Therapeutics Pharmacodynamics
Effects of Piragliatin, a Glucokinase Activator, on Fasting and Postprandial Plasma Glucose in Patients With Type 2 Diabetes Mellitus
The Journal of Clinical Pharmacology 2016, 56(2) 231–238 © 2015, The American College of Clinical Pharmacology DOI: 10.1002/jcph.589
Jianguo Zhi, PhD, FCP, ABCP, and Suoping Zhai, MD, PhD
Abstract To assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of piragliatin, a double-blind, randomized, placebo-controlled, multiple-ascending-doses study was conducted in patients with type 2 diabetes mellitus (T2D). Fifty-nine T2D patients were given piragliatin or placebo in a dose-escalation design as a single dose on day 1 followed by multiple doses on days 3 through 8 at doses of 10, 25, 50, 100, and 200 mg twice a day (BID) as well as 200 mg every day (QD). Blood and urine samples were collected for PK analysis. PD assessments included plasma glucose, insulin, C-peptide, glucagon, and GLP-1. Piragliatin exposure was dose proportional without appreciable accumulation or food effect. Piragliatin treatment at steady state yielded dose-dependent reductions up to 32.5% and 35.5% for the highest dose in fasting and postprandial plasma glucose. Piragliatin was well tolerated. Mild or moderate hypoglycemia with rapid recovery after sugar-containing drinks or scheduled meals was the only dose-limiting adverse event. It is concluded that multiple doses of piragliatin consistently showed rapid, dose-dependent glucose reduction of fasting and postprandial plasma glucose in T2D patients.
Keywords glucokinase activator, pharmacokinetics, pharmacodynamics
Type 2 diabetes (T2D) is a metabolic disorder characterized by elevated blood glucose resulting from deficiencies in insulin secretion/sensitivity and increased hepatic glucose production. Current pharmacological therapies for T2D are often inefficient in achieving glycemic control because they generally address only a single underlying defect.1 Glucokinase (GK) is an enzyme that catalyzes the first step of glucose metabolism, the phosphorylation of glucose to glucose 6-phosphate (G-6-P), in pancreatic b-cells and hepatocytes. Thus, increased GK activity is a potential mechanism of action for diabetes therapy.2 To date, several GK activators including piragliatin have completed phase 1 and/or phase 2 testing3–5 with a limited long-term success for treatment in patients with T2D. Piragliatin (or RO4389620) is a nonessential (not needed in maintaining homeostasis in cells and organisms), mixed-type activator of GK without hepatic lipidosis6 and was the first GK activator tested in the clinic.7–9 In a completed single-ascending-dose study in healthy volunteers, piragliatin effectively lowered fasting plasma glucose (FPG) in a dose-related manner.7 In another single-dose study, b-cell function was improved by piragliatin in patients with T2D.9 The aim of publishing details of the multiple-ascending-dose study in patients with T2D8 is to add to the literature the clinical pharmacology characteristics of a different molecule to aid further drug design for more effective GK activators.
Methods The study protocol was approved by participating sites’ IRBs in Germany and New Zealand and conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all subjects at prescreening. A data-safety-monitoring committee of independent experts assessed safety data on an ongoing basis. Partial details regarding subjects, study design, and analytical procedures have been provided.10 This study was to assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) following multiple ascending doses (MAD) of piragliatin. Food effect on piragliatin PK/PD was also examined. Men and women of nonchildbearing potential, aged 18–65 years, were eligible for inclusion if diagnosed with T2D 3 months before screening. Patients were either diet controlled or taken off current therapy for at least 3 weeks before randomization. Additional inclusion criteria included
Roche Innovation Center of New York, New York, NY, USA Submitted for publication 22 May 2015; accepted 10 July 2015. Corresponding Author: J. Zhi, PhD, FCP, ABCP, Department of Clinical Pharmacology, Roche Innovation Center of New York, New York, NY 10016 Email: [email protected]
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BMI of 20 and 35 kg/m2 and HbA1c at screening of >6.5% to 10% for patients not previously treated with hypoglycemic drugs or >6.5% to 8.5% for patients already treated with hypoglycemic drugs. FPG was 6.5 mM (117 mg/dL) to 11.1 mM (200 mg/dL) at screening and 7.0 mM (126 mg/dL) to 13.0 mM (240 mg/dL) at randomization, with evidence of insulin secretory capacity (fasting serum C-peptide levels above lower limit of normal) at screening. Exclusion criteria included insulin therapy or weightlowering drugs (eg, orlistat, sibutramine) or any other oral antidiabetic agent (including herbal remedies), and drugs that were CYP3A substrates, inhibitors, or inducers; significant cardiovascular, cerebrovascular, renal, hepatobiliary, bronchopulmonary, gastrointestinal, or neurological diseases; and any type of cancer.
occurred prior to chromatography on the analytical HPLC column. Results were calculated using peak area ratios. Calibration curves for piragliatin and RO4517354 in human plasma ranged from 0.100 to 100 ng/mL and were generated using weighted (1/concentration2) linear leastsquares regressions. Blood PD samples were collected for the assay of plasma levels of glucose, insulin, C-peptide, GLP-1, and glucagon as follows: fed 0–24 hours on day 1 (baseline) and day 7 (steady state), fasting PD 0–4 hours on day –2 (baseline), day 3, and day 8, plus daily FPG. Analytical procedures for measuring primary PD, eg, plasma glucose, have been described previously.10 Safety was assessed by routine monitoring of vital signs, physical examination, 12-lead ECG, adverse events (AEs), laboratory safety, and bedside glucose.
