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Since the introduction of suppressive antiretroviral therapy (ART), HIV has become a chronic disease, with infected people in high‐income countries approaching similar life expectancy to the general population. As this population ages, an increasing number of people with HIV are living with age‐, treatment‐, and disease‐related comorbidities. Lifestyle factors such as smoking, alcohol abuse, and substance misuse have a role in age‐related comorbidity. Some degree of immune dysfunction is suggested by the presence of markers of immune activation/inflammation despite effective suppression of HIV replication. Cumulative exposure to some antiretroviral drugs contributes to HIV‐associated comorbidities, with risk increasing with age. Specifically, tenofovir disoproxil fumarate (TDF), ritonavir‐boosted atazanavir, and ritonavir‐boosted lopinavir are associated with renal impairment, and TDF is known to cause loss of bone mineral density. Tenofovir alafenamide (TAF) was developed to improve on the safety profile of TDF, while maintaining its efficacy. TAF has better stability in plasma, and higher intracellular accumulation of tenofovir diphosphate in target cells, which has resulted in improved antiviral activity at lower doses with improved renal and bone safety. TAF has been studied extensively in randomized clinical trials and real‐world studies. TAF‐based regimens are recommended over TDF‐containing regimens for the improved safety profile. [ABSTRACT FROM AUTHOR]

Objectives Multiple guidelines exist for the use of live viral vaccines for measles-mumps-rubella ( MMR), varicella and yellow fever in people with HIV infections, but these guidelines do not make recommendations regarding live attenuated herpes zoster vaccine ( LAHZV), which is approved for people over 50 years in the general population. LAHZV is made with the same virus used in varicella vaccine. The incidence of herpes zoster remains increased in people with HIV infection, even when on suppressive antiretroviral therapy, and a growing proportion of HIV-infected patients are over 50 years of age. The purpose of this article is to review the use of varicella vaccine and LAHZV in people with HIV infection and to make recommendations about the use of LAHZV in adults with HIV infection. Methods A PubMed search was undertaken using the terms 'herpes zoster AND HIV' and 'varicella AND HIV'. Reference lists were also reviewed for pertinent citations. Results Varicella vaccine is recommended in varicella-susceptible adults, as long as they have a CD4 count > 200 cells/μL, the same CD4 threshold used for MMR and yellow fever vaccines. No transmission of vaccine strain Varicella zoster virus has been documented in people with HIV infections with a CD4 count above this threshold. LAHZV was administered to 295 HIV-infected adults with a CD4 count > 200 cells/μL, and was safe and immunogenic with no cases of vaccine strain infection. Conclusions It is recommended that LAHZV be administered to HIV-infected adults with a CD4 count above 200 cells/μL, the same CD4 threshold used for other live attenuated viral vaccines. [ABSTRACT FROM AUTHOR]

Objective: To compare the efficacy and safety of episodic patient-initiated oral famciclovir with placebo in recurrent genital herpes.Design: Randomized, double-blind, frequent-observation, dose-ranging study comparing twice-daily 125-mg, 250-mg, or 500-mg oral famciclovir with placebo. Patients initiated therapy after self-culturing, reported to the clinic within 12 hours, and were assessed twice daily for at least 5 days.Setting: Fifteen Canadian university, private practice, or public outpatient clinics.Patients: A total of 692 patients with culture-proven recurrent genital herpes were randomized; 467 patients experienced a symptomatic episode and commenced treatment.Main Outcome Measure: Time to complete healing of all lesions.Results: Famciclovir (all doses) was significantly more effective than placebo in reducing time to healing, time to cessation of viral shedding, and durations of lesion edema, vesicles, ulcers, and crusts. Times to cessation of all symptoms and of moderate to severe lesion tenderness, pain, and burning were also reduced. Patients who initiated famciclovir prior to viral shedding were more likely to not shed virus throughout. All doses were equally effective, safe, and well tolerated.Conclusions: Oral famciclovir reduced the onset and duration of viral shedding, lesion persistence, and uncomfortable symptoms. Several individual symptoms and lesion stages were also reduced in duration by this episodic therapy. Additionally, our twice-daily observation trial design proved to be a helpful tool for studying recurrent disease. Episodic oral famciclovir provides a convenient and effective alternative for those patients with recurrent genital herpes whose frequency rates do not require continuous antiviral suppression. [ABSTRACT FROM AUTHOR]

