Chronic Hepatitis B Finite Treatment: Similar and Different Concerns With New Drug Classes

Chronic hepatitis B, a major cause of liver disease and cancer, affects >250 million people worldwide. Currently there is no cure, only suppressive therapies. Efforts to develop finite curative hepatitis B virus (HBV) therapies are underway, consisting of combinations of multiple novel agents with or without nucleos(t)ide reverse-transcriptase inhibitors. The HBV Forum convened a webinar in July 2021, along with subsequent working group discussions to address how and when to stop finite therapy for demonstration of sustained off-treatment efficacy and safety responses. Participants included leading experts in academia, clinical practice, pharmaceutical companies, patient representatives, and regulatory agencies. This Viewpoints article outlines areas of consensus within our multistakeholder group for stopping finite therapies in chronic hepatitis B investigational studies, including trial design, patient selection, outcomes, biomarkers, predefined stopping criteria, predefined retreatment criteria, duration of investigational therapies, and follow-up after stopping therapy. Future research of unmet needs are discussed.

Long-term open-label vebicorvir for chronic HBV infection: Safety and off-treatment responses

Background & Aims

The investigational first-generation core inhibitor vebicorvir (VBR) demonstrated safety and antiviral activity over 24 weeks in two phase IIa studies in patients with chronic HBV infection. In this long-term extension study, patients received open-label VBR with nucleos(t)ide reverse transcriptase inhibitors (NrtIs).

Methods

Patients in this study (NCT03780543) previously received VBR + NrtI or placebo + NrtI in parent studies 201 (NCT03576066) or 202 (NCT03577171). After receiving VBR + NrtI for ≥52 weeks, stopping criteria (based on the treatment history and hepatitis B e antigen status in the parent studies) were applied, and patients either discontinued both VBR + NrtI, discontinued VBR only, or continued both VBR + NrtI. The primary efficacy endpoint was the proportion of patients with HBV DNA <20 IU/ml at 24 weeks off treatment.

Results

Ninety-two patients entered the extension study and received VBR + NrtI. Long-term VBR + NrtI treatment led to continued suppression of HBV nucleic acids and, to a lesser extent, HBV antigens. Forty-three patients met criteria to discontinue VBR + NrtI, with no patients achieving the primary endpoint; the majority of virologic rebound occurred ≥4 weeks off treatment. Treatment was generally well tolerated, with few discontinuations due to adverse events (AEs). There were no deaths. Most AEs and laboratory abnormalities were related to elevations in alanine aminotransferase and occurred during the off-treatment or NrtI-restart phases. No drug-drug interactions between VBR + NrtI and no cases of treatment-emergent resistance among patients who adhered to treatment were observed.

Conclusions

Long-term VBR + NrtI was safe and resulted in continued reductions in HBV nucleic acids following completion of the 24-week parent studies. Following treatment discontinuation, virologic relapse was observed in all patients. This first-generation core inhibitor administered with NrtI for at least 52 weeks was not sufficient for HBV cure.

Clinical trial number

NCT03780543.

Impact and implications

Approved treatments for chronic hepatitis B virus infection (cHBV) suppress viral replication, but viral rebound is almost always observed after treatment discontinuation, highlighting an unmet need for improved therapies with finite treatment duration producing greater therapeutic responses that can be sustained off treatment. First-generation core inhibitors, such as vebicorvir, have mechanisms of action orthogonal to standard-of-care therapies that deeply suppress HBV viral replication during treatment; however, to date, durable virologic responses have not been observed after treatment discontinuation. The results reported here will help researchers with the design and interpretation of future studies investigating core inhibitors as possible components of finite treatment regimens for patients with cHBV. It is possible that next-generation core inhibitors with enhanced potency may produce deeper and more durable antiviral activity than first-generation agents, including vebicorvir.

Safety, pharmacokinetics and antiviral activity of ABI-H2158, a hepatitis B virus core inhibitor: A randomized, placebo-controlled phase 1 study

Treatment for chronic hepatitis B virus infection (cHBV) is mostly indefinite, with new finite-duration therapies needed. We report safety, pharmacokinetics and antiviral activity of the investigational HBV core inhibitor ABI-H2158. This Phase 1a/b study (NCT03714152) had three parts: Part A, participants received a single ascending oral dose of ABI-H2158 (5-500 mg) or placebo; Part B, participants received multiple doses of ABI-H2158 300 mg once (QD) or twice (BID) daily or placebo, for 10 days; Part C, cHBV patients received ABI-H2158 (100, 300, or 500 mg QD or 300 mg BID) or placebo, for 14 days. Ninety-three participants enrolled. In Parts A/B, there were no serious adverse events (SAEs) or deaths, and all treatment-emergent AEs (TEAEs) were Grade 1. In Part C, two patients had Grade 3 TEAEs unrelated to ABI-H2158; there were no deaths, SAEs or Grade 4 TEAEs. In Part A, median time to maximum ABI-H2158 plasma concentration (T_max ) and mean terminal elimination half-life (t_½ ) were 1-4 and 9.8-20.7 h, and area under the plasma concentration-time curve increased dose proportionally. In Part B, Day 10 T_max was 2 h, mean t_½ was 15.5-18.4 h, and exposure accumulated 1.7- to 3.1-fold. In Part C, Day 14 T_max was 1 h, exposure accumulated 1.4- to 1.8-fold, and ABI-H2158 was associated with >2 log₁₀ declines in HBV nucleic acids. In conclusion, ABI-H2158 in cHBV patients following 14 days of dosing was well tolerated and demonstrated potent antiviral activity. Safety and pharmacokinetics supported future QD dosing.

Safety and efficacy of vebicorvir in virologically suppressed patients with chronic hepatitis B virus infection

BACKGROUND & AIMS

HBV nucleos(t)ide reverse transcriptase inhibitors (NrtIs) do not completely suppress HBV replication. Previous reports indicate persistent viremia during NrtI treatment despite HBV DNA being undetectable. HBV core inhibitors may enhance viral suppression when combined with NrtIs. This phase II trial (NCT03576066) evaluated the efficacy and safety of the investigational core inhibitor, vebicorvir (VBR), in virologically- suppressed patients on NrtIs.

METHODS

Non-cirrhotic, NrtI-suppressed patients with chronic HBV were randomised to VBR 300 mg once daily or matching placebo (PBO) for 24 weeks. Treatment was stratified by hepatitis B e antigen (HBeAg) status. The primary endpoint was change from Baseline in serum HBeAg or hepatitis B surface antigen (HBsAg) after 24 weeks.

RESULTS

Of 73 patients enrolled, 47 were HBeAg positive and 26 were HBeAg negative. In HBeAg-positive and -negative patients, there were no differences in the change from Baseline at Week 24 for HBsAg or HBeAg. Using a novel, high-sensitivity assay to detect HBV DNA, a greater proportion of patients with detectable HBV DNA at Baseline achieved undetectable HBV DNA at Week 24 in the VBR+NrtI vs. PBO+NrtI group. In HBeAg-positive patients, a greater change from Baseline in HBV pregenomic (pg)RNA was observed at Week 24 with VBR+NrtI vs. PBO+NrtI. Treatment-emergent adverse events (TEAEs) in VBR+NrtI patients included upper respiratory tract infection, nausea, and pruritus. No serious adverse events, Grade 4 TEAEs, or deaths were reported.

CONCLUSIONS

In this 24-week study, VBR+NrtI demonstrated a favourable safety and tolerability profile. While there were no significant changes in viral antigen levels, enhanced viral suppression was demonstrated by greater changes in DNA and pgRNA with the addition of VBR compared to NrtI alone.

CLINICAL TRIALS NUMBER

NCT03576066.

LAY SUMMARY

Core inhibitors represent a novel approach for the treatment of chronic hepatitis B virus (HBV) infection, with mechanisms of action distinct from existing treatments. In this study, vebicorvir added to existing therapy reduced HBV replication to a greater extent than existing treatment and was generally safe and well tolerated.

Association of CYP2B6 Single-Nucleotide Polymorphisms Altering Efavirenz Metabolism With Hepatitis C Virus (HCV) Treatment Relapse Among Human Immunodeficiency Virus/HCV-Coinfected African Americans Receiving Ledipasvir/Sofosbuvir in the ION-4 Trial

In the ION-4 trial, hepatitis C virus relapse was rare, occurring only in African American patients, 80% receiving efavirenz for human immunodeficiency virus infection. We observed no indication that CYP2B6 polymorphisms associated with increased plasma efavirenz exposure explained the relapses.

Drug-Drug Interaction Studies Between Hepatitis C Virus Antivirals Sofosbuvir/Velpatasvir and Boosted and Unboosted Human Immunodeficiency Virus Antiretroviral Regimens in Healthy Volunteers

Background

Combining antiviral regimens in the hepatitis C virus (HCV)/human immunodeficiency virus (HIV)-coinfected population can be complex as they share overlapping mechanisms for elimination that may result in drug interactions. The pharmacokinetics, safety, and tolerability of sofosbuvir/velpatasvir (SOF/VEL) with multiple antiretroviral (ARV) regimens were evaluated.

Methods

Healthy volunteers were enrolled into 2 phase 1, open-label, randomized, multiple-dose, cross-over studies. SOF/VEL and ARV regimens were administered alone and in combination; ARVs (and pharmacokinetic enhancers) included atazanavir (ATV), cobicistat (COBI), darunavir (DRV), dolutegravir (DTG), efavirenz (EFV), elvitegravir (EVG), emtricitabine (FTC), lopinavir (LPV), raltegravir (RAL), rilpivirine (RPV), ritonavir (RTV), tenofovir alafenamide (TAF), and tenofovir disoproxil fumarate (TDF). Geometric least squares means ratios (coadministration:alone) and 90% confidence intervals were constructed for area under the plasma concentration-time curve over the dosing interval, maximum concentration, and trough, for all analytes. Safety and tolerability were also evaluated.

