Safety, tolerability, pharmacokinetics and effect on serum uric acid of the myeloperoxidase inhibitor AZD4831 in a randomized, placebo‐controlled, phase I study in healthy volunteers

Aims Myeloperoxidase activity can contribute to impaired vascular endothelial function and fibrosis in chronic inflammation‐related cardiovascular disease. Here, we investigated the safety, tolerability and pharmacokinetics of the myeloperoxidase inhibitor, AZD4831. Methods In this randomized, single‐blind, placebo‐controlled, phase I, first‐in‐human study, healthy men in five sequential cohorts were randomized 3:1 to receive a single oral dose of AZD4831 (5, 15, 45, 135 or 405 mg) or placebo, after overnight fasting. After at least 7 days' washout, one cohort additionally received AZD4831 45 mg after a high‐calorie meal. Results Forty men participated in the study (eight per cohort: AZD4831, n = 6; placebo, n = 2). AZD4831 distributed rapidly into plasma, with a half‐life of 38.2–50.0 hours. The area under the plasma concentration–time curve (AUC) increased proportionally with dose (AUC0–∝ slope estimate 1.060; 95% confidence interval [CI] 0.9943, 1.127). Increases in maximum plasma concentration were slightly more than dose proportional (slope estimate 1.201; 95% CI 1.071, 1.332). Food intake reduced AZD4831 absorption rate but did not substantially affect overall exposure or plasma half‐life (n = 4). Serum uric acid concentrations decreased by 71.77 (95% CI 29.15, 114.39) and 84.42 (58.90, 109.94) μmol L−1 with AZD4831 135 mg and 405 mg, respectively. Maculopapular rash (moderate intensity) occurred in 4/30 participants receiving AZD4831 (13.3%). No other safety concerns were identified. Conclusions AZD4831 was generally well tolerated, rapidly absorbed, had a long plasma half‐life and lowered uric acid concentrations after single oral doses in healthy men. These findings support the further clinical development of AZD4831.


| INTRODUCTION
Myeloperoxidase is an emerging therapeutic target in the development of new treatments for inflammation-related cardiovascular diseases. The principal function of myeloperoxidase is to mediate the oxidative killing of microbes in neutrophil phagolysosomes. Some myeloperoxidase is, however, also released into the extracellular space, where its oxidative activity can contribute to tissue damage, fibrosis and impaired vascular endothelial function. [1][2][3] Extracellular myeloperoxidase binds with high avidity to negatively charged proteoglycans on the surface of vascular endothelial cells. 4,5 This blood vessel-associated myeloperoxidase can locally deplete nitric oxide, inhibit vasodilation and mediate the recruitment of circulating leukocytes, with resulting amplification of local inflammation. 2,6 Long-term elevation of myeloperoxidase activity may be involved in the development of cardiovascular disease in humans.
Leukocyte numbers and blood levels of myeloperoxidase are elevated in patients with coronary artery disease. 7 In patients with acute coronary syndromes or chronic heart failure, high plasma levels of myeloperoxidase are associated with advanced disease and an increased risk of future cardiovascular events. [8][9][10] Furthermore, increased incidence of atrial fibrillation is associated with elevated plasma levels of myeloperoxidase in patients with pacemakers. 1 Conversely, individuals with low myeloperoxidase levels are resistant to inflammation-induced endothelial dysfunction. 11 Inhibition of myeloperoxidase is associated with reduced plasma concentrations of uric acid, 12 a marker of oxidative stress and chronic inflammation. Uric acid levels are elevated in people with cardiovascular disease, and high levels are associated with vascular dysfunction and cardiovascular mortality. [13][14][15] Inhibiting myeloperoxidase may therefore provide therapeutic benefit in patients with cardiovascular diseases, by limiting impairment of vascular function and the subsequent development of fibrosis.
The canonical enzymatic activity of myeloperoxidase is the oxidation of chloride ions (Cl − ) in the presence of hydrogen peroxide (H 2 O 2 ) to produce hypochlorous acid (HOCl), which mediates the bactericidal effect. 16 Myeloperoxidase can also oxidize a range of other physiological substrates, 17 including tyrosine, 18  Here, we report the results from a first-in-human, phase I study of the safety, tolerability and pharmacokinetics of single ascending doses of AZD4831 in healthy volunteers. The study also assessed serum uric acid levels as an exploratory pharmacodynamic outcome.

