Abstract
The in vitro characterization of the inhibition potential of four representative maytansinoid species observed upon hepatic and/or tumor in vivo processing of antibody-maytansine conjugates (AMCs) with cleavable and noncleavable linkers is reported. We investigated the free maytansinoid species N2′-deacetyl-N2′-(3-mercapto-1-oxopropyl)-maytansine (DM1), (S)-methyl-DM1, and N2′-deacetyl-N2′-(4-mercapto-4-methyl-1-oxopentyl)-maytansine (DM4) as representative cleavable linker catabolites and Lysine-Nε-N-succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate-DM1 (Lys-MCC-DM1) as the representative noncleavable linker catabolite. Studies with recombinant human cytochromes P450 (P450s) indicate CYP2D6, CYP3A4, and CYP3A5 are the primary isoforms responsible for the oxidative metabolism of DM1, (S)-methyl-DM1, and DM4. Lys-MCC-DM1 was not metabolized by any of the P450 isoforms studied. DM1 was shown to be a reversible inhibitor of CYP2C8 (Ki = 11 ± 3 μM) and CYP2D6 (Ki = 14 ± 2 μM). Lys-MCC-DM1 and (S)-methyl-DM1 showed no reversible or time-dependent inactivation of any of the P450s studied. DM1 and DM4 inactivated CYP3A from human liver microsomes with Ki/kinact values of 4.8 ± 0.9 μM/0.035 ± 0.002 min−1 and 3.3 ± 0.2 μM/0.114 ± 0.002 min−1, respectively. DM1 and DM4 inactivated recombinant CYP3A4 with Ki/kinact values of 3.4 ± 1.0 μM/0.058 ± 0.005 min−1 and 1.4 ± 0.3 μM/0.117 ± 0.006 min−1, respectively. Because of instability in plasma, further characterization of the DM1 and DM4 intramolecular and intermolecular disulfide conjugates observed in vivo is required before an accurate drug-drug interaction (DDI) prediction can be made. AMCs with noncleavable thioether-linked DM1 as the cytotoxic agent are predicted to have no potential for a DDI with any of the major human P450s studied.
Footnotes
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ABBREVIATIONS:
- ADC
- antibody-drug conjugate
- AMC
- antibody-maytansine conjugate
- DM1
- N2′-deacetyl-N2′-(3-mercapto-1-oxopropyl)-maytansine
- DM3
- N2′-deacetyl-N2′-(4-mercapto-1-oxopentyl)-maytansine
- DM4
- N2′-deacetyl-N2′-(4-mercapto-4-methyl-1-oxopentyl)-maytansine
- SMCC
- N-succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate
- SPP
- N-succinimidyl 4-(2-pyridyldithio)pentanoate
- Lys-MCC-DM1
- lysine-Nε-SMCC-DM1
- DDI
- drug-drug interaction
- SPDB
- N-succinimidyl 4-(2-pyridyldithio)butyrate
- P450
- cytochrome P450
- LC-MS/MS
- liquid chromatography/tandem mass spectrometry
- HLM
- human liver microsomes
- ABT
- 1-aminobenzotriazole
- TDI
- time-dependent inactivation
- HPLC
- high-performance liquid chromatography
- amu
- atomic mass unit
- mmu
- milli-mass unit
- MS/MS
- tandem mass spectrometry
- T-DM1
- trastuzumab-DM1
- RES
- reticuloendothelial system.
- Received April 9, 2012.
- Accepted June 29, 2012.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
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