Horizon Pharma to Pay $800M for Rare-Disease Drug Developer

Horizon Pharma will spend about $800 million to buy Raptor Pharmaceutical and expand its portfolio of rare-disease treatments, a growing area of focus for drugmakers.

The Ireland-based drug developer said Monday that the deal will strengthen its business in the United States and provide a platform to expand in Europe and other international markets.

Raptor’s portfolio includes Procysbi, which treats a rare metabolic disorder, and Quinsair, approved for managing a chronic pulmonary infection in adult patients with cystic fibrosis.

Horizon Pharma Plc. will pay $9 in cash for each share of Novato, California-based Raptor Pharmaceutical Corp. and expects to close the deal in the fourth quarter.

Drugmakers in recent years have been shifting more money to developing rare-disease treatments, as mass-market drugs lose patent protections.

New York-traded shares of Horizon Pharma rose $1.53, or 8.9 percent, to $18.79 in trading Monday afternoon. Shares of Raptor Pharmaceutical jumped $1.51, or 20.3 percent, to $8.96.