2. Harvoni and Viekira Pak: Effective Oral Combinations for HCV Genotype 1

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2014 saw the long-awaited U.S. Food and Drug Administration (FDA) approval of new interferon-free combination regimens for people with genotype 1 chronic hepatitis C: Gilead Sciences sofosbuvir/ledipasvir coformulation (Harvoni) in October and AbbVie's paritaprevir/ritonavir/ombitasvir plus dasabuvir regimen (Viekira Pak, formerly known as "3D") in late December. 

The advent of direct-acting antivirals that target different steps of the hepatitis C virus (HCV) lifecycle has brought about a revolution in hepatitis C treatment. Last year saw the approval of Janssen's HCV protease inhibitor simeprevir (Olysio) and Gilead Sciences' nucleotide polymerase inhibitor sofosbuvir (Sovaldi), but most people still had to take them with pegylated interferon and ribavirin. The approval of Harvoni and Viekira Pak -- along with the FDA's supplemental approval of sofosbuvir plus simeprevir -- now offer well-tolerated interferon-free options for genotype 1, the most common HCV type in the U.S.

In clinical trials sofosbuvir/ledipasvir produced high rates of sustained virological response at 12 weeks post-treatment (SVR12), considered to be a cure. In the Phase 3 ION trialsSVR12 rates for sofosbuvir/ledipasvir with or without ribavirin ranged from 94% to 99%. ION-3 showed that many patients can be cured with just 8 weeks of treatment. The combination was shown to be effective for traditionally hard-to-treat populations including HIV/HCV coinfected people, liver transplant recipients, and patients with decompensated liver disease.

The Viekira regimen likewise demonstrated good efficacy in Phase 2 and 3 clinical trials, with SVR12 rates in the 90% to 100% range. It was also shown to be effective for HIV/HCV coinfected people, patients with liver cirrhosis, and liver transplant recipients.

Also in the running, European regulators approved Bristol-Myers Squibb's pan-genotypic HCV NS5A inhibitor daclatasvir (Daklinza) in August. Daclatasvir is still awaiting FDA approval, but the company withdrew its FDA request for its HCV protease inhibitor asunaprevir (Sunvepra).

These new interferon-free treatments can now cure almost all people with hepatitis C in 8 to 24 weeks with minimal side effects. Some experts have even predicted that a "treatment as prevention" effect could essentially wipe out the virus. But their high cost has led to restrictions on their use and a price war that has AbbVie and Gilead offering exclusive deals to competing payers.

NEXT: 3. High Hepatitis C Treatment Cost Leads to Restrictions, Sets Off Price War