Seattle-based biotechnology company Dendreon Corp. will lay off 70 workers at its newly opened Seal Beach plant, according to a regulatory filing.

The job cuts will take effect Nov. 6, according to Dendreon’s filing with the state Employment Development Department.

Dendreon, maker of the Provenge prostate cancer treatment, had previously said it would cut 500 jobs, or 25% of its companywide workforce, as part of a restructuring. The company announced the restructuring in early August, after reporting disappointing sales of Provenge.

The majority of the job cuts are at Dendreon’s plants in Seal Beach, Atlanta and New Jersey. A report in the Atlanta Business Chronicle said that 117 jobs would be cut at the company's plant in suburban Union City, Ga.

Dendreon has never given a precise number of employees at its plant here. In earlier interviews, executives indicated that the Seal Beach plant would account for a "few hundred" jobs.

The drug maker opened its Seal Beach plant earlier this summer in the Pacific Gateway Business Park near the Garden Grove (22) Freeway.