Efficacy and safety of cetagliptin as monotherapy in patients with type 2 diabetes: A randomized, double-blind, placebo-controlled phase 3 trial.

AIM: To assess the efficacy and safety of the dipeptidyl peptidase-4 inhibitor, cetagliptin, as monotherapy in Chinese patients with type 2 diabetes (T2D) and inadequate glycaemic control. MATERIALS AND METHODS: In total, 504 eligible patients with T2D were enrolled and randomized to cetagliptin 50 mg once daily, cetagliptin 100 mg once daily or placebo at a ratio of 2:2:1 for 24 weeks of double-blind treatment, then all patients received cetagliptin 100 mg once daily for 28 weeks of open-label treatment. The primary efficacy endpoint was the change in HbA1c level from baseline at week 24. RESULTS: After 24 weeks, HbA1c from baseline was significantly reduced with cetagliptin 50 mg (-1.08%) and cetagliptin 100 mg (-1.07%) compared with placebo (-0.35%). The placebo-subtracted HbA1c reduction was -0.72% with cetagliptin 50 mg and 100 mg. Patients with a baseline HbA1c of 8.5% or higher had a greater HbA1c reduction with cetagliptin than those patients with a baseline HbA1c of less than 8.5%. Both doses studied led to a significantly higher proportion of patients (42.3% with 100 mg and 45.0% with 50 mg) achieving an HbA1c of less than 7.0% compared with placebo (12.9%). Cetagliptin also significantly lowered fasting plasma glucose and 2-hour postmeal plasma glucose relative to placebo. The incidence of adverse experiences was similar between cetagliptin and placebo. No drug-related hypoglycaemia was reported. CONCLUSIONS: Cetagliptin monotherapy was effective and well tolerated in Chinese patients with T2D who had inadequate glycaemic control on exercise and diet.

A randomized, double-blind, placebo controlled, phase 3 trial to evaluate the efficacy and safety of cetagliptin added to ongoing metformin therapy in patients with uncontrolled type 2 diabetes with metformin monotherapy.

AIM: This trial was designed to assess the efficacy and safety of cetagliptin added to metformin in Chinese patients with type 2 diabetes who had inadequate glycaemic control with metformin monotherapy. METHODS: In total, 446 patients with type 2 diabetes on metformin monotherapy were randomized to receive the addition of once-daily cetagliptin 100 mg, cetagliptin 50 mg and placebo in a 2:2:1 ratio for 24-week double-blind treatment. At week 24, patients initially randomized to cetagliptin 50 mg and placebo were switched to cetagliptin 100 mg for 28 weeks open-label treatment. The primary endpoint was the change in haemoglobin A1c (HbA1c) from baseline, and the efficacy analyses were based on an all-patients-treated population using an analysis of co-variance. RESULTS: After 24 weeks, both add-on therapies led to greater glycaemic control. Reductions in HbA1c from baseline were -1.17 ± 0.794%, -1.23 ± 0.896% in cetagliptin 100 mg and 50 mg plus metformin group, respectively. No difference was observed between the cetagliptin 100 mg and 50 mg plus metformin group. Patients with higher baseline HbA1c levels (≥8.5%) experienced greater reductions in HbA1c. A significantly greater proportion of patients achieved an HbA1c <7.0% with cetagliptin 100 mg (49.4%) and cetagliptin 50 mg (51.1%) plus metformin than metformin monotherapy (14.4%). Both combination therapies also improved the homeostasis model assessment ß-function index and decreased systolic blood pressure. There was no increased risk of adverse effects with combination therapy, and both combination therapies were generally well tolerated. CONCLUSIONS: The addition of cetagliptin once daily to metformin was more efficacious and well tolerated than metformin monotherapy in Chinese patients with type 2 diabetes who had inadequate glycaemic control with metformin monotherapy.

A double-blind, randomized, placebo and positive-controlled study in healthy volunteers to evaluate pharmacokinetic and pharmacodynamic properties of multiple oral doses of cetagliptin.

