What happened

Shares of Tonix Pharmaceuticals (TNXP -2.88%) were crashing 28.3% lower as of 10:24 a.m. EDT on Monday. The big decline came after Tonix announced on Friday following the market close that it is halting enrollment in a late-stage clinical study evaluating TNX-102 SL in treating fibromyalgia.

So what

Tonix made the decision to stop enrollment in its late-stage study of TNX-102 SL after the study's Independent Data Monitoring Committee (IDMC) completed an interim analysis. The IDMC recommended stopping the study after concluding that TNX-102 SL was unlikely to demonstrate a statistically significant clinical improvement for patients with fibromyalgia.

Physician's hand held up in a halting gesture.

Image source: Getty Images.

CEO Seth Lederman said that the company was "surprised and disappointed" by the interim analysis findings. That's understandable, especially considering that TNX-102 SL met the primary endpoint of a previous late-stage study that was similar in design.

TNX-102 SL is Tonix's lead pipeline candidate. In addition to being evaluated in treating fibromyalgia, the company also has hopes for the drug in treating post-traumatic stress disorder-related sleep disturbance, agitation in patients with Alzheimer's disease, and alcohol use disorder.

Now what

What's next for the biotech company? Tonix isn't throwing in the towel on TNX-102 SL in fibromyalgia yet. The company plans to move forward with its late-stage study targeting fibromyalgia with the patients who are already enrolled. Top-line results are expected in the fourth quarter of this year, after which Tonix will decide the next steps it will take with the program.