UPDATE 2-US FDA objects to Dendreon promotions for Provenge

* FDA letter: Company overstated benefits, minimized risks

* Dendreon shares end higher (Adds company comment, details on product; updates shares)

WASHINGTON Aug 6 (Reuters) - Dendreon Corp (DNDN.O) exaggerated the benefits of its novel prostate cancer vaccine and downplayed risks in some sales materials for the product, U.S. regulators said in a letter released on Friday.

"These promotional materials are false or misleading because they omit and minimize the risks and overstate the efficacy of Provenge," the U.S. Food and Drug Administration said in a letter to the company.

Some of Dendreon's promotions included a chart that "does not provide sufficient contextual information for the presented survival rate estimates to convey the limitations of" the company's main study, the FDA said.

The materials also left out some information about sterility testing, the agency said.

The FDA asked Dendreon to immediately stop using the promotions and any others with similar claims.

Dendreon spokeswoman Katherine Stueland said the company "has spoken with the FDA and intends to comply with the request."

The FDA approved Provenge in April for treating advanced prostate cancer.

Unlike traditional vaccines that prevent a disease, Provenge treats prostate cancer by stimulating the body's own immune system to attack malignant cells. It is produced by taking cells from a patient's tumor and incorporating them into a vaccine that is injected back into the patient.

Dendreon shares fell slightly after the FDA letter was released but recovered to close 1.5 percent higher at $39.05 on Nasdaq.

The FDA posted the letter here. (Reporting by Lisa Richwine. Editing by Robert MacMillan, Bernard Orr)