The biotech field is littered with stocks under $5 that probably won't walk away from the crash landings that made them look so cheap. You'll be glad to know that sifting through the wreckage to find hidden gems is one daunting task that you don't need to slog through.

I recently noticed a few top biotech stocks you can buy for about the same price as an iced cappuccino. Geron Corporation (NASDAQ:GERN)Rigel Pharmaceuticals Inc. (NASDAQ:RIGL), and Agenus Inc. (NASDAQ:AGEN) don't have any FDA approved products to sell today. If their respective candidates approaching the finish line get the green light, though, you won't be able to pick up their shares for less than five bucks. Here's why.

Stack of $5 bills.

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A big first for a small biotech

Geron Corporation has circled its wagons around imetelstat, the first drug candidate to show a reversal of bone marrow damage for patients with myelofibrosis, albeit in a small pilot study. This bone marrow damaging disease might be rare, but there are enough patients with unmet need to expect peak annual sales of more than $500 million if approved. This is why Johnson & Johnson licensed the drug from Geron for $35 million upfront and promised around $900 million in additional milestone payments plus royalties on any future sales.

At the recent price of about $2.04 per share, all of Geron's outstanding shares add up to a market cap of about $328 million. Biotech stocks generally trade at mid-single digit multiples of their annual sales figures. In other words, success for imetelstat could eventually drive this stock's price several times higher.

Geron still has some obstacles to overcome and needs to show that imetelstat can repeat previous results in larger studies currently underway. Recent updates to the trials underway didn't exactly bolster confidence, but it's still too early to draw conclusions.

We won't have to wait too much longer to get a better handle on Geron's future. By the end of next September, Johnson & Johnson will make a decision about whether or not to continue developing imetelstat based on results from the recently modified study. If this little biotech's partner gives the thumbs up, you probably won't be able to buy its shares for less than $5 anymore.

Person with stethoscope accepting lots of cash from another hand.

Image source: Getty Images.

Application accepted

Like Geron, Rigel Pharmaceuticals sports a tiny market cap that's below peak annual sales estimates for its lead drug candidate. The FDA recently agreed to review an application that could make Tavalisse the first available drug approved to treat between 60,000 and 150,000 Americans with immune thrombocytopenic purpura.

The debilitating immune disorder is marked by the unnecessary destruction of platelets, and Tavalise significantly improved patient platelet levels compared to a placebo in the first of two small clinical trials supporting its application. In the second of these two similar trials, one patient in the placebo group showed an improvement, which rendered the second trial a statistical failure on its own.

That failure is the reason Rigel sports an ultra-low $281 million market cap at recent prices despite expected peak sales north of $300 million each year if Talvalise earns an approval. Fortunately, combined results from both trials show 29 of 101 patients treated with the candidate showed responded, versus just one of 49 patients given a placebo. That's a statistical slam dunk.

If the FDA were truly perturbed by one responder in a placebo group, I doubt it would have accepted the application. The Agency is expected to deliver a decision by mid-April next year. If you can still buy shares of Rigel for less than $5 after that, I'll be downright surprised.

Plenty of shots on goal

Agenus Inc.'s market cap has been pushed down to around $356 million recently for reasons that just don't seem fair. Checkpoint-inhibiting cancer therapies that take the brakes off the immune system so they can fight tumors have been all the rage, until recently. In a nutshell, they seem to produce amazing results for a smaller number of patients than expected.

Agenus owns two checkpoint inhibitors in mid-stage clinical trials similar to those that already generate billions in annual sales. Even if their peak potential has been slashed, they nearly justify the biotech's current price and there's plenty more in the pipeline.

Incyte is funding development of two candidates it licensed from Agenus that inhibit different immune system checkpoints. If successful, Agenus stands to earn some big milestone payments and a 15% royalty on any potential sales.

While we're waiting for earlier-stage drugs in the pipeline to bear fruit, odds are strong that Agenus will begin earning royalties from another partner, GlaxoSmithKline. The pharma giant's shingles vaccine candidate contains a booster it licensed from Agenus, and it's widely expected to earn marketing approvals in the months ahead.

Shingrix royalties probably won't be enough to carry the company all the way to profitability, but they would give Agenus and its partners more time to develop the experimental cancer drugs emerging pipeline. That chance to take plenty of shots on goal makes this a top biotech stock that could be worth a lot more than $5 in the years ahead.

Cory Renauer owns shares of Johnson & Johnson. The Motley Fool owns shares of and recommends Johnson & Johnson. The Motley Fool has a disclosure policy.