Gut Wall Metabolism. Application of Pre-Clinical Models for the Prediction of Human Drug Absorption and First-Pass Elimination.

Quantifying the multiple processes which control and modulate the extent of oral bioavailability for drug candidates is critical to accurate projection of human pharmacokinetics (PK). Understanding how gut wall metabolism and hepatic elimination factor into first-pass clearance of drugs has improved enormously. Typically, the cytochrome P450s, uridine 5'-diphosphate-glucuronosyltransferases and sulfotransferases, are the main enzyme classes responsible for drug metabolism. Knowledge of the isoforms functionally expressed within organs of first-pass clearance, their anatomical topology (e.g. zonal distribution), protein homology and relative abundances and how these differ across species is important for building models of human metabolic extraction. The focus of this manuscript is to explore the parameters influencing bioavailability and to consider how well these are predicted in human from animal models or from in vitro to in vivo extrapolation. A unique retrospective analysis of three AstraZeneca molecules progressed to first in human PK studies is used to highlight the impact that species differences in gut wall metabolism can have on predicted human PK. Compared to the liver, pharmaceutical research has further to go in terms of adopting a common approach for characterisation and quantitative prediction of intestinal metabolism. A broad strategy is needed to integrate assessment of intestinal metabolism in the context of typical DMPK activities ongoing within drug discovery programmes up until candidate drug nomination.

Prognostic factors in primary cutaneous anaplastic large cell lymphoma: characterization of clinical subset with worse outcome.

OBJECTIVES: To identify prognostic factors in primary cutaneous anaplastic large cell lymphoma (pcALCL), focusing on extensive limb disease (ELD), defined as initial presentation or progression to multiple skin tumors in 1 limb or contiguous body regions, and to study gene expression profiles of patients with pcALCL. DESIGN: Retrospective cohort study. SETTING: The Stanford Comprehensive Cancer Center and dermatology ambulatory clinics. PATIENTS: A total of 48 patients with pcALCL evaluated from 1990 through 2005. MAIN OUTCOME MEASURES: Hazard ratios (HRs) for prognostic factors for overall survival (OS) and disease-specific survival (DSS) and risk factors for progression to extracutaneous disease were identified using Cox regression. Gene expression profiles of 9 typical pcALCL and 3 ELD samples were investigated using complementary DNA microarrays. RESULTS: Univariate analysis demonstrated age, ELD, and progression to extracutaneous disease as significant prognostic factors for OS, whereas ELD and progression to extracutaneous disease were significant for DSS. In multivariate analysis, age (HR, 1.83; 95% confidence interval [CI], 1.02-3.26) and progression to extracutaneous disease (HR, 6.42; 95% CI, 1.39-29.68) remained significant for OS, whereas ELD (HR, 29.31; 95% CI, 1.72-500.82) and progression to extracutaneous disease (HR, 13.12; 95% CI, 1.03-167.96) remained independent prognostic factors for DSS. Presentation with T3 disease was a risk factor for progression to extracutaneous disease (HR, 10.20; 95% CI, 1.84-56.72). Microarray data revealed that patients with ELD and typical pcALCL formed distinct clusters. CONCLUSIONS: Patients with ELD have a more aggressive course associated with a differential gene expression profile. More aggressive treatments may be indicated for patients with ELD and those whose disease progresses to extracutaneous disease because they have poorer outcomes.