title: Design of Coltuximab Ravtansine, a CD19-Targeting Antibody-Drug Conjugate (ADC) for the Treatment of B-Cell Malignancies: Structure-Activity Relationships and Preclinical Evaluation.
abstract: Coltuximab ravtansine (SAR3419) is an antibody-drug conjugate (ADC) targeting CD19 created by conjugating a derivative of the potent microtubule-acting cytotoxic agent, maytansine, to a version of the anti-CD19 antibody, anti-B4, that was humanized as an IgG1 by variable domain resurfacing. Four different linker-maytansinoid constructs were synthesized (average ∼3.5 maytansinoids/antibody for each) to evaluate the impact of linker-payload design on the activity of the maytansinoid-ADCs targeting CD19. The ADC composed of DM4 (N(2')-deacetyl-N(2')-[4-mercapto-4-methyl-1-oxopentyl]maytansine) conjugated to antibody via the N-succinimidyl-4-(2-pyridyldithio)butyrate (SPDB) linker was selected for development as SAR3419. A molar ratio for DM4/antibody of between 3 and 5 was selected for the final design of SAR3419. Evaluation of SAR3419 in Ramos tumor xenograft models showed that the minimal effective single dose was about 50 μg/kg conjugated DM4 (∼2.5 mg/kg conjugated antibody), while twice this dose gave complete regressions in 100% of the mice. SAR3419 arrests cells in the G2/M phase of the cell cycle, ultimately leading to apoptosis after about 24 h. The results of in vitro and in vivo studies with SAR3419 made with DM4 that was [(3)H]-labeled at the C20 methoxy group of the maytansinoid suggest a mechanism of internalization and intracellular trafficking of SAR3419, ultimately to lysosomes, in which the antibody is fully degraded, releasing lysine-N(ε)-SPDB-DM4 as the initial metabolite. Subsequent intracellular reduction of the disulfide bond between linker and DM4 generates the free thiol species, which is then converted to S-methyl DM4 by cellular methyl transferase activity. We provide evidence to suggest that generation of S-methyl DM4 in tumor cells may contribute to in vivo tumor eradication via bystander killing of neighboring tumor cells. Furthermore, we show that S-methyl DM4 is converted to the sulfoxide and sulfone derivatives in the liver, suggesting that hepatic catabolism of the payload to less cytotoxic maytansinoid species contributes to the overall therapeutic window of SAR3419. This compound is currently in phase II clinical evaluation for the treatment of diffuse large B cell lymphoma.
authors: †ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States.
authors: E Erica
authors: EE
authors: Hong
authors: †ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States.
authors: Hans
authors: H
authors: Erickson
authors: †ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States.
authors: Robert J
authors: RJ
authors: Lutz
authors: †ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States.
authors: Kathleen R
authors: KR
authors: Whiteman
authors: †ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States.
authors: Gregory
authors: G
authors: Jones
authors: †ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States.
authors: Yelena
authors: Y
authors: Kovtun
authors: §Sanofi, 13 quai Jules Guesde, Vitry sur Seine, 94403 France.
authors: Veronique
authors: V
authors: Blanc
authors: †ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States.
authors: John M
authors: JM
authors: Lambert
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D005260:Female; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D008099:Liver / Q000378:metabolism; D008223:Lymphoma / Q000188:drug therapy; D008453:Maytansine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use; D051379:Mice; D016513:Mice, SCID; D013329:Structure-Activity Relationship; D023041:Xenograft Model Antitumor Assays
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D008453:Maytansine; C569646:coltuximab ravtansine
keywords: ADC; B cell lymphoma; CD19; DM4; SAR3419; antibody−drug conjugate; coltuximab ravtansine; immunoconjugate; maytansine