Protein-Ribofuranosyl Interactions Activate Orotidine 5'-Monophosphate Decarboxylase for Catalysis.

The role of a global, substrate-driven, enzyme conformational change in enabling the extraordinarily large rate acceleration for orotidine 5'-monophosphate decarboxylase (OMPDC)-catalyzed decarboxylation of orotidine 5'-monophosphate (OMP) is examined in experiments that focus on the interactions between OMPDC and the ribosyl hydroxyl groups of OMP. The D37 and T100' side chains of OMPDC interact, respectively, with the C-3' and C-2' hydroxyl groups of enzyme-bound OMP. D37G and T100'A substitutions result in 1.4 kcal/mol increases in the activation barrier ΔG⧧ for catalysis of decarboxylation of the phosphodianion-truncated substrate 1-(ß-d-erythrofuranosyl)orotic acid (EO) but result in larger 2.1-2.9 kcal/mol increases in ΔG⧧ for decarboxylation of OMP and for phosphite dianion-activated decarboxylation of EO. This shows that these substitutions reduce transition-state stabilization by the Q215, Y217, and R235 side chains at the dianion binding site. The D37G and T100'A substitutions result in <1.0 kcal/mol increases in ΔG⧧ for activation of OMPDC-catalyzed decarboxylation of the phosphoribofuranosyl-truncated substrate FO by phosphite dianions. Experiments to probe the effect of D37 and T100' substitutions on the kinetic parameters for d-glycerol 3-phosphate and d-erythritol 4-phosphate activators of OMPDC-catalyzed decarboxylation of FO show that ΔG⧧ for sugar phosphate-activated reactions is increased by ca. 2.5 kcal/mol for each -OH interaction eliminated by D37G or T100'A substitutions. We conclude that the interactions between the D37 and T100' side chains and ribosyl or ribosyl-like hydroxyl groups are utilized to activate OMPDC for catalysis of decarboxylation of OMP, EO, and FO.

Ledipasvir-Sofosbuvir for 12 Weeks in Children 3 to <6 Years Old With Chronic Hepatitis C.

For children under 12 years of age who have chronic hepatitis C virus (HCV) infection, there are currently no approved treatments with direct-acting antiviral agents. We therefore evaluated the safety and efficacy of ledipasvir-sofosbuvir in HCV-infected children aged 3 to <6 years. In an open-label study, patients 3 to <6 years old chronically infected with HCV genotype 1 (n = 33) or 4 (n = 1) received weight-based doses of combined ledipasvir-sofosbuvir as granules (33.75 mg/150 mg for weights <17 kg or 45 mg/200 mg for weights ≥17 kg) for 12 weeks. The primary endpoint was sustained virological response 12 weeks after treatment (SVR12). For the first 14 patients, intensive pharmacokinetic sampling was done on day 10 of treatment. All patients had been infected through perinatal transmission and were treatment naïve. No patients had known cirrhosis. Ten patients (29%) weighed <17 kg. SVR12 was achieved in 97% of patients (33 of 34); the patient who did not achieve SVR12 was 3 years old and discontinued treatment after 5 days because of an adverse event "abnormal drug taste." The most common adverse events were vomiting (24% of patients), cough (21%), and pyrexia (21%). No patients experienced a serious adverse event. Intensive pharmacokinetic analysis of 13 patients for whom data were evaluable confirmed that the doses selected were appropriate. Conclusion: Ledipasvir-sofosbuvir was well tolerated and highly effective in children 3 to <6 years old with chronic HCV infection.

Orotidine 5'-Monophosphate Decarboxylase: The Operation of Active Site Chains Within and Across Protein Subunits.

The D37 and T100' side chains of orotidine 5'-monophosphate decarboxylase (OMPDC) interact with the C-3' and C-2' ribosyl hydroxyl groups, respectively, of the bound substrate. We compare the intra-subunit interactions of D37 with the inter-subunit interactions of T100' by determining the effects of the D37G, D37A, T100'G, and T100'A substitutions on the following: (a) kcat and kcat/Km values for the OMPDC-catalyzed decarboxylations of OMP and 5-fluoroorotidine 5'-monophosphate (FOMP) and (b) the stability of dimeric OMPDC relative to the monomer. The D37G and T100'A substitutions resulted in 2 kcal mol-1 increases in ΔG† for kcat/Km for the decarboxylation of OMP, while the D37A and T100'G substitutions resulted in larger 4 and 5 kcal mol-1 increases, respectively, in ΔG†. The D37G and T100'A substitutions both resulted in smaller 2 kcal mol-1 decreases in ΔG† for the decarboxylation of FOMP compared to that of OMP. These results show that the D37G and T100'A substitutions affect the barrier to the chemical decarboxylation step while the D37A and T100'G substitutions also affect the barrier to a slow, ligand-driven enzyme conformational change. Substrate binding induces the movement of an α-helix (G'98-S'106) toward the substrate C-2' ribosyl hydroxy bound at the main subunit. The T100'G substitution destabilizes the enzyme dimer by 3.5 kcal mol-1 compared to the monomer, which is consistent with the known destabilization of α-helices by the internal Gly side chains [Serrano, L., et al. (1992) Nature, 356, 453-455]. We propose that the T100'G substitution weakens the α-helical contacts at the dimer interface, which results in a decrease in the dimer stability and an increase in the barrier to the ligand-driven conformational change.

