Chang Soo Choi

Characterization of Ebastine, Hydroxyebastine, and Carebastine Metabolism by Human Liver Microsomes and Expressed Cytochrome P450 Enzymes: Major Roles for CYP2J2 and CYP3A

Ebastine undergoes extensive metabolism to form desalkylebastine and hydroxyebastine. Hydroxyebastine is subsequently metabolized to carebastine. Although CYP3A4 and CYP2J2 have been implicated in ebastine N-dealkylation and hydroxylation, the enzyme catalyzing the subsequent metabolic steps (conversion of hydroxyebastine to desalkylebastine and carebastine) have not been identified. Therefore, we used human liver microsomes (HLMs) and expressed cytochromes P450 (P450s) to characterize the metabolism of ebastine and that of its metabolites, hydroxyebastine and carebastine. In HLMs, ebastine was metabolized to desalkyl-, hydroxy-, and carebastine; hydroxyebastine to desalkyl- and carebastine; and carebastine to desalkylebastine. Of the 11 cDNA-expressed P450s, CYP3A4 was the main enzyme catalyzing the N-dealkylation of ebastine, hydroxyebastine, and carebastine to desalkylebastine [intrinsic clearance (CLint) = 0.44, 1.05, and 0.16 μl/min/pmol P450, respectively]. Ebastine and hydroxyebastine were also dealkylated to desalkylebastine to some extent by CYP3A5. Ebastine hydroxylation to hydroxyebastine is mainly mediated by CYP2J2 (0.45 μl/min/pmol P450; 22.5- and 7.5-fold higher than that for CYP3A4 and CYP3A5, respectively), whereas CYP2J2 and CYP3A4 contributed to the formation of carebastine from hydroxyebastine. These findings were supported by chemical inhibition and kinetic analysis studies in human liver microsomes. The CLint of hydroxyebastine was much higher than that of ebastine and carebastine, and carebastine was metabolically more stable than ebastine and hydroxyebastine. In conclusion, our data for the first time, to our knowledge, suggest that both CYP2J2 and CYP3A play important roles in ebastine sequential metabolism: dealkylation of ebastine and its metabolites is mainly catalyzed by CYP3A4, whereas the hydroxylation reactions are preferentially catalyzed by CYP2J2. The present data will be very useful to understand the pharmacokinetics and drug interaction of ebastine in vivo.

Metabolism of 1- and 4-Hydroxymidazolam by Glucuronide Conjugation Is Largely Mediated by UDP-Glucuronosyltransferases 1A4, 2B4, and 2B7

Midazolam undergoes oxidative hydroxylation by CYP3A to its metabolites, which are excreted mainly as glucuronidated conjugates into the urine. In this study, we examined the glucuronidation of hydroxymidazolam in human liver microsomes (HLMs) and characterized the UDP-glucuronosyltransferases (UGTs) involved in 1′- and 4-hydroxymidazolam glucuronidation. Among the 12 UGT isoforms tested, the O- and N-glucuronidation of 1′-hydroxymidazolam was mediated by UGT2B4/2B7 and 1A4, respectively. In contrast, the glucuronidation of 4-hydroxymidazolam was mediated by UGT1A4. Consistent with these observations, the UGT1A4 inhibitor hecogenin and the UGT2B7 substrate diclofenac potently inhibited the N- and O-glucuronidation of 1′-hydroxymidazolam in HLMs, respectively. A correlation analysis of UGT enzymatic activity and the formation rate of glucuronide metabolites from 1′- and 4-hydroxymidazolam in 25 HLMs showed that hydroxymidazolam glucuronidation is correlated with UGT1A4-mediated lamotrigine glucuronidation and UGT2B7-mediated diclofenac glucuronidation activity. Taken together, these findings indicate that UGT1A4, 2B4, and 2B7 are major isoforms responsible for glucuronide conjugate formation from 1′- and 4-hydroxymidazolam, which are the two major oxidative metabolites of midazolam.