| Overview and objectives
This was a randomized, single-blind, placebo-controlled, phase I, firstin-human study of the safety and tolerability of the myeloperoxidase inhibitor, AZD4831, in healthy male volunteers (ClinicalTrials.gov identifier: NCT02712372). The study was originally designed to include a single ascending dose period and a multiple ascending dose period.
Based on results and experience from the single ascending dose period, the multiple ascending dose period was cancelled.
Multiple ascending doses in healthy volunteers were later tested in a separate study (ClinicalTrials.gov identifier: NCT03136991; to be reported elsewhere).
The study included two parts. In part A, sequential cohorts of participants received a single oral dose of AZD4831 or placebo under fasting conditions. In part B, one cohort of participants who had already received AZD4831 in part A then received a second single oral dose of AZD4831 under fed conditions.
The primary objective of the study was to evaluate the safety and tolerability of AZD4831 in healthy volunteers. Secondary objectives were to characterize the pharmacokinetics of AZD4831 and to investigate the effect of food intake on the pharmacokinetics. Evaluation of the pharmacodynamics of AZD4831 by assessment of uric acid concentration in serum was an exploratory objective.
What is already known about this subject • Myeloperoxidase activity in blood vessels can contribute to impaired vascular endothelial function and fibrosis.
• Elevated plasma myeloperoxidase levels are associated with increased cardiovascular morbidity and mortality in humans.
• Vessel-associated myeloperoxidase is a promising therapeutic target for the treatment of chronic inflammation-related cardiovascular disease.
What this study adds • AZD4831 was well tolerated, with moderate maculopapular rash as the only identified risk.
• AZD4831 administration decreased serum uric acid concentrations; these findings support the further clinical development of AZD4831.

| Conduct and ethics
The study took place between June 2016 and October 2016 at the PAREXEL Early Phase Clinical Unit in Berlin, Germany. It was conducted in accordance with the principles of the Declaration of Helsinki and the International Conference on Harmonisation and Good Clinical Practice. An independent ethics committee and institutional review board reviewed and approved the study protocol and its amendments.
All participants freely gave their written informed consent before starting the study. The study was registered with ClinicalTrials.gov (identifier: NCT02712372).

| Participants
Male volunteers, aged 18-50 years, weighing 50-100 kg and with a body mass index (BMI) of 18-29.9 kg m −2 , were eligible for the study.
Key exclusion criteria were: a history or presence of any disease or disorder that might influence study participation or results; a history or presence of any condition known to interfere with the absorption, distribution, metabolism or excretion of drugs, including gastrointestinal, hepatic or renal disease; the presence of infection; and a history or presence of thyroid disease. Volunteers with clinically significant abnormalities in vital signs, laboratory analyses or electrocardiogram findings were excluded from the study, as were those with any clinically significant illness, medical procedure or trauma within the previous 4 weeks.

| Part B: open-label, food effect evaluation stage
After a washout period of at least 7 days, participants who had received AZD4831 45 mg in cohort 3 in part A received a second dose of AZD4831 45 mg immediately after a high-calorie, high-fat breakfast. This dose was selected by the Safety Review Committee based on all available data for one or more higher doses in part A. Participants once again resided at the study centre until 48 hours postdose and attended a follow-up visit 7-10 days after dosing.

| Safety and tolerability outcomes
Safety assessments included adverse event (AE) monitoring, vital signs monitoring (systolic and diastolic blood pressure, pulse rate), electrocardiography, physical examinations and laboratory assessments (haematology, clinical chemistry and urinalysis).  When normalized to dose, AUC 0-∞ and C max were dose proportional in the range 45-405 mg and supra-proportional below 45 mg ( Figure 2). Coefficients of variation in AUC 0-∞ and C max were generally below 25% at doses of 45 mg or below (Table 1). Mean clearance rate and volume of distribution were similar across the entire dose range (Table 1).