Results

In total, 237 participants were enrolled. No clinically relevant differences in the pharmacokinetics (PK) of SOF, SOF metabolite GS-331007, or VEL were observed other than an approximate 50% decrease in VEL exposure when administered with EFV/FTC/TDF. No clinically relevant differences in the PK of ARVs were observed when administered with SOF/VEL. Study treatments were well tolerated, including no observed creatinine clearance changes during evaluation of TDF-containing regimens.

Conclusions

SOF/VEL and ARV regimens including ATV, COBI, DRV, DTG, EVG, FTC, LPV, RAL, RPV, RTV, TAF, or TDF may be coadministered without dose adjustment. Use of SOF/VEL with EFV-containing regimens is not recommended due to an approximate 50% reduction in VEL exposure.

Characterization of HCV resistance from a 3-day monotherapy study of voxilaprevir, a novel pangenotypic NS3/4A protease inhibitor

BACKGROUND

Voxilaprevir (VOX; GS-9857) is a pangenotypic HCV NS3/4A protease inhibitor (PI) with potent antiviral activity against HCV genotypes (GTs) 1-6 and improved coverage of GT1 NS3 resistance-associated substitutions (RAS) associated with other HCV PIs. In a 3-day Phase Ib monotherapy study in patients infected with HCV GT1a, 1b, 2, 3 and 4, VOX was well-tolerated and resulted in maximal mean viral load reduction >3 log₁₀ IU/ml at the 100 mg dose across all genotypes evaluated. This report characterizes the HCV NS3 RAS in the study.

METHODS

The NS3 gene was amplified and successfully deep sequenced using MiSeq for 66 patients at baseline and 61 patients post-baseline using 15% and 1% assay cutoffs.

RESULTS

With a 15% assay cutoff, pretreatment HCV NS3 RAS were present in the HCV of 38% (9/24) of patients with GT1a and 5% (1/19) with GT3a; there were no pretreatment NS3 RAS present in patients with GT1b (n=6), GT2 (n=7) or GT4 (n=4). In patients with and without pretreatment NS3 RAS, ≥3.4 log₁₀ mean maximal viral load reductions over 3 days of VOX administration were observed. The majority of patients did not have detectable treatment-emergent NS3 RAS and only 12% (7/53) and 26% (14/53) had emergent NS3 RAS using 15% and 1% cutoffs, respectively. No NS3 RAS were detected in patients with GT2 or GT4. A156T or A156V were the most prevalent emergent NS3 RAS in patients with GT1a or GT1b infection, but were not observed in patients with GT3 infection.

CONCLUSIONS

The lack of selection of NS3 RAS in the majority of patients demonstrates a high resistance barrier for VOX. ClinicalTrails.gov identifier NCT02185794.

Sofosbuvir/Velpatasvir/Voxilaprevir for patients with HCV who previously received a Sofosbuvir/Velpatasvir-containing regimen: Results from a retreatment study

This study evaluated 12-week retreatment with sofosbuvir/velpatasvir/voxilaprevir in patients with chronic hepatitis C virus (HCV) infection who did not achieve sustained virologic response after previous treatment with a sofosbuvir- and velpatasvir-containing regimen. All 31 patients maintained a sustained virologic response 12 weeks after the last sofosbuvir/velpatasvir/voxilaprevir dose.

Comparison of the efficacy of sofosbuvir plus ribavirin in Chinese patients with genotype 3a or 3b HCV infection

BACKGROUND AND AIM

Genotype 3b hepatitis C virus (HCV) infection represents approximately 50% of patients with genotype 3 in China. We compared the efficacy of sofosbuvir (SOF) plus ribavirin (RBV) in Chinese patients with genotype 3a and 3b HCV.

METHODS

The analyzed data are from a phase 3, open-label study of SOF plus RBV for 24 weeks conducted in China. The primary endpoint for the trial was sustained virologic response at 12 weeks after the end of therapy (SVR12).

RESULTS

Of 126 patients included in this analysis, 58 (46%) had genotype 3a and 68 (54%) had genotype 3b. Both the subtypes were similar in age, sex, body mass index, IL28B, and baseline HCV RNA. However, more treatment-experienced and cirrhotic patients were in the genotype 3b group. All 100% of patients with genotype 3a (95% confidence interval [CI], 94-100), and 91% (95% CI, 82-97) of patients with genotype 3b achieved SVR12 (P = 0.030). For treatment-experienced patients with genotype 3b, the SVR12 rate was 73% (95% CI, 39-94) and 88% (95% CI, 64-99) among patients with and without cirrhosis (P = 1.00), respectively.

CONCLUSION

SOF plus RBV for 24 weeks in patients with HCV genotype 3 infection resulted in high rates of SVR. However, the SVR12 rate among patients with genotype 3b was lower than that observed in patients with genotype 3a infection, particularly among treatment-experienced patients with cirrhosis.

Efficacy and safety of sofosbuvir-velpatasvir with or without ribavirin in HCV-infected Japanese patients with decompensated cirrhosis: an open-label phase 3 trial

BACKGROUND

In Japan, hepatitis C virus (HCV)-infected patients with decompensated cirrhosis currently have no treatment options. In this Phase 3 study, we evaluated sofosbuvir-velpatasvir with or without ribavirin for 12 weeks in patients with any HCV genotype and decompensated cirrhosis [Child-Pugh-Turcotte (CPT) class B or C] in Japan.

METHODS

Patients were randomized 1:1 to receive sofosbuvir-velpatasvir with or without ribavirin for 12 weeks. Randomization was stratified by CPT class and genotype. Sustained virologic response 12 weeks following completion of treatment (SVR12) was the primary efficacy endpoint.

RESULTS

Of the 102 patients enrolled, 57% were treatment naive, 78% and 20% had genotype 1 and 2 HCV infection, respectively, and 77% and 20% had CPT class B and C cirrhosis, respectively, at baseline. Overall, 61% of patients were female and the mean age was 66 years (range 41-83). SVR12 rates were 92% (47/51) in each group. Among patients who achieved SVR12, 26% had improved CPT class from baseline to posttreatment week 12. Most adverse events (AEs) were consistent with clinical sequelae of advanced liver disease or known toxicities of ribavirin. Four patients (8%) who received sofosbuvir-velpatasvir and seven (14%) who received sofosbuvir-velpatasvir plus ribavirin experienced a serious AE. The 3 deaths (bacterial sepsis, gastric varices hemorrhage, hepatocellular carcinoma) were attributed to liver disease progression.

CONCLUSION

Sofosbuvir-velpatasvir for 12 weeks provides a highly effective and well-tolerated therapy for Japanese patients with HCV and decompensated cirrhosis. Ribavirin did not improve efficacy but increased toxicity.

No impact of resistance-associated substitutions on the efficacy of sofosbuvir, velpatasvir, and voxilaprevir for 12 weeks in HCV DAA-experienced patients

BACKGROUND & AIMS

In phase III studies, the fixed dose combination of sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) administered for 12 weeks led to a sustained virologic response at 12 weeks (SVR12) in 96% of NS5A inhibitor-experienced patients, and an SVR12 rate of 98% in DAA-experienced patients who had not previously received an NS5A inhibitor. Herein, we evaluate the relationship between the presence of detectable resistance-associated substitutions (RASs) at baseline and treatment outcome, and whether RASs were selected for in cases of virologic failure.

METHODS

NS3, NS5A, and NS5B deep sequencing analyses were performed at baseline for all patients and at the time of virologic failure. Results are reported using a 15% cut-off.

RESULTS

A total of 82.7% of NS5A inhibitor-experienced patients (205/248) had baseline NS3 and/or NS5A RASs; 79% had baseline NS5A RASs. SVR12 rates were similar in patients with or without NS3 and/or NS5A RASs, and with or without VOX- or VEL-specific RASs. RASs at NS5A position Y93 were present in 37.3% of patients and 95% achieved SVR12. All patients with ≥2 NS5A RASs achieved SVR12. Baseline NS3 and/or NS5A RASs were present in 46.6% (83/178) of non-NS5A inhibitor DAA-experienced patients, all of whom achieved SVR12. All patients with baseline NS5B nucleoside inhibitor RASs, including two patients with S282T, achieved SVR12. Treatment-selected resistance was seen in one of seven patients who relapsed.

CONCLUSIONS

Baseline RASs had no impact on virologic response in DAA-experienced patients following treatment with SOF/VEL/VOX for 12 weeks. Selection of viral resistance with virologic relapse was uncommon.

LAY SUMMARY

In phase III studies, 12 weeks of treatment with the combination of sofosbuvir, velpatasvir and voxilaprevir (SOF/VEL/VOX) cured 97% of patients with hepatitis C virus who failed prior treatment with direct-acting antiviral drugs. Herein, we show that the presence of pretreatment drug resistance did not affect treatment outcome in these patients who had previously received direct-acting antivirals. We also showed that new drug resistance was rare in patients who failed treatment with SOF/VEL/VOX for 12 weeks. This has important implications for the selection of best retreatment strategies for these patients.

Efficacy of Sofosbuvir and Velpatasvir, With and Without Ribavirin, in Patients With Hepatitis C Virus Genotype 3 Infection and Cirrhosis

BACKGROUND & AIMS

In phase 3 trials and real-world settings, smaller proportions of patients with genotype 3 hepatitis C virus (HCV) infection and cirrhosis have a sustained virologic response 12 weeks after treatment (SVR12) with the combination of sofosbuvir and velpatasvir than in patients without cirrhosis. It is unclear whether adding ribavirin to this treatment regimen increases SVRs in patients with genotype 3 HCV infection and cirrhosis.