Detecting Protein-Ligand Interaction from Integrated Transient Induced Molecular Electronic Signal (i-TIMES).

Quantitative information about protein-ligand interactions is central to drug discovery. To obtain the quintessential reaction dissociation constant, ideally measurements of reactions should be performed without perturbations by molecular labeling or immobilization. The technique of transient induced molecular electrical signal (TIMES) has provided a promising technique to meet such requirements, and its performance in a microfluidic environment further offers the potential for high throughput and reduced consumption of reagents. In this work, we further the development by using integrated TIMES signal (i-TIMES) to greatly enhance the accuracy and reproducibility of the measurement. While the transient response may be of interest, the integrated signal directly measures the total amount of surface charge density resulted from molecules near the surface of electrode. The signals enable quantitative characterization of protein-ligand interactions. We have demonstrated the feasibility of i-TIMES technique using different biomolecules including lysozyme, N,N',N″-triacetylchitotriose (TriNAG), aptamer, p-aminobenzamidine (pABA), bovine pancreatic ribonuclease A (RNaseA), and uridine-3'-phosphate (3'UMP). The results show i-TIMES is a simple and accurate technique that can bring tremendous value to drug discovery and research of intermolecular interactions.

Safety and Efficacy of 8 Weeks Ledipasvir/Sofosbuvir for Chronic Hepatitis C Genotype 4 in Children Aged 4-10 Years.

OBJECTIVE: To evaluate the safety and efficacy of shortened 8-week regimen of ledipasvir/sofosbuvir (LED/SOF) combination therapy in treatment-naïve children without cirrhosis aged 4-10 years of age with chronic hepatitis C virus (HCV) infection. STUDY DESIGN: This observational single arm prospective study included 30 treatment-naïve children (20 males) with proved chronic HCV fulfilling inclusion criteria. Their body weights ranged from 17 to 26 kg. Four patients were excluded from the study. All the included children received a single oral dose of LED/SOF 45/200 mg for 8 weeks. Body weight, HCV-RNA, complete blood count, and liver function tests were monitored at 0, 2, 4, and 8 weeks and sustained virologic response was evaluated after 12 weeks after treatment (SVR12). The emergence of any side effects was also monitored. RESULTS: The most common risk factor (53.3%) was an parent or sibling with HCV infection. Twenty-nine patients (96.7%) were negative for HCV-RNA by week 2 of treatment and 1 patient became negative by week 4. The end of treatment response and SVR12 were 100%. Transaminases levels declined and returned to normal levels by week 2. Major side effects were fatigue in 90% (27/30) and headache in 76.7% (23/30). Side effects were minimal, tolerable, and did not interfere with daily activity or necessitate treatment discontinuation. CONCLUSIONS: A shortened 8-week regimen of LED/SOF (45/200 mg) is safe and effective with 100% SVR12 in treatment-naïve children with cirrhosis aged 4-10 years with chronic HCV infection genotype 4.

Cost-effectiveness of Using Kidneys From HCV-Viremic Donors for Transplantation Into HCV-Uninfected Recipients.