Context: Recurrent genital herpes simplex virus (HSV) may be treated episodically, but this may not be sufficient for patients with frequent recurrences.Objective: To determine the efficacy and safety of famciclovir in the suppression of recurrent genital HSV infection.Design: A randomized, double-blind, placebo-controlled, parallel-group study.Setting: Thirty university, hospital, or private outpatient referral centers in Canada and Europe.Patients: A total of 455 patients (223 men, 232 women) aged 18 years or older with a history of 6 or more episodes of genital herpes during 12 of the most recent 24 months, in the absence of suppressive therapy, received study medication.Intervention: Oral famciclovir, 125 mg or 250 mg 3 times daily or 250 mg twice daily, or placebo for 52 weeks.Main Outcome Measures: Time to the first recurrence of genital HSV infection; the proportion of patients remaining free of HSV recurrence at 6 months; frequency of adverse events.Results: In an intent-to-treat analysis, famciclovir significantly delayed the time to the first recurrence of genital herpes at all dose regimens (hazard ratios, 2.9-3.3; P<.001); median time to recurrence for famciclovir recipients was 222 to 336 days compared with 47 days for placebo recipients. The proportion of patients remaining free of HSV recurrence was approximately 3 times higher in famciclovir recipients (79%-86%) than in placebo recipients (27%) at 6 months (relative risks, 2.9-3.1; P<.001); efficacy was maintained at 12 months. Famciclovir was well tolerated with an adverse experience profile comparable to placebo.Conclusions: Oral famciclovir (125 mg or 250 mg 3 times daily or 250 mg twice daily) is an effective, well-tolerated treatment for the suppression of genital HSV infection in patients with frequent recurrences. [ABSTRACT FROM AUTHOR]

A multicenter, patient-initiated, double-blind, placebo-controlled trial of 15% undecylenic acid cream was conducted with 573 patients with recurrent herpes labialis. Treatment was applied 5 or 6 times daily until crusting and then thrice daily until healing. Patients were assessed daily until 48 h after crusting and then every other day until healing. Undecylenic acid significantly reduced the incidence and duration of viral shedding and the duration and severity of itching but did not increase abortive episodes or reduce times to healing, crusting, or progression of lesion size. When treatment was initiated during the prodrome, the time to crusting was reduced (P = .02) and the area under the symptom-time curve for pain and tenderness was reduced, approaching statistical significance (P = .06). Active treatment was well tolerated but caused dysgeusia and local irritation. Undecylenic acid 15% cream reduces viral shedding in recurrent herpes labialis, but clinical benefits are minimal and largely restricted to patients initiating therapy during the prodrome. [ABSTRACT FROM AUTHOR]

Background: Patients infected with hepatitis C virus (HCV) genotype 2 or 3 have sustained virologic response rates of approximately 80% after receiving treatment with peginterferon and ribavirin for 24 weeks. We conducted a large, randomized, multinational, noninferiority trial to determine whether similar efficacy could be achieved with only 16 weeks of treatment with peginterferon alfa-2a and ribavirin.Methods: We randomly assigned 1469 patients with HCV genotype 2 or 3 to receive 180 mug of peginterferon alfa-2a weekly, plus 800 mg of ribavirin daily, for either 16 or 24 weeks. A sustained virologic response was defined as an undetectable serum HCV RNA level (<50 IU per milliliter) 24 weeks after the end of treatment.Results: The study failed to demonstrate that the 16-week regimen was noninferior to the 24-week regimen. The sustained virologic response rate was significantly lower in patients treated for 16 weeks than in patients treated for 24 weeks (62% vs. 70%; odds ratio for 16 weeks vs. 24 weeks, 0.67; 95% confidence interval, 0.54 to 0.84; P<0.001). In addition, the rate of relapse (a detectable HCV RNA level during follow-up in patients who had undetectable HCV RNA at the end of treatment) was significantly greater in the 16-week group (31%, vs. 18% in the 24-week group; P<0.001). The sustained virologic response rates in patients with a pretreatment serum HCV RNA level of 400,000 IU per milliliter or less was 82% with the 16-week regimen and 81% with the 24-week regimen. Among patients with a rapid virologic response (an undetectable HCV RNA level by week 4), sustained virologic response rates were 79% in the 16-week group and 85% in the 24-week group (P=0.02).Conclusions: Treatment with peginterferon and ribavirin for 16 weeks in patients infected with HCV genotype 2 or 3 results in a lower overall sustained virologic response rate than treatment with the standard 24-week regimen. (ClinicalTrials.gov number, NCT00077636 [ClinicalTrials.gov].). [ABSTRACT FROM AUTHOR]

