Evanston, IL-based biopharma company Aptinyx Inc. (APTX) - Get Report is tanking Wednesday after the phase 2 trial for the company's diabetic peripheral neuropathy treatment did not meet its primary endpoint. 

Aptinyx shares closed down 66.46% Wednesday at $5.98. 

The company said that the trial did not demonstrate statistically significant separation in outcomes when compared to a placebo in the double-blind controlled study of 300 patients suffering from the disease. 

"This four-week proof-of-concept study of our novel NMDA receptor modulator, NYX-2925, in painful DPN was designed to evaluate a 20-fold dose range, determine whether efficacy and dose response could be observed on primary and secondary endpoints, and assess safety in a patient population," said Norbert Riedel, Ph.D., president and CEO of Aptinyx.

The company did see improvements in patients treated with 50 mg and 200 mg doses of the trial drug, but the improvement was not statistically significant from those observed in the placebo group.