Pfizer(PFE) - Get Report is buying Anacor Pharmaceuticals (ANAC) for $5.2 billion to strengthen its inflammation and immunology business, the companies said Monday.

The all-cash deal values Anacor at $99.25 per share, or a 55% premium to the stock's closing price of $63.04 on Friday.

Pfizer is buying Anacor primarily to gain access to crisaborole, an anti-inflammatory drug currently under U.S. Food and Drug Administration review for the treatment of mild-to-moderate atopic dermatitis, commonly referred to as eczema.

"We believe the acquisition of Anacor represents an attractive opportunity to address a significant unmet medical need for a large patient population with mild-to-moderate atopic dermatitis, which currently has few safe topical treatments available," said Albert Bourla, Group President of Pfizer's Global Innovative Pharma and Global Vaccines, Oncology and Consumer Healthcare Businesses. "Crisaborole is a differentiated asset with compelling clinical data that, if approved, has the potential to be an important first-line treatment option for these patients and the physicians who treat them."

Pfizer believes peak sales of crisaborole could reach $2 billion per year. The FDA is expected to make an approval decision on the drug by Jan. 7, 2017. 

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