The US Food and Drug Administration (FDA) on Tuesday warned of serious risks for some patients who have been infected with the hepatitis B virus (HBV) and are being treated with certain direct-acting antiviral (DAA) medicines for hepatitis C virus (HCV).

FDA identified 24 cases of HBV reactivation reported to FDA and from the published literature in HCV/HBV co-infected patients treated with DAAs between 22 November 2013 and 18 July 2016.

Of the cases reported, two patients died and one required a liver transplant, though FDA cautions that this number includes only cases submitted to FDA, so there are likely additional cases.

As a result, FDA is now requiring a boxed warning to be added to nine DAAs, including Gilead’s blockbusters Harvoni and Sovaldi, as well as Abbvie’s Viekra Pak and Bristol-Myers Squibb’s Daklinza.

DAA medicines used to treat chronic hepatitis C virus (HCV) infection are unique in that they reduce the amount of HCV in the body by preventing HCV from multiplying, and in most cases, cure HCV. 

The boxed warning adds the risk of HBV reactivation to the drug labels and directs health professionals to screen and monitor for HBV in all patients receiving DAA treatment.

The warning will also be included in the patient information leaflets and medication guides for the DAAs. 

In addition to FDA, the European Medicines Agency (EMA) in March began a similar investigation into DAAs, while Japan's Pharmaceuticals and Medical Devices Agency (PMDA) said in May that it is also reviewing such drugs in the country for links to a possible HBV reactivation, which could result in label changes.

FDA Drug Safety Communication: FDA warns about the risk of hepatitis B reactivating in some patients treated with direct-acting antivirals for hepatitis C