CROI 2015: Sustained Virological Response Represents a Long-term Cure for Hepatitis C

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Almost all patients with hepatitis C virus alone or HIV/HCV coinfection who achieved sustained virological response (SVR) to treatment with sofosbuvir (Sovaldi) plus ribavirin or sofosbuvir/ledipasvir (Harvoni) still had undetectable HCV RNA up to 2.4 years later, confirming that SVR represents a cure, according to a poster presented at the recent 2015 Conference on Retroviruses and Opportunistic Infections (CROI) in Seattle.

The advent of interferon-free therapy using combinations of direct-acting antiviral drugs has brought about a revolution in hepatitis C treatment. Sustained virological response, or continued undetectable HCV RNA at 12 or 24 weeks post-treatment, is considered a cure, but rare cases of apparent late relapse have been observed after this point. More often, HCV recurrence is due to reinfection.

While some studies have detected residual bits of HCV in the blood or the liver after successful treatment, this does not appear to indicate on-going active disease. Interferon-based therapy has been shown to have a late relapse rate below 5% -- usually occurring within 2 years after treatment -- but this is not yet well defined for interferon-free therapy because it is so new.

Aurielle Thomas from the National Institutes of Health (NIH) and colleagues analyzed data from 3 studies of sofosbuvir-based therapy, looking at the durability of SVR and associated changes in liver function biomarkers.

They included 159 participants who achieved SVR in the following Phase 2 clinical trials, the results of which have been previously reported:

All 3 studies, conducted by the NIH, enrolled primarily low-income people in the Washington, DC, area. A majority were men, 85% were African-American, and the median age was around 55 years. Most (72%) had harder-to-treat HCV subtype 1a and one-quarter had advanced fibrosis or cirrhosis (Metavir stage F3-F4).

For the current analysis, participants were followed with ongoing measurement of HCV viral load and alanine aminotransferase (ALT) liver enzyme levels. Follow-up time ranged from 1 to 125 weeks (2.4 years) after SVR12, for a maximum of SVR137. However, only participants in the SPARE study -- which started first -- had reached SVR73 or later, and only 15 people had data for SVR116 or later.

The researchers used a viral load test that is able to measure HCV RNA down to a limit of quantification of <12 IU/mL. (Although there is no standard conversion, for most tests 1 IU/mL is between 1 and 5 copies/mL.)

Results

"This study shows the long-term durability of SVR associated with [direct-acting antiviral]-based therapy in patients with HCV monoinfection and HIV/HCV coinfection during an on-going assessment of up to 125.2 weeks," the investigators concluded.

Only a small proportion of patients had persistently elevated ALT despite undetectable HCV viral load, leading the researchers to suggest, "It is plausible that this reflects the long-term histologic regression of necroinflammation and fibrosis described in patients who achieve SVR."

They added that monitoring and data collection, including liver biopsies, is ongoing.

3/13/15

Reference

AM Thomas, S Kattakuzhy, S Jones, et al. SVR Durability: HCV Patients Treated with IFN-Free DAA Regimens. 2015 Conference on Retroviruses and Opportunistic Infections. Seattle, February 23-24, 2015. Abstract 653.