Biotechnology firm Cell Genesys Inc. (Nasdaq: CEGE) shares rose sharply Tuesday, after the company said its prostate cancer drug therapy showed better-than-expected results in a clinical trial.

The San Francisco-based company's stock rose $1.39, or 32.3 percent, to $5.70 in afternoon trading on the Nasdaq Stock Market.

Results from a Phase II clinical trial of the GVAX therapy showed that patients with advanced prostate cancer had a median survival rate of 35 months, compared to a predicted 22 months survival rate.

In a previous Phase II trial, the median survival rate had been 26.2 months.

The firm said that the survival results from both independent studies compare favorably with the current standard care for such patients, who are treated with Taxotere, or docetaxel, chemotherapy plus prednisone medication.

The GVAX immunotherapy is currently being tested alone and in combination with docetaxel chemotherapy in two Phase III clinical trials.

Cell Genesys is currently focused on developing commercial biological therapies for patients with cancer.

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