RATIONALE & OBJECTIVE: Less than 4% of patients with kidney failure receive kidney transplants. Although discard rates of hepatitis C virus (HCV)-viremic kidneys are declining, ~39% of HCV-viremic kidneys donated between 2018 and 2019 were discarded. Highly effective antiviral agents are now available to treat chronic HCV infection. Thus, our objective was to examine the cost-effectiveness of transplanting kidneys from HCV-viremic donors into HCV-uninfected recipients. STUDY DESIGN: Markov state transition decision model. Data sources include Medline search results, bibliographies from relevant English language articles, Scientific Registry of Transplant Recipients, and the US Renal Data System. SETTING & POPULATION: US patients receiving maintenance hemodialysis who are on kidney transplant waiting lists. INTERVENTION(S): Transplantation with an HCV-unexposed kidney versus transplantation with an HCV-viremic kidney and HCV treatment. OUTCOMES: Effectiveness measured in quality-adjusted life-years and costs measured in 2018 US dollars. MODEL, PERSPECTIVE, AND TIMEFRAME: We used a health care system perspective with a lifelong time horizon. RESULTS: In the base-case analysis, transplantation with an HCV-viremic kidney was more effective and less costly than transplantation with an HCV-unexposed kidney because of the longer waiting times for HCV-unexposed kidneys, the substantial excess mortality risk while receiving dialysis, and the high efficacy of direct-acting antiviral agents for HCV infection. Transplantation with an HCV-viremic kidney was also preferred in sensitivity analyses of multiple model parameters. The strategy remained cost-effective unless waiting list time for an HCV-viremic kidney exceeded 3.1 years compared with the base-case value of 1.56 year. LIMITATIONS: Estimates of waiting times for patients willing to accept an HCV-viremic kidney were based on data for patients who received HCV-viremic kidney transplants. CONCLUSIONS: Transplanting kidneys from HCV-viremic donors into HCV-uninfected recipients increased quality-adjusted life expectancy and reduced costs compared with a strategy of transplanting kidneys from HCV-unexposed donors.

Resistance-associated substitution and ledipasvir/sofosbuvir therapy in Mongolian chronic hepatitis C patients.

BACKGROUND: Mongolia has the highest prevalence of hepatitis C virus (HCV) infection worldwide. Ledipasvir/sofosbuvir (LDV/SOF) was introduced to Mongolia since 2016 for HCV eradication. It has been reported that HCV resistance-associated substitutions (RASs) would affect the effectiveness of LDV/SOF in western chronic hepatitis C (CHC) patients. We thus investigated the effectiveness of LDV/SOF and the impact of RAS on the treatment outcome in Mongolian CHC patients. METHODS: Patients with genotype (GT) 1b HCV infection were prospectively enrolled in Mongolia and treated with LDV/SOF for 12 weeks. The proportion of pre-treatment NS5A Y93H RAS in viral quasispecies was measured with next-generation sequencing. The endpoint of LDV/SOF effectiveness was sustained virological response at post-treatment week 12 (SVR12). RESULTS: A total of 94 CHC patients were evaluated. The baseline Y93H proportion was <1% in 74 patients, 1-15% in 7, 15-50% in 2, and ≥50% in 11. All patients completed 12-week LDV/SOF treatment and the SVR rate was 90.4%. The rate of failure to achieve SVR12 for patients with Y93H < 1%, 1-15%, and ≥15% were 0%, 14.3%, and 61.5%, respectively (p for trend = 0.001). In univariable analysis, older age, baseline alanine transaminase level <40 U/mL, and a higher proportion of Y93H were associated with treatment failure. In multivariable analysis, only a higher proportion of Y93H was associated with treatment failure (p = 0.022). CONCLUSION: LDV/SOF therapy achieves a high SVR rate in Mongolian CHC GT1b patients without baseline Y93H RAS. A higher proportion of Y93H may severely undermine the effectiveness of LDV/SOF.

Ledipasvir/sofosbuvir with or without ribavirin for 8 or 12 weeks for the treatment of HCV genotype 4 infection: results from a randomised phase III study in Egypt.

OBJECTIVE: We evaluated the efficacy and safety of ledipasvir/sofosbuvir alone and with ribavirin for 8 and 12 weeks in Egyptian patients with and without cirrhosis, who were infected with hepatitis C virus (HCV) genotype 4, including those who had failed previous treatment with sofosbuvir regimens. DESIGN: In this open-label, multicentre, phase III study, treatment-naive patients were randomised to receive 8 or 12 weeks of ledipasvir/sofosbuvir±ribavirin. Interferon treatment-experienced patients were randomised to receive 12 weeks of ledipasvir/sofosbuvir±ribavirin, while sofosbuvir-experienced or ledipasvir/sofosbuvir-experienced patients received 12 weeks of ledipasvir/sofosbuvir+ribavirin. Randomisation was stratified by cirrhosis status. The primary endpoint was sustained virological response 12 weeks post-treatment (SVR12). RESULTS: We enrolled 255 patients from four centres in Egypt. Among treatment-naive patients, SVR12 rates were 95% and 90% for those receiving 8 weeks of ledipasvir/sofosbuvir alone and with ribavirin, respectively, and 98% for those receiving 12 weeks of ledipasvir/sofosbuvir both alone and with ribavirin. Among interferon-experienced patients, SVR rates were 94% for those receiving 12 weeks of ledipasvir/sofosbuvir and 100% for those receiving 12 weeks of ledipasvir/sofosbuvir plus ribavirin. All patients previously treated with sofosbuvir regimens who received ledipasvir/sofosbuvir plus ribavirin achieved SVR12. The most common adverse events, headache and fatigue, were more common among patients receiving ribavirin. CONCLUSION: Among non-cirrhotic treatment-naive patients with HCV genotype 4, 8 weeks of ledipasvir/sofosbuvir±ribavirin was highly effective. Twelve weeks of ledipasvir/sofosbuvir±ribavirin was highly effective regardless of presence of cirrhosis or prior treatment experience, including previous treatment with sofosbuvir or ledipasvir/sofosbuvir. TRIAL REGISTRATION NUMBER: NCT02487030.

