Population pharmacokinetic analysis of tesamorelin in HIV-infected patients and healthy subjects

Future trends in the treatment of non-alcoholic steatohepatitis

With an estimated prevalence of ≈25% in Western and Asian countries, non alcoholic fatty liver disease (NAFLD), caused by chronic excessive caloric intake, is the emerging as the most prevalent liver disorder worldwide. NAFLD exists in two clinical entities, non-alcoholic fatty liver disease (NAFL), a relative benign disease that carry on minimal risk of liver-related morbidity but significant risk of cardiovascular complications, and non-alcoholic steatohepatitis (NASH), a progressive liver disorder with a significant risk for development of liver-related morbidities and mortality. While, liver injury in NASH is contributed by lipid overload in hepatocytes, lipotoxicity, the main determinant of disease progression is an inflammation-driven fibrotic response. Here, we review the landscape of emerging pharmacological interventions in the treatment of NAFL and NASH. A consensus exists that, while treating the liver component of NASH requires development of novel pharmacological approaches, the future therapy of NASH needs to be tailored to the single patient and most likely will be a combination of agents acting on specific pathogenic mechanisms at different disease stage.

Predictors of Treatment Response to Tesamorelin, a Growth Hormone-Releasing Factor Analog, in HIV-Infected Patients with Excess Abdominal Fat

BACKGROUND

Tesamorelin, a synthetic analog of human growth hormone-releasing factor, decreases visceral adipose tissue (VAT) in human immunodeficiency virus (HIV)-infected patients with lipodystrophy.

OBJECTIVES

1) To evaluate the utility of patient characteristics and validated disease-risk scores, namely indicator variables for the metabolic syndrome defined by the International Diabetes Federation (MetS-IDF) or the National Cholesterol Education Program (MetS-NCEP) and the Framingham Risk Score (FRS), as predictors of VAT reduction during tesamorelin therapy at 3 and 6 months, and 2) To explore the characteristics of patients who reached a threshold of VAT <140 cm2, a level associated with lower risk of adverse health outcomes, after 6 months of treatment with tesamorelin.

METHODS

Data were analyzed from two Phase 3 studies in which HIV-infected patients with excess abdominal fat were randomized in a 2:1 ratio to receive tesamorelin 2 mg (n = 543) or placebo (n = 263) subcutaneously daily for 6 months, using ANOVA and ANCOVA models.

RESULTS

Metabolic syndrome (MetS-IDF or MetS-NCEP) and FRS were significantly associated with VAT at baseline. Presence of metabolic syndrome ([MetS-NCEP), triglyceride levels >1.7 mmol/L, and white race had a significant impact on likelihood of response to tesamorelin after 6 months of therapy (interaction p-values 0.054, 0.063, and 0.025, respectively). No predictive factors were identified at 3 months. The odds of a VAT reduction to <140 cm2 for subjects treated with tesamorelin was 3.9 times greater than that of subjects randomized to placebo after controlling for study, gender, baseline body mass index (BMI) and baseline VAT (95% confidence interval [CI] 2.03; 7.44).

CONCLUSIONS

Individuals with baseline MetS-NCEP, elevated triglyceride levels, or white race were most likely to experience reductions in VAT after 6 months of tesamorelin treatment. The odds of response of VAT <140 cm2 was 3.9 times greater for tesamorelin-treated patients than that of patients receiving placebo.

Population pharmacokinetic and pharmacodynamic analysis of tesamorelin in HIV-infected patients and healthy subjects

The objective of this analysis was to characterize the time course of selected pharmacodynamic (PD) markers of tesamorelin: growth hormone (GH) and insulin-like growth factor (IGF-1) concentrations in HIV-infected patients and healthy volunteers. A total of 41 subjects in Phase I trials receiving subcutaneous daily doses of 1 or 2 mg of tesamorelin during 14 consecutive days were included in this analysis. A previous pharmacokinetic (PK) model of tesamorelin was used as the input function for the PD model of GH. Tesamorelin was hypothesized to stimulate the secretion of GH in an "episodic" manner, i.e., for a finite duration of time. The resulting PK/PD model of GH was used to describe the time course of IGF-1. The effect of age, body weight, body mass index, sex, race, and health status on the model parameters was evaluated. The model was qualified using predictive checks and non-parametric bootstrap. Within the range of the values evaluated no covariates were significantly associated with GH or IGF-1 model parameters. Model evaluation procedures indicated accurate prediction of the selected pharmacodynamic markers. The time course of GH and IGF-1 concentrations following multiple doses of tesamorelin were well predicted by the sequential PK/PD model developed using Phase I data.