Shire PLC is buying privately-held Foresight Biotherapeutics Inc. for $300 million, gaining a developing treatment for conjunctivitis, or pinkeye.

The drug candidate, called FST-100, is in late-stage development. It fits with other Shire drug candidates in late-stage development, including the potential dry eye disease treatment lifitegrast.

Shire, based in Dublin, said that FST-100, if approved by regulators, would be the first agent to treat both viral and bacterial conjunctivitis. About 50 percent of infectious conjunctivitis cases are viral and that is highly infectious. There are 5.9 million cases of infectious conjunctivitis annually in the U.S. and about 5.4 million cases in the European Union.