METHODS

We performed a phase 2 trial of 204 patients with genotype 3 HCV infection and compensated cirrhosis (mean age 51 ± 7.4 years) at 29 sites in Spain from August 19, 2016 through April 18, 2017. Patients were assigned to groups given sofosbuvir and velpatasvir for 12 weeks (n = 101) or sofosbuvir and velpatasvir plus ribavirin for 12 weeks (n = 103). The primary efficacy end point was SVR12.

RESULTS

The overall rates of SVR12 were 91% (92 of 101; 95% CI 84-96) for the sofosbuvir-velpatasvir group and 96% (99 of 103; 95% CI 90-99) for the sofosbuvir-velpatasvir plus ribavirin group. In the sofosbuvir-velpatasvir group, a smaller proportion of patients with baseline resistance-associated substitutions (RASs) in nonstructural protein 5A (NS5A) achieved an SVR12 (84%) than did patients without (96%). In the sofosbuvir-velpatasvir plus ribavirin group, baseline RASs had less effect on the proportion of patients with an SVR12 (96% for patients with baseline RASs; 99% for patients without). The most common adverse events (which occurred in ≥10% of patients) were asthenia (12%) in the sofosbuvir-velpatasvir group and asthenia (27%), headache (24%), and insomnia (12%) in the sofosbuvir-velpatasvir plus ribavirin group.

CONCLUSIONS

Consistent with findings from previous studies, a high rate of patients (91% and 96%) with genotype 3 HCV infection and compensated cirrhosis achieved an SVR12 with sofosbuvir and velpatasvir, with or without ribavirin. Of patients treated with sofosbuvir and velpatasvir without ribavirin, fewer patients with baseline NS5A RASs achieved an SVR12 compared with patients without baseline NS5A. ClinicalTrials.govNCT02781558.

Sofosbuvir/velpatasvir for 12 weeks in genotype 1-4 HCV-infected liver transplant recipients

BACKGROUND & AIMS

Sofosbuvir, an NS5B inhibitor, combined with velpatasvir, an NS5A inhibitor (SOF/VEL), produces high sustained virologic response rates 12 weeks after treatment (SVR12) in patients with genotype 1-6 HCV infection, and has no anticipated clinically relevant drug-drug interactions with immunosuppressants. This study evaluated the safety and efficacy of SOF/VEL in adults with recurrent chronic genotype 1-4 HCV infection after liver transplant.

METHODS

Patients received SOF/VEL 400/100 mg daily for 12 weeks. Patients could be treatment experienced or treatment naïve with no cirrhosis or with compensated cirrhosis. The primary endpoints were SVR12 and discontinuations due to adverse events.

RESULTS

A total of 79 patients were enrolled and treated in this study (37 [47%] had genotype 1, 3 [4%] genotype 2, 35 [44%] genotype 3, and 4 [5%] genotype 4 HCV). Of these, 81% were male, 82% were white, 18% had compensated cirrhosis, and 59% were treatment experienced. The most commonly used immunosuppressants were tacrolimus (71%), mycophenolic acid (24%), cyclosporine (14%), and azathioprine (11%). Median (range) time from liver transplantation was 7.5 (0.3, 23.9) years. The SVR12 rate was 96%. By genotype, SVR12 rates were 95% (genotype 1), 100% (genotype 2), 97% (genotype 3), and 100% (genotype 4). Two patients experienced virologic relapse: one with genotype 1a infection was non-cirrhotic and treatment naïve, and one with genotype 3 infection was non-cirrhotic and treatment experienced. One patient discontinued SOF/VEL due to hyperglycemia. No serious or severe adverse events were deemed SOF/VEL-related by the investigator, and no liver transplant rejection episodes or deaths occurred during the study period.

CONCLUSIONS

Treatment with SOF/VEL for 12 weeks was highly effective and well tolerated in genotype 1-4 HCV-infected liver transplant recipients with and without cirrhosis.

LAY SUMMARY

Sofosbuvir/velpatasvir is a combination of two drugs in one tablet that is approved for the treatment of patients with chronic hepatitis C virus (HCV) infection. When patients with chronic HCV infection receive a liver transplant, the HCV infection usually recurs, and damages the transplanted liver. This study tested the effects of 12 weeks of sofosbuvir/velpatasvir treatment in patients who had HCV recurrence after a liver transplant. Three months following the end of treatment, 96% of patients were cured of HCV infection. Clinical trial number: NCT02781571.

Sofosbuvir-velpatasvir plus ribavirin in Japanese patients with genotype 1 or 2 hepatitis C who failed direct-acting antivirals

BACKGROUND/PURPOSE

In Japan, there is a growing population of patients with chronic hepatitis C virus (HCV) infection who failed a direct-acting antiviral (DAA)-based regimen. In this Phase 3 study, we evaluated sofosbuvir-velpatasvir plus ribavirin in Japanese patients with genotype 1 or 2 HCV infection who previously received DAAs.

METHODS

Patients were randomized 1:1 to receive sofosbuvir-velpatasvir plus ribavirin for 12 or 24 weeks. Randomization was stratified by HCV genotype and presence of cirrhosis. The primary endpoint was sustained virologic response 12-week post-treatment (SVR12).

RESULTS

Of 117 participants, 81% had HCV genotype 1 infection, 33% had cirrhosis, and 95% had NS5A resistance-associated substitutions (RAS) at baseline. Overall, SVR12 rates were 97% (58/60; 95% CI 88-100%) with 24 weeks of treatment and 82% (47/57; 95% CI 70-91%) with 12 weeks. For HCV genotype 1 and 2 infected patients, the SVR12 rates with 24 weeks of treatment were 98% and 92%, respectively. In both treatment groups, SVR12 rates in HCV genotype 1 patients were statistically superior to a historical control rate of 50% (p < 0.001). For patients with NS5A RASs at baseline, 85% (46/54) in the 12-week group and 96% (54/56) in the 24-week group achieved SVR12. The most common adverse events were upper respiratory tract viral infection, anemia, and headache. Three (2.6%) patients discontinued treatment because of adverse events.

CONCLUSION

Sofosbuvir-velpatasvir plus ribavirin was highly effective and well tolerated in Japanese patients who previously failed a DAA-based regimen. Baseline NS5A RASs did not affect treatment outcomes.

Deferred treatment with sofosbuvir-velpatasvir-voxilaprevir for patients with chronic hepatitis C virus who were previously treated with an NS5A inhibitor: an open-label substudy of POLARIS-1

BACKGROUND

Direct-acting antiviral regimens containing NS5A inhibitors are highly effective treatments for chronic hepatitis C virus (HCV) infection, but are not always successful. In the POLARIS-1 phase 3 study, sofosbuvir-velpatasvir-voxilaprevir for 12 weeks was highly effective in the treatment of chronic HCV infection in patients previously treated with a direct-acting antiviral regimen containing an NS5A inhibitor. We aimed to assess the efficacy and safety of sofosbuvir-velpatasvir-voxilaprevir in patients from the deferred treatment group of POLARIS-1, who were initially assigned to masked placebo treatment.

METHODS

This open-label, deferred treatment substudy was done at 73 clinical sites (hospitals and clinics) in the USA, France, Canada, the UK, Germany, Australia, and New Zealand. Patients who received placebo in the primary study and who did not have a new clinically significant illness at the post-treatment week 4 assessment were eligible to enter this substudy. Participants received a combination tablet of sofosbuvir (400 mg), velpatasvir (100 mg), and voxilaprevir (100 mg) once daily for 12 weeks. The primary efficacy outcome was achievement of sustained virological response (defined as HCV RNA concentration below the lower limit of quantification) 12 weeks after the end of treatment (SVR12). The primary safety outcome was the proportion of patients who discontinued treatment due to adverse events. This study is registered with ClinicalTrials.gov, number NCT02607735, and the EU Clinical Trials Register, number 2015-003455-21.

FINDINGS

152 patients received placebo in the primary study and were potentially eligible for participation in the open-label substudy, of whom 147 were enrolled from March 30, 2016, to Oct 12, 2016. All 147 patients completed treatment, and 143 (97%; 95% CI 93-99) achieved SVR12. Four (3%) patients had virological relapse; all had HCV genotype 1a infection and one also had compensated cirrhosis. The most common adverse events were fatigue (31 [21%]), headache (29 [20%]), diarrhoea (28 [19%]), and nausea (21 [14%]). No deaths, treatment discontinuations, or treatment-related serious adverse events occurred.

INTERPRETATION

Supporting the results from the blinded portion of the phase 3 primary study, the single-tablet regimen of sofosbuvir-velpatasvir-voxilaprevir for 12 weeks was safe, well tolerated, and highly effective in patients with chronic HCV infection who had previous treatment failure with NS5A inhibitor-containing regimens. A salvage regimen for this population represents an important advance for patients with limited retreatment options.

FUNDING

Gilead Sciences.

Sofosbuvir-Based Direct-Acting Antiviral Therapies for HCV in People Receiving Opioid Substitution Therapy: An Analysis of Phase 3 Studies

Background

Hepatitis C virus (HCV) direct-acting antiviral therapy is effective among people receiving opioid substitution therapy (OST), but studies are limited by small numbers of nongenotype 1 (GT1) patients. The aim of this study was to evaluate the treatment completion, adherence, SVR12, and safety of sofosbuvir-based therapies in HCV patients receiving and not receiving OST.

Methods

Ten phase 3 studies of sofosbuvir-based regimens included ION (ledipasvir/sofosbuvir ± ribavirin for 8, 12, or 24 weeks in GT1), ASTRAL (sofosbuvir/velpatasvir for 12 weeks in GT1-6), and POLARIS (sofosbuvir/velpatasvir and sofosbuvir/velpatasvir/voxilaprevir in GT1-6). Patients with clinically significant drug use (last 12 months) or noncannabinoids detected at screening were ineligible.

