If you're looking for a shot at doubling an investment, you'll want to take a look at the biotech industry. Biotech companies have been some of the best-performing stocks over the last couple of years thanks to the powerful confluence of numerous top-selling drugs losing patent protection, major changes in the regulatory process, the advent of game-changing drug development platforms, and rapidly aging populations in many Western nations with widespread access to medical care.

Source: Flickr via user Myfuture.com.

In fact, the list of the top five best-performing stocks in the broader market over the last 12 months is occupied exclusively by developmental-stage biopharmas, as illustrated by the chart below:

ESPR Chart

Although these are impressive gains by any standard, investors should always keep in mind the significant risks posed by these volatile stocks. One setback on the clinical or regulatory front, for instance, can cause share prices to nosedive at breakneck speed.

That's why I tend to favor clinical-stage biopharmas that have been de-risked, at least to some degree. With this in mind, I think Acadia Pharmaceuticals (NASDAQ:ACAD), Agenus (NASDAQ:AGEN), and Dynavax Technologies Corp. (NASDAQ:DVAX) are three developmental biotechs that could double their share price before the end of the year and offer investors some assurance that they won't utterly collapse overnight. 

Acadia is inching closer to regulatory approval for Nuplazid
Although Acadia is taking the slow train when it comes to filing a regulatory application for its experimental Parkinson's disease psychosis drug Nuplazid (pimavanserin), this pivotal event is expected sometime in the second half of this year. The holdup apparently stems from the company's inexperience at manufacturing drugs on a commercial scale. But Acadia believes these problems will be sorted out soon, facilitated, in part, by a recent change in management

Nuplazid's peak sales for this first indication are projected in the range of $3 billion. Given the company's current $3.42 billion market cap, the market would only need to assign a valuation of a little over two times peak sales for this stock to double. 

But I think Acadia could actually do far more than simply double. With a midstage Alzheimer's disease psychosis trial under way and Big Pharma paying massive premiums for novel drugs these days, I wouldn't be surprised if Acadia fetches a mind-boggling tender offer in the range of $8 billion to $10 billion. 

Agenus is riding the immuno-oncology wave
Immunotherapies are widely believed to be game changers in the treatment of cancer, with some Big Pharmas even predicting they could largely displace chemotherapies as the standard of care for many forms of the disease. As such, immunotherapies are projected to rake in over $35 billion in sales by as early as 2020. 

In February 2014, Agenus acquired 4-Antibody to redouble its efforts to become a leader in this rapidly growing field. As a direct result of that move, this tiny biotech quickly inked lucrative research agreements with both Incyte Corp. and Merck & Co. 

The juicy part of Agenus' story, though, centers around developments happening outside of the company. Over the last 12 months, Big Pharmas far and wide have been snatching up numerous small-cap companies working on immunotherapies. And the pace of these acquisitions has only increased since the start of this year.

With a broad-based immuno-oncology platform in hand, I think Agenus must be considered a strong buyout target. Nonetheless, the market has yet to catch on to the company's eye-popping potential, evinced by its sub-$400 million market cap. If all goes well for Agenus, that valuation won't last for long.

Dynavax's hepatitis B vaccine candidate has cleared its first major hurdles
A couple years back, Dynavax's market cap was closing in on $900 million. But after the Food and Drug Administration requested another late-stage trial to assess the safety profile of its lead product candidate, hepatitis B vaccine Heplisav-B, its shares and market cap plummeted:

DVAX Market Cap Chart

Following a second positive safety review by an independent monitoring committee for the vaccine's latest pivotal trial in March, though, shares have come roaring back, as shown by the chart above. 

All patients in this late-stage trial have now received two doses of the vaccine without reporting any serious adverse events that would halt or necessitate a change in design of the study. Moreover, this second vaccination was the last active dose patients will receive in this trial prior to its anticipated conclusion in October. So, although a third safety review will occur prior to the end of the trial, the likelihood of Heplisav-B being derailed by a safety concern now appears remote. 

Given that Heplisav-B is projected to generate somewhere around $700 million in peak sales, the company's current market cap of $653 million clearly doesn't reflect the vaccine's commercial potential. 

My expectation is that shares will shoot higher once the final safety review has been completed -- assuming no unexpected surprises -- setting this stock up for a potential double before year's end.

Are any of these stocks buys right now?
I personally like all three stocks, but Agenus is clearly the riskiest of the lot. Acadia's only major issues appear to be logistical, given that Nuplazid's late-stage trial results were overwhelmingly positive. And Dynavax's hep B vaccine probably would have run into safety problems by now if a major event was going to occur, as it's rare for patients to have a serious adverse reaction to a vaccination months after the fact.

Agenus, on the other hand, has yet to validate its immuno-oncology platform, which is likely the reason for its comparatively low market cap relative to its peers. That's why I think Acadia and Dynavax are great speculative buys right now, while Agenus might be better viewed as a watchlist candidate for the time being.