SILVER SPRING, MD. – A Food and Drug Administration advisory panel unanimously supported the approval of the antiviral drug simeprevir as a treatment for chronic hepatitis C.
The approval was based on the highly favorable benefit-risk profile of the drug in studies that included sustained viral response rates of 79%-80% in phase III studies of patients with chronic HCV.
At a meeting on October 24, the FDA’s Antiviral Drugs Advisory Committee voted 19-0 that simeprevir, a hepatitis C virus (HCV) protease inhibitor, in combination with pegylated interferon and ribavirin (PR), be approved for the treatment of chronic hepatitis C genotype 1 (GT1) infection in adults with compensated liver disease, including cirrhosis, who are treatment-naive or have failed previous interferon-based therapy. The dosing proposed by the manufacturer, Janssen Pharmaceutical Co., is a 150-mg capsule once a day for 12 weeks, combined with PR for 24 weeks, in patients who have never been treated for HCV and for those who have relapsed on treatment. For patients who have not responded to previous treatments, PR is continued for 48 weeks.
The panel agreed that the risk-benefit profile was favorable, and with the once-daily dose, simeprevir was much easier to take than the first-generation protease inhibitors currently approved for treating chronic HCV, telaprevir and boceprevir, which are the current standard of care and require a total of 6-12 pills a day, taken at three times a day. Simeprevir inhibits HCV NS3/4A serine protease, which is "essential for viral replication," according to Janssen.
"We clearly need better drugs, and evidence is strong that this is a better drug," said panelist Dr. Curt Hagedorn, chief of the medicine service, Central Arkansas Veterans Healthcare Services, Little Rock.
"As someone who treats patients with chronic hepatitis C every day, this regimen represents a much simpler one and much safer" than currently available treatments, added panelist Dr. Marc Ghany, staff physician in the liver disease branch of the National Institute of Diabetes, Digestive and Kidney Diseases.
Panelists, however, urged Janssen to study more black patients in postmarketing trials, since black patients were greatly underrepresented in the studies but make up a large proportion of those infected with HCV in the United States. Postmarketing studies should also evaluate the drug in Hispanics, those coinfected with HIV, pediatric patients, patients with renal failure, and more patients with cirrhosis, they added.
The main safety issue discussed was the higher rates of rashes and photosensitivity reactions associated with treatment, which the FDA has proposed be included in the warnings and precautions section of the drug’s prescribing information, including a recommendation for patients to use sun protection measures while taking the drug. The panel agreed with the FDA and the manufacturer that before starting treatment, patients with HCV genotype 1a infections should be screened for the "Q80K" viral polymorphism – which is common in the United States and was associated with lower efficacy rates in the studies.
If approved, simeprevir will be the third HCV protease inhibitor approved in the United States for treating hepatitis C. In May 2011, boceprevir (Victrelis) and telaprevir (Incivek), which are also HCV NS3/4A protease inhibitors, were approved. In addition to the number of daily pills required, adverse events associated with these drugs include anemia and rash.
In three phase III studies of almost 1,200 patients most of whom were white, with chronic HCV genotype 1 infections, who had not been treated previously or had relapsed on previous treatment, simeprevir, 150 mg once a day for 12 weeks, combined with PR, followed by PR alone for 12 or 36 weeks (depending on the patient’s response), was compared with PR alone for 48 weeks (which included a placebo for the first 12 weeks). The primary efficacy endpoint was the sustained virologic response at 12 weeks (SVR 12), defined as HCV RNA that was undetectable or was detected at a level below 25 IU/mL 12 weeks after treatment was planned to end. (In the different arms of the studies, 40%-57% of the patients had HCV genotype/subtype 1a, and 43%-59% had 1b.)
In the two studies of 785 treatment-naive patients, 80% of those treated with simeprevir achieved an SVR12, compared with 50% of controls. The "on-treatment failure" rates (those who had detectable HCV RNA at the end of treatment) were 8% of those treated with simeprevir, compared with 33% of controls. The rates of viral relapse were 12% among those on simeprevir, compared with 22% of those on placebo.
In the third study of 393 relapsers, the SVR12 rate was 79% among those on simeprevir, compared with 36% among those on PR alone. Among those on simeprevir, 3% were on-treatment failures and 19% had a viral relapse, compared with 29% and 48%, respectively, of those on placebo.