Results

Among 4743 patients, 4% (n = 194) were receiving OST (methadone; n = 113; buprenorphine, n = 75; other, n = 6). Compared with those not receiving OST (n = 4549), those receiving OST (n = 194) were younger (mean age, 48 vs 54), more often male (73% vs 61%), GT3 (38% vs 17%), treatment-naïve (78% vs 65%), and cirrhotic (36% vs 23%). Among those receiving and not receiving OST, there was no significant difference in treatment completion (97% vs 99%, P = .06), SVR12 (94% vs 97%, P = .06), relapse (0.5% vs 2.1%, P = .19), adverse events (78% vs 77%, P = .79), or serious adverse events (3.6% vs 2.4%, P = .24). There was no difference in SVR12 in patients with cirrhosis (99% vs 95%, P = .25) or those with G3 (95% vs 95%, P = .77) in those receiving OST. Among patients receiving OST, SVR12 was high among those receiving methadone (95%) and buprenorphine (96%).

Conclusion

Sofosbuvir-based therapies are effective and safe in patients receiving OST.

Efficacy of 8 Weeks of Sofosbuvir, Velpatasvir, and Voxilaprevir in Patients With Chronic HCV Infection: 2 Phase 3 Randomized Trials

BACKGROUND & AIMS

Patients with chronic hepatitis C virus (HCV) infection have high rates of sustained virologic response (SVR) after 12 weeks of treatment with the nucleotide polymerase inhibitor sofosbuvir combined with the NS5A inhibitor velpatasvir. We assessed the efficacy of 8 weeks of treatment with sofosbuvir and velpatasvir plus the pangenotypic NS3/4A protease inhibitor voxilaprevir (sofosbuvir-velpatasvir-voxilaprevir).

METHODS

In 2 phase 3, open-label trials, patients with HCV infection who had not been treated previously with a direct-acting antiviral agent were assigned randomly to groups given sofosbuvir-velpatasvir-voxilaprevir for 8 weeks or sofosbuvir-velpatasvir for 12 weeks. POLARIS-2, which enrolled patients infected with all HCV genotypes with or without cirrhosis, except patients with genotype 3 and cirrhosis, was designed to test the noninferiority of 8 weeks of sofosbuvir-velpatasvir-voxilaprevir to 12 weeks of sofosbuvir-velpatasvir using a noninferiority margin of 5%. POLARIS-3, which enrolled patients infected with HCV genotype 3 who had cirrhosis, compared rates of SVR in both groups with a performance goal of 83%.

RESULTS

In POLARIS-2, 95% (95% confidence interval [CI], 93%-97%) of patients had an SVR to 8 weeks of sofosbuvir-velpatasvir-voxilaprevir; this did not meet the criterion to establish noninferiority to 12 weeks of sofosbuvir-velpatasvir, which produced an SVR in 98% of patients (95% CI, 96%-99%; difference in the stratum-adjusted Mantel-Haenszel proportions of -3.2%; 95% CI, -6.0% to -0.4%). The difference in the efficacy was owing primarily to a lower rate of SVR (92%) among patients with HCV genotype 1a infection receiving 8 weeks of sofosbuvir-velpatasvir-voxilaprevir. In POLARIS-3, 96% of patients (95% CI, 91%-99%) achieved an SVR in both treatment groups, which was significantly superior to the performance goal. Overall, the most common adverse events were headache, fatigue, diarrhea, and nausea; diarrhea and nausea were reported more frequently by patients receiving voxilaprevir. In both trials, the proportion of patients who discontinued treatment because of adverse events was low (range, 0%-1%).

CONCLUSIONS

In phase 3 trials of patients with HCV infection, we did not establish that sofosbuvir-velpatasvir-voxilaprevir for 8 weeks was noninferior to sofosbuvir-velpatasvir for 12 weeks, but the 2 regimens had similar rates of SVR in patients with HCV genotype 3 and cirrhosis. Mild gastrointestinal adverse events were associated with treatment regimens that included voxilaprevir. ClinicalTrials.gov numbers: POLARIS-2, NCT02607800; and POLARIS-3, NCT02639338.

Sofosbuvir-velpatasvir-voxilaprevir with or without ribavirin in direct-acting antiviral-experienced patients with genotype 1 hepatitis C virus

The optimal retreatment strategy for hepatitis C virus (HCV) genotype 1-infected patients who fail direct-acting antiviral (DAA)-based regimens remains unknown. In this phase 2, open-label study conducted at a single center in the United States, patients with HCV genotype 1 infection who previously failed to achieve sustained virological response (SVR) on a DAA-based regimen were randomized to receive treatment with a fixed-dose combination tablet of sofosbuvir-velpatasvir-voxilaprevir with or without ribavirin (RBV) for 12 weeks. Patients were stratified by their cirrhosis and past nonstructural protein (NS) 5A inhibitor exposure. The primary efficacy endpoint was the proportion of patients with SVR at 12 weeks after treatment (SVR12). SVR12 was achieved by 24 of 24 patients (100%; 95% confidence interval [CI], 86-100) receiving sofosbuvir-velpatasvir-voxilaprevir alone and 24 of 25 (96%; 95% CI, 80-100) receiving the same treatment with RBV. None of the patients discontinued sofosbuvir-velpatasvir-voxilaprevir therapy because of an adverse event (AE). The most commonly reported AEs with sofosbuvir-velpatasvir-voxilaprevir alone were diarrhea and bronchitis; and with sofosbuvir-velpatasvir-voxilaprevir plus RBV were fatigue, anemia, gastroenteritis, and nausea.

CONCLUSION

A fixed-dose combination of sofosbuvir-velpatasvir-voxilaprevir was well tolerated and effective at achieving virological response in patients with HCV genotype 1 infection and past DAA treatment experience. (Hepatology 2017;65:1803-1809).

Sofosbuvir, Velpatasvir, and Voxilaprevir for Previously Treated HCV Infection

BACKGROUND

Patients who are chronically infected with hepatitis C virus (HCV) and who do not have a sustained virologic response after treatment with regimens containing direct-acting antiviral agents (DAAs) have limited retreatment options.

METHODS

We conducted two phase 3 trials involving patients who had been previously treated with a DAA-containing regimen. In POLARIS-1, patients with HCV genotype 1 infection who had previously received a regimen containing an NS5A inhibitor were randomly assigned in a 1:1 ratio to receive either the nucleotide polymerase inhibitor sofosbuvir, the NS5A inhibitor velpatasvir, and the protease inhibitor voxilaprevir (150 patients) or matching placebo (150 patients) once daily for 12 weeks. Patients who were infected with HCV of other genotypes (114 patients) were enrolled in the sofosbuvir-velpatasvir-voxilaprevir group. In POLARIS-4, patients with HCV genotype 1, 2, or 3 infection who had previously received a DAA regimen but not an NS5A inhibitor were randomly assigned in a 1:1 ratio to receive sofosbuvir-velpatasvir-voxilaprevir (163 patients) or sofosbuvir-velpatasvir (151 patients) for 12 weeks. An additional 19 patients with HCV genotype 4 infection were enrolled in the sofosbuvir-velpatasvir-voxilaprevir group.

RESULTS

In the three active-treatment groups, 46% of the patients had compensated cirrhosis. In POLARIS-1, the rate of sustained virologic response was 96% with sofosbuvir-velpatasvir-voxilaprevir, as compared with 0% with placebo. In POLARIS-4, the rate of response was 98% with sofosbuvir-velpatasvir-voxilaprevir and 90% with sofosbuvir-velpatasvir. The most common adverse events were headache, fatigue, diarrhea, and nausea. In the active-treatment groups in both trials, the percentage of patients who discontinued treatment owing to adverse events was 1% or lower.

CONCLUSIONS

Sofosbuvir-velpatasvir-voxilaprevir taken for 12 weeks provided high rates of sustained virologic response among patients across HCV genotypes in whom treatment with a DAA regimen had previously failed. (Funded by Gilead Sciences; POLARIS-1 and POLARIS-4 ClinicalTrials.gov numbers, NCT02607735 and NCT02639247 .).

Efficacy of Ledipasvir Plus Sofosbuvir for 8 or 12 Weeks in Patients With Hepatitis C Virus Genotype 2 Infection

BACKGROUND & AIMS

Patients with chronic hepatitis C virus (HCV) genotype 2 have high rates of response to treatment with sofosbuvir and ribavirin. However, ribavirin is associated with hemolytic events and is poorly tolerated by some patients. We evaluated the effectiveness of sofosbuvir and ledipasvir in treatment-naïve and treatment-experienced patients with HCV genotype 2, comparing 12 versus 8 weeks of treatment.

METHODS

This Phase 2, open-label study included 2 cohorts in New Zealand. The first received a fixed-dose combination tablet of ledipasvir-sofosbuvir (90/400 mg) once daily for 12 weeks. If this cohort had a 90% rate of sustained virologic response (SVR) 4 weeks after treatment, a second cohort receiving 8 weeks of ledipasvir-sofosbuvir was to be enrolled. The primary endpoint in both cohorts was the percentage of patients with HCV RNA <15 IU/mL 12 weeks after therapy (SVR12).

RESULTS

SVR12 rates were 96% (25/26; 95% CI, 80%-100%) for 12 weeks and 74% (20/27; 95% CI, 54%-89%) for 8 weeks of ledipasvir-sofosbuvir. The single patient receiving 12 weeks of ledipasvir-sofosbuvir who did not reach SVR12 did not complete treatment because of withdrawing consent after receiving 1 dose of study drug. Six of the 7 patients who did not reach SVR12 after 8 weeks of treatment experienced virologic relapse after stopping therapy. The most common adverse events were headache (26% of patients), fatigue (21%), and nausea (17%). No patients discontinued treatment because of an adverse event.