Ledipasvir/Sofosbuvir for 8 Weeks to Treat Acute Hepatitis C Virus Infections in Men With Human Immunodeficiency Virus Infections: Sofosbuvir-Containing Regimens Without Interferon for Treatment of Acute HCV in HIV-1 Infected Individuals.

BACKGROUND: Current guidelines for the management of hepatitis C virus (HCV) infections provide varying recommendations for the optimal treatment of acute HCV infections. There are limited data from small cohort studies to provide guidance on the best approach to treatment of this important patient population. METHODS: Sofosbuvir-Containing Regimens Without Interferon for Treatment of Acute HCV in HIV-1 Infected Individuals is an open-label, 2-cohort, Phase 1 clinical trial in which the second cohort assessed the safety and efficacy of 8 weeks of ledipasvir/sofosbuvir for the treatment of acute HCV infections in participants with chronic human immunodeficiency virus (HIV)-1 infections. This final analysis of the second cohort had a planned accrual of 27 participants, based on non-inferiority criteria, compared to the study-defined, historical, sustained virologic response (SVR) of 60% with pegylated-interferon/ribavirin. RESULTS: We enrolled 27 men (9 Hispanic; 11 White, non-Hispanic; 5 Black, non-Hispanic; 2 Asian or Pacific Islander; median age 46 years). Most (96%) had HCV genotype-1 infection and 59% had the favorable interleukin 28B CC genotype. The median baseline HCV RNA load was 6.17 log10 IU/mL (interquartile range 4.51 - 6.55). All participants (100%) achieved the primary outcome of a sustained virologic response 12 weeks after the date of the last dose of study treatment (90% confidence interval 90-100%), achieving non-inferiority versus the 60% historic benchmark. No treatment discontinuations occurred. CONCLUSIONS: This multicenter clinical trial, investigating 8 weeks of ledipasvir/sofosbuvir for acute HCV infections in men with HIV infections, reports a 100% SVR. This study provides the rationale for larger studies of shortened courses of direct-acting antiviral therapies in persons with HIV infections, including those with high baseline HCV RNA loads. CLINICAL TRIALS REGISTRATION: NCT02128217.

Role of the Carboxylate in Enzyme-Catalyzed Decarboxylation of Orotidine 5'-Monophosphate: Transition State Stabilization Dominates Over Ground State Destabilization.

Kinetic parameters kex (s-1) and kex/Kd (M-1 s-1) are reported for exchange for deuterium in D2O of the C-6 hydrogen of 5-fluororotidine 5'-monophosphate (FUMP) catalyzed by the Q215A, Y217F, and Q215A/Y217F variants of yeast orotidine 5'-monophosphate decarboxylase (ScOMPDC) at pD 8.1, and by the Q215A variant at pD 7.1-9.3. The pD rate profiles for wildtype ScOMPDC and the Q215A variant are identical, except for a 2.5 log unit downward displacement in the profile for the Q215A variant. The Q215A, Y217F and Q215A/Y217F substitutions cause 1.3-2.0 kcal/mol larger increases in the activation barrier for wildtype ScOMPDC-catalyzed deuterium exchange compared with decarboxylation, because of the stronger apparent side chain interaction with the transition state for the deuterium exchange reaction. The stabilization of the transition state for the OMPDC-catalyzed deuterium exchange reaction of FUMP is ca. 19 kcal/mol smaller than the transition state for decarboxylation of OMP, and ca. 8 kcal/mol smaller than for OMPDC-catalyzed deprotonation of FUMP to form the vinyl carbanion intermediate common to OMPDC-catalyzed reactions OMP/FOMP and UMP/FUMP. We propose that ScOMPDC shows similar stabilizing interactions with the common portions of decarboxylation and deprotonation transition states that lead to formation of this vinyl carbanion intermediate, and that there is a large ca. (19-8) = 11 kcal/mol stabilization of the former transition state from interactions with the nascent CO2 of product. The effects of Q215A and Y217F substitutions on kcat/Km for decarboxylation of OMP are expressed mainly as an increase in Km for the reactions catalyzed by the variant enzymes, while the effects on kex/Kd for deuterium exchange are expressed mainly as an increase in kex. This shows that the Q215 and Y217 side chains stabilize the Michaelis complex to OMP for the decarboxylation reaction, compared with the complex to FUMP for the deuterium exchange reaction. These results provide strong support for the conclusion that interactions which stabilize the transition state for ScOMPDC-catalyzed decarboxylation at a nonpolar enzyme active site dominate over interactions that destabilize the ground-state Michaelis complex.