Study Design This was a multicenter, double-blind, multiple-ascending-dose, randomized, placebo-controlled study to investigate the PK, PD, safety, and tolerability of piragliatin in WHO-defined T2D patients. The dose escalation was adaptive in nature. Safety, tolerability, PK, and PD data after each dose were assessed before escalation to the next dose. Eligible patients were sequentially randomized to each dose cohort receiving either piragliatin or matching placebo. The study drug piragliatin in soft gel capsules was orally administered as a single dose on day 1 followed by a 48-hour washout and then twice a day (BID) or every day (QD) for 51/2 or 6 consecutive days. Six cohorts of 10, 25, 50, 100, and 200 mg BID, as well as 200 mg QD, of piragliatin were completed with 10 patients (8 active and 2 placebo) per cohort. Food effect on piragliatin PK/PD was also examined: when the drug was given “with food,” it was given 1 hour before the start of meal consumption. Stopping criteria related to hypoglycemia were predetermined as follows: if 4 patients or more showed blood glucose levels of less than 3.0 mM (54 mg/dL) and/ or exhibited hypoglycemia symptoms during the course of treatment, dose escalation would be stopped.
Data Analysis A noncompartmental method was applied to determine PK parameters such as Cmax, AUC (AUC1 for SD and AUCt at SS), t1/2, CL/F, accumulation index, fluctuation factor, as appropriate, for SD and at SS with plasma concentration-versus-time data using WinNonlin 6.2, Pharsight. The total amounts of parent compound and metabolite excreted in urine after SD and at SS were calculated, and the amount excreted (Ae) in urine up to 48 hours postdose for a single dose or up to 12 hours at steady state (Ae0-48h or Ae0-12h) was computed. The relationship of PK parameters for SD and at SS with dose was evaluated to establish dose linearity. PK parameters under fasting and fed conditions were examined for potential food effects following SD and SS doses, respectively. The primary PD endpoint is the effect of piragliatin on 24-hour AUC-glucose. Primary PD parameters (absolute and percentage reductions in blood glucose concentrations from baseline and 24-hour AUCglucose) were derived from glucose concentrationversus-time profiles using a noncompartmental method for each patient. These PD parameters were compared between doses to explore the effect of dose-related treatments. Various AUCs (AUC0–4h, AUC0–16h, AUC16–24h, and AUC0–24h) were also computed and correlated with dose or PK exposure (AUC) through Emax modeling. Insulin, C-peptide, GLP-1, and glucagon were used as secondary PD parameters.
Pharmacokinetic/Pharmacodynamic/Safety Assessments Blood and urine PK samples were collected on day 1 (single dose or SD) at 0–48 hours postdose, on day 7 (steady state or SS and fed) at 0–24 hours postdose, and on day 8 (SS and fasting) at 0–48 hours postdose for the measurement of piragliatin and its major, reversible, inactive metabolite M4 (RO4517354). Plasma concentrations were measured by a specific online extraction LC/ MS/MS method. Piragliatin, RO4517354, and internal standards (d3-piragliatin and d3-RO4517354) were extracted from human plasma by protein precipitation. After centrifugation, the supernatant was injected onto a cohesive system where online solid-phase extraction
Results Fifty-nine patients with T2D were treated with a total of 51/2 to 6 days of dosing in 6 dose cohorts (each cohort consisted of 8 patients on active drug and 2 on placebo except for the last cohort, 200 mg BID, because it reached the stopping rule for the study) up to 400 mg/day (as 200 mg BID) in this multiple-ascending-dose study.
