ACD856, a novel positive allosteric modulator of Trk receptors, single ascending doses in healthy subjects: Safety and pharmacokinetics

PURPOSE

AlzeCure Pharma AB is developing novel positive allosteric modulators of Trk-receptors for treatment of Alzheimer's disease, depression, other psychiatric conditions and other disorders where cognition is impaired. The preceding candidate drug ACD855 was shown to have a too long half-life in humans to allow further development. To de-risk the development of the follow-up compound ACD856, the oral single ascending dose study of ACD856 in humans was preceded by an intravenous microdose study, assessing the elimination half-life in plasma.

METHODS

A phase 0 study with a microdose of ACD856 (0.100 mg), was conducted in six healthy male subjects all receiving ACD856. Sequentially, a randomized, placebo-controlled, double-blind Phase I single ascending oral dose study (1 - 150 mg) was conducted, including 56 healthy subjects. Both studies assessed the safety and tolerability, as well as the PK properties of ACD856 after single dose intravenous and oral administration.

RESULTS

ACD856 was well tolerated with no treatment emergent, or dose related adverse events or other safety assessments. In the microdose study, ACD856 exhibited a bi-exponential plasma decline, low distribution volume, low plasma clearance with a half-life of approximately 20 hours. Orally, ACD856 exhibited rapid absorption, an almost complete bioavailability and a dose proportional increase in exposure. While the Cmax was lowered and delayed by food intake, the effect on plasma half-life and the overall bioavailability was low. No renal elimination of ACD856 was detected.

CONCLUSION

The prediction proved accurate demonstrating the value of conducting a microdose study prior to ascending dose studies.

TRIAL REGISTRATION

NCT05783830 March 24, 2023 (microdose study, retrospectively registered) and NCT05077631 October 14, 2021 (single ascending dose study).

Safety, Tolerability, Pharmacokinetics and Quantitative Electroencephalography Assessment of ACD856, a Novel Positive Allosteric Modulator of Trk-Receptors Following Multiple Doses in Healthy Subjects

BACKGROUND

ACD856 is a positive allosteric modulator of tropomyosin receptor kinase (Trk) receptors which has shown to have pro-cognitive and anti-depressant-like effects in various animal models. It is currently in clinical development for the treatment of Alzheimer's disease and other disorders where cognition is impaired and is also considered for indications such as depression or other neuropsychiatric diseases. ACD856 has a novel mechanism of action modulating the activity of the Trk-receptors, resulting in increased stimulation of the neurotrophin signaling pathways. Previous studies applying single intravenous and oral doses of ACD856 indicate that ACD856 is safe and well-tolerated by healthy volunteer subjects, and that it has suitable safety and pharmacokinetic properties for further clinical development.

OBJECTIVES

To investigate the safety and tolerability of 7 days of treatment with multiple ascending oral doses of ACD856 in healthy subjects, and to characterize its pharmacokinetic (PK) properties. In addition, pharmacodynamic effects of ACD856 using quantitative electroencephalography (qEEG) as an indicator for central target engagement were assessed.

DESIGN

This was a prospective, phase I, double-blind, parallel-group, placebo-controlled, randomized study of the safety, tolerability, PK and pharmacodynamics of multiple ascending oral doses of ACD856 in healthy subjects. ACD856 or placebo were administered in 3 ascending dose cohorts of 8 subjects. Within each cohort, subjects were randomized to receive either ACD856 (n=6) or placebo (n=2).

SETTING

The study was conducted at a First-in-Human unit in Sweden.

PARTICIPANTS

Twenty-four healthy male and female subjects.

INTERVENTION

The study medication was administered as an oral solution, with ACD856 or the same contents without the active ingredient (placebo). The dose levels ranged from 10 mg to 90 mg. ACD856 was administered once daily for 7 days, targeting steady state.

MEASUREMENTS

Safety and tolerability assessments included adverse events, laboratory, vital signs, 12-lead electrocardiogram (ECG), physical examination, assessment of stool frequency and questionnaires to assess symptoms of anxiety, depression, as well as suicidal ideation and behavior. In addition, cardiodynamic ECGs were extracted to evaluate cardiac safety. PK parameters were calculated based on measured concentrations of ACD856 in plasma, urine, and cerebrospinal fluid (CSF) samples. Metabolite profiling, characterization and analysis was performed based on and urine samples. qEEG was recorded for patients in the two highest dose cohorts (30 and 90 mg/day) as a pharmacodynamic assessment to explore central target engagement.

RESULTS

Treatment with ACD856 was well tolerated with no serious adverse events. No treatment emergent or dose related trends were observed for any of the safety assessments. ACD856 was rapidly absorbed and reached maximum plasma exposure at 30 to 45 minutes after administration. Steady state was reached before Day 6, with an elimination half-life at steady state of approximately 20 hours. At steady state, ACD856 exhibited accumulation ratios for Cmax and AUC of approximately 1.6 and 1.9 respectively. The exposure, Cmax and AUC0-24, increased proportionally with the dose. There was no unchanged ACD856 detected in urine. The metabolic pattern in urine and plasma was similar, and in alignment with the metabolites observed in preclinical toxicology studies. The level of ACD856 measured in CSF at steady state increased with dose, indicating Central Nervous System (CNS) exposure at relevant levels for pharmacodynamic effects. ACD856 demonstrated significant dose-dependent treatment-associated changes on qEEG parameters. Specifically, increase of the relative theta power and decrease of the fast alpha and beta power was observed, leading to an acceleration of the delta+theta centroid and an increase in the theta/beta ratio.

CONCLUSIONS

ACD856 was well tolerated at the tested dose levels (10-90 mg/daily for 7 days) in healthy subjects. The compound has a robust pharmacokinetic profile, with rapid absorption and dose-dependent exposure. ACD856 was shown to pass the blood-brain-barrier, reach relevant exposure in the CNS and to induce dose-dependent treatment-related changes on qEEG parameters, indicating central target engagement.

First-in-Human Study to Assess the Safety, Tolerability, and Pharmacokinetics of Pirepemat, a Cortical Enhancer, in Healthy Volunteers

Pirepemat (IRL752) is a cortical enhancer being developed for the prevention of falls in patients with Parkinson disease. This first-in-human, randomized, double-blind, placebo-controlled phase 1 study evaluated safety, tolerability, and pharmacokinetics (PK) of pirepemat administered as oral single ascending doses (10, 35, 75, 175, 350 mg) and multiple ascending doses (100 and 250 mg 3 times daily) for 7 days to healthy male volunteers. Twenty and 24 subjects were randomly assigned in the single ascending dose and multiple ascending doses parts of the study, respectively. Pirepemat was generally well tolerated, although an increased frequency of adverse events of mild intensity within nervous system disorders (headache and dizziness) was seen after administration of 350 mg as a single dose and after multiple doses of 100 and 250 mg. PK of pirepemat showed a linear relationship over the dose range studied and exhibited dose proportionality after multiple-dose administration. Accumulation after 7 days of multiple dosing was minor. Absorption was rapid, with a median time to maximum concentration of 2.0 hours on day 1 and day 7 (100 and 250 mg) and a mean terminal half-life between 3.7 and 5.2 hours. Food intake had no (obvious) impact on PK. The results support 3-times-daily dosing and further clinical development.