Alexion Pharmaceuticals Inc. agreed to buy smaller biotech company Achillion Pharmaceuticals Inc. in a deal initially valued at $930 million.

The U.S. FDA gave Alexion Pharmaceuticals a thumbs-up for Soliris (eculizumab) to treat neuromyelitis optica spectrum disorder in adults that express a specific biomarker.

The U.S. FDA approved AstraZeneca Plc’s treatment for hairy cell leukemia, a slow-growing type of blood cancer.