Amgen Inc. of Thousand Oaks announced Monday the expansion of its commercial collaboration with Swiss pharma company Novartis International for migraine medication erenumab.

The companies have agreed to co-market erenumab in the United States, but Amgen will retain exclusive commercialization rights in Japan. Novartis will retain rights throughout the rest of the world but also gains exclusivity in Canada as part of the new arrangement. Both companies will continue co-developing the drug with Novartis responsible for a capped amount and costs being shared thereafter.

Under terms of the deal, Amgen will receive milestone payments from Novartis, slated to begin this year. The companies will share domestic commercialization costs, but Amgen will be responsible for sales, paying a royalty to Novartis on the net amount. The Swiss company will book sales for the rest of the world, excluding Japan, and will pay Amgen on net sales in those countries.

“Combining the U.S. capabilities of Amgen and Novartis in preparation for the launch of erenumab can create meaningful value over the life of this first-in-class program by enabling us to more effectively, and perhaps even more rapidly, reach people who live with the impact of migraine on a daily basis,” Anthony Hooper, Amgen’s vice president of global commercial operations, said in a statement.

Currently, the drug is in clinical trials and an application for approval to market the drug is expected to be filed with the U.S. Food and Drug Administration during the second quarter.

Amgen (AMGN) shares closed up $2.73, or 1.7 percent, to $163.14 on the Nasdaq.