AIMS: This study investigated the pharmacokinetics and pharmacodynamics properties, safety and tolerability of cetagliptin. METHODS: Forty-eight healthy subjects were enrolled in this study. Three cohorts were investigated in sequential order: 50, 100 and 200 mg cetagliptin. Positive control (sitagliptin 100 mg) was designed as open label. Blood samples were collected and analysed for pharmacokinetic and pharmacodynamic properties. Safety and tolerability were assessed throughout the study. RESULTS: Following multiple oral doses, cetagliptin was rapidly absorbed and reached peak plasma concentrations after approximately 1.0-1.5 hours. Plasma cetagliptin concentrations increased at a rate greater than dose. Accumulation of cetagliptin was modest, and steady state was generally achieved at day 5. Doses ≥50 mg of cetagliptin administered once daily will result in sustained dipeptidyl peptidase-4 (DPP-4) inhibition (≥80%). The plasma concentration giving 50% of maximum drug effect of DPP-4 inhibition for cetagliptin (5.29 ng/mL) was lower than that of sitagliptin (7.03 ng/mL). Active glucagon-like-1 peptide (GLP-1) concentrations were significantly increased in the cetagliptin groups by 2.3- to 3.1-fold at day 1 and 3.1- to 3.6-fold at steady state compared with that of placebo, and active GLP-1 concentrations were increased with increasing dose. Compared with sitagliptin, doses ≥100 mg once daily of cetagliptin produced postprandial increases in active GLP-1 level and induced to long-lasting glucose-lowering efficacy. Cetagliptin was well tolerated across all doses studied. CONCLUSION: Cetagliptin demonstrates the great potential for treatment with type 2 diabetes patients based on the inhibition of DPP-4, the increase in GLP-1 and insulin, the decrease in glucose, and might be more effective in DPP-4 inhibition than sitagliptin.

Disposition study of the novel dipeptidyl peptidase 4 inhibitor cetagliptin in rats.

Dipeptidyl peptidase-4 (DPP-4) inhibitor is a class of oral antihyperglycemic agents and therapeutic approach for type 2 diabetes. Cetagliptin is a novel oral and selective DPP-4 inhibitor and developed as a promising candidate for treatment of type 2 diabetes mellitus.This study aimed to evaluate the metabolism and excretion of cetagliptin in Sprague-Dawley (SD) rats, and to detect and identify metabolites of cetagliptin.The SD rats were administered with a single oral dose of 6 mg/kg with approximately 100 µCi of [14C] cetagliptin. The mean total recovery of radioactivity was 90.20% within 168h in SD rats excreta. Cetagliptin was the major radioactive component in SD rats plasma, urine and eliminated primarily by faecal excretion. The recovery of cetagliptin in urine and feces was 25.15% and 13.85% of the dose, respectively. Cetagliptin was well absorbed after oral administration in SD rats based on the total recovery of radioactivity in BDC SD rats bile and urine.Six major metabolites were observed and identified in SD rats, comprising 0.20 to 4.53% of total plasma AUC. These major metabolites were the hydroxylated, N-sulphate and N-carbamoyl glucuronic acid conjugates of the cetagliptin, two metabolites formed by glucuronide of a hydroxylated metabolite.

The metabolism and excretion of the dipeptidyl peptidase 4 inhibitor [14C] cetagliptin in healthy volunteers.

The metabolism and excretion of cetagliptin were investigated in healthy male subjects after a single oral dose of 100mg/50µCi [14C] cetagliptin.The mean concentration-time profile of cetagliptin was similar to that of total radioactivity in plasma after oral administration of [14C] cetagliptin in healthy male subjects. Cetagliptin was rapidly absorbed after oral administration. Unchanged cetagliptin was the most abundant radioactive component in all matrices investigated. Approximately 53.13% of plasma AUC of total radioactivity was accounted for by cetagliptin. Each metabolite plasma AUC was not higher than 2.93% of plasma AUC of total radioactivity. By 336 h after administration, 91.68% of the administered radioactivity was excreted, and the cumulative excretion in the urine and faeces was 72.88% and 18.81%, respectively. The primary route of excretion of radioactivity was via the kidneys.Four metabolites were detected at trace levels, and it involved hydroxylated (M436-1 and M436-3), N- sulphate (M500), and N-carbamoyl glucuronic acid conjugates (M640B) of cetagliptin. These metabolites were detected also in plasma, urine, and faeces at low levels, except that metabolite M640B was not detected in faeces. All metabolites were observed with <10% of parent compound systemic exposure after oral administration.

In vitro study of the drug-drug interaction potential of cetagliptin and clinical study of pharmacokinetic interaction of cetagliptin and metformin in healthy volunteers.

