Subjects
This was a phase 1, randomized, double-blind, placebo-controlled, single-center, safety and tolerability study of multiple rising doses of TAK-063 in HJS and SSS. The study site was in compliance with institutional review board (IRB) regulations, Good Clinical Practice regulations and guidelines, and all applicable local regulations. The study protocol was approved by the appropriate local IRB for each site.
Subjects aged 20–55 (HJS) and 18–55 years (SSS) were included in this study. HJS and SSS were enrolled in cohorts of approximately ten subjects each and randomized (8:2) to either TAK-063 or placebo. SSS who were on stable antipsychotic monotherapy for at least 1 month before screening and had a Clinical Global Impression of Severity (CGI-S) score of ≤ 4 and a total Positive and Negative Symptom Scale (PANSS) score of ≤ 70 at screening and check-in (day − 1) were included. HJS were ineligible if they had used nicotine within 28 days or had a history of mental disorders in the past 3 years. Any subject who tested positive for illicit drugs, had a history of substance abuse, or exhibited elevated suicide risk in the previous 6 months was excluded.
Study Design
The study consisted of a screening visit followed by a washout interval, during which subjects with stable schizophrenia were required to discontinue their psychotropic medications, including antipsychotics, for approximately 5 half-lives, followed by a 7-day treatment period, study exit (day 8), and follow-up on day 14 (Supplementary Fig. 1; see the electronic supplementary material). Baseline assessments were physical examination; vital signs; weight, height, and body mass index (BMI); clinical laboratory tests; electrocardiogram (ECG); CGI-Severity of Illness; PK urine collection; cognition battery; Columbia Suicide Severity Rating Scale (C-SSRS); PANSS; Extrapyramidal Symptom Rating Scale-Abbreviated (ESRS-A); sleepiness, mood, and alertness assessments; and pretreatment events. All baseline assessments were completed on day − 1. Study medication was administered as a tablet once daily with food over a 7-day period in the clinic followed by an exit visit on day 8 and a follow-up phone call on day 14. SSS taking other non-psychotropic medications for medical conditions (e.g., hypertension) were allowed to continue on their medication.
Dose levels were based on the safety data from a single-rising-dose study of TAK-063 [6] and emerging data from the present study. The dose groups for SSS were 3, 10, 20, 30, and 100 mg, and the dose groups for HJS were 3, 10, and 20 mg. Cohorts were staggered such that at a given dose level, SSS cohorts preceded cohorts of HJS at equivalent or higher doses (Supplementary Fig. 2). Decisions to increase or decrease subsequent dose levels occurred after review of blinded safety, tolerability, and PK data.
Study Endpoints
The primary endpoints were the percentage of subjects who experienced at least one AE after dosing and the percentage of subjects who met predefined criteria for markedly abnormal vital sign measurements, safety laboratory tests, or ECG parameters. Intensity of AEs was classified as mild, moderate, or severe, and each AE was assessed for association with the study drug. Documentation of AEs began on day 1, and AEs were assessed until the follow-up visit or call on day 14 (± 2 days). Vital signs were collected at screening, check-in, study days 1–7 (predose and 1, 4, 8, and 12 h postdose), and at study exit or early termination. Vital sign parameters were oral body temperature, respiration rate, and supine/standing blood pressure and pulse. Samples for hematology, serum chemistry, and urinalysis tests were collected following a minimum 10-h overnight fast at screening, check-in, predose on day 2, and at study exit. Samples for hormone tests (cortisol, growth hormone, prolactin, and thyroid-stimulating hormone) were collected on day 1 (predose as well as 3 and 24 h postdose), study exit, and early termination. ECGs were recorded at screening; at check-in; on days 1, 4, and 7 (predose and 1, 4, and 8 h postdose); and at study exit or early termination. Parameters measured by ECG were PR, RR, QRS, and QT intervals. Changes were considered to be clinically significant if intervention was needed or if the change exceeded the range of normal physiologic fluctuation.
