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.