Today shares of Chimerix (CMRX) fell by 40% after the company announced that it had to halt two phase 3 trials due to insufficient efficacy. The company reported results on its phase 3 SUPPRESS TRIAL, which recruited a total of 452 patients. These patients were recruited for the prevention of the Cytamegalovirus -- CMV -- due to undergoing hematopoietic Cell Transportation -- HCT. 

The primary endpoint of the trial was for the company's drug brincidofovir to prevent CMV in these patients over a 24-week period as compared to a placebo. Patients were given the drug for 14 weeks then monitored the other 10 weeks. At the end of the 24 weeks the drug, brincidofovir failed to improve CMV clinical outcome compared to the placebo. Thus, the trial failed to meet upon the primary endpoint. 

The company will now discuss with the FDA possible next steps of the brincidofovir drug in these patients with CMV. Although, Chimerix will have to attempt to a address a subset of patients who showed some clinical activity. In addition the company will continue on with other trials using the same drug. For example, the company will pursue a phase 2 trial using brincidofovir in kidney patients.