Assessment of Pharmacokinetics and Metabolism Profiles of SCH 58261 in Rats Using Liquid Chromatography-Mass Spectrometric Method

5-Amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c) pyrimidine (SCH 58261) is one of the new chemical entities that has been developed as an adenosine A_2A receptor antagonist. Although SCH 58261 has been reported to be beneficial, there is little information about SCH 58261 from a drug metabolism or pharmacokinetics perspective. This study describes the metabolism and pharmacokinetic properties of SCH 58261 in order to understand its behaviors in vivo. Rats were used as the in vivo model species. First, an LC-MS/MS method was developed for the determination of SCH 58261 in rat plasma. A GastroPlus™ simulation, in vitro microsomal metabolic stability, and bile duct-cannulated studies were also performed to understand its pharmacokinetic profile. The parameter sensitivity analysis of GastroPlus™ was used to examine the factors that influence exposure when the drug is orally administered. The factors are as follows: permeability, systemic clearance, renal clearance, and liver first-pass effect. In vitro microsomal metabolic stability indicates how much the drug is metabolized. The extrapolated hepatic clearance value of SCH 58261 was 39.97 mL/min/kg, indicating that the drug is greatly affected by hepatic metabolism. In vitro microsomal metabolite identification studies revealed that metabolites produce oxidized and ketone-formed metabolites via metabolic enzymes in the liver. The bile duct-cannulated rat study, after oral administration of SCH 58261, showed that a significant amount of the drug was excreted in feces. These results imply that the drug is not absorbed well in the body after oral administration. Taken together, SCH 58261 showed quite a low bioavailability when administered orally and this was likely due to significantly limited absorption, as well as high metabolism in vivo.

In Vitro, In Silico, and In Vivo Assessments of Pharmacokinetic Properties of ZM241385

Parkinson’s disease is one of the most common neurodegenerative diseases. Adenosine regulates the response to other neurotransmitters in the brain regions related to motor function. In the several subtypes of adenosine receptors, especially, adenosine 2A receptors (A_2ARs) are involved in neurodegenerative conditions. ZM241385 is one of the selective non-xanthine A2AR antagonists with high affinity in the nanomolar range. This study describes the in vitro and in vivo pharmacokinetic properties of ZM241385 in rats. A liquid chromatography-quadrupole time-of-flight mass spectrometric (LC-qToF MS) method was developed for the determination of ZM241385 in rat plasma. In vivo IV administration studies showed that ZM241385 was rapidly eliminated in rats. However, the result of in vitro metabolic stability studies showed that ZM241385 had moderate clearance, suggesting that there is an extra clearance pathway in addition to hepatic clearance. In addition, in vivo PO administration studies demonstrated that ZM241385 had low exposure in rats. The results of semi-mass balance studies and the in silico PBPK modeling studies suggested that the low bioavailability of ZM241385 after oral administration in rats was due to the metabolism and by liver, kidney, and gut.

P3674Patient characteristics and treatment patterns in the multicentre, retrospective chart review of first-time Opsumit (macitentan) users in the United States (OrPHeUS)

Introduction

The OPsumit® Historical USers cohort (OrPHeUS) is a multicentre, US, retrospective medical chart review conducted to supplement the OPsumit® USers (OPUS) Registry to fulfil the FDA request to characterise the safety of macitentan in clinical practice.

Purpose

To describe patient characteristics, treatment patterns, hepatic safety and survival in patients with pulmonary hypertension (PH) newly treated with macitentan.

Methods

OrPHeUS (NCT03197688) aimed to include 2200 new users of macitentan, between October 2013 and March 2017, who were not enrolled in OPUS. Here we present patients with follow-up data, including characteristics and treatment patterns at macitentan initiation, hepatic adverse events (HAEs) identified using preferred terms in chart entries and pharmacovigilance reporting, hospitalisations and survival.