Efficacy of Ledipasvir and Sofosbuvir Treatment of HCV Infection in Patients Coinfected With HBV.

BACKGROUND & AIMS: There have been reports of reactivation of hepatitis B virus (HBV) infection during treatment of hepatitis C virus (HCV) infection with direct-acting antiviral agents. We performed a prospective study of risks and outcomes of HCV infection treatment with ledipasvir and sofosbuvir in patients with HBV infection. METHODS: We performed a phase 3b, multicenter, open-label study in Taiwan of 111 patients with HCV infection (61% HCV genotype 1, 39% HCV genotype 2 infection; 62% women, 16% with compensated cirrhosis) along with HBV infection. All but 1 were positive for the hepatitis B surface antigen (HBsAg); 1 patient who was HBsAg-positive at screening was found to be HBsAg-negative at baseline. Overall, 33% of participants had received prior treatment for HCV and 5% had previously been treated for HBV; no patient was on HBV therapy at the start of the study. All patients received a fixed-dose combination of 90 mg of the HCV NS5A inhibitor ledipasvir with 400 mg of the NS5B nucleotide analogue inhibitor sofosbuvir, once daily for 12 weeks. The primary endpoint was sustained virologic response 12 weeks after the end of therapy. RESULTS: All 111 patients (100%) achieved a sustained virologic response. Of the 37 patients with baseline HBV DNA below 20 IU/mL, 31 (84%) had at least 1 episode of quantifiable HBV DNA through posttreatment week 12. Of the 74 patients with baseline HBV DNA levels of 20 IU/mL or more, 39 (53%) had increases of HBV DNA greater than 1 log10 IU/mL through posttreatment week 12. Overall, 5 patients had increased levels of HBV DNA concomitant with a level of alanine aminotransferase >2 times the upper limit of normal through posttreatment week 12. Of these, 3 patients started HBV treatment. In addition, 1 patient with HBV reactivation since week 8 and concomitant alanine aminotransferase elevation >2 times upper limit of normal at posttreatment week 48 started treatment at posttreatment week 53. This patient had clinical signs and symptoms associated with HBV reactivation. The most common adverse events were headache, upper respiratory infection, and fatigue. CONCLUSIONS: In a prospective study, the combination of ledipasvir and sofosbuvir for 12 weeks produced a sustained virologic response in 100% of patients with HCV infection who were coinfected with HBV. Most patients had an increase in level of HBV DNA not associated with signs or symptoms. ClinicalTrials.gov no: NCT02613871.

Low recurrence rate of hepatocellular carcinoma following ledipasvir and sofosbuvir treatment in a real-world chronic hepatitis C patients cohort.

The aims of the present study were to evaluate the efficacy and tolerability of ledipasvir/sofosbuvir (LDV/SOF) with or without ribavirin in the treatment of chronic hepatitis C (CHC) in patients with advanced liver disease and to analyse whether the use of LDV/SOF treatment is associated with a new occurrence of hepatocellular carcinoma (HCC) during and after LDV/SOF treatment. The Turkish Early Access Program provided LDV/SOF treatment to a total of 200 eligible CHC patients with advanced liver disease. The median follow-up period was 22 months. All patients were Caucasian, 84% were infected with genotype 1b, and 24% had a liver transplantation before treatment. The sustained virological response (SVR12) was 86.0% with ITT analysis. SVR12 was similar among patients with Child-Pugh classes A, B and C disease and transplant recipients. From baseline to SVR12, serum ALT level and MELD score were significantly improved (P < 0.001). LDV/SOF treatment was generally well tolerated. Only one patient developed a new diagnosed HCC. Seventeen of the 35 patients, who had a history of previous HCC, developed HCC recurrence during the LDV/SOF treatment or by a median follow-up of 6 months after treatment. HCC recurrence was less commonly observed in patients who received curative treatment for HCC compared with those patients who received noncurative treatment (P = 0.007). In conclusion, LDV/SOF with or without ribavirin is an effective and tolerable treatment in CHC patients with advanced liver disease. Eradication is associated with improvements in liver function and a reduced risk of developing a new occurrence of HCC.

