Discussion
In this first-in-human single ascending dosing (SAD) and multiple ascending dosing (MAD) study, we investigated the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of Org 48775-0 in healthy volunteers. This study demonstrates that Org 48775-0 has the capacity to significantly inhibit MAP-kinase activity in humans, without raising safety concerns. Single and multiple dose administration of Org 48775-0 to healthy volunteers did not result in any clinical significant changes in vital signs, ECG-parameters and laboratory parameters. There were no indications for any change in liver enzymes, signs of bone marrow depression, or infections. All adverse events were mild, transient and completely reversible without medical intervention. Special attention was paid to ALAT since increases in the level of this transaminase are most directly associated with hepatocyte injury, and the development of other MAP-kinase inhibitors was terminated due to hepatic safety issues.[13, 22] Org 48775-0 was rapidly absorbed and eliminated. Pharmacokinetics were linear up to a dose of 400 mg.
Results further indicate that Org 48775-0 doses equal to and greater than 30 mg significantly inhibited LPS-induced TNFα release, compared to placebo. Maximal drug effect was observed at a dose level of 200 mg, with an inhibition of 87% lasting from 1-4 hours after drug administration, which is in line with the pharmacokinetic behaviour of Org 48775-0. Doses of 400 mg and 600 mg did not induce a stronger or longer-lasting inhibition of TNFα release compared to 200 mg. Thein vitro Org 48775-0 effect, based on concentration-inhibition curves generated for each study participant in a pre-dose blood sample, very well predicted the ex vivo effect of the compound. After multiple dosing, Org 48775-0 treatment inhibited the LPS-induced TNFα release during the entire steady state period. Levels of inhibition amounted 30-75% for 30 mg, 53-80% for 70 mg, and 77-92% for 150 mg Org 48775-0. TNFα release returned to baseline levels within 3 days after the final administration of Org 48775-0.
In addition to the evaluation of the effects of single and multiple doses of Org-48775-0 in healthy males, the effect of food on the PK/PD characteristics of Org 48775-0 was evaluated, and potential differences in drug effect between genders were studied. In line with preclinical data, food intake resulted in an altered pharmacokinetic profile. Tmax was increased (3.3 versus 1.6 hours) and Cmax decreased (3810 versus 4490 ng/mL), without a relevant effect on AUC. The pharmacokinetic behavior of Org 48775-0 for females was comparable to males, with a slightly longer T1/2 and higher Cmax. Food intake did not have a significant effect on Org 48775-0 activity, indicating that differences in plasma lipid levels did not impact TNFα release after LPS stimulation in our study. Previous studies reported a potential dampening effect of lipids on LPS-driven inflammation due to a neutralization of the trigger, potentially via lipoprotein binding.[23, 24].
Literature suggests a potential gender difference in cytokine release after stimulation with LPS, male donors having a higher cytokine release than female donors.[23,24] Although our data do not show a significant difference in LPS response between postmenopausal females and males at baseline (possibly due to the relatively small sample size), the TNFα response in males was higher (436 pg/mL versus 305 pg/mL), which is in line with these reports. The maximal inhibition of the LPS-induced TNFα release by Org 48775-0 was comparable between males and post-menopausal females. However, the overall inhibition was smaller in the post-menopausal females compared to the males, as demonstrated by a significant difference in the 0-72 hrs inhibition profiles. This was in line with normalized in vitro inhibition curves, showing a higher EC50 for Org 48775-0 in females than in males (0.88 µM versus 0.64 µM).
In summary, this study demonstrates that Org 48775-0 administration did not raise safety concerns in healthy human volunteers. A whole blood-based biomarker, LPS-induced TNFα release, was used for evaluation of the pharmacodynamic activity of the investigational compound, bothin vitro and ex vivo . This biomarker showed that Org 48775-0 has the capacity to significantly inhibit MAP-kinase activity in humans, and that the compound exerted its maximal effect at concentrations exceeding 5000 ng/mL, occurring at dose levels of 100 mg and higher. Based on the pharmacodynamic activity of Org 48775-0ex vivo , the optimal dose and regimen for a phase 1B/2 study in the target population can be selected.