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Zhi and Zhai Table 1. Demographic and Baseline Characteristic Summary mg BID Demography and Baseline
Placebo
10
25
50
mg QD 100
200
200
N 12 8 8 8 8 7 8 Sex (M/F) 10/2 5/3 5/3 6/2 7/1 4/3 8/0 Race (W/O†) 11/1 8/0 6/2 8/0 8/0 7/0 8/0 Age (yr) 57 40–65 59 46–63 59 49–69 55 49–60 56 47–65 55 43–64 55 46–65 Weight (kg) 89.4 75.0–104.0 90.9 75.0–106.0 86.0 72.0–106.0 90.7 72.9–119.4 88.2 63.0–106.0 93.9 73.1–114.0 90.7 75.0–110.7 Height (cm) 173 155–183 170 158–185 172 157–186 172 159–186 174 158–184 172 161–183 179 169–189 BMI (kg/m2) 29.8 25.8–37.5 31.3 26.2–35.1 29.0 26.2–34.9 30.2 26.7–34.8 29.1 22.6–34.0 31.7 23.9–36.3 28.1 23.7–32.0 Duration of Diabetes (yr) 5.9 1.3–11.4 8.8 3.8–18.8 8.6 1.9–15.9 5.9 4.0–9.1 7.5 0.7–29.3 6.3 0.8–16.6 7.8 2.5–16.4 Screening C-Peptide (nM) 1.1 0.4–5.0 0.95 0.5–2.0 0.81 0.3–1.2 0.78 0.5–1.1 0.86 0.4–1.3 1.1 0.7–1.4 0.79 0.2–1.4 Screening HbA1C (%) 7.6 6.7–8.8 7.3 6.2–9.7 7.8 6.5–10.7 8.0 6.8–9.5 7.2 6.2–8.1 7.6 6.1–8.6 7.4 6.1–8.8 Screening FBG (mM) 9.6 7.8–12.6 9.1 6.1–13.0 8.4 7.1–10.1 9.9 8.7–10.8 9.2 7.2–12.9 9.3 7.7–11.5 8.9 7.2–10.8 Randomization (Day –2) FBG 8.6 7.4–10.0 8.2 6.2–11.4 9.2 7.9–10.5 8.7 7.2–10.9 9.1 7.7–12.1 8.1 7.1–10.5 8.1 6.8–9.5 Results are reported as mean and range, as applicable. FBG ¼ fasting blood glucose. For the placebo-treated group, 10 on BID and 2 on QD are combined. † W ¼ white, O ¼ other.
Subject Disposition and Baseline Characteristics Baseline demographics and characteristics were comparable across groups (Table 1). Overall, the patient population was predominantly male in the sixth decade of life and white. The proportion of females was comparable among the 7 groups. Of the 59 patients who completed the study, 24 were drug naive, which was evenly distributed per dose group. The mean BMI ranged from 28.1 to 31.7 kg/m2, and mean duration of diabetes ranged from 5.9 to 8.8 years. Baseline HbA1c ranged from 6.1% to 10.7%, and FPG ranged from 6.1 to 13.0 mM (110–230 mg/dL) at screening, values that were evenly distributed across groups; FPG was 6.2–12.1 mM (112–218 mg/dL) at randomization, and C-peptide ranged from 0.2 to 5 nM at entry. In view of the small sample size of each dose group, mean FPG, HbA1c, and C-peptide levels were considered well balanced. Pharmacokinetics Plasma and urine concentrations of piragliatin (parent) and its inactive metabolite RO4517354 were measured for up to 48 hours following the single and multiple doses. Mean plasma concentration-time profiles of piragliatin are presented in Figure 1 with primary PK parameters such as Cmax, AUCt, and t1/2 on the last day of treatment (steady state) presented in Table 2. Absorption of the drug was generally fast, with peak plasma concentration reached within 1–2 hours after dosing. Distribution also appears to be rapid. The PK profile of piragliatin in T2D patients showed dose proportionality over the dose range tested (Figure 1). There was no striking difference between day 7 (dosing with meal) and day 8 (dosing under fasting), both at steady state.
Pharmacodynamics Following multiple ascending doses in T2D patients, piragliatin treatment resulted in a dose-related glucoselowering effect. The time course of piragliatin-induced changes in FPG (Figure 2) demonstrated a dosedependent FPG reduction from baseline over 6 days, with no changes in FPG observed with placebo. At the highest dosage, 200 mg BID, there was a 32.5% reduction: from hyperglycemic 8 mM to normoglycemic 5.6 mM. At the 100-mg BID dose level, on average, glucose was reduced by 15.1% of baseline value. This reduction is clinically significant: a pretreatment glucose of 9.3 mM was reduced to 7.9 mM or less. Steady state (maximum change) was reached within 2–3 days after the start of multiple-dose treatment and was maintained throughout the multiple-dosing period. When treatment was stopped, patients’ glucose levels returned to pretreatment levels, also within 2–3 days at intermediate doses and a few days longer for the high-dosage groups. These results have demonstrated rapid onset and offset of the piragliatin-induced glucose-lowering effect. The primary PD endpoint was the effect of piragliatin on the 24-hour glucose AUC. The relationship between 24-hour glucose AUC reduction (effect) at steady state and dosage or exposure (piragliatin day –8 AUC24h) follows an apparent Emax PD model (Figure 3). Piragliatin treatment appeared to be twice as effective in naive patients (never received antidiabetic drug treatment previously) than in pretreated patients at high dosages (>25 mg). When both subpopulations are combined, the average decrease was 18.2% ( 15.7%) and 21.4% ( 10.5%) at 100 mg BID and 200 mg QD, respectively. Because of their large interpatient variability, the other 4 PD measures (insulin, C-peptide, GLP-1, and glucagon)
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Figure 1. Dose-mean piragliatin plasma concentration-time profiles at steady state (upper panel) and correlation between dose and exposure (AUC0-24h on day 8) for piragliatin (lower panel).