CONCLUSIONS

For treatment-naïve and -experienced patients, ledipasvir-sofosbuvir for 12 weeks is highly effective for the treatment of HCV genotype 2 (ClinicalTrials.gov: NCT02202980).

Ledipasvir-sofosbuvir and sofosbuvir plus ribavirin in patients with chronic hepatitis C and bleeding disorders

INTRODUCTION

Chronic hepatitis C virus (HCV) infection is prevalent among patients with inherited bleeding disorders and is a leading cause of mortality in those with haemophilia.

AIM

We evaluated the efficacy and safety of ledipasvir-sofosbuvir and sofosbuvir plus ribavirin in patients with chronic HCV genotype 1-4 infection and an inherited bleeding disorder.

METHODS

Ledipasvir-sofosbuvir was administered for 12 weeks to patients with genotype 1 or 4 infection and for 12 or 24 weeks to treatment-experienced cirrhotic patients with genotype 1 infection. Patients with genotype 2 and 3 infection received sofosbuvir plus ribavirin for 12 and 24 weeks respectively.

RESULTS

The majority of the 120 treated patients had a severe bleeding disorder (55%); overall, 65% of patients had haemophilia A and 26% of patients had haemophilia B; 22% were HIV coinfected. Sustained virologic response at 12 weeks posttreatment was 99% (98/99) in patients with genotype 1 or 4 infection; 100% (5/5) in treatment-experienced cirrhotic patients with genotype 1 infection; 100% (10/10) in patients with genotype 2 infection; and 83% (5/6) in patients with genotype 3 infection. There were no treatment discontinuations due to adverse events (AEs). The most frequent non-bleeding AEs were fatigue, headache, diarrhoea, nausea and insomnia. Bleeding AEs occurred in 22 patients, of which all but one were considered unrelated to treatment.

CONCLUSION

Treatment with ledipasvir-sofosbuvir for patients with HCV genotype 1 or 4 infection or sofosbuvir plus ribavirin for patients with genotype 2 or 3 infection was highly effective and well tolerated among those with inherited bleeding disorders.

Efficacy of Sofosbuvir, Velpatasvir, and GS-9857 in Patients With Hepatitis C Virus Genotype 2, 3, 4, or 6 Infections in an Open-Label, Phase 2 Trial

BACKGROUND & AIMS

Studies are needed to determine the optimal regimen for patients with chronic hepatitis C virus (HCV) genotype 2, 3, 4, or 6 infections whose prior course of antiviral therapy has failed, and the feasibility of shortening treatment duration. We performed a phase 2 study to determine the efficacy and safety of the combination of the nucleotide polymerase inhibitor sofosbuvir, the NS5A inhibitor velpatasvir, and the NS3/4A protease inhibitor GS-9857 in these patients.

METHODS

We performed a multicenter, open-label trial at 32 sites in the United States and 2 sites in New Zealand from March 3, 2015 to April 27, 2015. Our study included 128 treatment-naïve and treatment-experienced patients (1 with HCV genotype 1b; 33 with HCV genotype 2; 74 with HCV genotype 3; 17 with genotype HCV 4; and 3 with HCV genotype 6), with or without compensated cirrhosis. All patients received sofosbuvir-velpatasvir (400 mg/100 mg fixed-dose combination tablet) and GS-9857 (100 mg) once daily for 6-12 weeks. The primary end point was sustained virologic response 12 weeks after treatment (SVR12).

RESULTS

After 6 weeks of treatment, SVR12s were achieved by 88% of treatment-naïve patients without cirrhosis (29 of 33; 95% confidence interval, 72%-97%). After 8 weeks of treatment, SVR12s were achieved by 93% of treatment-naïve patients with cirrhosis (28 of 30; 95% CI, 78%-99%). After 12 weeks of treatment, SVR12s were achieved by all treatment-experienced patients without cirrhosis (36 of 36; 95% CI, 90%-100%) and 97% of treatment-experienced patients with cirrhosis (28 of 29; 95% CI, 82%-100%). The most common adverse events were headache, diarrhea, fatigue, and nausea. Three patients (1%) discontinued treatment due to adverse events.

CONCLUSIONS

In a phase 2 open-label trial, we found sofosbuvir-velpatasvir plus GS-9857 (8 weeks in treatment-naïve patients or 12 weeks in treatment-experienced patients) to be safe and effective for patients with HCV genotype 2, 3, 4, or 6 infections, with or without compensated cirrhosis. ClinicalTrials.gov ID: NCT02378961.

Efficacy of Sofosbuvir, Velpatasvir, and GS-9857 in Patients With Genotype 1 Hepatitis C Virus Infection in an Open-Label, Phase 2 Trial

BACKGROUND & AIMS

The best regimen to re-treat patients who do not respond to direct-acting antivirals (DAAs) and the feasibility of further shortening regimens is unclear. We assessed the efficacy and safety of the combination of the nucleotide polymerase inhibitor sofosbuvir, the NS5A inhibitor velpatasvir, and the NS3/4A protease inhibitor GS-9857 in patients with hepatitis C virus genotype 1 infection.

METHODS

We performed an open-label trial at 32 sites in the United States and at 2 sites in New Zealand of 197 patients with genotype 1 hepatitis C virus infection, with or without compensated cirrhosis, who were treatment-naive or were treated previously with a DAA. Between March 2, 2015, and September 1, 2015, patients received sofosbuvir-velpatasvir (400 mg/100 mg in a fixed-dose combination) plus GS-9857 (100 mg) once daily for 6-12 weeks, plus ribavirin for 1 treatment group consisting of treatment-naive patients with cirrhosis. The primary end point was sustained virologic response 12 weeks after treatment (SVR12).

RESULTS

Among treatment-naive patients without cirrhosis, 71% (24 of 34; 95% confidence interval [CI], 53-85) achieved SVR12 after 6 weeks of treatment and 100% (36 of 36; 95% CI, 90%-100%) achieved SVR12 after 8 weeks of treatment. Among treatment-naive patients with cirrhosis, 94% (31 of 33; 95% CI, 80-99) achieved SVR12 after 8 weeks of treatment and 81% (25 of 31; 95% CI, 63-93) achieved SVR12 after 8 weeks of treatment with ribavirin. Among DAA-experienced patients treated for 12 weeks, 100% without cirrhosis (31 of 31; 95% CI, 89-100) and 100% with cirrhosis (32 of 32; 95% CI, 89-100) achieved SVR12. The most common adverse events were headache, diarrhea, fatigue, and nausea. One patient (<1%) discontinued treatment because of adverse events.

CONCLUSIONS

In a phase 2 open-label trial, we found 8 weeks of treatment with sofosbuvir-velpatasvir plus GS-9857 to be safe and effective in treatment-naive patients; 12 weeks was safe and effective in patients previously treated with DAAs. The combination was safe and effective in patients with or without compensated cirrhosis. Clinicaltrials.gov no: NCT02378935.

Efficacy of the Combination of Sofosbuvir, Velpatasvir, and the NS3/4A Protease Inhibitor GS-9857 in Treatment-Naïve or Previously Treated Patients With Hepatitis C Virus Genotype 1 or 3 Infections

BACKGROUND & AIMS

We performed a phase 2 trial of the efficacy and safety of 4, 6, and 8 weeks of sofosbuvir, given in combination with the NS5A inhibitor velpatasvir and the NS3/4A protease inhibitor GS-9857, in patients with hepatitis C virus (HCV) infection.

METHODS

We enrolled 161 treatment-naïve or previously treated patients infected with HCV genotypes 1 or 3 with or without compensated cirrhosis at 2 centers in New Zealand, from September 2014 through March 2015. All patients received sofosbuvir (400 mg) and velpatasvir (100 mg) plus GS-9857 (100 mg) once daily. The primary efficacy end point was sustained virologic response at 12 weeks after therapy (SVR12). The duration of therapy was determined by baseline patient characteristics: 4 or 6 weeks for treatment-naïve patients without cirrhosis, 6 weeks for treatment-naïve patients with cirrhosis, and 6 or 8 weeks for treatment-experienced patients with or without cirrhosis.

RESULTS

Four weeks of sofosbuvir, velpatasvir, and GS-9857 produced an SVR12 in 4 of 15 (27%) treatment-naïve patients with HCV genotype 1 without cirrhosis. Six weeks of this combination produced a SVR12 in 14 of 15 (93%) treatment-naïve patients with HCV genotype 1 without cirrhosis, in 13 of 15 (87%) treatment-naïve genotype 1 patients with cirrhosis, in 15 of 18 (83%) treatment-naïve patients with HCV genotype 3 with cirrhosis, and in 20 of 30 (67%) patients with HCV genotype 1 who had failed an all-oral regimen of 2 or more direct-acting antiviral agents. Eight weeks of the drug combination produced an SVR12 in 17 of 17 (100%) patients with HCV genotype 1, in 19 of 19 (100%) patients with HCV genotype 3 and cirrhosis who had failed pegylated interferon plus ribavirin, in 25 of 28 (89%) patients with HCV genotype 1 who had failed protease inhibitor-based triple therapy, and in 4 of 4 (100%) patients with HCV genotype 3 who had failed an all-oral regimen of ≥2 direct-acting antiviral agents. The most common reported adverse events were headache, nausea, and fatigue.

CONCLUSIONS

Eight weeks of treatment with the combination of sofosbuvir, velpatasvir, and GS-9857 produced an SVR12 in most treatment-naïve or previously treated patients with HCV genotype 1 or 3 infections, including those with compensated cirrhosis. ClinicalTrials.gov, Number: NCT02202980.

