Cell Therapeutics ( CTIC) has one approved cancer drug on the market with decent, albeit not huge, sales; two other experimental cancer drugs are involved in late-stage, pivotal clinical studies. What's a portfolio like this worth to Wall Street? Biotech investors have certainly awarded other, similarly positioned companies market valuations of around $1 billion. Onyx Pharmaceuticals ( ONXX), which has just a single cancer drug in phase III studies, sports a market cap of $1.3 billion. Telik ( TELK) has a bit more going on in its drug pipeline, although investors are only really focused on a single product in phase III studies. Market value: $945 million. So, what gives with Cell Therapeutics? The Seattle biotech firm tallies a paltry market value of just $296 million. The stock closed Wednesday down 61 cents, or 9%, to $5.89 -- a new 52-week low. At that price, Cell Therapeutics is off 38% year to date and 50% in the past 12 months -- that's a wide underperformance relative to its biotech peers any way you slice it. Let's just say that investors, when it comes to Cell Therapeutics, are in a serious "show-me" mood. You can lay part of the blame on a listless market that's not whetting anyone's appetite for added biotech risk. However, Cell Therapeutics has a history of overpromising and underperforming. Investors are likely to wait for documented good news from this company -- and not just happy talk from executives and analysts -- before they hop back on the investing wagon. On Wednesday, the company announced plans to sell 8 million shares in a follow-on offering, a move that will further dilute current shareholders and is not likely to boost the company's stock price anytime soon. Cell Therapeutics executives could not be reached for comment. The showpiece of Cell Therapeutics' cancer drug pipeline is Xyotax, a reformulation of the blockbuster chemotherapy agent paclitaxel, sold for years by Bristol-Myers Squibb ( BMY) as Taxol before it went generic.