Editor's note: This story, which originally was published March 25, 2009, has been updated with details of Cell Therapeutics' prior ownership of Zevalin.On the morning of Sept. 11, 2001, as hijacked planes slammed into the World Trade Center and Pentagon, an advisory committee to the Food and Drug Administration was simultaneously recommending the approval of a new cancer drug. That drug, Zevalin, is still struggling to find its way more than seven years later. Last week, Spectrum Pharmaceuticals ( SPPI) became the latest drug company to take ownership of Zevalin, and now it will try to make the drug a commercial success. Zevalin is a very effective drug for patients with non-Hodgkin's lymphoma, based on a substantial amount of clinical data collected both before the drug's approval and in subsequent clinical trials. Analysts expected Zevalin sales to exceed $200 million three or four years after the drug's launch in 2002. But good clinical data never translated into meaningful sales. Zevalin has been a commercial bust, to put it mildly. Last year, sales barely topped $11 million, down from sales of $17 million and $18 million in 2007 and 2006, respectively. Three different companies have tried to make Zevalin into a meaningful commercial product, and none has succeeded. Enter Spectrum Pharmaceuticals, the fourth and latest company to take ownership of Zevalin and attempt to turn the drug's fortunes around. With a stock price hovering around $1.50, a $48 million market cap and adequate cash reserves, Spectrum is a cheap drug stock with the potential for significant upside if Zevalin succeeds. Zevalin is a monoclonal antibody that seeks out and attaches itself to cancer cells. But unlike other such drugs, Zevalin carries a radioactive payload designed to kill the cancer cells while leaving neighboring healthy cells intact. Zevalin was the first in a new class of "radio-immunotherapies" approved by the FDA. Since its approval, only one other radio-immunotherapy drug has made it to the market.