Background: Bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) is approved for treatment of HIV without known resistance to its components. Several studies have demonstrated efficacy of B/F/TAF in patients with nucleoside reverse transcriptase inhibitor (NRTI) resistance-associated mutations (RAMs), mainly identified by proviral DNA testing, but data on the efficacy of B/F/TAF in patients with NRTI RAMs identified in viraemic plasma are limited., Methods: We used a retrospective analysis of patients receiving B/F/TAF identified by searching electronic health records with eligibility confirmed by review of individual patient records. Patients included were ≥ 18 years, had 2019 International Antiviral Socitey-USA (IAS-USA) major RAMs affecting NRTIs detected in viraemic plasma prior to starting B/F/TAF and one or more HIV viral load (VL) after starting B/F/TAF., Results: In all, 50 patients met the study criteria: mean age of 54 years, mean proximal CD4 count of 609 cells/μL, 64% male. A total of 46 were virologically suppressed (< 200 copies/mL) when B/F/TAF was initiated, two were treatment-naïve, one stopped prior antiretroviral therapy (ART) and one had a VL of 961 HIV-1 RNA copies/mL on ART. Twenty-nine had one NRTI RAM (24 were M184V/I), nine had two NRTI RAMs, three had three NRTI RAMs, four had four NRTI RAMs, two had five NRTI RAMs, one had six NRTI RAMs, one had seven RAMs and one had eight NRTI RAMs. At the last VL on B/F/TAF, a mean of 18.6 months after starting B/F/TAF, 49 out of 50 had VL < 100 copies/mL and one had a VL of 208 copies/mL at 11 months but only filled 5 months of B/F/TAF., Conclusions: B/F/TAF was effective in maintaining HIV VL suppression in patients with previously documented NRTI RAMs without integrase resistance., (© 2022 British HIV Association.)

Introduction: With the availability of direct-acting antivirals, Hepatitis C (HCV) is now considered a treatable disease. Patients who are co-infected with human immunodeficiency virus (HIV) and HCV represent an ideal patient population to treat for HCV, as (1) patients are routinely taking medication for HIV, and therefore would be able to complete HCV drug regimens, and (2) HIV infection has been shown to increase HCV disease progression., Objective: We sought to determine the occurrence of HCV co-infection among HIV patients in our provincial cohort, determine whether they received treatment for HCV, and identify currently viremic patients who can be linked to care., Materials and Methods: HCV laboratory testing data (HCV antibody and HCV RNA) and HCV medication dispensation data was collected for all HIV positive patients. Current and previous HCV infection and treatment was assessed. Chart reviews were conducted for HCV viremic patients to assess their HIV care and social determinants., Results: Of the 2417 HIV positive patients, 392 (16.2%) were identified as being co-infected with HCV. 198 (50.5%) of the HIV-HCV co-infected patients received HCV treatment and 232 (59.2%) were not viremic on the most recent HCV RNA test. 99 (69.2%) had a suppressed HIV infection suggesting they are active in their HIV care and good candidates for HCV treatment., Conclusion: Despite the availability of direct-acting antivirals, many patients who are co-infected with HIV and HCV are not being treated for HCV. Routine surveillance of HIV-HCV co-infected patients could improve HCV treatment rates in a high-risk population., (Copyright © 2020 Fundación Clínica Médica Sur, A.C. Published by Elsevier España, S.L.U. All rights reserved.)