Table 2. Piragliatin Pharmacokinetic Results at Steady State (Day 8) BID PK Parameter tmax (h) Cmax (ng/mL) AUC0-t (ng h/mL) t1/2 (h) CL/F (L/h) Ae (%)‡
10 mg (N ¼ 7) 1.2 73.0 375 11.0 28.2 14.2
(0.4) (20.4) (98) (2.6) (7.4) (3.4)
†
25 mg (N ¼ 8) 1.1 146 798 10.8 32.4 12.7
(0.3) (45) (165) (2.2) (6.1) (2.2)
50 mg (N ¼ 8) 0.8 355 1499 10.1 34.9 12.5
(0.4) (113) (334) (2.4) (7.8) (7.2)
QD 100 mg (N ¼ 7) 1.5 602 3034 10.1 33.9 16.1
(0.9) (137) (535) (2.4) (5.9) (4.5)
†
200 mg (N ¼ 6) 1.2 1299 6010 10.0 35.0 16.2
Results are reported as mean (SD). AUC0–12h for BID and AUC0–24h for QD. † Due to withdrawals of non-drug-related SAE or protocol violation, only 7 out of 8 patients were available for day 8 PK. ‡ Amount recovered in urine as percentage of piragliatin dose.
(0.3) (367) (1344) (3.0) (9.3) (8.8)
200 mg (N ¼ 8) 1.3 1014 5808 8.1 36.5 12.8
(0.5) (253) (1592) (1.6) (9.8) (2.0)
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Figure 2. Dose-mean daily fasting plasma glucose as percentage changes from baseline (upper panel) and day-8 changes (lower panel) following placebo and piragliatin administration.
did not indicate consistent dose responses. There were no clear dosage-related alterations for any of these 4 PD measurements following piragliatin administration for 5–6 days of BID and QD treatments. However, as the 24-hour glucose AUC was reduced in a dose-related manner, the 4 unchanged PD parameters suggest a relative change; an example of an insulin profile is presented in Figure 4. Safety and Tolerability Adverse Events. The most common adverse events were related to venipuncture site reactions, headache/dizziness, and gastrointestinal adverse events (including nausea, indigestion, constipation, loose stool). The majority of nervous system disorders occurred in the placebo group (6/10 patients), with fewer events reported in the active
treatment groups (no more than 3/8 patients in each actively treated group) and without dose dependency. All other adverse events reported were limited in numbers (no more than 2 patients in each actively treated group) and also did not show any dose dependency. No deaths, dosage-related serious adverse events, or premature withdrawals due to drug-related adverse events were reported. There was 2 unrelated premature withdrawals, 1 patient in the 10-mg BID dose group for an unrelated serious adverse event of renal colic (patient was discharged from the hospital after surgery) and the other in the 100-mg BID group for protocol violation due to continuous obstructive sleep apnea syndrome requiring the regular use of a CPAP device not declared at the study start. Another unrelated serious adverse event was also reported during the follow-up visit for a 56-year-old male
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Figure 3. Post-prandial plasma glucose AUC reduction on day 7 from baseline as a function of piragliatin dose (left panel) or exposure (right panel).
Figure 4. Dose versus mean insulin concentration (upper panel) and insulin/glucose ratio-time profiles on day 7 (lower panel).
Zhi and Zhai
patient in the 50-mg BID dose cohort due to atrial fibrillation that required hospitalization. No subject in the 4 BID dose cohorts had symptomatic hypoglycemia. However, at the dose of 200 mg QD, 2 of 8 subjects experienced symptomatic hypoglycemia during treatment. Except for the event of hypoglycemia described above, there was no relationship between the overall incidence of adverse events or types, intensity, or treatment relationship of adverse events and the piragliatin dose. Vital Signs, Biochemistry, Hematology, and Laboratory Findings. No clinically significant laboratory or vital sign abnormalities were reported, and no clinically significant changes in hematological and biochemical parameters, including functional tests for liver, heart, and kidney were observed.
