Baseline resistance-associated substitutions (RASs) have variable impacts in clinical trials but their prevalence and impact in real-world patients remains unclear. We performed baseline resistance testing using a commercial assay (10% cutoff) for 486 patients treated with LDV/SOF or SMV/SOF, with or without ribavirin, in the multi-center, observational HCV-TARGET cohort. Linkage of RASs was evaluated in selected samples using a novel quantitative single variant sequencing assay. Our results showed that the prevalence of NS3, NS5A, NS5B RASs was 45%, 13%, and 8%, respectively, and 10% of patients harbored RASs in 2 or more drug classes. Baseline LDV RASs in GT1a, TE, and cirrhosis LDV/SOF subgroup was associated with 2-4% lower SVR12 rates. SMV RASs was associated with lower SVR12 rates in GT1a, treatment-experienced, cirrhotics SMV/SOF subgroup. Pooled analysis of all patients with baseline RASs revealed that SVR12 was 100% (19/19) in patients treated for longer than 98 days but was 87% (81/93) in patients treated for shorter than 98 days. These results demonstrate that RASs prevalence and their impact in real world practice are in general agreement with registration trials, and suggest that longer treatment duration may overcome the negative impact of baseline RASs on SVR12 rates in clinical practice.

Background & aims

The combination of ledipasvir and sofosbuvir has been approved for treatment of genotype 1 hepatitis C virus (HCV) infection, including an 8-week regimen for treatment-naïve patients without cirrhosis and a baseline level of HCV RNA <6 million IU/mL. We analyzed data from a multicenter, prospective, observational study to determine real-world sustained virologic responses 12 weeks after treatment (SVR12) with regimens containing ledipasvir and sofosbuvir and identify factors associated with treatment failure.

Methods

We collected data from 2099 participants in the HCV-TARGET study with complete virologic data (per-protocol population). We analyzed data from 1788 patients receiving ledipasvir-sofosbuvir (282 for 8 weeks, 910 for 12 weeks, 510 for 24 weeks, and 86 for a different duration) and 311 receiving ledipasvir-sofosbuvir plus ribavirin (212 for 12 weeks and 81 for 24 weeks, 18 for other duration) to estimate SVR12 (with 95% confidence interval [CI]), and logistic regression methods to identify factors that predicted an SVR12.

Results

The overall study population was 25% black, 66% with HCV genotype 1A infection, 41% with cirrhosis, 50% treatment-experienced, and 30% receiving proton pump inhibitors at start of treatment. In the per-protocol population, SVR12s were achieved by 96% of patients receiving ledipasvir-sofosbuvir for 8 weeks (95% CI, 93%-98%), 97% receiving the drugs for 12 weeks (95% CI, 96%-98%), and 95% receiving the drugs for 24 weeks (95% CI, 93%-97%). Among patients also receiving ribavirin, SVR12 was achieved by 97% of the patients receiving the drugs for 12 weeks (95% CI, 94%-99%) and 95% receiving the drugs for 24 weeks (95% CI, 88%-99%). Of the 586 patients who qualified for 8 weeks of treatment, only 255 (44%) received the drugs for 8 weeks. The rate of SVR12 among those who qualified for and received 8 weeks of therapy was similar in those who qualified for 8 weeks but received 12 weeks therapy (96%; 95% CI, 92%-99% vs 98%; 95% CI, 95%-99%). Factors that predicted SVR12 were higher albumin (≥3.5 g/dL), lower total bilirubin (≤1.2 g/dL), absence of cirrhosis, and absence of proton pump inhibitor use.

Conclusions

Regimens containing ledipasvir and sofosbuvir are highly effective for a broad spectrum of patients with HCV genotype 1 infection treated in different clinical practice settings. Expanded use of 8-week treatment regimens for eligible patients is supported by these real-world results. Modification of proton pump inhibitor use may increase rates of SVR. ClinicalTrials.gov no. NCT01474811.