Background and Aim: Elderly patients with hepatitis C virus (HCV) infection have worse interferon-based treatment outcomes than young patients. Direct-acting antiviral (DAA) regimens have enabled the treatment of previously difficult-to-cure populations. There are few studies that specifically assess DAA treatment outcomes in patients over 75 years of age., Methods: Design: This was a cohort study. Setting: The setting was three Canadian HCV specialty sites. Participants: Patients aged 75 years and older and treated with DAA without interferon were enrolled. Measurements: Patient demographics, liver fibrosis by transient elastography, treatment regimen, and treatment outcome data were collected., Results: The mean age of 78 patients in our analysis was 78.6 years (SD 3.5; range: 75-88 years). The most common genotype was 1b (35%). The most frequently utilized regimens included sofosbuvir-velpatasvir (33%) and ledipasvir-sofosbuvir (32%). Ribavirin was included for 17% of recipients. Sustained virological response (SVR) was achieved in 94% of patients (69% of those receiving ribavirin and 98% of patients on ribavirin-free regimens). Ribavirin toxicity contributed to the lower SVR rates in ribavirin-exposed patients. Ribavirin dosage was decreased in three patients and ultimately discontinued in two of these patients. All treatment was discontinued in another two patients., Conclusion: Ribavirin-free DAA therapy is safe and achieves SVR rates in older adults comparable to those described in the general population. RBV inclusion frequently results in complications, often leads to treatment modification or interruption, and does not improve SVR rates in those with advanced age., (© 2020 The Authors. JGH Open: An open access journal of gastroenterology and hepatology published by Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Background and Aims: Achieving sustained virological response (SVR; cure) in hepatitis C patients using a simple regimen is key to making elimination by 2030 possible. In the largest real-world analysis to date, the effectiveness of pangenotypic, panfibrotic, single-tablet, sofosbuvir/velpatasvir (SOF/VEL) once-daily for 12 weeks was assessed in 12 clinical real-world cohorts from various geographical areas, settings and treatment practices. Factors affecting risk of not achieving SVR were assessed., Methods: Adults treated with SOF/VEL 400/100 mg, without ribavirin, were included. All HCV patients reaching Week 12 or 24 post-treatment were assessed for SVR12/24. Factors associated with not achieving SVR12/24 for virological reasons were evaluated using logistic regression analysis., Results: Overall, 5552 patients were included: 13.3% treatment-experienced; 20.7% compensated cirrhotic; 30.2% genotype 1; 29.5% genotype 2; 32.9% genotype 3; 4.7% genotype 4; 3.7% HIV coinfection; 13.4% current/former intravenous drug use. Of the 5196 patients evaluated for effectiveness, 98.9% achieved SVR12/24. High SVR12/24 rates occurred in all genotypes including genotype 3 (98.3%; 1649/1677) and in those with compensated cirrhosis (97.9; 1055/1078). Only 55 patients did not achieve SVR12/24 due to a virological reason; the only factor statistically significantly associated with an increased risk of not achieving SVR12/24 was compensated cirrhosis (P = .002). Overall, 6% (332/5552) of patients did not achieve SVR12/24 for non-virological reasons (67% lost to follow-up; 26.5% early treatment discontinuation)., Conclusions: In this large cohort, representative of clinical practice, a simple 12-week regimen of SOF/VEL without ribavirin resulted in high SVR12/24 rates in diverse patient populations, even among those with compensated cirrhosis., (© 2020 The Authors. Liver International published by John Wiley & Sons Ltd.)

Sofosbuvir-velpatasvir is approved for the treatment of chronic hepatitis C virus (HCV) infection. In this single-arm, open-label, phase 3, deferred treatment study, we investigated the efficacy and safety of sofosbuvir-velpatasvir among patients randomized to the placebo group in the ASTRAL-1 study. Patients received sofosbuvir-velpatasvir (400/100 mg) once daily for 12 weeks. The primary efficacy endpoint was the proportion of patients with sustained virologic response 12 weeks after the end of therapy (SVR12). The primary safety endpoint was any adverse events (AEs) leading to the permanent discontinuation of study drug. Overall, 108/111 (97%, 95% confidence interval [CI], 92%-99%) achieved SVR12, and only one patient had virological failure. SVR12 was achieved by 61/63 (97%, 95%CI, 89%-100%) genotype 1 patients, 20/20 (100%; 95%CI, 83%-100%) with genotype 2, 19/19 (100%; 95%CI, 82%-100%) with genotype 4 and 8/9 (89%; 95% CI, 52%-100%) with genotype 6. All (19/19; 95%CI, 82-100) patients with cirrhosis and all (31/31, 95%CI, 89-100) with prior treatment experience achieved SVR12. The safety profile during treatment was similar to that observed in patients receiving placebo treatment. The most common AEs were headache, fatigue and nausea. One patient (1%) discontinued treatment due to an AE of gallbladder carcinoma, which was not considered related to treatment. Of five reported serious AEs, none were considered related to study drug. Sofosbuvir-velpatasvir for 12 weeks was effective and well tolerated among untreated and previously treated patients with HCV genotype 1, 2, 4 or 6 infection, including those with compensated cirrhosis (ClinicalTrials.gov NCT02346721)., (© 2019 John Wiley & Sons Ltd.)