Implication of minimal extrathyroidal extension as a prognostic factor in papillary thyroid carcinoma

PURPOSE Extrathyroidal extension (ETE) of papillary thyroid carcinoma (PTC) is a risk factor for tumor recurrence. By TNM Classification (7th edition), differentiated thyroid carcinoma with ETE is designated T3 (minimal invasion), T4a (extended invasion), or T4b (more extensive unresectable invasion), according to the degree of tumor involvement. We subsequently focused our investigation on minimal ETE (MEE), analyzing the clinicopathologic characteristics, recurrence rate, and recurrence-free survival (RFS) in this setting. METHODS A retrospective study was conducted, based on 332 patients undergoing thyroidectomy for PTC between January 2005 and December 2006. RESULTS The study population was stratified into two groups: PTC with MEE (103/332; 31.0%) and PTC without MEE (229/332; 69.0%). In patients with PTC, MEE correlated with gender, tumor size, multifocality, lymph node (LN) metastasis, underlying Hashimotos thyroiditis, and the nature of the surgery. However, no significant intergroup differences were evident with respect to age, recurrence rate, and LN metastasis. In multivariate analysis, LN metastasis (odds ratio = 2.273; 95% confidence interval, 1.280-4.037) was recognized as an independent correlate of mETE (p = 0.005). However, recurrence-free survival did not differ significantly between the groups (p = 0.153), even when further stratified by the presence or absence of LN metastasis. CONCLUSION In patients with PTC, MEE does not impact RFS. Thus, appropriate surgical intervention and postoperative follow up are mandatory in PTC, regardless of its extent.

The Degrees of Hepatocyte Cytoplasmic Expression of Hepatitis B Core Antigen correlate with Histologic Activity of Liver Disease in the Young Patients with Chronic Hepatitis B Infection

Subcellular localizaton of HBcAg have been found to be related to the activity of liver disease and HBV replication. The aim of this study was to determine whether the degree of expression of HBcAg in the hepatocyte nucleus and cytoplasm reflects the level of viral replication and histological activity in chronic HBV infection. A total of 102 patients with biopsy proven chronic hepatitis B were included. There was a highly significant correlation between the levels of HBV DNA in serum and the degree of expression of HBcAg in the nucleus for HBeAg-positive(p=0.000) and negative patients(p=0.04). There was a highly significant, correlation between the degrees of expression of HBcAg in hepatocyte cytoplasm and histologic activities (p<0.01) for HBeAg-positive patients. The degrees of expression of HBcAg in the hepatocyte cytoplasm correlated positively with the lobular activities (p<0.01), but not correlated with the portal activity and fibrosis for HBeAg-negative patients. In conclusion, in the young patients with chronic B viral hepatitis, the degree of expression of HBcAg in the hepatocyte nucleus may affect viral load, and the degree of expression of HBcAg in the hepatocyte cytoplasm may affect histologic activities of liver disease.

X gene mutations in hepatitis B patients with cirrhosis, with and without hepatocellular carcinoma

Specific mutations in the hepatitis B virus (HBV) genome have been reported to be associated with the development of hepatocellular carcinoma (HCC). The goal of this study was to determine whether mutations in the HBV X gene are associated with the development of HCC in hepatitis B patients with cirrhosis. Forty‐two patients infected with HBV genotype C2 with cirrhosis and HCC were compared with 46 patients with cirrhosis but without HCC. X gene mutations were determined by direct sequencing in all patients. The HCC and non‐HCC groups were similar with respect to clinical characteristics, and the presence of T1762/A1764, T1653, and V1753 mutations was not significantly different between the two groups (P = 0.068, P = 0.097, P = 0.442, respectively). Only the B1499 mutation was associated significantly with HCC (P = 0.015) (odds ratio: 3.42, 95% CI: 1.24–9.48). In hepatitis Be antigen (HBeAg)‐positive patients, advanced age was associated significantly with HCC (P = 0.038), whereas in HBeAg‐negative patients, the B1499 mutation was associated more significantly with HCC (P = 0.01). Patients in the B1499 mutation group exhibited significantly higher AST and ALT levels compared with patients infected the wild‐type virus. In conclusion, B1499 is a novel mutation associated with HCC in Korean patients with cirrhosis infected with HBV genotype C2. J. Med. Virol. 81:1721–1725, 2009.

