Yesterday, shares of Biocryst Pharmaceuticals (BCRX) tumbled by 71% after the company had announced that the phase 2 trial failed to produce statistically significant results. The phase 2 trial, known as the OPuS-2 trial, tested the company's drug BCX4161 — avoralstat — compared to a placebo compound. 

A total of 108 patients were recruited for the trial. About 36 patients took 500 mg of avoralstat, 36 patients took 300 mg of avoralstat, and the remaining 36 patients took a placebo compound instead. The primary endpoint of the trial was to see if avoralstat could produce a lower mean attack rate compared to placebo in these patients with hereditary angioedema — HAE. 

HAE is a rare fatal genetic disorder that occurs in 1 in 10,000 to 1 in 50,000 people. The disease causes parts of the body to swell sometimes without cause at random, and other times when a trauma/stress occurs. Swelling that occurs in the hands and feet is severe, but the disease is fatal when swelling occurs in other parts of the body such as the airway and intestinal tract. 

The attack rates were as follows for the 300 mg and 500 mg of avoralstat: 0.71 and 0.63 respectively. On the other hand the placebo scored better against both doses with an attack rate of 0.61 — lower attack rate than both doses. The company is in the process of running another trial with other doses and expects to release this data by mid-year. For now the stock will struggle, but there is a small chance the stock can recover if the new data proves to be useful.