Background & Aims: Although off-label use of sofosbuvir-containing regimens occurs regularly in patients with hepatitis C virus (HCV) infection undergoing dialysis for severe renal impairment or end-stage renal disease (ESRD), these regimens are not licensed for this indication, and there is an absence of dosing recommendations in this population. This study evaluated the safety and efficacy of sofosbuvir/velpatasvir in patients with HCV infection with ESRD undergoing dialysis., Methods: In this phase II, single-arm study, 59 patients with genotype 1-6 HCV infection with ESRD undergoing hemodialysis or peritoneal dialysis received open-label sofosbuvir/velpatasvir (400 mg/100 mg) once daily for 12 weeks. Patients were HCV treatment naive or treatment experienced without cirrhosis or with compensated cirrhosis. Patients previously treated with any HCV NS5A inhibitor were not eligible. The primary efficacy endpoint was the proportion of patients achieving sustained virologic response (SVR) 12 weeks after discontinuation of treatment (SVR12). The primary safety endpoint was the proportion of patients who discontinued study drug due to adverse events., Results: Overall, 56 of 59 patients achieved SVR12 (95%; 95% CI 86-99%). Of the 3 patients who did not achieve SVR12, 2 patients had virologic relapse determined at post-treatment Week 4 (including 1 who prematurely discontinued study treatment), and 1 patient died from suicide after achieving SVR through post-treatment Week 4. The most common adverse events were headache (17%), fatigue (14%), nausea (14%), and vomiting (14%). Serious adverse events were reported for 11 patients (19%), and all were deemed to be unrelated to sofosbuvir/velpatasvir., Conclusions: Treatment with sofosbuvir/velpatasvir for 12 weeks was safe and effective in patients with ESRD undergoing dialysis., Lay Summary: Sofosbuvir/velpatasvir is a combination direct-acting antiviral that is approved for treatment of patients with hepatitis C virus (HCV) infection. Despite the lack of dosing recommendations, sofosbuvir-containing regimens (including sofosbuvir/velpatasvir) are frequently used for HCV-infected patients undergoing dialysis. This study evaluated the safety and efficacy of sofosbuvir/velpatasvir for 12 weeks in patients with HCV infection who were undergoing dialysis. Treatment with sofosbuvir/velpatasvir was safe and well tolerated, resulting in a cure rate of 95% in patients with HCV infection and end-stage renal disease. Clinical Trial Number: NCT03036852., (Copyright © 2019 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background: Hepatitis C virus (HCV) is currently classified into 8 genotypes and 86 subtypes. The objective of this study was to characterize novel HCV subtypes and to investigate the impact of subtypes on treatment outcome., Methods: Full-genome sequencing was performed on HCV plasma samples with <85% sequence homology of NS3, NS5A, and/or NS5B to HCV genotype (GT) 1-8 reference strains., Results: A total of 14 653 patients with GT1-6 HCV infection were enrolled in clinical studies of sofosbuvir-based regimens. For the majority of the patients, a specific subtype could be assigned based on a close genetic relationship to previously described subtypes. However, for 19 patients, novel subtypes were identified with <85% homology compared with previously described subtypes. These novel subtypes had the following genotypes: 9 in GT2, 5 in GT4, 2 in GT6, and 1 each in GT1, GT3, and GT5. Despite the presence of polymorphisms at resistance-associated substitution positions, 18 of the 19 patients treated with sofosbuvir-containing therapy achieved SVR12., Conclusions: Nineteen novel HCV subtypes were identified, suggesting an even greater genetic diversity of HCV subtypes than previously recognized.

Background: Optimal treatment for patients with HCV genotype-3 infection and liver cirrhosis remains a medical priority. Daclatasvir+sofosbuvir and ribavirin is a recommended option for such patients, but clinical trial data are lacking for treatment >16 weeks., Methods: This was a single-arm, Phase III study of daclatasvir+sofosbuvir+ribavirin for 24 weeks in patients with compensated cirrhosis and HCV genotype-3 infection. The primary end point was sustained virological response at post-treatment week 12 (SVR12); the primary objective was to demonstrate statistical superiority to historical SVR12 data for 12 weeks' daclatasvir+sofosbuvir without ribavirin in genotype-3-infected patients with cirrhosis (95% CI lower bound >79.0%)., Results: A total of 78 patients were treated (54 treatment-naive, 24 treatment-experienced including 8 with prior sofosbuvir exposure). SVR12 was achieved by 87% (68/78; 95% CI 77.7, 93.7%) of patients in the primary analysis of central laboratory data. One additional patient achieved SVR12 by local testing resulting in an overall SVR12 rate of 88% (95% CI 79.2, 94.6%) and the lower bound of the 95% CI above the historical threshold. SVR12 rates were 93% (50/54) for treatment-naive and 79% (19/24) for treatment-experienced patients. Of the nine non-SVR12 patients, four were lost to follow-up, two relapsed (both sofosbuvir-experienced), two had end-of-treatment virological failure and one discontinued early. There were no unexpected safety signals; only one patient discontinued for an adverse event., Conclusions: Daclatasvir+sofosbuvir+ribavirin for 24 weeks was well tolerated and efficacious in HCV genotype-3-infected patients with compensated cirrhosis, with SVR12 outcomes comparable to previously reported outcomes in patients treated with this regimen for 12-16 weeks. ClinicalTrials.gov ID NCT02673489.