| Effect of food intake on plasma pharmacokinetics of AZD4831
Administration of AZD4831 45 mg immediately after a high-fat, high-calorie meal led to a reduced rate of absorption compared with administration under fasting conditions ( Figure 1B; Table 1). C max was reduced by 44% and t max was delayed by 2.5 hours. Food intake before dosing also slightly reduced AUC 0-∞ and slightly increased t 1/2λz (Table 1).

| Urinary pharmacokinetics of AZD4831 under fasted conditions
The mean fraction of the AZD4831 dose excreted in urine over the first 48 hours was similar across the doses tested, ranging from 28.0% to 32.3%. Mean renal clearance ranged from 8.882 L h −1 (AZD4831 405 mg) to 15.42 L h −1 (AZD4831 5 mg) ( Table 1).

| Adverse events
In part A, 21 AEs in total were reported in 12/30 volunteers who received AZD4831 (40.0%) and 4/10 volunteers who received  one received treatment with topical methylprednisolone and one did not receive any treatment. The participant who experienced maculopapular rash in the AZD4831 45 mg cohort was withdrawn from the study before part B (with protocol noncompliance as the reason for discontinuation). AEs of maculopapular rash had a duration of 5-9 days and were reported 7-9 days after dosing; all had resolved by the end of the study.

| Laboratory and physical assessments
There were no systemic or dose-related changes in clinical chemistry (Table S1), haematology (Table S2) (Table S1). There were no clinically significant changes in vital signs or electrocardiography parameters during the study (Table S3).

| DISCUSSION
Myeloperoxidase inhibitors hold therapeutic potential as novel treat- Uric acid generation from purines is augmented by tissue hypoxia, and has been reported to be increased in the cardiac tissue of patients with heart failure. 13 This suggests an alternative or additional potential mechanism for reduced uric acid levels following AZD4831 inhibition of myeloperoxidase. A reduction in vascular myeloperoxidase activity could lead to increased nitric oxide bioavailability, which may improve vascular endothelial function and tissue perfusion, 11 with a resulting decrease in hypoxia-dependent uric acid generation from purines.   Whether this mechanism contributed to the reduced uric acid levels seen in the current study in healthy volunteers is unclear, as is whether greater effects on uric acid would been seen in patients with hypoxia. The present study did not aim to investigate the mechanisms underlying the effects of AZD4831 in the exploratory pharmacodynamic assessments. The phase I multiple ascending dose study of AZD4831 in healthy volunteers (ClinicalTrials.gov identifier: NCT03136991) will provide additional data on uric acid levels over a 10-day treatment period. Future studies will aim to investigate the mechanism of AZD4831-mediated uric acid reduction by comparing functional and biochemical outcomes. A planned study in patients referred for cardiac catheterization (ClinicalTrials.gov identifier: NCT03611153) will assess the effect of AZD4831 on haemodynamics, exercise capacity and endothelial function.
The present study provided clear pharmacokinetic parameters and the first safety data for AZD4831 in healthy human volunteers. The following aspects of the study should be borne in mind when interpreting the results. The number of participants in the study was the smallest required to meet study objectives without unnecessarily placing healthy volunteers at potential risk from an investigational drug. The study design did not anticipate the long half-life of AZD4831, which resulted in amendment of the sampling schedule after the first cohort, to include additional time points. Finally, the study was not designed to assess the pharmacodynamics of AZD4831, except as an exploratory objective.
This first study of AZD4831 in humans revealed that oral administration led to rapid and dose-dependent absorption, with generally low interparticipant variability in systemic exposure. AEs were mild or moderate, with maculopapular rash identified for monitoring in future studies.
These findings support the further clinical development of AZD4831 as a treatment for chronic, inflammatory cardiovascular diseases.