Dendreon

One of Thursday's hardest-hit stocks was Dendreon, maker of the prostate cancer vaccine Provenge, which plunged 67% after reporting disappointing results. But, weirdly, Debdreon's disease seemed to infect the entire sector, dragging down companies with proven drugs. Are biotechs bargains right now?

It's been heck of a ride on Wall Street: the ups, the downs, a 500-plus point selloff. But some stocks suffered far more than others this week. Here's a look at 10 of the biggest decliners.

Stem cell research is still too hot for most investors, but NeoStem is starting to change that, thanks to some unexpected events. Among them are the Catholic Church's surprising embrace of NeoStem's research and NeoStem's foothold in China's vast health care market.

Among the day's top stories for investors: Does your family need tech detox? Why Dendreon keeps going up? And, what do 50 Cent, Carmen Electra, and Shaq have in common?

Much like Dendreon, which has a promising prostate cancer drug, ImmunoCellular is developing a cancer drug. In this case, it battles brain cancer, and a Phase I trial turned in remarkable results. But unlike Dendreon, ImmunoCellular is still pretty much an unknown.

Dendreon's Provenge, which targets prostate cancer, catapulted that company's stock to record highs recently. Prima Biomed's CVac works similarly, but it has the potential to target multiple forms of cancer, giving the company an intriguing future.

Several biotech stocks were on the move Monday after Deutsche Bank started rating them. The bank's analyst, Robyn Karnauskas, took a generally wary view on the biotech sector, putting buy ratings only on Gilead and Dendreon.

The stock sank on Thursday after the Centers for Medicare and Medicaid Services said it was evaluating data on Provenge, the company's prostate cancer vaccine, to decide whether to cover the drug for seniors nationwide.

Prostate cancer patients face rationing and delays of Dendreon's breakthrough treatment Provenge. The drug maker says it can only produce enough of the vaccine to treat about 2% of eligible patients until manufacturing increases in mid-2011.

Dendreon is developing immunologically based drugs to fight cancer, and it's No. 1 drug is Provenge, which battles prostate cancer. The excitement is about whether Provenge finally gets the FDA's approval this year. If so, the stock could keep scoring.