By Bill Berkrot
Nov 2 (Reuters) - A combination of two oral hepatitis Ctreatments developed by Merck & Co led to high curerates in previously untreated patients, indicating the companyis a contender in the race to find new treatments for the liverdestroying virus.
The treatments tested with and without the older drugribavirin led to cure rates of 96 percent to 100 percent,according to interim data from a small midstage clinical trial.
The results appear to confirm Merck will be competitive inthe crowded race to develop interferon-free treatments forhepatitis C, assuming they are repeated in larger studies thatinclude more difficult to treat patient populations, such asthose not helped by prior therapy.
The 65-patient, 3-arm study tested MK-5172, a proteaseinhibitor, combined with MK-8742 from a highly promising newclass of drugs called NS5A inhibitors for 12 weeks of treatment.
Based on data available at the time the interim results werereleased, 55 of 56 patients who completed the therapy wereconsidered to be cured of the virus which is transmitted throughinfected blood from sources such as infected hypodermic needlesor blood transfusions.
Patients who have no detectable levels of the virus in theirblood 12 weeks after completing 12 weeks of treatment weredeemed to be cured - a measure known as SVR 12, for sustainedvirologic response.
In the arm of the study that did not include the older oralmedicine ribavirin, all 11 patients who completed therapy withMK-5172 and the higher 50 milligram dose of MK-8742 taken once aday achieved SVR 12.
All 12 patients who began that arm of the study had Genotype1b of the liver disease, which is prevalent in Europe and Japan.It is considered somewhat easier to treat than Genotype 1a, themost common form of the virus seen in the United States, whichmay require a third drug in the regimen to achieve similarlyhigh cure rates.
The other two arms - one testing 50 mg of MK-8742 and oneusing 20 mg - did include ribavirin given twice a day.
With the lower dose of the NS5A inhibitor, all 21 patientswho completed therapy were deemed cured. In the group thatreceived the higher dose in the three-drug combination, 23 of24, or 96 percent, reached SVR 12. About three quarters of thepatients in those arms were Genotype 1a.
Of the 65 patients in the study, only one had experienced arelapse of the virus, according to the data to be presented onSunday at the American Association for the Study of LiverDiseases (AASLD) meeting in Washington.
"We are encouraged by these preliminary data for thecombination of MK-5172 and MK-8742. It's a one-two punch withboth arms equally strong," said Eliav Barr, head of infectiousdiseases for Merck.
SHORTER TREATMENT DURATION
Current standard treatment regimens for hepatitis C take 24or 48 weeks and includes injected interferon, which causesmiserable flu-like symptoms that lead many patients to avoid ordiscontinue treatment.
Several companies are developing new all-oral combinationsthat in clinical trials have cut treatment duration to 12 weeksfor many patients while significantly increasing cure rates fromabout 75 percent with current drugs.
Ultimately, physicians would like to also see regimens thatdo not require ribavirin, which has its own side effect issues,including anemia and rash.
It is believed that tens of thousands of hepatitis Cpatients have delayed treatment while awaiting the new drugsexpected to start reaching the market next year.
Gilead Sciences is widely seen as being in the leadwith a safe and effective all-oral combination, withBristol-Myers-Squibb and AbbVie close behind.
Gilead last week won an approval recommendation from a U.S.Food and Drug Administration advisory panel for its highlyregarded sofosbuvir.
Some analysts believe the market for all-oral hepatitis Ctreatments could reach $20 billion as many more people gettested for the virus, given the very high cure rates, shortertreatment durations and tolerable side effects.
An estimated 170 million people worldwide are infected withhepatitis C, which if left untreated can lead to cirrhosis, needfor a transplant or liver cancer.
The Merck drugs were well tolerated with no serious adverseside effects reported. The most common side effects werefatigue, headache and nausea.
Merck plans to expand the Phase II trial to about 400additional patients, testing its drugs with and withoutribavirin, and including those also infected with the HIV virus,those with cirrhosis and patients who have failed to be cured byprior treatments. It is also looking at a regimen of only 8weeks in previously untreated patients that would includeribavirin.
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