Assessment of Hepatic Cytochrome P450 3A Activity Using Metabolic Markers in Patients with Renal Impairment.

BACKGROUND: The renal function of individuals is one of the reasons for the variations in therapeutic response to various drugs. Patients with renal impairment are often exposed to drug toxicity, even with drugs that are usually eliminated by hepatic metabolism. Previous study has reported an increased plasma concentration of indoxyl sulfate and decreased plasma concentration of 4ß-hydroxy (OH)-cholesterol in stable kidney transplant recipients, implicating indoxyl sulfate as a cytochrome P450 (CYP) inhibiting factor. In this study, we aimed to evaluate the impact of renal impairment severity-dependent accumulation of indoxyl sulfate on hepatic CYP3A activity using metabolic markers. METHODS: Sixty-six subjects were enrolled in this study; based on estimated glomerular filtration rate (eGFR), they were classified as having mild, moderate, or severe renal impairment. The plasma concentration of indoxyl sulfate was quantified using liquid chromatography-mass spectrometry (LC-MS). Urinary and plasma markers (6ß-OH-cortisol/cortisol, 6ß-OH-cortisone/cortisone, 4ß-OH-cholesterol) for hepatic CYP3A activity were quantified using gas chromatography-mass spectrometry (GC-MS). The total plasma concentration of cholesterol was measured using the enzymatic colorimetric assay to calculate the 4ß-OH-cholesterol/cholesterol ratio. The correlation between variables was assessed using Pearson's correlation test. RESULTS: There was a significant negative correlation between MDRD eGFR and indoxyl sulfate levels. The levels of urinary 6ß-OH-cortisol/cortisol and 6ß-OH-cortisone/cortisone as well as plasma 4ß-OH-cholesterol and 4ß-OH-cholesterol/cholesterol were not correlated with MDRD eGFR and the plasma concentration of indoxyl sulfate. CONCLUSION: Hepatic CYP3A activity may not be affected by renal impairment-induced accumulation of plasma indoxyl sulfate.

Clinical and cost effectiveness of bevacizumab + FOLFIRI combination versus FOLFIRI alone as first-line treatment of metastatic colorectal cancer in South Korea.

BACKGROUND: Bevacizumab has been extensively investigated in combination with various standard chemotherapies in the treatment of metastatic colorectal cancer (mCRC). However, a comparison to irinotecan + infusional 5-fluorouracil/leucovorin (FOLFIRI) is lacking. OBJECTIVE: To explore clinical effectiveness and cost-effectiveness of adding bevacizumab to a regimen of FOLFIRI for the first-line treatment of mCRC in the Republic of Korea by conducting an indirect treatment comparison. METHODS: A health-economic model was developed to investigate the possible health outcomes (life-years gained [LYG]), direct costs, and incremental cost-effectiveness ratio (ICER) of adding bevacizumab to a FOLFIRI regimen. Data on progression-free and overall survival were derived from randomized clinical trials and were used in the indirect treatment comparison. The annual discount rate for costs and outcomes was 5%. A lifetime horizon of 8 years was used. Sensitivity analyses were carried out on all pivotal model assumptions. RESULTS: Incremental mean overall survival among patients treated with bevacizumab + FOLFIRI varied between 8.6 and 15.7 months compared with patients treated with FOLFIRI alone. The deterministic base-case result was 1.177 LYG. The discounted ICERs ranged from µ31.8 to µ39.5 million/LYG, with the base-case result being µ34.5 million/LYG. Treatment effect had the most impact on the outcomes in this model. CONCLUSIONS: Although there is no formal threshold for ICER per LYG in Korea, funding may be considered for bevacizumab + FOLFIRI, particularly if the severity and end-of-life nature of mCRC is taken into account.

Cost-effectiveness of bevacizumab-based therapy versus cisplatin plus pemetrexed for the first-line treatment of advanced non-squamous NSCLC in Korea and Taiwan.

AIMS: The aim of this analysis is to investigate the mean incremental costs and life expectancy associated with two first-line treatments for advanced non-squamous non-small cell lung cancer (NSCLC) in Korea and Taiwan; bevacizumab plus cisplatin and gemcitabine (BevCG) and cisplatin plus pemetrexed (CP). METHODS: A health economic (area under curve) model with three health states was developed to assess health outcomes (life-years gained [LYG]), direct costs, and incremental cost-effectiveness ratio (ICER). Progression-free survival (PFS) and overall survival (OS) were derived from randomized clinical trials and used in an indirect comparison in order to estimate their cost effectiveness. A life-time horizon was used. Costs and outcomes were discounted yearly by 5% in Korea and by 3% in Taiwan. RESULTS: The incremental LYG for the BevCG patients compared with patients treated with CP were 1.10 (13.2 months) in Korea and 1.19 (14.3 months) in Taiwan. The incremental costs were 37,439,968 ($ 33,322) in Korea and NT$ 1,910,615 ($ 64,541) in Taiwan. The incremental cost-effectiveness ratio was 34,064,835 ($ 30,318) in Korea and NT$ 1,607,960 ($ 54,317) in Taiwan. The inputs tested in one-way sensitivity analyses had very little impact on the overall cost effectiveness. CONCLUSION: This analysis shows that BevCG is more costly but is also associated with additional life-years in Korea and Taiwan. The ICER per LYG suggests that BevCG is a cost-effective therapy when compared to CP for patients with advanced NSCLC in Korea and Taiwan.