Association between Hepatitis B Virus X Gene Mutations and Clinical Status in Patients with Chronic Hepatitis B Infection

BACKGROUND/AIMS Few reports have described the association between mutations in the entire X gene of the hepatitis B virus (HBV) and the clinical status of HBV-infected patients. We studied the association between HBV X gene mutations and the disease status of patients infected with HBV genotype C. METHODS Mutations in the HBV X genes of 194 patients were determined by direct sequencing. The subject population consisted of patients with chronic hepatitis (n=60), liver cirrhosis (n=65), and hepatocellular carcinoma (HCC) (n=69). The sequencing results of these 3 groups were compared. RESULTS Each of the mutations G1386M, C1485T, C1653T, T1753V, A1762T, and G1764A was significantly associated with the patients clinical status. The T1753V (p<0.001) and A1762T/G1764A (p<0.001) mutations were found more frequently in Hepatitis B e antigen (HBeAg)-negative than in HBeAg-positive patients. Specific X gene mutations (G1386M, C1653T, and A1762T/G1764A) were more prevalent in patients with liver cirrhosis and HCC than in chronic hepatitis patients (p<0.005 for all). In addition, the T1753V (p<0.001) and C1485T (p<0.001) mutations were significantly more prevalent in HCC patients than in chronic hepatitis patients. Only the prevalence of the T1753V mutation increased as the HBV infection progressed from liver cirrhosis to HCC (p=0.023). CONCLUSIONS Our findings show a difference in the pattern of X gene mutations that were associated with the clinical status of patients with chronic HBV infection.

Clinical features and outcomes of gastric variceal bleeding: retrospective Korean multicenter data

Background/Aims While gastric variceal bleeding (GVB) is not as prevalent as esophageal variceal bleeding, it is reportedly more serious, with high failure rates of the initial hemostasis (>30%), and has a worse prognosis than esophageal variceal bleeding. However, there is limited information regarding hemostasis and the prognosis for GVB. The aim of this study was to determine retrospectively the clinical outcomes of GVB in a multicenter study in Korea. Methods The data of 1,308 episodes of GVB (males:females=1062:246, age=55.0±11.0 years, mean±SD) were collected from 24 referral hospital centers in South Korea between March 2003 and December 2008. The rates of initial hemostasis failure, rebleeding, and mortality within 5 days and 6 weeks of the index bleed were evaluated. Results The initial hemostasis failed in 6.1% of the patients, and this was associated with the Child-Pugh score [odds ratio (OR)=1.619; P<0.001] and the treatment modality: endoscopic variceal ligation, endoscopic variceal obturation, and balloon-occluded retrograde transvenous obliteration vs. endoscopic sclerotherapy, transjugular intrahepatic portosystemic shunt, and balloon tamponade (OR=0.221, P<0.001). Rebleeding developed in 11.5% of the patients, and was significantly associated with Child-Pugh score (OR=1.159, P<0.001) and treatment modality (OR=0.619, P=0.026). The GVB-associated mortality was 10.3%; mortality in these cases was associated with Child-Pugh score (OR=1.795, P<0.001) and the treatment modality for the initial hemostasis (OR=0.467, P=0.001). Conclusions The clinical outcome for GVB was better for the present cohort than in previous reports. Initial hemostasis failure, rebleeding, and mortality due to GVB were universally associated with the severity of liver cirrhosis.

Efficacy and tolerability of pegylated interferon-α2a plus ribavirin versus pegylated interferon-α2b plus ribavirin in treatment-naive chronic hepatitis C patients.

