Seattle-based Cell Therapeutics (NASDAQ: CTIC) said today it has raised $25 million by granting preferred stock and warrants to a single institutional investor. The investor, whose name isn’t being disclosed, also obtained the right to buy more shares in the company for an additional $25 million at a future date. Cell Therapeutics, a cancer drug developer founded in 1991, has accumulated a deficit of about $1.54 billion through its history, according to its most recent quarterly report. The investor will now have about a 9.7 percent ownership stake in the company. Cell Therapeutics said it may use the new money to pay down some old debt, or acquire new technologies. Shares of Cell Therapeutics closed yesterday at about 39 cents.