UPDATE 1-Dendreon Corp expects Provenge to overtake chemo

* Sees Provenge adoption topping current chemo market

* Says drug study data boosts partnership talks

NEW YORK, Aug 17 (Reuters) - Dendreon Corp DNDN.O on Monday said it expects quick success for its Provenge prostate cancer treatment if it is approved by U.S. regulators, with initial demand for the world's first cancer vaccine exceeding supply.

The company’s Chief Financial Officer Gregory Schiffman said its New Jersey manufacturing plant was unlikely to keep pace with prescriptions for Provenge, but several other plants should be up and running and be able to fully meet its needs within several years after Provenge is launched.

Schiffman cited market estimates that perhaps 40 percent to 65 percent of patients with prostate cancer that has spread to other parts of the body now seek treatment with standard chemotherapy treatments, most notably Sanofi-Aventis' SASY.PATaxotere.

He predicted use of Provenge -- which has been shown to prolong life by about four months, compared with about a 2 1/2- month benefit seen with Taxotere in separate trials -- will eventually overtake use of standard treatments. Provenge causes few side effects, whereas Taxotere and other chemo agents cause serious ones.

“If you look at the survival benefit -- greater than chemo -- and the side effect profile, we would expect to get a greater level of adoption,” Schiffman said in an interview.

Provenge was shown to be safe and effective in a late-stage trial whose results were disclosed in April. Schiffman said the widely publicized data have increased interest among potential partners to market the product overseas.

“We are in active discussion with partners; there has been a lot of interest since the data were released because the data were exciting,” he said.

Dendreon’s shares were down about 20 cents at $22.28 on the Nasdaq in afternoon trading. (Reporting by Ransdell Pierson, editing by Maureen Bavdek)