(Reuters) -Japan’s Astellas Pharma said on Monday it agreed to buy U.S. drugmaker Iveric Bio Inc for about $5.9 billion in its biggest acquisition, giving it access to a range of ophthalmology treatments.

Through Berry Merger Sub Inc, a wholly-owned subsidiary of Astellas U.S. Holding, the Japanese company agreed to acquire Iveric for $40 per share in cash, Astellas said in a release.

The price is a 22% premium to Iveric’s $32.89 closing price on April 28.

New Jersey-based Iveric, formerly branded as Ophthotech, is focused on developing treatments for retinal diseases. The company’s key asset is ACP, currently in trials for treating geographic atrophy, the advanced stage of macular degeneration, a common cause of vision loss in the elderly.

ACP targets the C5 protein that is suspected in causing the growth of scarring associated with geographic atrophy.

The U.S. Food and Drug Administration in February granted priority review of ACP, and if approved, the treatment could be commercialised by the end of this year.

Astellas has been aggressively chasing cross-border acquisitions for new treatments in recent years, announcing deals in late 2019 to buy U.S. biotech Xyphos Biosciences for up to $665 million and Audentes Therapeutics Inc for about $3 billion.

Prior to that, its biggest ever acquisition was its $3.8 billion purchase of OSI Pharmaceuticals Inc in 2010.

Astellas shares gained 1.9% in Tokyo trading, outperforming a 0.7% advance in the benchmark Nikkei gauge.

(Reporting by Baranjot Kaur in Bengaluru, Rocky Swift in Tokyo; Editing by Kim Coghill and Sonali Paul)