Dendreon (NASDAQ: DNDN), which won FDA approval last week for a new treatment to stimulate the immune system to fight prostate cancer, has found a bigger new home. The company signed a letter of intent to lease a new four-story, 200,000 square foot building on Seattle’s waterfront, according to The Seattle Times. The building, developed by Martin Selig, is at 635 Elliott Avenue. Dendreon spokeswoman Katherine Stueland said the lease is for 15 years, and has two five-year extension clauses. Real estate brokers say this could be one of the biggest local real estate deals of the year, according to The Times.