Seattle-based Dendreon Corp. will keep its Seal Beach plant open as part of a manufacturing shakeup.

Dendreon makes Provenge, a treatment for advanced prostate cancer. The company said it was closing a plant in Morris Plains, N.J., and restructuring its administrative department.

The drug maker will cut 600 jobs over the next 12 months as the result of closing the New Jersey plant and other moves. It said that it expects to cut costs by $150 million a year as a result of the change.

Dendreon opened its Seal Beach plant last year. It is located in the Pacific Gateway Business Center near the Garden Grove (22) Freeway. The company opened its Seal Beach operation in 2011 with several hundred employees. It cut about 70 within a few months.

The company has struggled for the past year. Its shares are down nearly 80% over the period, a drop that started after officials acknowledged that acceptance of Provenge, which costs $93,000 a treatment, would be a more gradual process than first believed.