Korea’s biosimilar company Celltrion is likely to accelerate its move to expand its share in the Japanese breast cancer market.

Celltrion said on Monday that it has won a patent suit involving Herzuma, a biosimilar product referencing Roche’s blockbuster breast cancer drug Herceptin, in Japan.

Targeting the breast cancer treatment market in Japan, Celltrion has tried to invalidate Roche’s patent since 2016. After winning the two appeals trials for invalidation of the patent, the Korean company began to seek approval for the additional indication of Herzuma.

Celltrion hoped that it could obtain the additional indication early next year and sell Herzuma to Japanese breast cancer patients.

“Japan has been regarded as a conservative market for pharmaceuticals, but the government recently announced biosimilar-friendly policies. We will do our best to help Herzuma arrive in the Japanese market as early as possible,” an official at Celltrion said.

Herzuma is an anticancer, antibody biosimilar for the treatment of breast cancer and gastric cancer. Roche’s Herceptin, the original drug, was developed by Genentech.

Herceptin sells about 400 billion won ($357.7 million) a year in Japan, industry watchers estimate.

Japan’s Ministry of Health, Labor and Welfare gave the nod for Herzuma’s indication for gastric cancer in March. Celltrion Healthcare began selling the biosimilar through a local distributor, Nippon Kayaku in August.