Results

OrPHeUS included 2982 patients newly treated with macitentan and with follow-up data; the reason for macitentan prescription was pulmonary arterial hypertension (PAH) in 2362 (79.3%) patients, other PH aetiologies in 612 (20.6%) patients and 8 patients with other/unknown reasons. At macitentan initiation, the median (Q1, Q3) age of the patients was 62 (51, 72) years and 73.9% were female. WHO functional class (FC) was documented in 654 (21.9%) patients, 35.6% of patients were in FC I/II and 64.4% in FC III/IV; median (Q1, Q3) 6-minute walk distance, documented in 411 (13.8%) patients, was 293 (200, 383) metres. At macitentan initiation, 41.5% (n=1239) of patients were not receiving PAH therapy, 46.3% (n=1382) were already receiving one PAH therapy and 11.9% (n=356) were already receiving two PAH therapies. The median (Q1, Q3) exposure to macitentan was 14.9 (5.6, 27.1) months; 57% and 43% of patients had exposures of >12 and >18 months. During the exposure period, 933 (31.3%) patients discontinued treatment, including 474 (15.9%) patients who discontinued due to an adverse event (AE), 6 (0.2%) due to a HAE, 449 (15.1%) for reasons other than an AE/HAE, and 4 (0.1%) for unknown reasons. There were 275 (9.2%) patients who experienced ≥1 HAE (incidence rate [IR]: 0.07 [95% CI, 0.06, 0.08] per 1 person-year); alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥3x upper limit of normal (ULN) were experienced by 113 (3.8%) patients (IR: 0.028 [95% CI, 0.023, 0.033] per 1 person-year); ALT/AST ≥x3 ULN and bilirubin ≥2x ULN was experienced by 33 (1.1%) patients (IR: 0.008 [95% CI, 0.006, 0.011] per 1 person-year). There were 1148 (38.5%) patients who experienced at least one hospitalisation (IR: 0.36 [95% CI, 0.34, 0.39] per 1 person-year). The 12-month Kaplan-Meier survival estimate was 92% (95% CI, 91, 93).

Conclusion

OrPHeUS provides additional real-world evidence in patients newly treated with macitentan, confirming the hepatic safety profile of macitentan.

Acknowledgement/Funding

Actelion Pharmaceuticals Ltd

P4673Macitentan in chronic thromboembolic pulmonary hypertension (CTEPH): combined data from OPUS and OrPHeUS real-world data sets

Introduction

The OPsumit® USers Registry (OPUS) provides real-world data in patients (pts) with pulmonary hypertension newly started on macitentan. The OPsumit® Historical USers cohort (OrPHeUS) study was conducted to supplement OPUS to fulfil the FDA request to characterise the safety of macitentan in clinical practice. Both studies included pts with CTEPH.

Purpose

To describe the characteristics and safety outcomes of CTEPH pts newly treated with macitentan.

Methods

OPUS is a prospective, US, multicentre, long-term, observational drug registry (NCT02126943) ongoing since Apr 2014. OrPHeUS was a retrospective, US, multicentre medical chart review (NCT03197688); data collected Oct 2013-Mar 2017. This subgroup analysis describes CTEPH patient characteristics at macitentan initiation, hospitalisations, survival and liver function tests (LFTs) in the combined OPUS/OrPHeUS data set. LFTs are also provided for the OPUS/OrPHeUS pulmonary arterial hypertension (PAH) population.

Results

As of Oct 2018, OPUS/OrPHeUS included 144 CTEPH pts with follow-up data. At macitentan initiation, median (Q1, Q3) age was 66 (56, 73) years; of the 53 pts with a WHO functional class (FC) assessment, 35.8%, 49.1% and 15.1% were in FC II, III and IV, respectively. Median (Q1, Q3) time from CTEPH diagnosis was 18.6 (7.4, 56.4) months (n=141). At macitentan initiation, 32.6% of pts had no PAH therapy, 63.9% were receiving one and 3.5% were receiving two PAH therapies. Median (Q1, Q3) exposure to macitentan was 15.9 (4.3, 30.4) months. There were 43 (29.9%) CTEPH pts who discontinued treatment; 23 due to an adverse event (AE), 0 due to a hepatic AE (HAE) and 20 not due to an AE/HAE. There were 58 (40.3%) CTEPH pts who experienced ≥1 hospitalisation and 9 (6.3%) pts died. LFTs are presented in the table.

