What goes up must come down. But what about the other way around?

That could be the case for three beaten-down biotech stocks: Celldex Therapeutics (CLDX 6.88%), Geron (GERN -1.28%), and Vertex Pharmaceuticals (VRTX -1.13%). Here's why buying these biotech stocks could pay off big in 2017.

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Celldex: Potential catalysts with glemba

Celldex Therapeutics was once a high-flying stock. But that was before the company's lead candidate, Rintega, flopped in a late-stage study for treating a type of brain tumor. Over the past 12 months, Celldex's shares have plunged close to 70%. 

I suspect there's a decent chance, though, that Celldex could rebound in 2017. The biotech should announce results from a phase 2 clinical study of glembatumumab vedotin ("glemba" for short) in treating uveal melanoma early this year. More importantly, a pivotal study of glemba in treating triple-negative breast cancer is scheduled to wrap up in December.

Those aren't the only potential catalysts for Celldex in 2017, though. A phase 2 clinical trial featuring glemba in combination with another of the biotech's pipeline candidates, varlilumab, in treating advanced melanoma should complete in November.

I wouldn't be surprised if the biotech's stock climbs throughout 2017 assuming Celldex reports positive results early this year from the uveal melanoma study. Good news from this study would likely renew investor interest in Celldex and heighten expectations for the later clinical trials.

Geron: A big partner and a big opportunity

Geron didn't tank quite as much as Celldex, but shares of the clinical-stage biotech still fell 40% over the past 12 months. In September, Geron announced that its partner, Johnson & Johnson, was discontinuing investigation of a lower-dosage of telomerase inhibitor imetelstat in treating myelofibrosis.

Although that announcement was disappointing, Geron could still have a big opportunity with imetelstat. There were enough "encouraging trends" with the higher-dose arm in the phase 2 study to keep going. In addition, an interim review of another clinical study of imetelstat in treating myelodysplastic syndromes (MDS) gave a green light for the study to continue with no changes.

Geron hopes to receive better news from the myelobrosis study this summer. If the results are positive, it will bode well for imetelstat's prospects in the nearly wide-open myelofibrosis market. There is only one drug currently approved for the indication -- Incyte's Jakafi. 

Vertex: Looking to win the expectations game

Vertex Pharmaceuticals was the smallest loser of these three biotech stocks. The company's shares dropped around 15% over the last 12 months. Vertex's woes stemmed from three factors: failing to meet Wall Street earnings expectations, a negative FDA approval decision, and a canceled late-stage clinical study.

There's definitely an opportunity for Vertex to regain investors' confidence in 2017. The company hopes to make significant progress in finalizing reimbursement for cystic fibrosis (CF) drug Orkambi in European countries. That's not an easy task, though, since deals must be negotiated separately with each nation.

Vertex could also get a boost from its pipeline candidate tezacaftor. Results from several late-stage studies of the drug in combination with Kalydeco in treating CF are expected in the first half of this year. If all goes well, Vertex should submit the combo for regulatory approval in the U.S. in the second half of 2017.

Most likely to rebound

Of these three beaten-down biotech stocks, I'd say that Vertex has the highest chances of rebounding. It should just be a matter of time before European countries agree to reimburse Orkambi. Finalizing those arrangements appears to be the company's main hurdle to jump right now.

On the other hand, I suspect that Geron might be the biggest winner in 2017 among these three stocks. It all depends on the myelofibrosis study results for imetelstat. If those results are positive, Geron's shares will undoubtedly skyrocket.