NEW YORK (AP) -- Idenix Pharmaceuticals Inc. said Monday that it is ending development of two hepatitis C drugs after regulators told the biopharmaceutical company the drugs would remain on clinical hold.
Shares of the Cambridge, Mass.-based company fell in after-hours trading.
The two Idenix drugs, IDX184 and IDX19368, as well as another drug from Bristol-Myers Squibb Co. called BMS-986094, work in similar ways. All three products are nucleotide inhibitors, meaning they are designed to prevent the hepatitis C virus from making copies of itself.
In August Bristol-Myers halted testing of BMS-986094 after one patient in the clinical trial died of heart failure following treatment. The drugmaker eventually abandoned development of the product.
Idenix has said there are important differences between the drugs, but the Food and Drug Administration placed IDX184 on clinical hold Aug. 16. At the time, it was Idenix's most advanced experimental drug. The FDA also had placed a hold on IDX19368, which hadn't begun patient dosing.
The company submitted cardiac safety data on IDX184 to the FDA in December, but said Monday it received word from the FDA this month that the programs for both IDX184 and IDX19368 would remain on hold.
Shares of the company slipped nearly 6 percent to $4.45 in after-hours trading, after giving up 13 cents, or 2.7 percent, to close at $4.73, during the regular session. The stock is down 42 percent in the past six months.
"Although we are choosing not to continue our IDX184 and IDX19368 programs, we intend to maintain our strong presence in developing nucleotide polymerase inhibitors for HCV (hepatitis C virus) based on our broad discovery platform," said Ron Renaud, Idenix's president and chief executive.
Hepatitis C is a virus that can lead to life-threatening liver damage and is the main cause of liver transplants in the U.S. The disease is spread through the blood, which can happen through sharing intravenous drug needles or having sex with an infected person. There are around 3 million Americans with the disease, which can go undetected for many years until the liver is severely damaged. More people are expected to be diagnosed as the baby boomer generation ages.
That group account for about two-thirds of the 3.2 million Americans thought to be infected.