(Reuters) - Amgen Inc <AMGN.O> said on Wednesday its migraine treatment met the main goal of reducing monthly migraine days in patients with episodic migraine in a second late-stage study.

Patients receiving 70 milligram of the drug, erenumab, experienced reduction of 3.2 days from baseline in monthly migraine days, while those on 140 milligram experienced reduction of 3.7 days. Those in the placebo experienced a 1.8-day reduction, the company said.

At baseline, patients were experiencing an average of 8.3 migraine days per month, Amgen said.

Amgen, which is co-developing the treatment with Swiss drugmaker Novartis AG <NOVN.S>, said patients received the injectable drug once monthly for six months.

Erenumab is also being tested for episodic migraine prevention and chronic migraine prevention.

Worldwide, about 90 percent of people diagnosed with migraine have episodic migraine, which is characterized by up to 14 migraine days a month, the company said.

Amgen's shares, which closed at $147.23 in regular trading, were up marginally after market on Wednesday.

(Reporting by Divya Grover in Bengaluru)