Cetagliptin is an oral, potent, and newly developed selective inhibitor of dipeptidyl peptidase-4 (DPP-4). We evaluated the in vitro drug-drug interaction (DDI) potential of cetagliptin, as well as the pharmacokinetics of cetagliptin and metformin and the interaction between cetagliptin and metformin.Cetagliptin did not inhibit CYP1A2, CYP2C8, CYP2B6, CYP2C9, CYP2C19, and CYP3A4, only has a moderate inhibitory effect on CYP2D6, and did not induce CYP1A2, CYP2B6, and CYP3A4. Plasma protein binding of cetagliptin didn't have species differences or concentration dependence. Cetagliptin was a substrate for P-glycoprotein (P-gp).The 34 healthy subjects enrolled were randomly divided into two sequences (A and B) with 17 subjects in each sequence. Coadministration with metformin had no effect on cetagliptin AUC0-120 (GMR, 99.25%; 90% CI, 95.96%-102.65%). There was a slightly increase in cetagliptin Cmax (GMR, 117.33%; 90% CI, 102.54%-134.25%). Coadministration with cetagliptin did not affect the metformin's AUC0-24 (GMR, 108.54%; 90% CI, 101.41%-116.17%) or Cmax (GMR, 97.67%; 90% CI, 90.96%-104.89%).Based on in vitro study results, cetagliptin is unlikely to cause CYP-mediated, clinically relevant DDI. Although the possibility of transporter-mediated, clinically relevant DDI cannot be ruled out, there is little or no risk of side effects. Coadministration of cetagliptin and metformin had no clinically meaningful effect on the pharmacokinetics of each drug. There was no drug-drug interaction between cetagliptin and metformin. Both monotherapies and combination therapy were well tolerated. No serious AEs and hypoglycaemia was reported.

Development and validation of an ultrasensitive LC-MS/MS method for the quantification of cetagliptin in human plasma and its application in a microdose clinical trial.

This study established and validated an LC-MS/MS method for the ultrasensitive determination of cetagliptin in human plasma. Sample pretreatment was achieved by liquid-liquid extraction with ethyl acetate, and chromatographic separation was performed on an XB-C18 analytical column (50 × 2.1 mm, 5 µm) with gradient elution (0.1% formic acid in acetonitrile and 0.1% formic acid) at a flow rate of 1.0 mL/min. For mass spectrometric detection, multiple reaction monitoring was used, and the ion transitions monitored were m/z 421.2-86.0 for cetagliptin and m/z 424.2-88.0 for cetagliptin-d3. Method validation was performed according to the U.S. Food and Drug Administration Bioanalytical Method Validation Guidance, for which the calibration curve was linear in the range of 50.0-2000 pg/mL. All of the other results, such as selectivity, lower limit of quantitation, precision, accuracy, matrix effect, recovery, and stability, met the acceptance criteria. The validated method was successfully applied in a microdose clinical trial to systematically investigate the pharmacokinetic profile of cetagliptin in healthy subjects. Both rapid absorption and prolonged duration demonstrate the potential value of cetagliptin for diabetes treatment.

Use of a PK/PD Model to Select Cetagliptin Dosages for Patients with Type 2 Diabetes in Phase 3 Trials.

BACKGROUND: Cetagliptin is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor developed for the treatment of patients with type 2 diabetes (T2D). Several phase 1 studies have been conducted in China. Modelling and simulation were used to obtain cetagliptin dose for phase 3 trials in T2D patients. METHODS: A pharmacokinetic (PK)/pharmacodynamic (PD) model and model-based analysis of the relationship between hemoglobin A1c (HbA1c) and dosage was explored to guide dose selection of cetagliptin for phase 3 trials. The PK/PD data were derived from four phase 1 clinical studies, and sitagliptin 100 mg was employed as a positive control in studies 1, 3, and 4. RESULTS: The PK profiles of cetagliptin were well described by a two-compartment model with first-order absorption, saturated efflux, and first-order elimination. The final PD model was a sigmoid maximum inhibitory efficacy (Emax) model with the Hill coefficient. The final model accurately captured cetagliptin PK/PD, demonstrated by goodness-of-fit plots. Based on weighted average inhibition (WAI), the relationship between HbA1c and dose was well displayed. Cetagliptin 50 mg once daily or above as monotherapy or as add-on therapy appeared more effective in HbA1c reduction than sitagliptin 100 mg. Cetagliptin 50 mg or 100 mg once daily was selected as the dose for phase 3 trials of cetagliptin in T2D patients. CONCLUSIONS: The PK/PD model supports dose selection of cetagliptin for phase 3 trials. A model­informed approach can be used to replace a dose-finding trial and accelerate cetagliptin's development.

Effect of vapor pressure deficit on growth and water status in muskmelon and cucumber.

Climatic warming and water shortages have become global environmental issues affecting agricultural production. The change of morphology and anatomical structures in plant organs can greatly affect plant growth. The study combined temperature and relative humidity to regulate vapor pressure deficit (VPD) to form low and high VPD environments (LVPD and HVPD, respectively) in two climate-controlled greenhouses. The effects of different VPD conditions on gas exchange parameters, dry matter, and leaf and stem anatomical structure parameters of muskmelon and cucumber were compared and studied. The results show that the background VPD conditions give different internal structure of muskmelon and cucumber, therefore it can improve the transport capacity of water to the leaf surface under LVPD conditions. At the same time, the stomatal closure induced by atmospheric drought stress is avoided and the gas exchange capacity of the leaf stomata is enhanced, thereby maintaining high photosynthetic rate. Thus, reducing VPD is the key to achieving high yield and productivity in greenhouse muskmelon and cucumber production.

