Pfizer Inc. agreed to acquire Serenex Inc., a privately held biotechnology company, the latest effort by the New York-based drug giant to broaden its pipeline amid the loss of patent protection for high-revenue drugs.

The transaction is expected to close in the second quarter, and no financial terms were disclosed.

Serenex, of Durham, N.C., has an extensive compound library that targets heat shock protein 90 (Hsp90), a cancer target. Under the deal, Pfizer will acquire the rights to an oral Hsp90 inhibitor, SNX-5422, currently in Phase I trials for the potential treatment of solid tumors and hematological malignancies, Pfizer said.

In addition, Pfizer will acquire Serenex's proprietary drug discovery technology and extensive small-molecule Hsp90 inhibitor compound library.

But the challenge for Pfizer will be to broaden the Hsp90 target to include diseases outside cancer, Seamus Fernandez, an analyst with Leerwink Swann, told BioWorld Today.

Serenex's compound library could have potential uses in treating other disease such as neurodegenerative diseases, and anti-inflammatory diseases, such as Alzheimer's disease, Parkinson's disease and arthritis, Pfizer said.

Fernandez, who is taking a "wait-and-see approach" with the Serenex acquisition, said, "The proof will ultimately be whether or not a candidate emerges from the pipeline."

Pfizer's business development history with late-stage products "has been disappointing," he said, citing a deal with Vicuron Pharmaceuticals Inc., whose antibiotic dalbavacin could not gain approval without additional data. Seamus also noted the insomnia drug indiplon, which Pfizer abandoned after the FDA requested additional analyses from then-partner Neurocrine BioSciences Inc.

Pfizer has made a string of recent acquisitions, most recently Houston-based Encysive, Wellesley, Mass-based Coley Pharmaceuticals Group Inc. and CovX Pharmaceuticals Inc., of LaJolla, Calif. Those acquisitions come amid the loss of patent protection for such high-revenue items as Norvasc for high blood pressure, the antibiotic Zithromax and the antidepressant Zoloft. The anticholesterol pill Lipitor (atorvastatin), the largest-selling drug in the world, is facing threats from generic drugmakers.

Serenex Chief Financial Officer Ian Howes said his company is pleased with the acquisition by Pfizer, adding that Pfizer paid "a reasonable amount for the assets."

Serenex has raised $81 million in venture cash to date, he said. The company has 37 employees, and Howes said it is an open question whether Pfizer will keep those employees after the deal is complete.

SNX-1012, another compound in clinical development for the treatment of oral mucositis in cancer patients, is not included in the agreement.