antibodies 5E9 [anti-(transferrin receptor)] and G28.1 (anti-CD37), (which internalize from the surface of target cells following binding) were more cytotoxic in vitro and had greater antitumor activity against Daudi B lymphoma tumor xenografts than a non-internalizing immunoconjugate prepared with mAb 2H7 (anti-CD20). In addition, the 13-acylhydrazone bond linking the drug to the mAb was labile at pH 5 and released unmodified ADM at a rapid rate (t1/2 = 2.5 h). Immunoconjugates prepared with an oxime linkage at the C-13 position were stable to acid and were not cytotoxic. These findings suggest that internalization of ADM-Hzn immunoconjugates and release of free ADM from the mAb in acidic intracellular compartments were important steps in the mechanism of action of ADM-Hzn immunoconjugates.
authors.affiliation: Bristol-Myers Squibb, Wallingford, CT 06492-7600.
authors.forename: G R
authors.initials: GR
authors.lastname: Braslawsky
authors.forename: K
authors.initials: K
authors.lastname: Kadow
authors.forename: J
authors.initials: J
authors.lastname: Knipe
authors.forename: K
authors.initials: K
authors.lastname: McGoff
authors.forename: M
authors.initials: M
authors.lastname: Edson
authors.forename: T
authors.initials: T
authors.lastname: Kaneko
authors.forename: R S
authors.initials: RS
authors.lastname: Greenfield
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism* / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004317:Doxorubicin / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D006868:Hydrolysis; D000922:Immunotoxins / Q000378:metabolism* / Q000494:pharmacology*; D007457:Iodine Radioisotopes; D008223:Lymphoma / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015394:Molecular Structure; D009368:Neoplasm Transplantation; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014410:Tumor Stem Cell Assay
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D000922:Immunotoxins; D007457:Iodine Radioisotopes; D004317:Doxorubicin