Nonstructural protein 5A resistance profile in patients with chronic hepatitis C treated with ledipasvir-containing regimens without sofosbuvir.

The study aimed to evaluate the effects of baseline hepatitis C virus (HCV) nonstructural protein 5A (NS5A) resistance-associated substitutions (RASs) on sustained virologic response to ledipasvir (LDV)-containing regimens in the absence of sofosbuvir (SOF) in patients with HCV genotype (GT) 1 infection across 6 phase 2 clinical studies. We analysed data from 1103 patients who received either LDV + vedroprevir (NS3 protease inhibitor) + tegobuvir (NS5B inhibitor) ± ribavirin or LDV + ribavirin + pegylated interferon. Population sequencing of HCV NS5A was performed at baseline and at virologic failure from patient plasma samples. Of 1045 patients with available baseline sequences, 747 (67.7%) had GT1a, and 298 (26.9%) had GT1b infection. The overall prevalence of NS5A RASs at baseline was 9.4%; 7.6% (57/747) and 13.8% (41/298) of patients with GT1a and GT1b infection, respectively. The majority of GT1a-infected patients with NS5A RASs at baseline had a single NS5A RAS (78.9%) at NS5A positions K24R, M28T, Q30H/L, L31M and Y93H/N/C/S. The spectrum of NS5A RASs detected in GT1b patients was much less diverse compared to GT1a patients, with all patients harbouring a single NS5A RAS either L31M or Y93H/C. For patients treated with LDV-containing regimens in the absence of SOF, the presence of baseline NS5A RASs was associated with low SVR rates. In patients with virologic failure, nearly all had either pre-existing and/or emergent NS5A RASs: 287/287 (100%) and 40/42 (95.2%) patients with GT1a and GT1b infection, respectively. Three novel NS5A substitutions were identified as emergent NS5A RASs: K26E and S38F in GT1a; and L31I in GT1b. In conclusion, the presence of NS5A RASs at baseline reduced the SVR rate in patients treated with LDV in combination vedroprevir + tegobuvir ± ribavirin or ribavirin + pegylated interferon. Virologic failure was associated with the detection of NS5A RASs in nearly all patients. These results suggest that the resistance barrier may differ depending on HCV drug combination and may be more important than that of the individual DAAs.

No detectable resistance to tenofovir disoproxil fumarate in HBeAg+ and HBeAg- patients with chronic hepatitis B after 8 years of treatment.

A major hurdle in the long-term treatment of chronic hepatitis B (CHB) patients is to maintain viral suppression in the absence of drug resistance. To date, no evidence of resistance to tenofovir disoproxil fumarate (TDF) has been observed. A cumulative evaluation of CHB patients who qualified for resistance surveillance over 8 years of TDF treatment was conducted. Patients in studies GS-US-174-0102 (HBeAg-) and GS-US-174-0103 (HBeAg+) were randomized 2:1 to receive TDF or adefovir dipivoxil (ADV) for 48 weeks followed by open-label TDF through year 8. Population sequencing of HBV pol/RT was attempted for all TDF-treated patients at baseline and, annually if viremic, at discontinuation, or with addition of emtricitabine. Overall, 88/641 (13.7%) patients qualified for sequence analysis at one or more time points. The percentage of patients qualifying for sequence analysis declined over time, from 9 to 11% in years 1-2 to <4% over years 3-8. Forty-one episodes of virologic breakthrough (VB) occurred throughout the study, with most (n=29, 70%) associated with nonadherence to study medication. Fifty-nine per cent of VB patients with an opportunity to resuppress HBV achieved HBV DNA resuppression. A minority of patients who qualified for sequencing had polymorphic (41/165, 24.8%) or conserved (17/165, 10.3%) site changes in pol/RT, with six patients developing lamivudine and/or ADV resistance-associated mutations. No accumulation of conserved site changes was detected. The long-term treatment of CHB with TDF monotherapy maintains effective suppression of HBV DNA through 8 years, with no evidence of TDF resistance or accumulation of conserved site changes.

A deficit in collagenase activity contributes to impaired migration of aged microvascular endothelial cells.

Angiogenesis is impaired in aging. Delayed neovascularization is due, in part, to slowed endothelial cell migration. Migration requires an optimal level of adhesion to matrix proteins, a process mediated by matrix-degrading metalloproteases (MMPs) such as MMP1. To determine whether impaired angiogenesis in aging is associated with altered synthesis and activity of MMP1, we examined the expression of collagenase and tissue inhibitor of metalloprotease 1 (TIMP1) by immunostain of angiogenic sponge implants from young and aged mice. To characterize the relevance of MMP activity during the movement of aged endothelial cells, the secretion of MMP1 and TIMP1 by late-passage human microvascular endothelial cells (hmEC aged in vitro) and their non-aged (young) counterparts was quantified. The migration of aged human microvascular endothelial cells and the effect of inhibition of TIMP1 on the migration of aged hmEC or collagen I was also measured. Relative to young mice, granulation tissue from aged mice showed less expression of collagenase and increased expression of TIMP1. In vitro, aged hmEC were deficient in MMP1 secretion (55 +/- 13% relative to young cells) and activity but showed increased expression of TIMP1 (280 +/- 109% relative to young cells). Aged hmEC migrated significantly less distance than did young hmEC over a 5-day period (59 +/- 8% relative to young cells). In the presence of a blocking antibody to TIMP1, aged hmEC showed a significant increase in the distance migrated on collagen I over a 5 day period (142 +/- 11% relative to untreated aged hmEC). We propose that deficient MMP1 activity contributes to impaired cellular movement in aged microvascular endothelial cells and that perturbations that enhance collagenase activity increase their migratory ability and angiogenic potential.