Sporadic colorectal cancer (CRC) is a result of complex interactions between the host and its environment. Environmental stressors act by causing host cell DNA alterations implicated in the onset of cancer. Here we investigate the stressor ability of CRC-associated gut dysbiosis as causal agent of host DNA alterations. The epigenetic nature of these alterations was investigated in humans and in mice. Germ-free mice receiving fecal samples from subjects with normal colonoscopy or from CRC patients were monitored for 7 or 14 wk. Aberrant crypt foci, luminal microbiota, and DNA alterations (colonic exome sequencing and methylation patterns) were monitored following human feces transfer. CRC-associated microbiota induced higher numbers of hypermethylated genes in murine colonic mucosa (vs. healthy controls’ microbiota recipients). Several gene promoters including SFRP1,2,3, PENK, NPY, ALX4, SEPT9, and WIF1 promoters were found hypermethylated in CRC but not in normal tissues or effluents from fecal donors. In a pilot study (n = 266), the blood methylation levels of 3 genes (Wif1, PENK, and NPY) were shown closely associated with CRC dysbiosis. In a validation study (n = 1,000), the cumulative methylation index (CMI) of these genes was significantly higher in CRCs than in controls. Further, CMI appeared as an independent risk factor for CRC diagnosis as shown by multivariate analysis that included fecal immunochemical blood test. Consequently, fecal bacterial species in individuals with higher CMI in blood were identified by whole metagenomic analysis. Thus, CRC-related dysbiosis induces methylation of host genes, and corresponding CMIs together with associated bacteria are potential biomarkers for CRC.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Population pharmacokinetic data for mycophenolic acid (MPA) have been reported in adult and paediatric kidney transplant recipients but not in paediatric liver transplant recipients. • MPA AUC during a dosage interval (AUC(0,12 h) is routinely used to optimize mycophenolate mofetil (MMF) dosages in solid organ transplant recipients. WHAT THIS STUDY ADDS • This study describes MPA population pharmacokinetics in paediatric liver transplant recipients for the first time. • The age of the children and the time elapsed since the transplantation were found to affect MPA pharmacokinetics significantly, mainly the apparent volume of distribution. • The limited sampling strategy chosen to estimate individual MPA AUC(0,12 h) with concentrations measured 0, 1 and 4 h after MMF administration may be useful to optimize child care during the post transplantation period. AIMS The aims were to estimate the mycophenolic acid (MPA) population pharmacokinetic parameters in paediatric liver transplant recipients, to identify the factors affecting MPA pharmacokinetics and to develop a limited sampling strategy to estimate individual MPA AUC(0,12 h). METHODS Twenty‐eight children, 1.1 to 18.0 years old, received oral mycophenolate mofetil (MMF) therapy combined with either tacrolimus (n= 23) or ciclosporin (n= 5). The population parameters were estimated from a model‐building set of 16 intensive pharmacokinetic datasets obtained from 16 children. The data were analyzed by nonlinear mixed effect modelling, using a one compartment model with first order absorption and first order elimination and random effects on the absorption rate (ka), the apparent volume of distribution (V/F) and apparent clearance (CL/F). RESULTS Two covariates, time since transplantation (≤ and >6 months) and age affected MPA pharmacokinetics. ka, estimated at 1.7 h−1 at age 8.7 years, exhibited large interindividual variability (308%). V/F, estimated at 64.7 l, increased about 2.3 times in children during the immediate post transplantation period. This increase was due to the increase in the unbound MPA fraction caused by the low albumin concentration. CL/F was estimated at 12.7 l h−1. To estimate individual AUC(0,12 h), the pharmacokinetic parameters obtained with the final model, including covariates, were coded in Adapt II® software, using the Bayesian approach. The AUC(0,12 h) estimated from concentrations measured 0, 1 and 4 h after administration of MMF did not differ from reference values. CONCLUSIONS This study allowed the estimation of the population pharmacokinetic MPA parameters. A simple sampling procedure is suggested to help to optimize pediatric patient care.

