Sometimes shares of small specialty-pharma stocks rise and fall much more than warranted on every piece of news, and this appears to have happened Thursday to Rule Breakers pick Encysive Pharmaceuticals (NASDAQ:ENCY). Don't get me wrong. I think Encysive's shares are undervalued now, based on the prospects for its lead drug, Thelin. What boosted the shares more than 6% on Thursday was that the U.S. Food and Drug Administration told Encysive it could resume trials for one of its drug candidates.

TBC3711 has been in clinical testing since 2000. In March, all clinical development of the drug was stopped after a rat that had been given a dose of it developed an unusual reaction. The worst part about stopping the testing was that Encysive had just started a phase 2 trial of the drug in patients with resistant hypertension, or high blood pressure.

It's usually good news to have more drugs go into a company's pipeline, but it's hard to get excited about TBC3711 because it has bounced around early-stage trials for six years now. If the drug was so promising (by looking at the animal studies, this doesn't appear to be so), Encysive could have pushed it forward faster or found a partner to help it advance through the trials.

Regardless, an investment in Encysive now is all about Thelin. The drug is approved to treat pulmonary arterial hypertension in the European Union and has received two approvable letters from the FDA in the U.S.

On Nov. 2, Encysive responded to the second approvable letter, and it usually only takes around 30 days for the FDA to say whether it accepts the response and when it will complete the new review -- in either one more month or five more months. The delay in the FDA's response could be for any number of reasons not related to Thelin or Encysive, so it's useless to speculate, but there should be some sort of update coming shortly.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy .