This is an exciting time to own shares of Galapagos NV (NASDAQ:GLPG), TG Therapeutics Inc. (NASDAQ:TGTX), or Mirati Therapeutics Inc. (NASDAQ:MRTX). All three of these biotechs are presenting clinical trial results that could send their stock prices soaring, or sinking, in the weeks ahead.

Galapagos NV: Did Falcon soar?

When Galapagos NV began the two-part Falcon study in April, the biotech was expecting top-line results from the first half of the cystic fibrosis (CF) trial during the third quarter. Now that we're well into October, investors are getting worried the company is dragging its feet.  

Smiling scientist in a lab.

Image source: Getty Images.

Phase one of the Falcon study enrolled just eight cystic fibrosis patients with two copies of the most common mutation in the CFTR gene. The group was treated with GLPG2451 plus GLPG2222 for two weeks before adding GLPG2737 during the last weeks of the trial. Galapagos will measure for signs the triple combo can safely help patients breathe well enough to give Vertex Pharmaceuticals (NASDAQ:VRTX) some competition.

At the moment, Vertex Pharmaceuticals markets the only CF treatments that get at the root cause of the genetic breathing disorder. Based on second-quarter sales, Vertex's CF franchise is on pace to generate $2.1 billion in sales this year. If Galapagos can show us its triple combo has what it takes to gain a share of this space, the stock could soar.

TG Therapeutics: Ublituximab for multiple sclerosis

This stock recently tanked after an interim analysis of an ongoing pivotal study with leukemia patients failed to give an overall response rate the company could use to apply for an accelerated approval. While there's still a chance that the combination of the company's two lead candidates, ublituximab and umbralisib, will show a survival benefit that will allow for a longer approval process, the combo therapy's future looks grim.

Luckily, one component of TG Therapeutics' leukemia combo is also in a pivotal study as a potential treatment for multiple sclerosis (MS). Ublituximab's 96-week pivotal Ultimate studies with MS patients began enrolling patients last summer and won't have any meaningful results for a while. On Oct. 11, though, investigators are scheduled to present final, 48-week data from a mid-stage MS study with ublituximab. 

Miniature shopping cart full of pills on a pile of money.

Image source: Getty Images.

Ublituximab treats MS in a similar manner to Ocrevus, a rising star in Roche's (OTC:RHHBY) new product lineup that earned approval last spring and is already on pace to generate more than $2 billion in annual revenue. We'll need to see head-to-head data before we make any meaningful comparisons, but ublituximab's ability to lower relapse rates so far has been impressive.

Mirati Therapeutics Inc.: Sitravatinib plus Opdivo

At this year's meeting of the European Society for Medical Oncology, Mirati Therapeutics Inc. intends to present mid-stage data for sitravatinib in combination with Opdivo from Bristol-Myers Squibb (NYSE:BMY) as a treatment for a small, genetically defined group of lung cancer patients who have already relapsed after standard chemotherapy and checkpoint inhibitors, such as Opdivo itself.

Last year, Mirati stock surged when 3 out of the first 11 patients treated with the sitravatinib-plus-Opdivo combination showed partial responses. That might not seem like much, but this is a very difficult group to treat.

The ongoing mid-stage trial is intended to enroll 209 advanced-stage lung cancer patients who didn't respond well to drugs similar to popular immunotherapies, and it's long past time for the company to share tumor response data from a larger group of patients.

Cancer patient speaking with doctor in hospital.

Image source: Getty Images.

Bristol has been known to offer large sums for rights to treatments that might boost Opdivo's market share, and Mirati owns sitravatinib outright. If it looks like Mirati's candidate can help Bristol bring more advanced-stage lung cancer patients into the fold, this stock will fly again.

They don't always soar

While incoming catalysts could send these stocks soaring, you should also consider the risks. Among the three, only Galapagos has regular product sales, and they aren't nearly enough to cover expenses. Unlike Mirati or TG Therapeutics, Galapagos also has several promising programs that make it the least risky and perhaps worth a closer look.

Adding novel new drug candidates to drugs like Opdivo has produced a lot of interesting data in early studies that just haven't panned out in the long run. If it turns out that the initial responses Mirati showed us last year were another flash in the pan, the company's $1.4 billion market cap has a long way to fall.

Bargain shoppers may have noticed that TG Therapeutics' market cap has fallen to just $437 million at recent prices. While a positive result down the line could lift the stock again, it might be best to sit this one out until the company is ready to present pivotal data.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.