BACKGROUND Circulating tumor DNA (ctDNA) has emerged as a good candidate for tracking tumor dynamics in different cancer types, potentially avoiding repeated tumor biopsies. Many different genes can be mutated within a tumor, complicating procedures for tumor monitoring, even with highly sensitive next-generation sequencing (NGS) strategies. Droplet-based digital PCR (dPCR) is a highly sensitive and quantitative procedure, allowing detection of very low amounts of circulating tumor genetic material, but can be limited in the total number of target loci monitored. METHODS We analyzed hypermethylation of 3 genes, by use of droplet-based dPCR in different stages of colorectal cancer (CRC), to identify universal markers for tumor follow-up. RESULTS Hypermethylation of WIF1 (WNT inhibitory factor 1) and NPY (neuropeptide Y) genes was significantly higher in tumor tissue compared to normal tissue, independently of tumor stage. All tumor tissues appeared positive for one of the 2 markers. Methylated ctDNA (MetctDNA) was detected in 80% of metastatic CRC and 45% of localized CRC. For samples with detectable mutations in ctDNA, MetctDNA and mutant ctDNA (MutctDNA) fractions were correlated. During follow-up of different stage CRC patients, MetctDNA changes allowed monitoring of tumor evolution. CONCLUSIONS These results indicate that MetctDNA could be used as a universal surrogate marker for tumor follow-up in CRC patients, and monitoring MetctDNA by droplet-based dPCR could avoid the need for monitoring mutations.

f Hepatitis C virus (HCV) recurrence is the most important complication in HCV liver transplant patients. Boceprevir with pegylated interferon and ribavirin (PegIFN/RBV) enabled improvement in sustained virological response rates of patients with genotype 1 HCV. Boceprevir interacts with immunosuppressive therapy (IT) by inhibiting the cytochrome P450 3A enzyme. Our aim was to study interactions and assess the safety of boceprevir in the context of HCV recurrence. Boceprevir (800 mg three times a day) initiated after a 4-week lead-in phase was associated with cyclosporine (three patients), tacrolimus (two patients), and everolimus (one patient) in five liver transplant patients with genotype 1 HCV infection who experienced HCV recurrence. The mean follow-up period after HCV therapy was 14.8 ؎ 3.1 weeks. Estimated oral clearances of IT decreased on average by 50%, requiring reduced dosing regimens. Anemia occurred in all patients, with a mean fall in hemoglobin levels between baseline and week 12 of 3.12 ؎ 2.27 g/dl. All patients required administration of ␤-erythropoietin (n ‫؍‬ 5), three needed ribavirin dose reduction, and one needed a blood transfusion. A virological response was observed in all patients (mean HCV viral load [HVL] decrease at week 12, 6.64 ؎ 0.35 log 10 IU/ml). These preliminary results in liver transplant patients with HCV recurrence demonstrate the feasibility and safety of coadministration of boceprevir and IT. E nd-stage liver disease due to hepatitis C virus (HCV) is still a common indication for liver transplantation (LT) (6). However, a recurrence of HCV infection is the most frequent cause of death and graft loss, accounting for two-thirds of graft failures. The natural history of HCV is accelerated after LT, leading to cirrhosis in 20 to 30% of patients 5 years post-LT (4). The decompensation rate is higher than 70% at 3 years in liver transplant recipients with established cirrhosis, versus less than 10% in immunocompetent patients (4). Progression from decompensation to death is also accelerated after LT, with a 3-year survival rate of Ͻ10% following the onset of HCV-related allograft failure (4). Few patients (Ͻ5%) experience cholestatic hepatitis, but their prognosis is the poorest (7). To prevent or to treat these occurrences, standard anti-HCV therapy, represented by pegylated interferon and ribavirin, can achieve a sustained virological response (SVR) in 30% of patients, who have a less severe outcome and lower mortality than nonresponders (21). Boceprevir is a novel peptidometic NS3 protease inhibitor that forms a covalent and reversible complex with the NS3 protease in vitro in the HCV replicon system. Recently, two phase III trials showed that combining boceprevir with pegylated interferon and ribavirin increased SVR rates in naive and previously treated nontransplant patients with genotype 1 HCV from 38% to 66% (SPRINT-2) and 21% to 66% (RESPOND-2), respectively (2, 20). The administration of such drugs in the context of HCV recurrence on the liver graft is one of the most...