(Reuters) - Amgen Inc and Novartis said late on Wednesday that episodic migraine sufferers reported fewer debilitating headaches per month after using the companies' investigational drug erenumab, compared to trial participants who got a placebo.

The companies are racing rivals including Eli Lilly, Alder Biopharmaceuticals, Allergan and Teva Pharmaceuticals to have a new, more effective migraine treatment approved by U.S. and European regulators.

Novartis anticipates filing for approval of erenumab, also known as AMG 334, next year, and will now discuss the latest data will regulators, it said.

In a second late-stage study of Amgen and Novartis's protein-blocking migraine drug, patients receiving once monthly 70 milligram doses experienced a 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 companies said in separate releases about the study, in which patients were experiencing an average of 8.3 migraine days per month.

Analysts said this latest data underscored results from earlier studies and builds on additional trials that the companies have conducted with erenumab against chronic migraine, another form of the condition.

Jefferies analyst Jeffrey Holford, in a note on Thursday, forecast $1.5 billion in peak sales for the drug, with estimates for Novartis reaping about $440 million annually from 2020.

Under the collaboration agreement, Amgen holds sales rights for the United States, Canada and Japan, while Novartis would sell the drug in Europe and the rest of the world.

Amgen said patients received the injectable drug once a month for six months.

Worldwide, about 90 percent of people diagnosed with migraine have episodic migraine characterized by up to 14 migraine days a month, the company said. Chronic migraine sufferers have at least 15 migraine days per month.

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

Novartis shares were little changed on Thursday.

(Reporting by Divya Grover in Bengaluru and John Miller in Zurich; Editing by Susan Fenton)