Safety and Efficacy of Ledipasvir-Sofosbuvir With or Without Ribavirin for Chronic Hepatitis C in Children Ages 6-11.

Currently, there are no interferon-free treatments available for hepatitis C virus (HCV)-infected patients younger than 12 years. We evaluated the safety and effectiveness of the all-oral regimen ledipasvir-sofosbuvir ± ribavirin in HCV-infected children aged 6 to <12 years. In an open-label study, patients aged 6 to <12 years received ledipasvir 45 mg-sofosbuvir 200 mg as two fixed-dose combination tablets 22.5/100 mg once daily, with or without ribavirin, for 12 or 24 weeks, depending on HCV genotype and cirrhosis status. The primary efficacy endpoint was sustained virologic response 12 weeks after therapy (SVR12). Twelve patients underwent intensive pharmacokinetic sampling to confirm the appropriateness of the ledipasvir and sofosbuvir dosages. Ninety-two patients were enrolled (88 genotype 1, 2 genotype 3, and 2 genotype 4), with a median age of 9 years (range, 6-11). Most were perinatally infected (97%) and treatment-naive (78%). Two were confirmed to have cirrhosis, while the degree of fibrosis was unknown in 55 patients. The overall SVR12 rate was 99% (91/92; 95% confidence interval, 94%-100%). The single patient not reaching SVR relapsed 4 weeks after completing 12 weeks of treatment. The most common adverse events were headache and pyrexia. One patient had three serious adverse events, which were considered to be not related to study treatment: tooth abscess, abdominal pain, and gastroenteritis. The area under the concentration-time curve and maximum concentration values for sofosbuvir, its primary metabolite GS-331007, and ledipasvir were within predefined pharmacokinetic equivalence boundaries (50%-200%) compared to values in adults in phase 2/3 of the ledipasvir and sofosbuvir studies. Conclusion: Ledipasvir-sofosbuvir was well tolerated and highly effective in children 6 to <12 years old with chronic HCV.

Cytokine balance is restored as patient-reported outcomes improve in patients recovering from chronic hepatitis C.

BACKGROUND & AIMS: Chronic hepatitis C (CHC) has a negative impact on patient-reported outcomes (PROs). Although most CHC patients who achieve sustained virologic response (SVR) show an improvement in PRO scores, some continue to experience impairment in PROs. The aim was to investigate if serum biomarkers (selected neurotransmitters and cytokines) are associated with changes in PROs in CHC patients who achieve SVR. METHODS: Data were utilized from a prospective clinical trial of ledipasvir/sofosbuvir fixed-dose combination. Chronic genotype 1 HCV subjects without cirrhosis (N = 40, age: 45.3 ± 11.5, 48% male, 90% white) were treated for 12 weeks open label with 97% achieving SVR24. PRO questionnaires included Short Form-36 (SF-36), Fatigue Severity Scale (FSS), Beck Depression Inventory-II (BDI-II), Chronic Liver Disease Questionnaire-HCV (CLDQ-HCV) and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F). Sera were used for measurement of selected neurotransmitters and cytokines. Data were collected at baseline and follow-up week 24. RESULTS: Changes in physical health correlated with changes in several biomarkers. BDNF negatively correlated with SF-36 physical health summary score (rho = -0.34, P < 0.05), SF-36 physical functioning (rho = -0.34, P < 0.05), SF-36 bodily pain (rho = -0.39, P < 0.05) and FACIT-F physical well-being (rho = -0.54, P < 0.001). Changes in emotional well-being (FACIT-F) were positively associated with changes in serotonin (rho = 0.34, P < 0.05), but negatively associated with changes in GABA and BDNF (rho = -0.4, P = 0.01, and rho = -0.35, P < 0.05 respectively). CONCLUSIONS: These data indicate relationships between PROs and serum biomarkers pre- and post-SVR in CHC. These concomitant changes may have important clinical relevance.

Tolerability and effectiveness of generic direct-acting antiviral drugs in eradication of hepatitis C genotype 4 among Egyptian patients.

