The Center for Biologics Evaluation and Research (CBER) hit Dendreon with an untitled letter for false and misleading professional marketing materials for its prostate cancer treatment Provenge.

In a letter dated August 3, Robert Sausville of CBER’s Office of Compliance and Biologics Quality said an in-service kit and detail aid for Provenge minimize the risks and overstate the efficacy of the drug. The kit, said CBER, presented a misleading product timeline and omits or contradicts information in the Warnings and Precautions section of the PI. The detail aid, meanwhile, distorts survival rate estimates by failing to present them in context, the letter said.

CBER requested that Dendreon cease dissemination of the kit and detail aid.

Provenge won FDA approval for the treatment of advanced prostate cancer in April. The product is made from the patient’s own immune cells. Last week the company reported in second quarter results that sales of the treatment have grown from $340,000 in May to $2.4 million in June and $5.2 million in July.