GS-9857 in patients with chronic hepatitis C virus genotype 1-4 infection: a randomized, double-blind, dose-ranging phase 1 study

GS-9857, an inhibitor of the hepatitis C virus (HCV) nonstructural protein (NS) 3/4A, demonstrates potent activity against HCV genotypes 1-6 and improved coverage against commonly encountered NS3 resistance-associated variants (RAVs). In this study, the safety, tolerability, antiviral activity and pharmacokinetics (PK) of GS-9857 were evaluated in patients with chronic HCV genotype 1-4 infection. Patients with genotype 1-4 infection received placebo or once-daily GS-9857 at doses ranging from 50 to 300 mg for 3 days under fasting conditions. GS-9857 was well tolerated; all reported adverse events (AEs) were mild or moderate in severity. Diarrhoea and headache were the most commonly reported AEs. Grade 3 or 4 laboratory abnormalities were observed in 17% of patients receiving GS-9857; there were no Grade 3 or 4 abnormalities in alanine aminotransferase, aspartate aminotransferase or alkaline phosphatase levels. GS-9857 demonstrated potent antiviral activity in patients with chronic HCV infection, achieving mean and median maximum reductions in HCV RNA of ≥3 log10 IU/mL following administration of a 100-mg dose in patients with HCV genotype 1a, 1b, 2, 3 or 4 infection. The antiviral activity of GS-9857 was unaffected by the presence of pretreatment NS3 RAVs. In patients with genotype 1-4 infection, GS-9857 exhibited linear PK and was associated with a median half-life of 29-42 h, supporting once-daily dosing. Thus, the tolerability, efficacy and pharmacokinetic profile of GS-9857 support its further evaluation for treatment of patients with chronic HCV infection.

Successful Re-treatment of Hepatitis C Virus in Patients Coinfected With HIV Who Relapsed After 12 Weeks of Ledipasvir/Sofosbuvir

We assessed the efficacy and safety of ledipasvir/sofosbuvir plus ribavirin for 24 weeks in 9 human immunodeficiency virus/hepatitis C virus-coinfected patients who relapsed after receiving 12 weeks of treatment with ledipasvir/sofosbuvir. Eight of 9 (89%) achieved sustained virologic response 12 weeks after the end of treatment. One patient relapsed at posttreatment week 4. These results suggest an effective salvage therapy for patients for whom direct-acting antiviral treatment has failed.

CLINICAL TRIALS REGISTRATION

NCT02073656.

Intermediate filaments enable pathogen docking to trigger type 3 effector translocation

Type 3 secretion systems (T3SSs) of bacterial pathogens translocate bacterial effector proteins that mediate disease into the eukaryotic cytosol. Effectors traverse the plasma membrane through a translocon pore formed by T3SS proteins. In a genome-wide selection, we identified the intermediate filament vimentin as required for infection by the T3SS-dependent pathogen Shigella flexneri. We found that vimentin is required for efficient T3SS translocation of effectors by S. flexneri and other pathogens that use T3SS, Salmonella Typhimurium and Yersinia pseudotuberculosis. Vimentin and the intestinal epithelial intermediate filament keratin 18 interact with the C-terminus of the Shigella translocon pore protein IpaC. Vimentin and its interaction with IpaC are dispensable for pore formation, but are required for stable docking of S. flexneri to cells; moreover, stable docking triggers effector secretion. These findings establish that stable docking of the bacterium specifically requires intermediate filaments, is a process distinct from pore formation, and is a prerequisite for effector secretion.

Dysregulation of distal cholesterol biosynthesis in association with relapse and advanced disease in CHC genotype 2 and 3 treated with sofosbuvir and ribavirin

BACKGROUND & AIMS

Hepatitis C virus (HCV) modulates host lipid metabolism for its replication and lifecycle. Our aims were to assess changes in the serum lipid and distal (post-squalene) cholesterol biosynthesis metabolite profile of HCV genotypes (GT) 2 and 3 patients treated with sofosbuvir+ribavirin.

METHODS

Serum samples [baseline, treatment week 12, 4weeks post-treatment] were analyzed for apolipoproteins B and E (apoB/E), total cholesterol, HDL, LDL, and 11 post-squalene sterol metabolites using a GC/MS platform.

RESULTS

We selected 127 patients (GT2 n=50, GT3 n=77), 50% cirrhotic patients, and 42% who experienced a virological relapse. At baseline, GT3 patients had lower level of serum lipids, apoB/E, 7-dehydrocholesterol, desmosterol, lathosterol, compared to GT2 (p<0.006). Baseline lathosterol was lower in relapsers with cirrhosis compared to cirrhotic patients with SVR (p=0.003). From baseline to treatment week 12, serum lipids, apoB/E, and key sterol pathway metabolites (7-dehydrocholesterol, desmosterol, lathosterol, lanosterol) increased in GT3. In contrast, in GT2 patients, apoB/E and dihydrolanosterol decreased with viral suppression (p<0.025). At follow-up week 4, cirrhotic SVR patients showed substantially greater increases in apoB and total sterols compared to cirrhotic relapsers regardless of HCV genotype. After adjustment for genotype and gender, baseline lathosterol was independently associated with virologic response (p=0.04).

CONCLUSION

HCV GT3 is associated with reduced circulation of lipids involved in the distal cholesterol biosynthesis pathway, resulting in relative hypocholesterolemia. HCV suppression during sofosbuvir+ribavirin restores distal sterol metabolites indicating viral interference with de novo lipogenesis or selective retention by hepatocytes.

Ledipasvir/sofosbuvir treatment of hepatitis C virus is associated with reduction in serum apolipoprotein levels

The interaction of lipoproteins with hepatitis C virus (HCV) has pathogenic and therapeutic implications. Our aim was to evaluate changes in the apolipoprotein profile of patients with chronic hepatitis C during and after successful cure with ledipasvir and sofosbuvir (LDV/SOF) with and without ribavirin (RBV). One hundred HCV genotype 1 patients who had achieved SVR-12 after treatment with 12 weeks of LDV/SOF ± RBV were selected from the ION-1 clinical trial. Frozen serum samples from baseline, end of treatment and week 4 of follow-up were used to assay apolipoproteins (apoAI, apoAII, apoB, apoCII, apoCIII, apoE) using the Multiplex platform to assess for changes in the apolipoprotein levels. At the end of treatment compared to baseline, a significant reduction in apoAII levels (-14.97 ± 63.44 μg/mL, P = 0.0067) and apoE levels (-4.38 ± 12.19 μg/mL, P < 0.001) was noted. These declines from baseline in apoAII (-16.59 ±66.15 μg/mL, P = 0.0075) and apoE (-2.66 ± 12.64 μg/mL, P = 0.015) persisted at 4 weeks of post-treatment follow-up. In multivariate analysis, treatment with LDV/SOF + RBV was independently associated with reduction in apoE (beta = 5.31 μg/mL, P = 0.002) (compared to RBV-free LDV/SOF) (P < 0.05). In contrast, apoCII levels overall increased from baseline to end of treatment (+2.74 ±11.76 μg/mL, P = 0.03) and persisted at 4 weeks of follow-up (+4.46 ± 12.81 μg/mL from baseline, P = 0.0005). Subgroup analysis revealed an increase in apoCII during treatment only in patients receiving LDV/SOF without RBV (+5.52 ± 11.92 μg/mL, P = 0.0007) but not in patients receiving LDV/SOF + RBV (P = 0.638). Treatment with LDV/SOF ± RBV is associated with a persistent reduction in the apolipoprotein AII and E after achieving cure. These data suggest that treatment with LDV/SOF ± RBV may be associated with alterations in serum apolipoproteins which could potentially impact viral eradication.

The safety and efficacy of ledipasvir/sofosbuvir for the treatment of a nosocomial outbreak of HCV in patients with significant cardiovascular disease

BACKGROUND

There is an unmet need for interferon- and ribavirin-free treatment for chronic HCV infection in patients with comorbidities including cardiovascular disease (CVD). The aim of this study was to evaluate the rates of sustained virological response (SVR) and adverse events in a cohort of patients with nosocomially acquired HCV genotype-1b following 12 weeks of therapy with fixed-dose combination (FDC) ledipasvir/sofosbuvir (LDV/SOF).

METHODS

This is a prospective, single-centre, open-label study of five non-cirrhotic patients with HCV genotype-1b and significant comorbid CVD, conducted at the Massachusetts General Hospital. All patients were prescribed an FDC tablet (LDV 90 mg/SOF 400 mg) once daily for 12 weeks. Serial measurements of safety parameters, virology, host immune correlates and adherence were performed. The primary outcome was the proportion of patients with SVR (plasma HCV RNA level <25 IU/ml), 12 weeks after treatment completion (SVR12).

RESULTS

All five patients (100%) achieved SVR12, with no episodes of on- or post-treatment relapse. The most commonly reported adverse events were gastrointestinal illness and upper respiratory viral-type illness. There were no serious adverse events or discontinuations of medication attributable to the study drug. Deep sequencing analysis revealed no baseline NS3, NS5A or NS5B resistance-associated variants.

CONCLUSIONS

In this open-label, uncontrolled, pilot study enrolling patients with HCV genotype-1b and significant CVD, administration of a fixed-dose, oral combination of LDV and SOF for 12 weeks was associated with high rates of SVR and minimal adverse events. Larger prospective studies that also include patients with cirrhosis and prior treatment non-responders are necessary.