Discussion The PK of piragliatin and its inactive metabolite RO4517354 exhibited similar characteristics and appeared to be dose proportional over the range tested (10– 200 mg BID and 200 mg QD) without appreciable accumulation or food effect. The apparent terminal half-life of piragliatin was in the range of 8–11 hours, supporting a BID dosing regimen. Renal excretion of the drug was 14% and plays a role in drug elimination, suggesting that patients’ renal function can have an impact on piragliatin systemic exposure. Our patient population had baseline creatinine clearance values ranging from 50 to 160 mL/min. When creatinine clearance was 80 mL/min, there was no change in exposure (dose-normalized AUC/100 mg fluctuated around a mean value of 2800 ng h/mL 100 mg) to the drug; however, when creatinine clearance was reduced to 50 mL/min, the dose-normalized exposure was increased to 4000 ng h/mL 100 mg. A prospective study with a therapeutic dose was planned to address the potential impact of the more severe renally impaired condition on piragliatin PK and exposure. The food effect on piragliatin PK was also assessed. At steady state, there appeared very slightly higher (
Effects of Piragliatin, a Glucokinase Activator, on Fasting and Postprandial Plasma Glucose in Patients With Type 2 Diabetes Mellitus
The Journal of Clinical Pharmacology 2016, 56(2) 231–238 © 2015, The American College of Clinical Pharmacology DOI: 10.1002/jcph.589
Jianguo Zhi, PhD, FCP, ABCP, and Suoping Zhai, MD, PhD
Abstract To assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of piragliatin, a double-blind, randomized, placebo-controlled, multiple-ascending-doses study was conducted in patients with type 2 diabetes mellitus (T2D). Fifty-nine T2D patients were given piragliatin or placebo in a dose-escalation design as a single dose on day 1 followed by multiple doses on days 3 through 8 at doses of 10, 25, 50, 100, and 200 mg twice a day (BID) as well as 200 mg every day (QD). Blood and urine samples were collected for PK analysis. PD assessments included plasma glucose, insulin, C-peptide, glucagon, and GLP-1. Piragliatin exposure was dose proportional without appreciable accumulation or food effect. Piragliatin treatment at steady state yielded dose-dependent reductions up to 32.5% and 35.5% for the highest dose in fasting and postprandial plasma glucose. Piragliatin was well tolerated. Mild or moderate hypoglycemia with rapid recovery after sugar-containing drinks or scheduled meals was the only dose-limiting adverse event. It is concluded that multiple doses of piragliatin consistently showed rapid, dose-dependent glucose reduction of fasting and postprandial plasma glucose in T2D patients.
Keywords glucokinase activator, pharmacokinetics, pharmacodynamics
Type 2 diabetes (T2D) is a metabolic disorder characterized by elevated blood glucose resulting from deficiencies in insulin secretion/sensitivity and increased hepatic glucose production. Current pharmacological therapies for T2D are often inefficient in achieving glycemic control because they generally address only a single underlying defect.1 Glucokinase (GK) is an enzyme that catalyzes the first step of glucose metabolism, the phosphorylation of glucose to glucose 6-phosphate (G-6-P), in pancreatic b-cells and hepatocytes. Thus, increased GK activity is a potential mechanism of action for diabetes therapy.2 To date, several GK activators including piragliatin have completed phase 1 and/or phase 2 testing3–5 with a limited long-term success for treatment in patients with T2D. Piragliatin (or RO4389620) is a nonessential (not needed in maintaining homeostasis in cells and organisms), mixed-type activator of GK without hepatic lipidosis6 and was the first GK activator tested in the clinic.7–9 In a completed single-ascending-dose study in healthy volunteers, piragliatin effectively lowered fasting plasma glucose (FPG) in a dose-related manner.7 In another single-dose study, b-cell function was improved by piragliatin in patients with T2D.9 The aim of publishing details of the multiple-ascending-dose study in patients with T2D8 is to add to the literature the clinical pharmacology characteristics of a different molecule to aid further drug design for more effective GK activators.
Methods The study protocol was approved by participating sites’ IRBs in Germany and New Zealand and conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all subjects at prescreening. A data-safety-monitoring committee of independent experts assessed safety data on an ongoing basis. Partial details regarding subjects, study design, and analytical procedures have been provided.10 This study was to assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) following multiple ascending doses (MAD) of piragliatin. Food effect on piragliatin PK/PD was also examined. Men and women of nonchildbearing potential, aged 18–65 years, were eligible for inclusion if diagnosed with T2D 3 months before screening. Patients were either diet controlled or taken off current therapy for at least 3 weeks before randomization. Additional inclusion criteria included
Roche Innovation Center of New York, New York, NY, USA Submitted for publication 22 May 2015; accepted 10 July 2015. Corresponding Author: J. Zhi, PhD, FCP, ABCP, Department of Clinical Pharmacology, Roche Innovation Center of New York, New York, NY 10016 Email: [email protected]
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BMI of 20 and 35 kg/m2 and HbA1c at screening of >6.5% to 10% for patients not previously treated with hypoglycemic drugs or >6.5% to 8.5% for patients already treated with hypoglycemic drugs. FPG was 6.5 mM (117 mg/dL) to 11.1 mM (200 mg/dL) at screening and 7.0 mM (126 mg/dL) to 13.0 mM (240 mg/dL) at randomization, with evidence of insulin secretory capacity (fasting serum C-peptide levels above lower limit of normal) at screening. Exclusion criteria included insulin therapy or weightlowering drugs (eg, orlistat, sibutramine) or any other oral antidiabetic agent (including herbal remedies), and drugs that were CYP3A substrates, inhibitors, or inducers; significant cardiovascular, cerebrovascular, renal, hepatobiliary, bronchopulmonary, gastrointestinal, or neurological diseases; and any type of cancer.
occurred prior to chromatography on the analytical HPLC column. Results were calculated using peak area ratios. Calibration curves for piragliatin and RO4517354 in human plasma ranged from 0.100 to 100 ng/mL and were generated using weighted (1/concentration2) linear leastsquares regressions. Blood PD samples were collected for the assay of plasma levels of glucose, insulin, C-peptide, GLP-1, and glucagon as follows: fed 0–24 hours on day 1 (baseline) and day 7 (steady state), fasting PD 0–4 hours on day –2 (baseline), day 3, and day 8, plus daily FPG. Analytical procedures for measuring primary PD, eg, plasma glucose, have been described previously.10 Safety was assessed by routine monitoring of vital signs, physical examination, 12-lead ECG, adverse events (AEs), laboratory safety, and bedside glucose.