First-in-Human, Single-Ascending Dose and Food Effect Studies to Assess the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of Cetagliptin, a Dipeptidyl Peptidase-4 Inhibitor for the Treatment of Type 2 Diabetes Mellitus.

BACKGROUND AND OBJECTIVES: Cetagliptin is a highly selective dipeptidyl peptidase-4 inhibitor under development to treat type 2 diabetes mellitus. This first-in-human study was conducted to characterise the pharmacokinetics, pharmacodynamics and tolerability of single-ascending oral doses of cetagliptin in healthy subjects. In addition, the effect of food on pharmacokinetics was evaluated. METHODS: Study 1 enrolled 66 healthy subjects in a double-blind, randomised, placebo-controlled, single-dose escalation study; sitagliptin was employed as a positive open-label control. Forty-four subjects were assigned to seven cohorts (cetagliptin 12.5, 25, 50, 100, 200, 300 or 400 mg); 12 subjects were assigned to the placebo group. The remaining ten subjects received sitagliptin 100 mg as the positive control. Blood, urine and faeces were collected for the pharmacokinetic analysis and determination of plasma dipeptidyl peptidase-4 inhibition, active glucagon-like peptide-1, glucose and insulin levels. In Study 2, 14 healthy subjects were assigned to a randomised, open-label, two-period crossover study, and received a single oral dose of cetagliptin 100 mg in the fasted state or after a high-fat meal, with a 14-day washout period between treatments. Blood samples were collected to evaluate the effects of food on the pharmacokinetics of cetagliptin. RESULTS: Following administration of a single oral dose, cetagliptin was rapidly absorbed, presenting a median time to maximum concentration of 1.0-3.25 h. The terminal half-life ranged between 25.8 and 41.3 h, which was considerably longer than that of sitagliptin. The area under the plasma concentration-time curve was approximately dose proportional between 25 mg and 400 mg, and the increase in maximum concentration was greater than dose proportional. The unchanged drug was mainly excreted in the urine (27.2-46.2% of dose) and minimally via the faeces (1.4% of dose). Dipeptidyl peptidase-4 inhibition, an increase in active glucagon-like peptide-1 and a slight decrease in blood glucose were observed, whereas insulin was not significantly altered when compared with placebo. The weighted average dipeptidyl peptidase-4 inhibition by cetagliptin 100 mg was higher than that mediated by sitagliptin 100 mg. Cetagliptin was well tolerated up to a single oral dose of 400 mg. No food effects were noted. CONCLUSIONS: Cetagliptin inhibited plasma dipeptidyl peptidase-4 activity, increased levels of active glucagon-like peptide-1 and was well tolerated at single doses up to 400 mg, eliciting no dose-limiting toxicity in healthy volunteers. Food did not affect the pharmacokinetics of cetagliptin. CLINICAL TRIAL REGISTRATION: The studies were registered at http://www.chinadrugtrials.org.cn (Nos. CTR20180167 and CTR20181331).

The Response of Water Dynamics to Long-Term High Vapor Pressure Deficit Is Mediated by Anatomical Adaptations in Plants.

Vapor pressure deficit (VPD) is the driver of water movement in plants. However, little is known about how anatomical adaptations determine the acclimation of plant water dynamics to elevated VPD, especially at the whole plant level. Here, we examined the responses of transpiration, stomatal conductance (gs), hydraulic partitioning, and anatomical traits in two tomato cultivars (Jinpeng and Zhongza) to long-term high (2.2-2.6 kPa) and low (1.1-1.5 kPa) VPD. Compared to plants growing under low VPD, no variation in gs was found for Jinpeng under high VPD conditions; however, high VPD induced an increase in whole plant hydraulic conductance (Kplant), which was responsible for the maintenance of high transpiration. In contrast, transpiration was not influenced by high VPD in Zhongza, which was primarily attributed to a coordinated decline in gs and Kplant. The changes in gs were closely related to stomatal density and size. Furthermore, high VPD altered hydraulic partitioning among the leaf, stem, and root for both cultivars via adjustments in anatomy. The increase in lumen area of vessels in veins and large roots in Jinpeng under high VPD conditions improved water transport efficiency in the leaf and root, thus resulting in a high Kplant. However, the decreased Kplant for Zhongza under high VPD was the result of a decline of water transport efficiency in the leaf that was caused by a reduction in vein density. Overall, we concluded that the tradeoff in anatomical acclimations among plant tissues results in different water relations in plants under high VPD conditions.