Temporal dynamics of inflammatory cytokines/chemokines during sofosbuvir and ribavirin therapy for genotype 2 and 3 hepatitis C infection

The analysis of inflammatory cytokines and chemokines produced during hepatitis C virus (HCV) infection has advanced our understanding of viral-host interactions and identified predictors of treatment response. Administration of interferons (IFNs) made it difficult to interpret biomarkers of immune activation during treatment. Direct-acting antiviral (DAA) regimens without IFN are now being used to treat HCV with excellent efficacy. To gain insight into HCV-host interactions occurring before, during, and after HCV treatment, we performed a case-control study that measured serial plasma levels of IFN-γ-inducible protein 10 (IP-10), monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 1 beta (MIP-1β), and interleukin-18 (IL-18) in 131 patients with chronic HCV treated with sofosbuvir (SOF) plus ribavirin (RBV). A linear regression analysis using baseline factors identified strong positive associations between elevated alanine aminotransferase and pretreatment IP-10 and between the presence of cirrhosis and elevated pretreatment IL-18. Mean IP-10, MCP-1, MIP-1β, and IL-18 levels all decline on therapy, but display different dynamics late in treatment and after cessation of therapy. On treatment, IP-10 and MIP-1β levels were significantly higher in individuals who achieved sustained virological response (SVR). Logistic regression analyses examining treatment response in all patients demonstrated significant associations between higher baseline MIP-1β levels and smaller decreases in MIP-1β early in treatment and SVR. Higher early MIP-1β levels were also significantly associated with SVR in subsets of patients with cirrhosis and individuals with genotype 3 (GT3) infection, two factors associated with decreased responsiveness to treatment.

CONCLUSION

Changes in IP-10 levels mirror HCV RNA, suggesting that IP-10 is an indicator of innate immune viral recognition. MIP-1β levels remain elevated in GT2/3 patients who achieved SVR, suggesting differential immune activation in those who respond to SOF/RBV therapy and a potential role in predicting treatment responses.

Ledipasvir and Sofosbuvir for HCV in Patients Coinfected with HIV-1

BACKGROUND

Effective treatment for hepatitis C virus (HCV) in patients coinfected with human immunodeficiency virus type 1 (HIV-1) remains an unmet medical need.

METHODS

We conducted a multicenter, single-group, open-label study involving patients coinfected with HIV-1 and genotype 1 or 4 HCV receiving an antiretroviral regimen of tenofovir and emtricitabine with efavirenz, rilpivirine, or raltegravir. All patients received ledipasvir, an NS5A inhibitor, and sofosbuvir, a nucleotide polymerase inhibitor, as a single fixed-dose combination for 12 weeks. The primary end point was a sustained virologic response at 12 weeks after the end of therapy.

RESULTS

Of the 335 patients enrolled, 34% were black, 55% had been previously treated for HCV, and 20% had cirrhosis. Overall, 322 patients (96%) had a sustained virologic response at 12 weeks after the end of therapy (95% confidence interval [CI], 93 to 98), including rates of 96% (95% CI, 93 to 98) in patients with HCV genotype 1a, 96% (95% CI, 89 to 99) in those with HCV genotype 1b, and 100% (95% CI, 63 to 100) in those with HCV genotype 4. Rates of sustained virologic response were similar regardless of previous treatment or the presence of cirrhosis. Of the 13 patients who did not have a sustained virologic response, 10 had a relapse after the end of treatment. No patient had confirmed HIV-1 virologic rebound. The most common adverse events were headache (25%), fatigue (21%), and diarrhea (11%). No patient discontinued treatment because of adverse events.

CONCLUSIONS

Ledipasvir and sofosbuvir for 12 weeks provided high rates of sustained virologic response in patients coinfected with HIV-1 and HCV genotype 1 or 4. (Funded by Gilead Sciences; ION-4 ClinicalTrials.gov number, NCT02073656.).

Characterization of hepatitis C virus intergenotypic recombinant strains and associated virological response to sofosbuvir/ribavirin

To date, intergenotypic recombinant hepatitis C viruses (HCVs) and their treatment outcomes have not been well characterized. This study characterized 12 novel HCV recombinant strains and their response to sofosbuvir in combination with ribavirin (SOF/RBV) treatment. Across the phase II/III studies of SOF, HCV samples were genotyped using both the Siemens VERSANT HCV Genotype INNO-LiPA 2.0 Assay (Innogenetics, Ghent, Belgium) and nonstructural (NS)5B sequencing. Among these patient samples, genotype assignment discordance between the two methods was found in 0.5% of all cases (12 of 2,363), of which all were identified as genotype 2 by INNO-LiPA (12 of 487; 2.5%). HCV full-genome sequences were obtained for these 12 samples by a sequence-independent amplification method coupled with next-generation sequencing. HCV full-genome sequencing revealed that these viruses were recombinant HCV strains, with the 5' part corresponding to genotype 2 and the 3' part corresponding to genotype 1. The recombination breakpoint between genotypes 2 and 1 was consistently located within 80 amino acids of the NS2/NS3 junction. Interestingly, one of the recombinant viruses had a 34-amino-acid duplication at the location of the recombination breakpoint. Eleven of these twelve patients were treated with a regimen for genotype 2 HCV infection, but responded as if they had genotype 1 infection; 1 patient had received placebo.

CONCLUSION

Twelve new HCV intergenotypic recombinant genotype 2/1 viruses have been characterized. The antiviral response to a 12- to 16-week course of SOF/RBV treatment in these patients was more similar to responses among genotype 1 patients than genotype 2 patients, consistent with their genotype 1 NS5B gene.

Concordance of sustained virological response 4, 12, and 24 weeks post-treatment with sofosbuvir-containing regimens for hepatitis C virus

Historically, clinical trials of regimens to treat chronic infection with hepatitis C virus (HCV) have used, as their primary efficacy endpoint, a sustained virological response (SVR)—defined as HCV RNA levels below a designated threshold of quantification—24 weeks after the end of treatment (SVR24). More recently, regulatory authorities have begun to accept SVR at 12 weeks post-treatment (SVR12) as a valid efficacy endpoint because of its high rate of concordance with SVR24. However, the concordance between SVR12 and SVR24 has not been systematically assessed with new regimens of recently approved direct-acting antiviral agents. The aim of this study was to assess the concordance between SVR at various post-treatment time points in phase III clinical trials of sofosbuvir (SOF)-containing regimens. We conducted a retrospective analysis of five trials enrolling 863 patients infected with HCV genotypes 1-6. The concordance between SVR at 4 weeks post-treatment (SVR4) and SVR12, and between SVR12 and SVR24, were determined, as well as positive predictive values (PPVs) and negative predictive values (NPVs). Overall, 779 of 796 patients (98.0%) with an SVR4 also achieved an SVR12, making the PPV of SVR4 for SVR12 98% and the NPV 100%. Of the 779 patients with an SVR12, 777 (99.7%) also achieved an SVR24, making the PPV of SVR12 for SVR24 >99% and the NPV 100%. Of patients who relapsed post-therapy, 77.6% did so within 4 weeks of completing therapy.

CONCLUSION

Data from phase III studies demonstrate that with SOF-based regimens, with or without interferon, SVR12 and SVR24 correlate closely. Thus, SVR12 can be used effectively to determine "cure" rates in trials and in clinical practice.

Caging targets for destruction

Intracellular bacterial pathogens engage in a tug-of-war with innate host defenses. In this issue of Cell Host & Microbe, Mostowy et al. (2010) identify a role for the septin family of cytoskeletal proteins in targeting intracellular Shigella to the autophagy pathway.

Role of the WASP family proteins for Mycobacterium marinum actin tail formation

Mycobacterium marinum, a natural pathogen of fish and frogs and an occasional pathogen of humans, is capable of inducing actin tail formation within the cytoplasm of macrophages, leading to actin-based motility and intercellular spread. Actin tail formation by M. marinum is markedly reduced in macrophages deficient in the Wiskott-Aldrich syndrome protein (WASP), which still contain the closely related and ubiquitously expressed protein N-WASP (neuronal WASP). In fibroblasts lacking both WASP and N-WASP, M. marinum is incapable of efficient actin polymerization and of intercellular spread. By reconstituting these cells, we find that M. marinum is able to use either WASP or N-WASP to induce actin polymerization. Inhibition or genetic deletion of tyrosine phosphorylation, Nck, WASP-interacting protein, and Cdc42 does not affect M. marinum actin tail formation, excluding the participation of these molecules as upstream activators of N-WASP in the initiation of actin-based motility. In contrast, deletion of the phosphatidylinositol 4,5-bisphosphate-binding basic motif in N-WASP eliminates M. marinum actin tail formation. Together, these data demonstrate that M. marinum subversion of host actin polymerization is most similar to distantly related Gram-negative organisms but that its mechanism for activating WASP family proteins is unique.

Mycobacterium marinum: the generalization and specialization of a pathogenic mycobacterium

Mycobacterium marinum is being used increasingly as a model for understanding pathogenic mycobacteria. However, recently discovered differences between M. marinum and M. tuberculosis suggest that adaptation to specialized niches is reflected in unique strategies of pathogenesis. This review emphasizes the areas in which studying M. marinum has made contributions to the understanding of tuberculosis, as well as the potential for using characteristics unique to M. marinum for understanding general issues of host-pathogen interactions.

Mycobacterium marinum escapes from phagosomes and is propelled by actin-based motility

Mycobacteria are responsible for a number of human and animal diseases and are classical intracellular pathogens, living inside macrophages rather than as free-living organisms during infection. Numerous intracellular pathogens, including Listeria monocytogenes, Shigella flexneri, and Rickettsia rickettsii, exploit the host cytoskeleton by using actin-based motility for cell to cell spread during infection. Here we show that Mycobacterium marinum, a natural pathogen of fish and frogs and an occasional pathogen of humans, is capable of actively inducing actin polymerization within macrophages. M. marinum that polymerized actin were free in the cytoplasm and propelled by actin-based motility into adjacent cells. Immunofluorescence demonstrated the presence of host cytoskeletal proteins, including the Arp2/3 complex and vasodilator-stimulated phosphoprotein, throughout the actin tails. In contrast, Wiskott-Aldrich syndrome protein localized exclusively at the actin-polymerizing pole of M. marinum. These findings show that M. marinum can escape into the cytoplasm of infected macrophages, where it can recruit host cell cytoskeletal factors to induce actin polymerization leading to direct cell to cell spread.

