sank 2% after the company released results from an interim safety analysis of its hepatitis C drug telaprevir.
Of patients who received the drug in clinical trials, 9% discontinued treatment due to side effects such as rash, gastrointestinal disorders and anemia, and 3% stopped treatment due to side effects that were considered serious. After 12 weeks, 65 out of 74 patients had undetectable levels of the virus, Vertex says.
"Evaluation of telaprevir's safety and antiviral activity in multiple large clinical trials is Vertex's top clinical priority in the year ahead," said Dr. Joshua Boger, the company's president and CEO. "This interim analysis ... is an important step forward in the telaprevir clinical development program, as it strongly supports the initiation and conduct of large clinical trials designed to evaluate the safety and antiviral activity of telaprevir."
Based on the results reported Wednesday, Vertex earned a $15 million milestone payment from its partner,
Johnson & Johnson
unit Janssen Pharmaceutica.
Vertex shares fell 75 cents to $38.65 in heavy trading.