Secondary endpoints included evaluation of the following plasma PK parameters: maximum observed plasma concentration (C
max), time to reach maximum observed plasma concentration (t
max), area under the plasma concentration–time curve from time 0 to 24 h postdose (AUC0–24), area under the plasma concentration–time curve from time 0 to last quantifiable concentration (AUCt), oral clearance (CL/F) (TAK-063 only), average plasma concentration at steady state (C
av,ss), C
max and AUC molar ratios between TAK-063 and the TAK-063 oxidative metabolite M-I, and accumulation ratio (AR) between day 7 and day 1 AUC0–24 for TAK-063 and M-I. Serial blood samples were collected predose as well as 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 16, and 24 h postdose on days 1 and 7 from all subjects; blood samples were collected predose on days 5 and 6 to confirm steady-state levels. Urine PK parameters included total amount excreted in urine from time 0 to 24 h (Ae24), fraction of drug excreted in urine (f
e) (TAK-063 only), and renal clearance (CLR). Serial urine samples were collected at predose; postdose intervals of − 12–0 h, 0–6 h, 6–12 h, and 12–24 h on day 1; and postdose intervals of 0–6 h, 6–12 h, and 12–24 h on day 7. Plasma and urine samples were frozen at − 20 °C in duplicate sets, and plasma and urine concentrations of TAK-063 and M-I were measured by validated liquid chromatography and tandem and mass spectrometry with validated ranges of 0.5–1000 ng/mL and 5.5–2750 ng/mL, respectively, for both analytes. Elimination half-life (t
½) was not included as an endpoint, but was reported in this study.
Exploratory endpoints included assessment of change from baseline to day 7 postdose in ESRS-A scores in SSS and HJS, C-SSRS in SSS and HJS, and the change from baseline to day 7 or end of treatment in PANSS and CGI-S scores after 7 days of dosing in SSS. ESRS-A scores were evaluated for all subjects at check-in, day 1 at predose and 4 (± 1) h postdose, and day 7 at 4 (± 1) h postdose or early termination. C-SSRS was conducted at screening, at check-in, and on day 8 or early termination. PANSS and CGI-S assessments were conducted in SSS at screening, at check-in, and on day 7 postdose or early termination. In addition, assessments of cognition and mood were conducted in both HJS and SSS using a validated computerized cognition battery and computerized Bond-Lader Visual Analog Scale via the Cognitive Drug Research Computerized Assessment System. The cognition battery was conducted at check-in and on days 1, 2, 4, 6, and 7, and Bond-Lader Visual Analog Scale assessments were conducted on days 1 and 7 at predose and 2 (± 1), 6 (± 2), and 12 (± 1) h postdose or early termination. Electroencephalogram recordings, event-related potentials, and electromyographic recordings of pre-pulse inhibition were also conducted in SSS. Cognition, mood, and EEG results are reported elsewhere.
Pharmacokinetic/Adverse Event Modeling
PK/AE modeling analyses for somnolence were conducted with data from both HJS and SSS, and the EPS model was based on data from SSS. The incidence of AEs was modeled using a logistic regression model given by the expression f[P(AE
i
= 1)] = log[p/(1 − p)] = β + f
exp, where AE
i
= 1 if subject i has an AE at some time during the study and AE
i
= 0 otherwise, using NONlinear Mixed Effects Modeling 7.2. Data processing and graphs were produced using R. The parameter β denotes the logit for subjects on placebo. The function f
exp describes the exposure response relationship as a linear function (SLOPE × PK) where PK represents individual C
max and AUC values. E
max type [E
max·PK/(PK + EC50)] functions were also used, but did not improve the fit. EC50 represents the drug concentration that yields a half-maximal response and PK represents individual Cmax and AUC values estimated with non-compartmental methods.
Statistical Analyses
All data analyses were generated using SAS Version 9.2. Unless otherwise stated, all statistical tests were two-tailed at α = 0.05; no adjustments were made for multiple comparisons. Subjects who received placebo in each cohort group were analyzed as one group for safety summaries. Dose proportionality was assessed for HJS (up to 20 mg) and SSS (up to 30 mg and over the entire range) using analysis of variance models for repeated measures. Natural log-transformed, dose-normalized plasma TAK-063 and M-I C
max and AUCs were used as the responses, and treatment group, day, and day-by-treatment group interaction were used as the factors in the models. For SSS, dose proportionality was evaluated for two TAK-063 dose ranges: up to 30 mg, and the entire range, using a power model ln(PK parameter) = β
0 + β
1·ln(Dose) + ε, in which β
0 is the intercept, β
1 is the slope, and ε is the random error term. Dose proportionality was also presented graphically using box plots. PK parameters were determined using non-compartmental analysis with WinNonlin Enterprise Version 6.3 (Pharsight Corp., Mountain View, CA, USA). Plasma and urine PK parameters for TAK-063 and M-I were determined from the concentration–time profiles for all evaluable subjects.