Deltamethrin-impregnated dog collars have a potent anti-feeding and insecticidal effect on Lutzomyia longipalpis and Lutzomyia migonei

Deltamethrin-impregnated PVC dog collars were tested to assess if they were effective in protecting dogs from sand fly bites of Lutzomyia longipalpis and Lu. migonei. A protective effect against Old World species Phlebotomus perniciosus was demonstrated before. Four dogs wearing deltamethrin collars and three dogs wearing untreated collars (not impregnated with deltamethrin) were kept in separate kennels for over eight months in a village on the outskirts of Fortaleza in Ceará, Brazil. Periodically, a dog from each group was sedated, placed in a net cage for 2 h in which 150 female sand flies had been released 10-15 min before. Lu. longipalpis were used 4, 8, 12, 16, 22, 27, and 35 weeks after the attachment of the collars. Lu. migonei were used 3, 7, 11, 15, 22, 26, and 36 weeks after attachment. During 35 weeks, only 4.1% (81 of 2,022) Lu. longipalpis recovered from the nets with the deltamethrin collared dogs were engorged, an anti-feeding effect of 96%. Mortality initially was over 90% and at 35 weeks was 35% with half of the sand flies dying in the first 2 h. In contrast, 83% of the 2,094 Lu. longipalpis recovered from the nets containing the untreated collared dogs were engorged and the mortality ranged from zero to 18.8% on one occasion with 1.1% dying in the first 2 h. Similar findings were found with Lu. migonei: of 2,034 sand flies recovered over this period, only 70 were engorged, an anti-feeding effect of 96.5%, and mortality ranged from 91% initially to 46% at 36 weeks. In contrast, engorgement of controls ranged from 91 to71% and a mortality ranged from 3.5 to 29.8%. These studies show that deltamethrin impregnated collars can protect dogs against Brazilian sand flies for up to eight months. Thus, they should be useful in a program to control human and canine visceral leishmaniasis.

Interleukin-4-deficient BALB/c mice develop an enhanced Th1-like response but control cardiac inflammation following Borrelia burgdorferi infection

Interleukin-4 has been reported to critically modulate Borrelia burgdorferi infection and Lyme arthritis in experimental murine models. To determine the in vivo role of IL-4 in controlling Lyme carditis, we compared immunological responses and the severity of cardiac inflammation in wild-type BALB/c (IL-4 +/+) and IL-4 deficient BALB/c (IL-4 -/-) mice infected with B. burgdorferi by tick-bite. At day 15 and 30 post-infection IL-4 -/- mice produced significantly greater titers of spirochete-specific IgG2a than the wild-type IL-4 +/+ mice, which produced significantly more spirochete-specific IgG1. Following in vitro antigenic stimulation with B. burgdorferi antigen, splenocytes from infected IL-4 -/- and IL-4 +/+ mice displayed similar magnitudes of proliferative responses at day 15 and 30 post-infection. At day 30 antigen-stimulated splenocytes from infected IL-4 -/- mice, however, produced significantly more IFN-gamma than those derived from similarly infected IL-4 +/+ mice, suggesting that Th1-influenced responses predominated in IL-4 -/- mice. Moreover, inflamed hearts from IL-4 -/- mice displayed higher levels of IFN-gamma and TNF-alpha transcripts as compared to IL-4 +/+ mice. At both time points antigen-stimulated splenocytes from IL-4 +/+ and IL-4 -/- mice produced significant amounts of IL-10 but those from IL-4 +/+ mice produced either no or little IL-4. Histopathology demonstrated typical Lyme carditis in both IL-4 +/+ and IL-4 -/- mice at day 15 and day 30. Although Borrelia-infected IL-4 -/- mice developed a more severe carditis on day 30, the carditis resolved by day 50, as it did in IL4 +/+ mice. These results indicate that although IL-4 may help limit the severity of Lyme carditis, its absence does not preclude resolution of cardiac lesions.

NK cell-deficient mice develop a Th1-like response but fail to mount an efficient antigen-specific IgG2a antibody response

NK cells have been shown to play a role in the modulation of B cell differentiation and Ab production. Using a novel murine model of NK cell deficiency, we analyzed the in vivo role of NK cells in the regulation of Ag-specific Ab production. After immunization with OVA or keyhole limpet hemocyanin in CFA, NK cell-deficient (NK-T+) mice developed an efficient Th1 response and produced significant levels of IFN-gamma but displayed markedly reduced or absent Ag-specific IgG2a production. There were no differences in the levels of Ag-specific IgG, IgG1, and IgG2b between NK-T+ and NK+T+ mice. Furthermore, NK cell-reconstituted, NK+T+ (tgepsilon26Y) mice produced significant amounts of Ag-specific IgG2a after immunization with OVA. These results indicate that NK cells are involved in the induction of Ag-specific IgG2a production in vivo. Moreover, they also demonstrate that the lack of Ag-specific IgG2a Ab production in NK-T+ mice is not associated with the impaired Th1 response and IFN-gamma production.

NK Cell-Deficient Mice Develop a Th1-Like Response but Fail to Mount an Efficient Antigen-Specific IgG2a Antibody Response

NK cells have been shown to play a role in the modulation of B cell differentiation and Ab production. Using a novel murine model of NK cell deficiency, we analyzed the in vivo role of NK cells in the regulation of Ag-specific Ab production. After immunization with OVA or keyhole limpet hemocyanin in CFA, NK cell-deficient (NK−T+) mice developed an efficient Th1 response and produced significant levels of IFN-γ but displayed markedly reduced or absent Ag-specific IgG2a production. There were no differences in the levels of Ag-specific IgG, IgG1, and IgG2b between NK−T+ and NK+T+ mice. Furthermore, NK cell-reconstituted, NK+T+ (tgε26Y) mice produced significant amounts of Ag-specific IgG2a after immunization with OVA. These results indicate that NK cells are involved in the induction of Ag-specific IgG2a production in vivo. Moreover, they also demonstrate that the lack of Ag-specific IgG2a Ab production in NK−T+ mice is not associated with the impaired Th1 response and IFN-γ production.

STAT-4 mediated IL-12 signaling pathway is critical for the development of protective immunity in cutaneous leishmaniasis

Recent studies have demonstrated that two IL-12 signaling pathways, a STAT 4 - dependent and STAT4 - independent, are involved in the development of a Th1-like response. To determine their roles in the development of protective immunity against Leishmania major, we monitored progression of cutaneous Leishmania major infection in STAT4-deficient mice (STAT4-/-) compared to similarly infected wild-type (STAT4+/+) mice. Although the onset of lesion growth was delayed in STAT4-/- mice during the early phase of infection, these mice eventually developed large, non-healing lesions, whereas STAT4+/+ mice resolved their lesions. As infection progressed, both STAT4+/+ and STAT4-/- mice infected with L. major displayed similar titers of Leishmania-specific IgG1 and IgE but later produced lower IgG2a. On days 20 and 40 post-infection, Leishmania antigen-stimulated lymphnode cells from STAT4-/- mice produced significantly lower amounts of IFN-gamma than those from STAT4+/+ mice as measured by enzyme-linked immunosorbent assay. There was no significant difference, however, in IL-4 and IL-12 production between the two groups. These results indicate that STAT4-mediated IL-12 signaling is critical for the development of protective Th1 response following L. major infection in genetically resistant mice. Additionally, they demonstrate that, although genetically resistant mice lacking STAT4 signaling pathway develop large, non-healing lesions, they do not default towards a Th2-like response.

Mice Lacking NK Cells Develop an Efficient Th1 Response and Control Cutaneous Leishmania major Infection

NK cells are believed to play a critical role in the development of immunity against Leishmania major. We recently found that transplantation of wild-type bone marrow cells into neonatal tgε 26 mice, which are deficient in T and NK cells, resulted in normal T cell development, but no or poor NK cell development. Using this novel model we analyzed the role of NK cells in the development of Th1 response and control of cutaneous L. major infection. Mice selectively lacking NK cells (NK−T+) developed an efficient Th1-like response, produced significant amounts of IL-12 and IFN-γ, and controlled cutaneous L. major infection. Administration of neutralizing IL-12 Abs to NK−T+ mice during L. major infection resulted in exacerbation of the disease. These results demonstrate that NK cells are not critical for development of protective immunity against L. major. Furthermore, they indicate that IL-12 can induce development of Th1 response independent of NK cells in NK−T+ mice following L.major infection.

Mice lacking NK cells develop an efficient Th1 response and control cutaneous Leishmania major infection

NK cells are believed to play a critical role in the development of immunity against Leishmania major. We recently found that transplantation of wild-type bone marrow cells into neonatal tgepsilon 26 mice, which are deficient in T and NK cells, resulted in normal T cell development, but no or poor NK cell development. Using this novel model we analyzed the role of NK cells in the development of Th1 response and control of cutaneous L. major infection. Mice selectively lacking NK cells (NK-T+) developed an efficient Th1-like response, produced significant amounts of IL-12 and IFN-gamma, and controlled cutaneous L. major infection. Administration of neutralizing IL-12 Abs to NK-T+ mice during L. major infection resulted in exacerbation of the disease. These results demonstrate that NK cells are not critical for development of protective immunity against L. major. Furthermore, they indicate that IL-12 can induce development of Th1 response independent of NK cells in NK-T+ mice following L.major infection.