Looking for cheap biotech stocks? Shares of ACADIA Pharmaceuticals (NASDAQ:ACAD), Agenus Inc. (NASDAQ:AGEN), and Geron Corp. (NASDAQ:GERN) have all taken big hits over the past few months.

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There are reasons to suspect all three biotechs might be bargains. Let's take a closer look at each to be sure.

ACADIA Pharmaceuticals

This biotech boasts the first FDA-approved treatment of Parkinson's disease psychosis, Nuplazid. Its recent launch has been more successful than expected, and data due any day now could send it much higher.

Approximately 60,000 Americans receive a Parkinson's disease diagnosis each year, and roughly half eventually experience the debilitating hallucinations and delusions Nuplazid is now approved to treat. There's a strong chance the antipsychotic could be an effective treatment for similar symptoms associated with Alzheimer's disease.

Among about 5 million Alzheimer's disease patients in the U.S., somewhere between 25% and 50% suffer hallucinations and delusions. Given the drug's list price of $23,500 per year, an expansion to Alzheimer's could turn Nuplazid into a multibillion-dollar blockbuster.

With a market cap around $3.08 billion at recent prices, but just $5.27 billion in third-quarter sales, ACADIA is going to soar -- or plummet. We'll find out which soon, as we expect the company to announce data from its Alzheimer's study with Nuplazid any day now. If the results are good, this might be the best biotech bargain of the year.

Agenus Inc.

A wider-than-expected loss incited the market to beat down this biotech's market cap from about $630 million in early October to about $363.3 million at recent prices. While it's valued far lower than ACADIA, Agenus has a wider variety of growth drivers that suggest the stock is in bargain territory.

Its vaccine booster, QS-21 Stimulon, belongs near the top of the list. It's a component of two GlaxoSmithKline vaccine programs aimed at shingles and malaria. Shingrix is currently under FDA review and could eventually generate annual sales around $1 billion. If it's successful, Agenus is entitled to a 2% royalty on the vaccine sales.

Vaccine royalties won't drive Agenus to profitability on its own, but they could douse the flames flickering above its cash pile. After it lost $101 million during the first nine months of the year, the company's cash, cash equivalents, and short-term investments dwindled to just $95 million at the end of September.

While there will almost certainly be another equity offering in Agenus' near future, investors have plenty to look forward to. An unnamed third party is testing its Prophage cancer vaccine in combination with a checkpoint antagonist. If I had to guess, I'd say it's Keytruda from Merck & Co., because the American pharma is also testing Keytruda in a combination trial with the biotech's anti-CTLA-4 candidate. In partnership with Incyte, Agenus has two cancer-fighting antibodies in early clinical-stage development as well.

With several irons in the fire and deep-pocketed collaborators ready to write big checks as its candidates approach finish lines, Agenus looks like a bargain biotech with safety nets.

Geron Corp.

Agenus isn't the only beaten-up biotech with big partnerships. Healthcare heavyweight Johnson & Johnson handed Geron $35 million upfront to license its telomerase inhibitor imetelstat, and could deliver another $900 million in milestone payments plus a royalty percentage if it's successful.

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We'll have a better chance to gauge Geron's chances of collecting from Johnson & Johnson next year, when mid-stage clinical trials in myelofibrosis and myelodysplastic syndromes produce some more data. During a small study, Imetelstat previously drove some patients' myelofibrosis into remission, which is something Incyte's competing drug, Jakafi, can't claim. Jakafi is on pace to reach over $1 billion in sales next year, and if imetelstat repeats previous results, it could also pass the 10-figure mark.

Geron looks like a first-rate bargain, but it's not for the faint of heart. If its lead candidate flops, this biotech's pipeline would be as barren as Mother Hubbard's cupboards.

If you're willing to accept that possibility, you'll be pleased to know that J&J is a first-rate partner with a proven record in blood cancer. Adjusted for risk, Geron's recent market cap of around $329 million looks too cheap for intrepid investors to ignore.