Dendreon Corp. (DNDN) expects to file for marketing approval for prostate cancer treatment Provenge in mid-November and hopes to get a regulatory decision in the middle of next year.

The Seattle-based drug maker reported in April that the drug successfully prolonged patient's lives, which could make it the first immunotherapy approved for cancer. It had previously projected filing with the Food and Drug Administration by the end of the year.

Provenge uses a patients' own cells to prompt the body to fight the disease, leading many to call it a vaccine. Some observers on Wall Street expect it to eventually be a blockbuster drug.

Dendreon shares was recently down 1% to $27.88 in pre-market trading.

In applying to the FDA, Dendreon filed an amendment to its previously rejected marketing application for Provenge. A FDA advisory recommended the approval of Provenge in 2007, but the agency requested more data.

Although Dendreon's data were performed under a special protocol assessment, Dendreon still must pass a cautious FDA in bringing an entirely new type of therapy to the market, including the resolution of manufacturing questions.

Unlike making a pill, Provenge's production involves taking a patient's cells, shipping them to the company for processing, then returning them to a physician to be delivered via intravenous infusion. This entire process must be performed three times over four weeks.

-By Thomas Gryta; Dow Jones Newswires; 212-416-2169; thomas.gryta@dowjones.com