When a stock's share price is lower than a North Dakota thermometer in February, investors tend to give it the cold shoulder. But as fortunes change and the market warms to a stock's prospects, its price can heat up in a hurry. Unfortunately, it's hard to tell that a stock is melting investors' hearts until after it's made that upward leap.

Taking the market's temperature
But Motley Fool CAPS' proprietary ratings, aggregated from the opinions of 180,000-plus members, offer a great way to monitor investor sentiment. Following a CAPS rating trend, we can find previously low-rated companies that have recently enjoyed a bump in investor confidence and see whether they're truly heating up -- or headed back to the deep freeze.

Obviously, such stocks are not ones you automatically buy. Rather, they're just a starting point for further research. Yet if some of the best investing minds are taking notice of these stocks, maybe we should, too.

Caution: Contents may be hot
Biotechs like Anthera Pharmaceuticals (Nasdaq: ANTH) are poised on a trip wire set to go off on any news about the drugs in their pipeline. Positive clinical trials can send them aloft; negative ones can shred them to pieces.

Anthera was shepherding its acute coronary syndrome therapy varespladib through clinical trials with hopes it would be able to take a part of the estimated $8 billion opportunity the condition represented. Less than a year earlier, AstraZeneca (NYSE: AZN) got its ACS treatment Brilinta approved and generated $11 million in U.S. sales and $21 million worldwide on its way to an estimated $1 billion by 2016. But an independent review board in March determined varespladib was likely no more effective than a placebo, and Anthera shelved further study.

Boom. Its stock was shredded, losing 45% of its value in one day, and it continued dropping afterwards until it lost more than three quarters of its value in total.

Lately, though, Anthera has been on the move, as there's promise it can try for the brass ring again with a treatment for lupus. Last year, Human Genome Sciences (Nasdaq: HGSI) won the distinction of being the first company in 50 years to have a drug for treating the disease approved by the FDA, but with a lot of caveats attached to Benlysta, sales of the drug have been slower than originally hoped.

Anthera's in mid-stage studies right now on Blisibimod, and while several analysts have suddenly taken an interest in the stock, it's obviously a risky bet. First, Anthera is an all-in bet on Blisibimod, and as HGS's results have shown, success at the FDA level doesn't necessarily mean success in the market. Moreover, much larger, better-financed rivals like Eli Lilly (NYSE: LLY) have dogs in the race that are in late-stage development. Anthera still has a long way to go, and as varespladib highlighted, even advancing to the next round is no guarantee it will work out.

Yet the CAPS community is coming around to the Anthera story, and though it still flies under the radar of most investors, 91% of those on CAPS think it can beat the market averages, and all but one of the baker's dozen of All-Stars rating it agree. Tell me on the Anthera Pharmaceuticals CAPS page or in the comments box below your views on whether it can withstand the FDA gauntlet, and then add the stock to your Watchlist to be alerted to events as they occur.

The next big thing
The situation's not much different over at Pozen (Nasdaq: POZN), where the FDA says it disagreed with the pharmaceutical's assessment that its drug PA32540 was a bioequivalent to a type of enteric-coated aspirin and wants it to run an in vivo bioequivalence study for the combination product. Pozen lost 16% of its value on the news. The less dramatic market reaction to the news than what Anthera investors witnessed can be attributed to Pozen's having a drug on the market for which it generates revenues. But it's still a one-trick pony at the moment, receiving royalties from AstraZeneca for Vimovo, an arthritis and gastric ulcer treatment.

Pozen has proved itself capable of successfully developing drugs, though they may not have been commercial blockbusters, as its anti-inflammatory treatment Treximet, developed in collaboration with GlaxoSmithKline, shows. PA32540 was to be the next in line of marketable drugs.

It was studying the aspirin drug against one already on the market that Pozen believes is a bioequivalent. The FDA wants it to test the drug against a different aspirin component, and the pharma will be meeting with the regulatory agency next month to discuss the decision. If the FDA stands firm, it could cost Pozen $1 million to run new tests, but the drug developer thinks it will prevail and prove its case. That could be what CAPS members are buying into here, and while arguably not nearly as risky as Anthera, it still presents a level of doubt to be considered.

Pozen generated just $1.3 million in Vimovo royalty revenue from AstraZeneca in the first quarter, up from $400,000 a year ago, but back then it also enjoyed $4.1 million in revenues from Treximet royalties. Pozen really could use approval of the wholly owned PA32540.

CAPS member zzlangerhans doesn't buy the happy talk behind Pozen's PR machine, noting that Vimovo and Treximet "proved to be predictable failures, and I don't see any reason why PA32540 won't follow the same path." Our CAPS biotech guru is looking for the stock to continue dropping.

Weigh in yourself on the Pozen CAPS page, and then add its stock to the Fool's personalized -- and free -- stock-tracking service, where you can be alerted to what happens at the July FDA meeting.

Checking the mercury
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