Study Design This was a multicenter, double-blind, multiple-ascending-dose, randomized, placebo-controlled study to investigate the PK, PD, safety, and tolerability of piragliatin in WHO-defined T2D patients. The dose escalation was adaptive in nature. Safety, tolerability, PK, and PD data after each dose were assessed before escalation to the next dose. Eligible patients were sequentially randomized to each dose cohort receiving either piragliatin or matching placebo. The study drug piragliatin in soft gel capsules was orally administered as a single dose on day 1 followed by a 48-hour washout and then twice a day (BID) or every day (QD) for 51/2 or 6 consecutive days. Six cohorts of 10, 25, 50, 100, and 200 mg BID, as well as 200 mg QD, of piragliatin were completed with 10 patients (8 active and 2 placebo) per cohort. Food effect on piragliatin PK/PD was also examined: when the drug was given “with food,” it was given 1 hour before the start of meal consumption. Stopping criteria related to hypoglycemia were predetermined as follows: if 4 patients or more showed blood glucose levels of less than 3.0 mM (54 mg/dL) and/ or exhibited hypoglycemia symptoms during the course of treatment, dose escalation would be stopped.
Data Analysis A noncompartmental method was applied to determine PK parameters such as Cmax, AUC (AUC1 for SD and AUCt at SS), t1/2, CL/F, accumulation index, fluctuation factor, as appropriate, for SD and at SS with plasma concentration-versus-time data using WinNonlin 6.2, Pharsight. The total amounts of parent compound and metabolite excreted in urine after SD and at SS were calculated, and the amount excreted (Ae) in urine up to 48 hours postdose for a single dose or up to 12 hours at steady state (Ae0-48h or Ae0-12h) was computed. The relationship of PK parameters for SD and at SS with dose was evaluated to establish dose linearity. PK parameters under fasting and fed conditions were examined for potential food effects following SD and SS doses, respectively. The primary PD endpoint is the effect of piragliatin on 24-hour AUC-glucose. Primary PD parameters (absolute and percentage reductions in blood glucose concentrations from baseline and 24-hour AUCglucose) were derived from glucose concentrationversus-time profiles using a noncompartmental method for each patient. These PD parameters were compared between doses to explore the effect of dose-related treatments. Various AUCs (AUC0–4h, AUC0–16h, AUC16–24h, and AUC0–24h) were also computed and correlated with dose or PK exposure (AUC) through Emax modeling. Insulin, C-peptide, GLP-1, and glucagon were used as secondary PD parameters.
Pharmacokinetic/Pharmacodynamic/Safety Assessments Blood and urine PK samples were collected on day 1 (single dose or SD) at 0–48 hours postdose, on day 7 (steady state or SS and fed) at 0–24 hours postdose, and on day 8 (SS and fasting) at 0–48 hours postdose for the measurement of piragliatin and its major, reversible, inactive metabolite M4 (RO4517354). Plasma concentrations were measured by a specific online extraction LC/ MS/MS method. Piragliatin, RO4517354, and internal standards (d3-piragliatin and d3-RO4517354) were extracted from human plasma by protein precipitation. After centrifugation, the supernatant was injected onto a cohesive system where online solid-phase extraction
Results Fifty-nine patients with T2D were treated with a total of 51/2 to 6 days of dosing in 6 dose cohorts (each cohort consisted of 8 patients on active drug and 2 on placebo except for the last cohort, 200 mg BID, because it reached the stopping rule for the study) up to 400 mg/day (as 200 mg BID) in this multiple-ascending-dose study.
