Methotrexate Dose in Patients With Early Rheumatoid Arthritis Impacts Methotrexate Polyglutamate Pharmacokinetics, Adalimumab Pharmacokinetics, and Efficacy: Pharmacokinetic and Exposure-response Analysis of the CONCERTO Trial.

PURPOSE: Methotrexate (MTX) and adalimumab are well-recognized treatments of rheumatoid arthritis (RA), the efficacy of which may be driven by intracellular polyglutamates (PGs). The aim of this analysis was to characterize MTX PG concentrations and adalimumab pharmacokinetics in the CONCERTO trial. In addition, the relationships between MTX dose/pharmacokinetics, adalimumab pharmacokinetics, and efficacy were evaluated. METHODS: CONCERTO was a double-blind, parallel-arm study in patients with early RA randomized to adalimumab 40 mg SC every other week plus blinded MTX 2.5, 5, 10, or 20 mg PO once weekly, for 26 weeks. Blood samples were obtained through week 26 for the determination of concentrations of MTX PG, adalimumab, and anti-adalimumab antibody (AAA). Clinical outcomes were also assessed. FINDINGS: A total of 395 patients were included in the analysis (MTX, 329; adalimumab, 395). The mean time to steady-state MTX PG concentration was increased with MTX dose, from 8 to >26 weeks, depending on PG chain length. Dose proportionality changed with PG chain length. As MTX dose was increased, the percentage of short-chain PGs increased less than dose proportionally, while the percentage of long-chain PGs increased more than dose proportionally. For very-long-chain PGs, dose proportionality could not be assessed due to the nonmeasurable concentrations in the 2.5- and 5-mg MTX dose groups. As MTX dose increased, mean adalimumab concentrations also increased (P < 0.001). The percentage of patients with AAA decreased with increasing MTX dose, and at week 26, AAA+ status was significantly correlated with MTX dose level (P = 0.005). In general, rates of response, defined using the 28-joint count disease activity score based on C-reactive protein (DAS28[CRP]; response, <3.2), were greater in the subgroup without AAA. The likelihood of a patient achieving a DAS28(CRP) response was related to the baseline measurement (P < 0.001) and to the concentration of adalimumab (P = 0.001), but not to the MTX regimen (P = 0.689). IMPLICATIONS: The dose-response characteristics of MTX PG pharmacokinetics and the resultant effects of MTX on adalimumab exposures should be considered when determining the benefit-risk profile of MTX and adalimumab combination therapy in patients with early RA. ClinicalTrials.gov identifier: NCT01185301.

A high-throughput liquid chromatography/tandem mass spectrometry method for simultaneous quantification of a hydrophobic drug candidate and its hydrophilic metabolite in human urine with a fully automated liquid/liquid extraction.

ABT-869 (A-741439) is an investigational new drug candidate under development by Abbott Laboratories. ABT-869 is hydrophobic, but is oxidized in the body to A-849529, a hydrophilic metabolite that includes both carboxyl and amino groups. Poor solubility of ABT-869 in aqueous matrix causes simultaneous analysis of both ABT-869 and its metabolite within the same extraction and injection to be extremely difficult in human urine. In this paper, a high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method has been developed and validated for high-speed simultaneous quantitation of the hydrophobic ABT-869 and its hydrophilic metabolite, A-849529, in human urine. The deuterated internal standards, A-741439D(4) and A-849529D(4), were used in this method. The disparate properties of the two analytes were mediated by treating samples with acetonitrile, adjusting pH with an extraction buffer, and optimizing the extraction solvent and mobile phase composition. For a 100 microL urine sample volume, the lower limit of quantitation was approximately 1 ng/mL for both ABT-869 and A-849529. The calibration curve was linear from 1.09 to 595.13 ng/mL for ABT-869, and 1.10 to 600.48 ng/mL for A-849529 (r2 > 0.9975 for both ABT-869 and A-849529). Because the method employs simultaneous quantification, high throughput is achieved despite the presence of both a hydrophobic analyte and its hydrophilic metabolite in human urine.

A high-throughput, fully automated liquid/liquid extraction liquid chromatography/mass spectrometry method for the quantitation of a new investigational drug ABT-869 and its metabolite A-849529 in human plasma samples.

ABT-869 is a novel ATP-competitive inhibitor for all the vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptor tyrosine kinases (RTKs). It is one of the oncology drugs in development at Abbott Laboratories and has great potential for enhanced anti-tumor efficacy as well as activity in a broad range of human cancers. We report here an accurate, precise and rugged liquid chromatography/mass spectrometry (LC/MS/MS) assay for the quantitative measurement of ABT-869 and its acid metabolite A-849529. A fully automated 96-well liquid/liquid extraction method was achieved utilizing a Hamilton liquid handler. The only manual intervention required prior to LC/MS/MS injection is to transfer the 96-well plate to a drying rack to dry the extracts then transfer the plate back to the Hamilton for robotic reconstitution. The linear dynamic ranges were from 1.1 to 598.8 ng/mL for ABT-869 and from 1.1 to 605.8 ng/mL for A-849529. The coefficient of determination (r2) for all analytes was greater than 0.9995. For the drug ABT-869, the intra-assay coefficient of variance (CV) was between 0.4% and 3.7% and the inter-assay CV was between 0.9% and 2.8%. The inter-assay mean accuracy, expressed as percent of theoretical, was between 96.8% and 102.2%. For the metabolite A-849529, the intra-assay CV was between 0.5% and 5.1% and the inter-assay CV was between 0.8% and 4.9%. The inter-assay mean accuracy, expressed as percent of theoretical, was between 96.9% and 100.6%.