Background: Hepatitis C virus (HCV) exhibits great genetic diversity and is classified into 7 genotypes (GTs), with varied geographic prevalence. Until the recent development of pangenotypic direct-acting antiviral regimens, the determination of HCV GT was necessary to inform optimal treatment., Methods: Plasma samples with unresolved GT using standard commercial genotyping methods were subjected to HCV full-genome sequencing, and phylogenetic analysis was performed to assign GT., Results: Four patients, previously classified as GT5 by LiPA or Abbott RealTime polymerase chain reaction assays, were identified as infected with a novel HCV GT. This novel HCV GT, GT8, is genetically distinct from previously identified HCV GT1-7 with >30% nucleotide sequence divergence to the established HCV subtypes. All 4 patients were originally from Punjab, India, but now reside in Canada and are epidemiologically unlinked. Despite presence of baseline resistance-associated substitutions within the GT8 virus of all 4 patients (NS3: V36L, Q80K/R; NS5A: Q30S, Y93S), all patients achieved a sustained virologic response; 2 treated with sofosbuvir/velpatasvir/voxilaprevir for 8 weeks, 1 with sofosbuvir/ledipasvir plus ribavirin for 24 weeks and 1 with sofosbuvir plus daclatasvir for 12 weeks., Conclusions: The discovery of a novel HCV GT8 confirms the circulation of this newly identified lineage in the human population.

Background & Aims: The fixed-dose combination of sofosbuvir/velpatasvir was highly efficacious in patients infected with genotype (GT)1-6 hepatitis C virus (HCV) in the ASTRAL studies. This analysis evaluated the impact of baseline resistance-associated substitutions (RASs) on treatment outcome and emergence of RASs in patients infected with HCV GT1-6 who were treated with sofosbuvir/velpatasvir., Methods: Non-structural protein 5A and 5B (NS5A and NS5B) deep sequencing was performed at baseline and at the time of relapse for all patients treated with sofosbuvir/velpatasvir for 12 weeks (n = 1,778) in the ASTRAL-1-3, ASTRAL-5 and POLARIS-2-3 studies., Results: Patients with 37 known and 19 novel HCV subtypes were included in these analyses. Overall, 28% (range 9% to 61% depending on genotype) had detectable NS5A class RASs at baseline, using a 15% sequencing assay cut-off. There was no significant effect of baseline NS5A class RASs on sustained virologic response at week 12 (SVR12) with sofosbuvir/velpatasvir; the SVR12 rate in the presence of NS5A class RASs was 100% and 97%, in patients with GT1a and GT1b infection, respectively, and 100% in patients with GT2 and GT4-6 infections. In GT3 infection, the SVR rate was 93% and 98% in patients with and without baseline NS5A class RASs, respectively. The overall virologic failure rate was low (20/1,778 = 1.1%) in patients treated with sofosbuvir/velpatasvir. Single NS5A class resistance was observed at virologic failure in 17 of the 20 patients., Conclusions: Sofosbuvir/velpatasvir taken for 12 weeks once daily resulted in high SVR rates in patients infected with GT1-6 HCV, irrespective of baseline NS5A RASs. NS5A inhibitor resistance, but not sofosbuvir resistance, was detected in the few patients with virologic failure. These data highlight the high barrier to resistance of this regimen for the treatment of chronic HCV across all genotypes in the vast majority of patients., Lay Summary: Sofosbuvir/velpatasvir taken once daily for 12 weeks resulted in high sustained virologic response rates in patients infected with HCV, irrespective of the presence of NS5A resistance-associated variants prior to treatment. Single class NS5A inhibitor resistance, but not sofosbuvir resistance, was detected in the few patients with virologic failure. These data highlight the high barrier to resistance of this regimen for the treatment of chronic HCV across all genotypes in the vast majority of patients., (Copyright © 2017 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)