BACKGROUND: We investigated tolerability and effectiveness of generic, less expensive direct antiviral drugs in the treatment of hepatitis C virus genotype 4 (HCV GT-4) in an Egyptian cohort. PATIENTS AND METHODS: Retrospectively, we analysed data from 648 patients with HCV GT4 attending Alexandria Main University Hospital from January 2016 to May 2017 [488 treatment naïve/160 treatment-experienced/288 with chronic hepatitis/360 with cirrhosis]. Patients received generic sofosbuvir/ledipasvir (n = 168, treatment naïve = 136, treatment-experienced = 32) or sofosbuvir/daclatasvir (n = 480, treatment naïve = 352, treatment-experienced = 128) ± ribavirin. We assessed sustained virologic response 12 weeks after treatment, non-response, relapse, treatment discontinuation and drug adverse reactions. RESULTS: An overall sustained virologic response 12 weeks after treatment was achieved in 97.8%, non-response in 0.6%, relapse in 0.3% and discontinuation of treatment in 1.3% of patients. Sofosbuvir/ledipasvir ± ribavirin regimen attained an overall sustained virologic response 12 weeks after treatment in 96.4% of patients (100% of treatment-experienced vs 95.6% of treatment naïve, P = 0.28), vs 98.3% for sofosbuvir/daclatasvir ± ribavirin regimen (100% of treatment-experienced vs 97.7% of treatment naïve, P = 0.08). No severe drug adverse events or deaths were reported except anaemia due to ribavirin. CONCLUSION: Generic direct antiviral drugs used in treating Egyptian patients with HCV GT-4 demonstrated equal potency, safety and tolerability compared to original brands, with low cost which would help to provide treatment to a larger scale of patients.

Real-World Study on Sofosbuvir-based Therapies in Asian Americans With Chronic Hepatitis C.

BACKGROUND: Limited data exist with regard to treatment outcomes in Asian Americans with chronic hepatitis C (CHC). We evaluated sofosbuvir (SOF)-based regimens in a national cohort of Asian Americans. METHODS: Eligible Asian Americans patients with CHC who had posttreatment follow-up of 24 weeks for SOF -based therapies from December 2013 to June 2017 were enrolled from 11 sites across the United States. The primary endpoint was sustained virologic response (SVR) rates at posttreatment weeks 12 and 24. Secondary endpoints were to evaluate safety by tolerability and adverse events (AEs). RESULTS: Among 231 patients screened, 186 were enrolled. At baseline, 31% (57/186) patients were cirrhotic, 34% (63/186) were treatment experienced. Most of the subjects (42%, 79/186) received ledispavir/SOF therapy. The overall SVR12 was 95%, ranging from 86% in genotype (GT) 1b on SOF+ribavirin to 100% in GT 1b patients on ledipasvir/SOF at subgroup analyses. SVR12 was significantly lower in cirrhotic than in noncirrhotic patients [88% (50/57) vs. 98% (126/129), P<0.01]. Stratified by GT, SVR12 were: 96% (43/45) in GT 1a; 93% (67/72) in GT 1b; 100% (23/23) in GT 2; 90% (19/21) in GT 3; 100% (1/1) in GT 4; 83% (5/6) in GT 5; and 100% (16/16) in GT 6. Cirrhotic patients with treatment failure were primarily GT 1, (GT 1a, n=2; GT 1b, n=4) with 1 GT 5 (n=1). Patients tolerated the treatment without serious AEs. Late relapse occurred in 1 patient after achieving SVR12. CONCLUSIONS: In Asian Americans with CHC, SOF-based regimens were well tolerated without serious AEs and could achieve high SVR12 regardless of hepatitis C viral infection GT.

Shortened 8-Week Course of Sofosbuvir/Ledipasvir Therapy in Adolescents With Chronic Hepatitis C Infection.

Treatment-naïve, noncirrhotic adults with chronic hepatitis C virus genotype 1 infection and with viremia levels <6 million IU/mL could be effectively treated with sofosbuvir/ledipasvir for 8 weeks. The aim of this pilot, prospective, open-label, multicenter study was to evaluate the efficacy and safety of this shortened treatment course in adolescents (≥12 years). The efficacy endpoint was sustained virological response 12 weeks after the end of treatment. Safety was assessed by adverse events and clinical/laboratory data. Fourteen consecutive adolescents (median age 16.5 years, Q1 14.1-Q3 17.4; female 57.1%), vertically infected, were enrolled and treated (June 2018-January 2019). Overall, the end of treatment response and sustained virological response 12 weeks after the end of treatment were 100%. No grade 3 to 4 adverse event or a serious adverse event was observed. Further studies are needed to confirm the optimal efficacy of the shortened 8-week treatment with sofosbuvir/ledipasvir for treatment-naïve, noncirrhotic adolescents with chronic hepatitis C virus genotype 1 infection and pretreatment viremia level < 6 million IU/mL.