233
Zhi and Zhai Table 1. Demographic and Baseline Characteristic Summary mg BID Demography and Baseline
Placebo
10
25
50
mg QD 100
200
200
N 12 8 8 8 8 7 8 Sex (M/F) 10/2 5/3 5/3 6/2 7/1 4/3 8/0 Race (W/O†) 11/1 8/0 6/2 8/0 8/0 7/0 8/0 Age (yr) 57 40–65 59 46–63 59 49–69 55 49–60 56 47–65 55 43–64 55 46–65 Weight (kg) 89.4 75.0–104.0 90.9 75.0–106.0 86.0 72.0–106.0 90.7 72.9–119.4 88.2 63.0–106.0 93.9 73.1–114.0 90.7 75.0–110.7 Height (cm) 173 155–183 170 158–185 172 157–186 172 159–186 174 158–184 172 161–183 179 169–189 BMI (kg/m2) 29.8 25.8–37.5 31.3 26.2–35.1 29.0 26.2–34.9 30.2 26.7–34.8 29.1 22.6–34.0 31.7 23.9–36.3 28.1 23.7–32.0 Duration of Diabetes (yr) 5.9 1.3–11.4 8.8 3.8–18.8 8.6 1.9–15.9 5.9 4.0–9.1 7.5 0.7–29.3 6.3 0.8–16.6 7.8 2.5–16.4 Screening C-Peptide (nM) 1.1 0.4–5.0 0.95 0.5–2.0 0.81 0.3–1.2 0.78 0.5–1.1 0.86 0.4–1.3 1.1 0.7–1.4 0.79 0.2–1.4 Screening HbA1C (%) 7.6 6.7–8.8 7.3 6.2–9.7 7.8 6.5–10.7 8.0 6.8–9.5 7.2 6.2–8.1 7.6 6.1–8.6 7.4 6.1–8.8 Screening FBG (mM) 9.6 7.8–12.6 9.1 6.1–13.0 8.4 7.1–10.1 9.9 8.7–10.8 9.2 7.2–12.9 9.3 7.7–11.5 8.9 7.2–10.8 Randomization (Day –2) FBG 8.6 7.4–10.0 8.2 6.2–11.4 9.2 7.9–10.5 8.7 7.2–10.9 9.1 7.7–12.1 8.1 7.1–10.5 8.1 6.8–9.5 Results are reported as mean and range, as applicable. FBG ¼ fasting blood glucose. For the placebo-treated group, 10 on BID and 2 on QD are combined. † W ¼ white, O ¼ other.
Subject Disposition and Baseline Characteristics Baseline demographics and characteristics were comparable across groups (Table 1). Overall, the patient population was predominantly male in the sixth decade of life and white. The proportion of females was comparable among the 7 groups. Of the 59 patients who completed the study, 24 were drug naive, which was evenly distributed per dose group. The mean BMI ranged from 28.1 to 31.7 kg/m2, and mean duration of diabetes ranged from 5.9 to 8.8 years. Baseline HbA1c ranged from 6.1% to 10.7%, and FPG ranged from 6.1 to 13.0 mM (110–230 mg/dL) at screening, values that were evenly distributed across groups; FPG was 6.2–12.1 mM (112–218 mg/dL) at randomization, and C-peptide ranged from 0.2 to 5 nM at entry. In view of the small sample size of each dose group, mean FPG, HbA1c, and C-peptide levels were considered well balanced. Pharmacokinetics Plasma and urine concentrations of piragliatin (parent) and its inactive metabolite RO4517354 were measured for up to 48 hours following the single and multiple doses. Mean plasma concentration-time profiles of piragliatin are presented in Figure 1 with primary PK parameters such as Cmax, AUCt, and t1/2 on the last day of treatment (steady state) presented in Table 2. Absorption of the drug was generally fast, with peak plasma concentration reached within 1–2 hours after dosing. Distribution also appears to be rapid. The PK profile of piragliatin in T2D patients showed dose proportionality over the dose range tested (Figure 1). There was no striking difference between day 7 (dosing with meal) and day 8 (dosing under fasting), both at steady state.
Pharmacodynamics Following multiple ascending doses in T2D patients, piragliatin treatment resulted in a dose-related glucoselowering effect. The time course of piragliatin-induced changes in FPG (Figure 2) demonstrated a dosedependent FPG reduction from baseline over 6 days, with no changes in FPG observed with placebo. At the highest dosage, 200 mg BID, there was a 32.5% reduction: from hyperglycemic 8 mM to normoglycemic 5.6 mM. At the 100-mg BID dose level, on average, glucose was reduced by 15.1% of baseline value. This reduction is clinically significant: a pretreatment glucose of 9.3 mM was reduced to 7.9 mM or less. Steady state (maximum change) was reached within 2–3 days after the start of multiple-dose treatment and was maintained throughout the multiple-dosing period. When treatment was stopped, patients’ glucose levels returned to pretreatment levels, also within 2–3 days at intermediate doses and a few days longer for the high-dosage groups. These results have demonstrated rapid onset and offset of the piragliatin-induced glucose-lowering effect. The primary PD endpoint was the effect of piragliatin on the 24-hour glucose AUC. The relationship between 24-hour glucose AUC reduction (effect) at steady state and dosage or exposure (piragliatin day –8 AUC24h) follows an apparent Emax PD model (Figure 3). Piragliatin treatment appeared to be twice as effective in naive patients (never received antidiabetic drug treatment previously) than in pretreated patients at high dosages (>25 mg). When both subpopulations are combined, the average decrease was 18.2% ( 15.7%) and 21.4% ( 10.5%) at 100 mg BID and 200 mg QD, respectively. Because of their large interpatient variability, the other 4 PD measures (insulin, C-peptide, GLP-1, and glucagon)
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Figure 1. Dose-mean piragliatin plasma concentration-time profiles at steady state (upper panel) and correlation between dose and exposure (AUC0-24h on day 8) for piragliatin (lower panel).
