Drugmaker Bristol-Myers Squibb Co. is suspending a midstage study of a potential hepatitis C treatment after at least one patient suffered heart failure.
The New York company hasn't determined the cause or whether it is tied to the potential treatment, so it is examining all patients who took the drug.
"We are working in close collaboration with clinical trial investigators and health authorities to ensure the appropriate steps are being taken to protect patient safety," spokeswoman Sonia Choi said Thursday in an email to The Associated Press.
Shares of Bristol-Myers plunged 7.6 percent, or $2.70, to $32.90 in midday trading Thursday.
The drugmaker is an important maker of medicines for viruses, including Baraclude for hepatitis B and several HIV drugs. It is searching for fresh sources of revenue because its top-selling product, the blood thinner Plavix, now faces competition in the United States from cheaper generic drugs. Plavix sales plummeted 60 percent to $741 million in the second quarter after several generic rivals debuted in May.
As part of that plan, Bristol-Myers is pushing to become a player in the hepatitis C drug market, which is expected to grow as baby boomers get older.
The drug, labeled BMS-986094, is one of two main potential hepatitis C treatments from Bristol-Myers that investors are focused on, Bernstein analyst Dr. Tim Anderson said in a research note. The other is a compound labeled daclatasvir that has started late-stage testing, the last step before drugmakers submit a product to regulators for approval.
