Published: Nov 18, 2013
By Michael Smith, North American Correspondent, MedPage Today
A four-drug oral regimen for hepatitis C (HCV) achieved near-perfect cure rates in a large clinical trial, according to the company developing the drugs.
First results from the phase III SAPPHIRE-1 study show that 96% of treated patients had undetectable virus 12 weeks after the end of therapy, according to a release from AbbVie, of North Chicago, Ill.
That endpoint -- a virologic response sustained for 12 weeks after stopping treatment , or SVR12 -- is regarded as a cure, since few patients relapse after that point.
While the company released some details, results of the 631-patient study have not yet been presented at scientific meetings or in peer-reviewed journals.
The SAPPHIRE-1 study is one of six phase III trials evaluating three so-called direct-acting agents being developed by AbbVie -- ABT-333, a non-nucleoside polymerase inhibitor; ABT-450/r, an HCV NS3/4A protease inhibitor boosted with the protease inhibitor ritonavir (Norvir); and ABT-267, which blocks the viral nonstructural protein NS5A.
The latter two drugs were given in a fixed-dose combination.
All patients in the treatment arm were also given ribavirin, an oral medication that, withpegylated interferon, forms the backbone of standard therapy. But interferon, which is given by injection and has severe side effects, was not used, the company said.
The goal of much recent investigation has been to develop all-oral regimens that do not include either ribavirin or interferon, and several of the other phase III trials directed by AbbVie are testing only the company's three direct-acting agents.
Study participants had genotype 1 HCV, the most prevalent form of the virus, and no evidence of liver cirrhosis; 473 patients were randomly assigned to the treatment arm for 12 weeks and the remaining 158 got placebos.
After the initial 12-week period, placebo patients were switched to open-label treatment with the four drugs for another 12 weeks. The company did not report outcomes for that treatment period.
Among the 473 patients in the treatment arm, 455 reached an SVR12 in an intent-to-treat analysis where patients with missing data were considered failures.
There was a slight difference in outcomes based on genotype 1 subtype, the company release said: 148 of the 151 patients with genotype 1b achieved SVR12 compared with 307 of the 322 with genotype 1a, or 98% versus 95%.
The company said the most commonly reported adverse events were fatigue, headache, and nausea; the proportion of patients stopping the trial because of adverse events was 0.6% in each arm.
Among patients in the active arm, the combined rate of virologic relapse (after treatment and before 12 weeks) or breakthrough (during therapy) was 1.7%.