LFTs CTEPH follow-up pts PAH follow-up pts (N=144) (N=4072) ALT or AST ≥3x ULN   Pts with ≥1 event, n (%) 1 (0.7) 132 (3.2)   Incidence rate per 1 person-year (95% CI) 0.005 (0.001, 0.035) 0.024 (0.020, 0.029) ALT or AST ≥3x ULN and total bilirubin ≥2x ULN   Pts with ≥1 event, n (%) 1 (0.7) 27 (0.7)   Incidence rate per 1 person-year (95% CI) 0.005 (0.001, 0.035) 0.005 (0.003, 0.007) ALT: alanine aminotransferase; AST: aspartate aminotransferase; CI: confidence interval; ULN: upper limit of normal.

Conclusions

Analysis of OPUS/OrPHeUS data provides further insight into real-world use of macitentan in CTEPH pts. The observed hepatic safety profile in CTEPH pts is in line with that of PAH pts.

Acknowledgement/Funding

Actelion Pharmaceuticals Ltd

The value of quantitative CT texture analysis in differentiation of angiomyolipoma without visible fat from clear cell renal cell carcinoma on four-phase contrast-enhanced CT images

AIM

To investigate the diagnostic performance and usefulness of texture analysis in differentiating angiomyolipoma (AML) without visible fat from clear cell renal cell carcinoma (ccRCC) on four-phase contrast-enhanced computed tomography (CECT).

MATERIALS AND METHODS

Seventeen patients with AML without visible fat and 50 patients with ccRCC of size ≤4.5 cm who had also undergone preoperative four-phase CECT were included in this study. The histogram, grey-level co-occurrence matrix (GLCM), and grey-level run length matrix (GLRLM) were evaluated. Sequential feature selection (SFS) and support vector machine (SVM) classifier with leave-one-out cross validation were used.

RESULTS

Using the SFS and SVM classifiers, five texture features were selected; mean (unenhanced), standard deviation (unenhanced and excretory), cluster prominence (nephrographic), and long-run high grey-level emphasis (corticomedullary). Diagnostic performance of the five selected texture features for all CT phases was as follows: 82% sensitivity, 76% specificity, 85% accuracy, and 85 area under the receiver operating characteristic curve (AUC). In the subgroup analysis, the AUCs of each phase were significantly >0.5 (p<0.05). In the pairwise comparison of AUCs between four phases, there were no significant differences between the four phases except the unenhanced and corticomedullary phases (p=0.015), i.e., the unenhanced phase showed slightly higher AUC than the corticomedullary phase.

CONCLUSIONS

Texture analysis of small renal masses (≤4.5 cm) on four-phase CECT can accurately differentiate AML without visible fat from ccRCC and showed good diagnostic performance for both the unenhanced and enhanced phases.

Quantitative Analysis of Tozadenant Using Liquid Chromatography-Mass Spectrometric Method in Rat Plasma and Its Human Pharmacokinetics Prediction Using Physiologically Based Pharmacokinetic Modeling

Tozadenant is one of the selective adenosine A2a receptor antagonists with a potential to be a new Parkinson's disease (PD) therapeutic drug. In this study, a liquid chromatography-mass spectrometry based bioanalytical method was qualified and applied for the quantitative analysis of tozadenant in rat plasma. A good calibration curve was observed in the range from 1.01 to 2200 ng/mL for tozadenant using a quadratic regression. In vitro and preclinical in vivo pharmacokinetic (PK) properties of tozadenant were studied through the developed bioanalytical methods, and human PK profiles were predicted using physiologically based pharmacokinetic (PBPK) modeling based on these values. The PBPK model was initially optimized using in vitro and in vivo PK data obtained by intravenous administration at a dose of 1 mg/kg in rats. Other in vivo PK data in rats were used to validate the PBPK model. The human PK of tozadenant after oral administration at a dose of 240 mg was simulated by using an optimized and validated PBPK model. The predicted human PK parameters and profiles were similar to the observed clinical data. As a result, optimized PBPK model could reasonably predict the PK in human.