Updated from 2:08 p.m. EDT

Geron ( GERN) was the best health care performer of Thursday's sluggish session, following positive news out of a recently study.

Shares jumped 15.1% after Geron said that its scientists have seen progress in using embryonic stem cells as an effective treatment for type 1 diabetes. Recently, Geron closed up $1.24o $9.48

Despite the advance in its stock, Geron was unable to support the Nasdaq Biotechnology Index, which slumped 0.7. Among its other components, Genzyme ( GENZ) lost 3.2% and Amgen ( AMGN) shed 1.2%.

Angiotech Pharmaceuticals ( ANPI) was up 5.2% after a regulatory approval for a wound closure product. The company's Quill SRS received European approval and is expected to launch there at midyear. Recently, Angio closed up 34 cents at $6.89.

Onyx Pharmaceuticals ( ONXX) was another winner, courtesy of an upgrade from Friedman Billings. The firm raised its rating for Onyx to market perform from underperform, while nearly doubling its stock price target to $30 from $17.

An analyst with Friedman said it will take years for Pfizer ( PFE) to come up with a drug that can compete with Onyx's a liver cancer treatment, Nexavar. Recently, Onyx added 57 cents, or 1.8%, to $31.87. Pfizer was down by 4 cents earlier in the day but closed up 4 cents at $27.36.

Also among winners, Avanir Pharmaceutical ( AVNR) was higher by 21.8%, Dendreon ( DNDN) climbed 6.5%, and CV Therapeutics ( CVTX) was up 6.2%.

On the losing side, medical device makers were having a rough session. Among individual names, Boston Scientific ( BSX) fell 2.3%, Medtronic ( MDT) slumped 1.6%, and St. Jude Medical ( STJ) was off 1.2%.

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