Pharmacokinetics, Safety, and Tolerability of GLPG0259, a Mitogen-Activated Protein Kinase-Activated Protein Kinase 5 (MAPKAPK5) Inhibitor, Given as Single and Multiple Doses to Healthy Male Subjects

BACKGROUND AND OBJECTIVES: GLPG0259 is a small-molecule inhibitor of mitogen-activated protein kinase-activated protein kinase 5 (MAPKAPK5), a kinase enzyme that plays a role in important inflammatory pathways. The main objectives of the phase I clinical studies in early development were to characterize the pharmacokinetics, tolerability, and safety of GLPG0259 in healthy subjects, including the development of a solid dosage form (free-base pellets and fumarate salt capsules) and the potential for interaction of GLPG0259 with methotrexate. SUBJECTS AND METHODS: Four phase I studies were initiated. Study 1 was a randomized, double-blind, placebo-controlled study to evaluate the safety, tolerability, and pharmacokinetics of single ascending doses (1.5-150 mg) and multiple oral doses (20 and 50 mg once daily) of GLPG0259 in healthy male subjects (n = 34). Study 2 was a randomized, double-blind, placebo-controlled study to evaluate the safety, tolerability, and pharmacokinetics of oral multiple ascending doses of GLPG0259 (25-75 mg once daily) given for 14 days to healthy male subjects, and to get preliminary information on the potential pharmacokinetic interaction between GLPG0259 and methotrexate (n = 24). Studies 3 and 4 were open-label, randomized, crossover studies to compare the oral bioavailability of two solid dosage forms of GLPG0259 (a capsule) relative to an oral solution after a 100 mg or 50 mg single dose and to evaluate the effect of food on these formulations (n = 12 for each study). MAIN OUTCOME MEASURES: The non-compartmental pharmacokinetic parameters for plasma concentrations of GLPG0259 were determined, and a population pharmacokinetic model of GLPG0259 was developed to support the planning of the number and timing of the sparse samples to be taken per patient in the phase II study. Safety and tolerability data are also summarized. RESULTS: The absorption of GLPG0259 was slow, with a decrease in the absorption rate with increasing dose, and there was decreased elimination, with an apparent terminal elimination half-life of 26.0 hours. On the basis of statistical analysis of variance, the exposure to GLPG0259 increased in proportion to the dose over a 30-150 mg single-dose range and a 25-75 mg repeated-dose range. Between- and within-subject variability in GLPG0259 pharmacokinetics was low/moderate (coefficient of variation [CV] 16-30%). After once-daily repeated dosing, steady-state plasma concentrations were reached at between 5 and 8 dosing days, which is consistent with the long apparent elimination half-life of GLPG0259. Food increased the bioavailability of GLPG0259 given in a solid dosage form. Co-administration of GLPG0259 with a single dose of methotrexate 7.5 mg did not result in any change in the pharmacokinetic profiles of either GLPG0259 or methotrexate. CONCLUSION: In summary, the investigation of safety/tolerability and pharmacokinetics in the early development phase showed that single and repeated doses of GLPG0259 were safe and well tolerated. The most common adverse event reported was mild gastrointestinal discomfort. The pharmacokinetics characterized in healthy male subjects showed no major obstacles and supports a once-daily oral regimen in patients.