Study Design
This study was a prospective, double-masked, randomized, placebo-controlled, parallel-group, phase 2 study that evaluated efficacy and safety of three concentrations (0.01%, 0.02%, and 0.04%) of netarsudil ophthalmic solution over a 4-week treatment period in Japanese patients at least 20 years of age with POAG or OHT. The study was conducted at 25 sites in Japan from March 19, 2019 to September 19, 2019 (registered with ClinicalTrials.gov as NCT03844945). All study-related documents were reviewed and approved by appropriate ethics committees (Table S1 in the supplementary material). The study was conducted in accordance with ethical principles based on the Declaration of Helsinki and the guidance stipulated in Article 14, Paragraph 3, and Article 80–2 of the Pharmaceuticals, Medical Devices and Other Therapeutic Products Act of Japan, Ministry of Health, Labour and Welfare (MHLW) Ordinance on Good Clinical Practice (MHLW Ordinance No. 28 [March 27, 1997]), International Council for Harmonization Guideline E6 (R2), the study protocol, and the standard operating procedures. All patients provided their written informed consent before participating in the study.
The patients attended a total of six study visits, including the screening visit (visit 1), qualification visit 1 (visit 2, after a washout period of pre-study ocular hypotensive medication varying from 5 days to at least 6 weeks; 5 days for muscarinic agonists or carbonic anhydrase inhibitors; 2 weeks for adrenergic agonists; 4 weeks for prostaglandins or β-adrenoceptor antagonists; 6 weeks for Rho kinase inhibitor), qualification visit 2/day 1/baseline (visit 3; 2–7 days after qualification visit 1), and post-treatment visits at week 1 (visit 4; day 8 ± 2 days), week 2 (visit 5; day 15 ± 3 days), and week 4 (visit 6; day 29 ± 3 days). Those patients who met the study eligibility criteria at screening visit and qualification visits 1 and 2 were considered eligible to participate in the study. All the eligible patients were enrolled at qualification visit 2 (day 1) and were randomized (1:1:1:1) by a computer-generated randomization list using an interactive web response system to receive the placebo or netarsudil ophthalmic solution 0.01%, 0.02%, or 0.04%. The study medication was dosed (one drop) into each eye QD in the evening (between 8 and 10 p.m.), beginning on day 1 and up to and including the evening before week 4.
Patients and designated study site personnel (investigators, sponsor, monitor, data manager, statistician, and personnel involved in study management) were fully masked to treatment assignments. Patients were permitted to have intermittent use of artificial tear lubricant products (a gap of at least 10 min between the use of artificial tear lubricant products and the study medication) and wear contact lenses (a gap of 30 min between the contact lens wear and instillation of study medication). Patients were prohibited to use any form of ocular hypotensive medications; miotics; epinephrine-related compounds; carbonic anhydrase inhibitors; α- and β-adrenoceptor antagonists; muscarinic agonists; ocular prostaglandins analogues; ROCK inhibitors; any corticosteroids containing ocular or systemic drug; or systemic medications known to cause corneal deposits or cornea verticillata.
Procedures included efficacy (IOP) and safety assessments, including ocular symptoms/adverse events (AEs); National Eye Institute Visual Function Questionnaire (VFQ-25); contrast sensitivity (CS) testing; best corrected visual acuity (BCVA); biomicroscopic examinations of the eyelids, conjunctiva, cornea, anterior chamber, iris, pupil, and lens of the eye; dilated ophthalmoscopy examination of the retina, vitreous, macula, choroid, optic nerve, and vertical cup/disc ratio; vital signs (heart rate and blood pressure); and clinical laboratory assessments (urine pregnancy test, blood chemistry, hematology, and urinalysis). The IOP was measured at screening visit, qualification visit 1, and day 1 and weeks 1, 2, and 4 (9
a.m. + 30 min, 11
a.m. + 30 min, and 4
p.m. ± 30 min) at all study visits using a calibrated Goldmann applanation tonometer (the most clinically accurate and the standard tonometer used in the diagnosis and treatment of glaucoma [
3]). Two consecutive IOP measurements of each eye were obtained at each time point. If the two measurements differed by more than 2 mmHg, a third measurement was obtained. The IOP was recorded as the mean of two measurements or the median of three measurements [
36]. AEs were collected from the time of administration until 30 days after the last dose of study medication. The VFQ-25 (Japanese version) and CS testing were done at day 1; BCVA and vitals at screening visit, qualification visit 1, and day 1 and weeks 1, 2, and 4; biomicroscopy at screening visit, qualification visit 1, and day 1 and weeks 1, 2, and 4; dilated ophthalmoscopy at screening visit and week 4; and clinical laboratory tests at screening visit and week 4.
CS was assessed using the CSV-1000E test at the recommended test distance of 8 ft (2.5 m), and at the spatial frequencies of 3, 6, 12, and 18 cycles/degree. BCVA was measured using a Landolt-C chart or its equivalents, at a distance as per the site’s standard practice, with the patient’s best correction from the manifest refraction in place. A decrease in BCVA of three lines or more in visual acuity from baseline was defined as clinically significant. The BCVA assessment preceded IOP measurements and the administration of topical anesthetic agents, or any examination requiring contact with the anterior segment. Biomicroscopic abnormal findings were graded on scales of 0 (none) to 3 (severe), or 0–4 (cells and cornea verticillata), and lens status was reported as phakic, pseudophakic, or aphakic; and dilated ophthalmoscopy findings were assessed as 0 (normal) or 1 (abnormal). The cup/disc ratio was scored on a scale of 0.1 to 1.0 in 0.1 increments. A change of 0.2 units from baseline in either eye was considered as clinically significant.
