June 8 (Reuters) - An experimental drug for prevention of chronic migraine headaches from Amgen Inc met the main goal of a midstage study by reducing the number of monthly attacks compared with a placebo, the company said on Wednesday.
The biotech drug, erenumab, which is being co-developed with Swiss drugmaker Novartis, was tested at two doses in a 12-week, 667-patient Phase II study of subjects who were experiencing about 18 migraine days a month.
Patients who received either the 70 milligram or 140 mg doses injected once monthly experienced a 6.6-day reduction in monthly migraine days, according to initial results. That compared with a 4.2-day reduction for those who received a placebo, a difference deemed to be statistically significant.
Amgen expects to release more detailed data, including secondary goals such as reduction of at least 50 percent in monthly migraine days and change in cumulative monthly headache hours, at a later date.
The company is also expecting data later this year from a late stage study of the medicine for patients who suffer from episodic migraines. Chronic was defined as having at least 15 headache days per month over 3 months, while 4 to 14 headache days per month was considered episodic.
Between three and seven million Americans suffer from chronic migraines, which often involve nausea, vomiting and intense sensitivity to light and sound, in addition to incapacitating head pain.
"Migraine is the sixth leading cause of disability worldwide," Sean Harper, Amgen's research chief, said in a statement.
The safety of erenumab was similar to placebo, the company said. The most common side effects involved injection site pain and upper respiratory tract infections.
Under the collaboration agreement with Novartis, Amgen holds the sales rights for the United States, Canada and Japan, while Novartis would sell the drug in Europe and the rest of the world if it wins regulatory approval.
Reporting by Bill Berkrot; Editing by Andrew Hay