Pfizer (NYSE:PFE) finally put an end to Esperion Therapeutics' (NASDAQ:ESPR) fantastic year-long run by acquiring the biotech company for $1.3 billion in an all-cash deal. At $35 per share, that's a 54% premium to Espiron's Friday close.

Driving investor enthusiasm is ETC-216, a therapeutic protein that has been shown to actually reverse atherosclerosis -- the clogging of arteries. In early November, Esperion reported that ETC-216 reduced plaque volume by 4.2% in patients in a Phase II trial. These patients were given weekly injections of the drug over the course of only five weeks.

And the deal is a fit.

David Nierengarten noted here last month that the compound "would be a good complement to statin therapies that lower overall cholesterol levels." Among these statin therapies is Pfizer's Lipitor, which Esperion CEO Roger Newton co-discovered and developed. The idea is that patients will use ETC-216 in the event of emergency -- such as a heart attack -- and then follow up with a long-term regimen of Lipitor and toretrapib.

A Phase II study has shown that particular combination to enhance the "bad"-cholesterol-lowering effect of Lipitor while at the same time increasing "good" cholesterol.

Pfizer, which had previously acquired co-marketing rights for ETC-216 through its merger with Pharmacia, broadens its cardiovascular reach while stuffing its pipeline. In addition to ETC-216, Esperion brings a second Phase II compound in ETC-588 for carotid atherosclerosis, as well as several early-stage compounds.

The deal also caps a stunning rise in Esperion's shares, which in February hovered at just over $6.

Discuss the acquisition on the Pfizer discussion board -- only at Fool.com. Jeff Hwang can be reached at JHwang@fool.com.