Table 2. Piragliatin Pharmacokinetic Results at Steady State (Day 8) BID PK Parameter tmax (h) Cmax (ng/mL) AUC0-t (ng h/mL) t1/2 (h) CL/F (L/h) Ae (%)‡
10 mg (N ¼ 7) 1.2 73.0 375 11.0 28.2 14.2
(0.4) (20.4) (98) (2.6) (7.4) (3.4)
†
25 mg (N ¼ 8) 1.1 146 798 10.8 32.4 12.7
(0.3) (45) (165) (2.2) (6.1) (2.2)
50 mg (N ¼ 8) 0.8 355 1499 10.1 34.9 12.5
(0.4) (113) (334) (2.4) (7.8) (7.2)
QD 100 mg (N ¼ 7) 1.5 602 3034 10.1 33.9 16.1
(0.9) (137) (535) (2.4) (5.9) (4.5)
†
200 mg (N ¼ 6) 1.2 1299 6010 10.0 35.0 16.2
Results are reported as mean (SD). AUC0–12h for BID and AUC0–24h for QD. † Due to withdrawals of non-drug-related SAE or protocol violation, only 7 out of 8 patients were available for day 8 PK. ‡ Amount recovered in urine as percentage of piragliatin dose.
(0.3) (367) (1344) (3.0) (9.3) (8.8)
200 mg (N ¼ 8) 1.3 1014 5808 8.1 36.5 12.8
(0.5) (253) (1592) (1.6) (9.8) (2.0)
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Figure 2. Dose-mean daily fasting plasma glucose as percentage changes from baseline (upper panel) and day-8 changes (lower panel) following placebo and piragliatin administration.
did not indicate consistent dose responses. There were no clear dosage-related alterations for any of these 4 PD measurements following piragliatin administration for 5–6 days of BID and QD treatments. However, as the 24-hour glucose AUC was reduced in a dose-related manner, the 4 unchanged PD parameters suggest a relative change; an example of an insulin profile is presented in Figure 4. Safety and Tolerability Adverse Events. The most common adverse events were related to venipuncture site reactions, headache/dizziness, and gastrointestinal adverse events (including nausea, indigestion, constipation, loose stool). The majority of nervous system disorders occurred in the placebo group (6/10 patients), with fewer events reported in the active
treatment groups (no more than 3/8 patients in each actively treated group) and without dose dependency. All other adverse events reported were limited in numbers (no more than 2 patients in each actively treated group) and also did not show any dose dependency. No deaths, dosage-related serious adverse events, or premature withdrawals due to drug-related adverse events were reported. There was 2 unrelated premature withdrawals, 1 patient in the 10-mg BID dose group for an unrelated serious adverse event of renal colic (patient was discharged from the hospital after surgery) and the other in the 100-mg BID group for protocol violation due to continuous obstructive sleep apnea syndrome requiring the regular use of a CPAP device not declared at the study start. Another unrelated serious adverse event was also reported during the follow-up visit for a 56-year-old male
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Figure 3. Post-prandial plasma glucose AUC reduction on day 7 from baseline as a function of piragliatin dose (left panel) or exposure (right panel).
Figure 4. Dose versus mean insulin concentration (upper panel) and insulin/glucose ratio-time profiles on day 7 (lower panel).
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patient in the 50-mg BID dose cohort due to atrial fibrillation that required hospitalization. No subject in the 4 BID dose cohorts had symptomatic hypoglycemia. However, at the dose of 200 mg QD, 2 of 8 subjects experienced symptomatic hypoglycemia during treatment. Except for the event of hypoglycemia described above, there was no relationship between the overall incidence of adverse events or types, intensity, or treatment relationship of adverse events and the piragliatin dose. Vital Signs, Biochemistry, Hematology, and Laboratory Findings. No clinically significant laboratory or vital sign abnormalities were reported, and no clinically significant changes in hematological and biochemical parameters, including functional tests for liver, heart, and kidney were observed.
Discussion The PK of piragliatin and its inactive metabolite RO4517354 exhibited similar characteristics and appeared to be dose proportional over the range tested (10– 200 mg BID and 200 mg QD) without appreciable accumulation or food effect. The apparent terminal half-life of piragliatin was in the range of 8–11 hours, supporting a BID dosing regimen. Renal excretion of the drug was 14% and plays a role in drug elimination, suggesting that patients’ renal function can have an impact on piragliatin systemic exposure. Our patient population had baseline creatinine clearance values ranging from 50 to 160 mL/min. When creatinine clearance was 80 mL/min, there was no change in exposure (dose-normalized AUC/100 mg fluctuated around a mean value of 2800 ng h/mL 100 mg) to the drug; however, when creatinine clearance was reduced to 50 mL/min, the dose-normalized exposure was increased to 4000 ng h/mL 100 mg. A prospective study with a therapeutic dose was planned to address the potential impact of the more severe renally impaired condition on piragliatin PK and exposure. The food effect on piragliatin PK was also assessed. At steady state, there appeared very slightly higher (
