Clinical Pharmacology of the Antibody-Drug Conjugate Enfortumab Vedotin in Advanced Urothelial Carcinoma and Other Malignant Solid Tumors.

Enfortumab vedotin is an antibody-drug conjugate comprised of a human monoclonal antibody directed to Nectin-4 and monomethyl auristatin E (MMAE), a microtubule-disrupting agent. The objectives of this review are to summarize the clinical pharmacology of enfortumab vedotin monotherapy and demonstrate that the appropriate dose has been selected for clinical use. Pharmacokinetics (PK) of enfortumab vedotin (antibody-drug conjugate and total antibody) and free MMAE were evaluated in five clinical trials of patients with locally advanced or metastatic urothelial carcinoma (n = 748). Intravenous enfortumab vedotin 0.5-1.25 mg/kg on days 1, 8, and 15 of a 28-day cycle showed linear, dose-proportional PK. No significant differences in exposure or safety of enfortumab vedotin and free MMAE were observed in mild, moderate, or severe renal impairment versus normal renal function. Patients with mildly impaired versus normal hepatic function had a 37% increase in area under the concentration-time curve (0-28 days), a 31% increase in maximum concentration of free MMAE, and a similar adverse event profile. No clinically significant PK differences were observed based on race/ethnicity with weight-based dosing, and no clinically meaningful QT prolongation was observed. Concomitant use with dual P-glycoprotein and strong cytochrome P450 3A4 inhibitors may increase MMAE exposure and the risk of adverse events. Approximately 3% of patients developed antitherapeutic antibodies against enfortumab vedotin 1.25 mg/kg. These findings support enfortumab vedotin 1.25 mg/kg monotherapy on days 1, 8, and 15 of a 28-day cycle. No dose adjustments are required for patients with renal impairment or mild hepatic impairment, or by race/ethnicity.

Identification of Uridine 5'-Diphosphate-Glucuronosyltransferases Responsible for the Glucuronidation of Mirabegron, a Potent and Selective ß3-Adrenoceptor Agonist, in Human Liver Microsomes.

BACKGROUND AND OBJECTIVES: Mirabegron is cleared by multiple mechanisms, including drug-metabolizing enzymes. One of the most important clearance pathways is direct glucuronidation. In humans, M11 (O-glucuronide), M13 (carbamoyl-glucuronide), and M14 (N-glucuronide) have been identified, of which M11 is one of the major metabolites in human plasma. The objective of this study was to identify the uridine 5'-diphosphate (UDP)-glucuronosyltransferase (UGT) isoform responsible for the direct glucuronidation of mirabegron using human liver microsomes (HLMs) and recombinant human UGTs (rhUGTs). METHODS: Reaction mixtures contained 1-1000 µM mirabegron, 8 mM MgCl2, alamethicin (25 µg/mL), 50 mM Tris-HCl buffer (pH 7.5), human liver microsome (HLM) or rhUGT (1.0 mg protein/mL), and 2 mM UDP-glucuronic acid in a total volume of 200 µL for 120 min at 37 °C. HLMs from 16 individuals were used for the correlation study, and mefenamic acid and propofol were used for the inhibition study. RESULTS: Regarding M11 formation, rhUGT2B7 showed high activity among the rhUGTs tested (11.3 pmol/min/mg protein). This result was supported by the correlation between M11 formation activity and UGT2B7 marker enzyme activity (3-glucuronidation of morphine, r 2 = 0.330, p = 0.020) in individual HLMs; inhibition by mefenamic acid in pooled HLMs (IC50 = 22.8 µM); and relatively similar K m values between pooled HLMs and rhUGT2B7 (1260 vs. 486 µM). Regarding M13 and M14 formation, rhUGT1A3 and rhUGT1A8 showed high activity among the rhUGTs tested, respectively. CONCLUSIONS: UGT2B7 is the main catalyst of M11 formation in HLMs. Regarding M13 and M14 formation, UGT1A3 and UGT1A8 are strong candidates for glucuronidation, respectively.

Elucidation of the effects of the CYP1A2 deficiency polymorphism in the metabolism of 4-cyclohexyl-1-ethyl-7-methylpyrido[2,3-d]pyrimidine-2-(1h)-one (YM-64227), a phosphodiesterase type 4 inhibitor, and its metabolites in dogs.