Objectives: The authors compared the efficacies and tolerabilities of pegylated interferon-α2a (PEG-IFN-α2a) + ribavirin and pegylated interferon-α2b (PEG-IFN-α2b) + ribavirin for the initial treatment of chronic hepatitis C. Methods: A total of 126 treatment-naive patients (29.4% genotype 1, 70.6% genotype non-1) were treated with PEG-IFN-α2a 180 µg/week (group A, n = 79) or PEG-IFN-α2b 1.5 µg/kg/week (group B, n = 47) with ribavirin (800 mg/day for genotype non-1 or 1,000–1,200 mg/day for genotype 1) for 24 (genotype non-1) or 48 weeks (genotype 1). Results: End-of-treatment virologic response, sustained virologic response, and biochemical response were not significantly different in groups A and B (84.8 vs. 89.4%, 70.9 vs. 72.3%, and 70.9 vs. 74.5%, respectively; p > 0.05). In patients with the HCV genotype 1 or non-1, treatment responses were not significantly different. Multivariate analysis showed that HCV genotype only was an independent factor that affected sustained virologic response (p = 0.048). The proportions of treatment discontinuations in groups A and B were similar (10.1 vs. 10.6%; p = 1.000). Conclusions: PEG-IFN-α2a or PEG-IFN-α2b + ribavirin combination therapies showed similar efficacies and tolerabilities as initial treatments for chronic hepatitis C.

T4 stage and preoperative anemia as prognostic factors for the patients with colon cancer treated with adjuvant FOLFOX chemotherapy.

BackgroundFOLFOX-based adjuvant chemotherapy is a benefit for high-risk stage II and stage III colon cancer after curative resection. But, the prognostic factor or predictive marker for the efficacy of FOLFOX remains unclear. This study was aimed to identify the prognostic value and cumulative impact of adjuvant FOLFOX on the stage II and III colon cancer patients.MethodsA total of 196 stage II and III colon cancer patients were retrospectively enrolled in prospectively collected data. They underwent curative resection followed by FOLFOX4 adjuvant chemotherapy. The oncological outcomes included the 5-year disease-free survival (DFS) rate and 5-year overall survival (OS) rate. Cox-regression analysis was performed to identify the prognostic value, and its cumulative impact was analyzed.ResultsThe 5-year DFS rate of the patients was 71.94% and the 5-year OS rate was 81.5%. The prognostic values for the 5-year DFS rate and 5-year OS rate were T4 stage and preoperative anemia in a multivariate analysis. Each patient group who had no prognostic value, single, or both factors revealed 95.35%, 69.06%, and 28.57% in the 5-year DFS rate, respectively (p < 0.0001). The 5-year OS rate also showed the significant differences in each group who had no prognostic value, single, or both factors revealed 100%, 79.3%, and 45.92%, respectively (p < 0.0001).ConclusionOur results showed similar efficacy to MOSAIC study in stage II and stage III colon cancer patients treated with adjuvant FOLFOX chemotherapy after curative resection. Patients who had T4 stage and/or preoperative anemia showed worse prognosis than patients without any prognostic value. These findings suggest that FOLFOX could not be effective in the patients with T4 stage colon cancer accompanied by preoperative anemia.

Treatment Outcomes of Clevudine versus Lamivudine at Week 48 in Naïve Patients with HBeAg Positive Chronic Hepatitis B

The authors assessed the efficacy and antiviral resistance of 48-week clevudine therapy versus lamivudine in treatment of naïve patients with HBeAg positive chronic hepatitis B. In this retrospective study, a total of 116 HBeAg positive patients, who received 30 mg of clevudine once daily (n=53) or 100 mg of lamivudine once daily (n=63) for 48 weeks, were included. At week 48, clevudine therapy produced a significantly greater mean reductions in serum HBV DNA levels from baseline than lamivudine therapy (-5.2 vs. -4.2 log10IU/mL; P=0.005). Furthermore, a significantly higher proportion of patients on clevudine achieved negative serum HBV DNA by PCR (<13 IU/mL) at week 48 (60.4% vs. 38.1%; P=0.025). The incidence of virologic breakthrough in the clevudine group was significantly lower than in the lamivudine group (9.4% vs. 25.4%; P=0.031). However, rates of alanine aminotransferase normalization and HBeAg loss or seroconversion were similar in the two groups (83.0% vs. 81.0%, 11.3% vs. 11.1%; P=0.813, 1.000, respectively). In conclusion, clevudine is more potent for viral suppression and lower for antiviral resistance at week 48 than lamivudine in treatment of naïve patients with HBeAg positive chronic hepatitis B.