Sofosbuvir-based direct acting antiviral therapies for patients with hepatitis C virus genotype 2 infection.

BACKGROUND AND AIM: Data regarding the comparative effectiveness and safety of sofosbuvir (SOF) in combination with ribavirin (RBV), daclatasvir (DCV), or ledipasvir (LDV) for hepatitis C virus genotype 2 (HCV-2) patients were limited. We aimed to evaluate the performance of these regimens in Taiwan. METHODS: One hundred eighty-seven HCV-2 patients with compensated liver diseases receiving SOF in combination with RBV (n = 82), DCV (n = 66), or LDV (n = 39) for 12 weeks were retrospectively enrolled. The effectiveness was determined by sustained virologic response 12 weeks off therapy (SVR12 ). The patient characteristics potentially related to SVR12 were compared. The safety profiles and laboratory abnormalities were assessed. RESULTS: The SVR12 rates were 93.9% (95% confidence interval [CI]: 86.5-97.4%), 98.5% (95% CI: 91.9-99.7%), and 100% (95% CI: 91.0-100%) in patients receiving SOF combined with RBV, DCV, and LDV, respectively. All patients tolerated treatment well. The stratified SVR12 rates were comparable regardless of baseline characteristics or week 4 viral decline among these regimens. Six (3.2%) patients had serious adverse events which were not related to treatment. The rates of fatigue, pruritus, and anemia tended to be higher in patients receiving RBV (22.0%, 19.5%, and 8.5%) combination than those receiving DCV (10.6%, 6.1%, and 1.5%) or LDV (10.3%, 5.1%, and 0%) combination. CONCLUSIONS: Sofosbuvir in combination with RBV, DCV, or LDV for 12 weeks is effective and well-tolerated for HCV-2 patients. Compared with DCV or LDV combination, the risks of fatigue, pruritus, and anemia are higher in patients receiving RBV combination.

A role for the Perlman syndrome exonuclease Dis3l2 in the Lin28-let-7 pathway.

The pluripotency factor Lin28 blocks the expression of let-7 microRNAs in undifferentiated cells during development, and functions as an oncogene in a subset of cancers. Lin28 binds to let-7 precursor (pre-let-7) RNAs and recruits 3' terminal uridylyl transferases to selectively inhibit let-7 biogenesis. Uridylated pre-let-7 is refractory to processing by Dicer, and is rapidly degraded by an unknown RNase. Here we identify Dis3l2 as the 3'-5' exonuclease responsible for the decay of uridylated pre-let-7 in mouse embryonic stem cells. Biochemical reconstitution assays show that 3' oligouridylation stimulates Dis3l2 activity in vitro, and knockdown of Dis3l2 in mouse embryonic stem cells leads to the stabilization of pre-let-7. Our study establishes 3' oligouridylation as an RNA decay signal for Dis3l2, and identifies the first physiological RNA substrate of this new exonuclease, which is mutated in the Perlman syndrome of fetal overgrowth and causes a predisposition to Wilms' tumour development.

Comparing drug interaction frequencies of various hepatitis C treatment regimens among monoinfected patients.

INTRODUCTION AND OBJECTIVES: Four regimens are recommended for treating hepatitis C (HCV) genotype 1 infection. Study aims were to (1) compare frequencies of contraindicated drug interactions (XDDIs) when each HCV regimen is added to medication profiles of HCV-monoinfected patients, (2) quantify the proportion of patients with XDDIs to all four regimens and (3) determine covariates independently associated with having a XDDI to all four regimens. MATERIALS AND METHODS: A cross-sectional study was performed within Upstate New York Veterans Healthcare Administration. INCLUSION CRITERIA: (1) age ≥18 years, (2) HCV monoinfection and (3) available medication list. Data extracted were: demographics, comorbidities, and medication list. Primary outcome was XDDIs involving patient's home medications and each HCV regimen. University of Liverpool drug interaction website was used to define XDDIs. Two-way comparisons of regimens were performed using McNemar's test where p<0.0083 was considered statistically significant. Multivariate regression analyses were performed to determine predictors. RESULTS: Of the 4047 subjects, mean±standard deviation age was 59.8±7.6. Median (interquartile range) number of medications used was 7 [4-11]. Frequencies of XDDIs after the addition of each regimen ranged from 2.8% to 17.8% and were mostly statistically different from one another. There were 95 (2.3%) patients with XDDIs to all four regimens. Predictors of having XDDIs to all four regimens were ≥6 medications and HCV infection ≥10 years. CONCLUSION: The frequencies of XDDIs varied between HCV regimens. Number of medications and duration of HCV infection were predictors of having XDDIs to all four regimens.