Patients
Eligible patients had a diagnosis of POAG or OHT in both eyes or POAG in one eye and OHT in another (fellow) eye; age at least 20 years; medicated IOP 14 mmHg or higher in at least one eye and less than 30 mmHg in both eyes at the screening visit; BCVA 0.1 or better in the decimal unit using Landolt-C chart or its equivalent (+ 1.0 logMAR or better by Early Treatment of Diabetic Retinopathy Study or 20/200 or better by Snellen chart); and were able and willing to provide signed informed consent and follow study instructions. The unmedicated (post washout) IOP for POAG eyes was at least 15 mmHg and less than 35 mmHg in the study eye and for OHT eyes, it was at least 22 mmHg and less than 35 mmHg in the study eye at qualification visit 1 (9 a.m.) and qualification visit 2 (9 a.m., 11 a.m., and 4 p.m.).
Patients were excluded from entry into the study if they had clinically significant ocular disease; pseudoexfoliation or pigment dispersion glaucoma, history of angle closure or narrow angles; ocular hyperemia score of moderate (+ 2) or severe (+ 3) at day 1; previous intraocular glaucoma or refractive surgery in either eye; ocular trauma within 6 months or ocular surgery or non-refractive laser treatment within 3 months prior to screening; evidence of ocular infection or inflammation in either eye, clinically significant blepharitis, conjunctivitis, keratitis or a history of herpes simplex or zoster keratitis in either eye at screening; any corneal disease or condition in either eye that in the investigator’s opinion may have confounded assessment of the cornea; current evidence of corneal deposits or cornea verticillata in either eye; use of ocular medication in either eye within 30 days of screening and throughout the study with the exception of ocular hypotensive medications, lid scrubs, lubricating drops, non-steroid allergy drops, cataract medicinal treatment, and topical nutritional supplement; mean central corneal thickness greater than 620 μm in either eye at screening; any abnormality preventing reliable applanation tonometry of either eye; known hypersensitivity to benzalkonium chloride or excipients of netarsudil ophthalmic solution; or cannot demonstrate proper delivery of the eye drop or in the investigator’s opinion unable to deliver the eye drop consistently. Patients were also excluded from the study if they were currently using systemic medications known to cause corneal deposits or cornea verticillata; had clinically significant abnormalities in laboratory tests at screening or clinically significant systemic disease which might have interfered with the study; had participated in any interventional study within 30 days before screening; or had used systemic medication(s) that could have had a substantial effect on IOP within 30 days before screening, or that were anticipated during the study, including any corticosteroid-containing drug regardless of route of administration. Women of childbearing potential who were pregnant, nursing, planning a pregnancy, or not using a medically acceptable form of birth control were also excluded from the study. All women of childbearing potential must have a negative urine pregnancy test result at the screening examination and must not intend to become pregnant during the study.
Statistical Analysis
The statistical analyses were conducted using SAS® (SAS Institute, Cary, North Carolina, USA), version 9.4. The intent-to-treat (ITT) population was used for efficacy analyses where the ITT population included all randomized patients who received at least one dose of the study medication.
The analysis of the primary efficacy variable employed an analysis of covariance (ANCOVA) model with mean diurnal IOP at week 4 as the response, baseline mean diurnal IOP as a covariate, and treatment as the main effect, using the ITT population with Monte Carlo Markov chain multiple imputation techniques to impute the missing data. The ANCOVA model explains additional variability (i.e., reduces standard error) through inclusion of baseline covariates and therefore improves statistical power. The LS means calculated from this model are the means adjusted for the covariate. LS means are better estimates of true population means compared to arithmetic means. The LS mean difference (netarsudil − placebo) was calculated separately for netarsudil 0.01%, 0.02%, and 0.04% as well as two-sided p values and 95% confidence intervals (CIs). Superiority for netarsudil concentration (0.01%, 0.02% and 0.04%) was concluded if the two-sided p value for testing the LS mean difference (netarsudil − placebo) to 0 was less than 0.05 and the point estimate of the LS mean difference was less than 0 at week 4. A similar ANCOVA model to the primary variable was used for the analysis of mean diurnal IOP at weeks 1 and 2 and IOP at each post-treatment time point. The change in IOP was tested using a two-sample t test and 95% t distribution CIs on the difference. Fisher’s exact test (two-sided p values) was used to test differences between netarsudil (0.01%, 0.02%, 0.04%) versus placebo for each category (number and percentage of study eyes obtaining a mean diurnal IOP of ≤ 22 to ≤ 14 mmHg, mean diurnal IOP reduction from baseline of ≥ 4 to ≥ 12 mmHg, and mean diurnal IOP percentage reduction from baseline of ≥ 5% to ≥ 40%) at each visit.
The safety analyses were done on the safety population, which included all randomized (as treated) patients who received at least one dose of study medication. The AEs were coded using the Medical Dictionary for Regulatory Activities/Japanese translation version 21.1. The other safety variables were summarized by the descriptive statistics where all continuous study assessments were summarized by number of observations (n), arithmetic mean, standard deviation (SD), median, and range (minimum, maximum) and the categorical study assessments were summarized by frequency counts and percentages.
The sample size was based on assumptions of a two-sided test with alpha = 0.05, a common SD of 3.5 mmHg at each time point yielding a common SD of 3.0 for the mean diurnal IOP, and a correlation among time points of 0.60. It was estimated that 49 patients per arm in the ITT population would yield at least 90% power to demonstrate superiority (assuming a difference of at least 2.0 mmHg) in the mean diurnal study eye IOP of netarsudil (0.01%, 0.02%, or 0.04%) to placebo at week 4. Accounting for approximately 5.0% discontinuation rate, 52 patients per arm (208 total) were planned for enrollment.