The canine CYP1A2 1117 C>T single nucleotide polymorphism is responsible for a substantial portion of the interindividual variability seen in the pharmacokinetics of 4-cyclohexyl-1-ethyl-7-methylpyrido[2,3-d]pyrimidine-2-(1H)-one (YM-64227). The purpose of this study is to investigate the contribution of CYP1A2 to the metabolism of YM-64227 and its five metabolites (MM-1 to MM-5), as well as to determine the interindividual variability between the pharmacokinetic profiles of the compounds with respect to the CYP1A2 deficiency polymorphism. alpha-Naphthoflavone and anti-CYP1A1/2 antibody inhibited the metabolic activities at which MM-2 and MM-3 were formed from YM-64227 in C/C- and C/T-type microsomes. In T/T type, the rate of MM-2 and MM-3 formation was lower, and alpha-naphthoflavone and anti-CYP1A1/2 antibody were shown to have no effect. A positive correlation between the overall metabolism of YM-64227 and phenacetin O-deethylation, a CYP1A2 activity marker, was observed in all the genotypes. The in vitro metabolic clearances in the T/T type of MM-1, MM-3, MM-4, and MM-5 were less than 50% lower than those in the C/C type. The anti-CYP1A1/2 antibody inhibited the metabolism of MM-1, MM-3, MM-4, and MM-5 in the C/C and C/T types. These results suggest that the formation of MM-2 and MM-3 from YM-64227 is catalyzed by CYP1A2, and that CYP1A2 contributes mainly to the subsequent metabolism of the primary metabolites of YM-64227, with the exception of MM-2. It is possible that the interindividual variability of YM-64227 with respect to the CYP1A2 deficiency polymorphism is caused by a decrease in the metabolic activities of both the unchanged drug and its metabolites.

The canine CYP1A2 deficiency polymorphism dramatically affects the pharmacokinetics of 4-cyclohexyl-1-ethyl-7-methylpyrido[2,3-D]-pyrimidine-2-(1H)-one (YM-64227), a phosphodiesterase type 4 inhibitor.

In a previous study, it was shown that the novel canine single nucleotide polymorphism (SNP) CYP1A2 1117C>T yields an inactive enzyme. In this study, the effect that this SNP has on the pharmacokinetics of 4-cyclohexyl-1-ethyl-7-methylpyrido[2,3-d]pyrimidine-2-(1H)-one (YM-64227) was investigated. Plasma concentrations of the unchanged drug and five of its metabolites (MM-1 to MM-5) were determined after either intravenous or oral administration of YM-64227 to genotyped dogs (C/C, C/T, and T/T groups). Liver microsomes were prepared from these dogs to determine the in vitro metabolic clearance of YM-64227. After a single oral administration, the maximum plasma concentration and absolute bioavailability of YM-64227 in the T/T group were 17.1 times and 27.2 times higher than those in the C/C group, respectively, whereas the pharmacokinetics of YM-64227 after intravenous administration were not affected by genotype. The metabolic profiles in the T/T group were quite distinct from the others; i.e., the main metabolite was MM-2 in the C/C group, whereas MM-1 and MM-5 were the main metabolites in the T/T group. The formation clearances of MM-2 and MM-3 in the microsomes derived from T/T type dogs were significantly lower, whereas those of MM-1, MM-4, and MM-5 were not affected. A statistically significant correlation was observed between the in vivo and in vitro metabolic intrinsic clearances (r = 0.82, p < 0.001). The canine CYP1A2 1117C>T SNP proved to be responsible for a substantial portion of the interindividual variability in the pharmacokinetics of YM-64227.

Simultaneous determination of YM-64227, a phosphodiesterase type 4 inhibitor, and its five metabolites in dog plasma by high-performance liquid chromatography with fluorescence detection.

We developed and validated a reversed-phase high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of YM-64227 [4-cyclohexyl-1-ethyl-7-methylpyrido(2,3-d)pyrimidin-2-(1H)-one], a novel and selective phosphodiesterase type 4 inhibitor, and its fi ve hydroxylated metabolites in dog plasma. The plasma samples were extracted with tert-butyl methyl ether under alkali conditions. The analytes were well separated on a phenyl ethyl column (5 microm, 250 x 4.6 mm i.d.), opreating at 40 degrees C and using an acetonitrile-acetic acid gradient at a fl ow rate of 1.0 mL/min. The fluorescence signal was monitored at an excitation and emission wavelength of 330 and 400 nm, respectively. No interfering peak was observed at the retention time of YM-64227, its metabolites or the internal standard. The validated quantitation range of the method was 0.4-200 ng/mL for all analytes using 0.5 mL of the plasma sample. The recovery of analytes in the extraction process was more than 65.5%. The intra- and inter-assay precision was less than 5.1 and 12.6%, respectively, and the intra- and inter-assay accuracy ranged from -8.1 to 11.8% and -8.0 to 9.9%, respectively. Using this assay, the plasma concentration of YM-64227 and metabolites can be determined after the oral administration of YM-64227 to beagle dogs.