Chimerix Inc said its oral antiviral drug did not significantly reduce a certain kind of infection in stem cell transplant patients in a late-stage study, sending its shares to a record low.
The company's shares fell as much as 79.7 percent in morning trading to $7.21.
Patients taking the drug, brincidofovir, did not experience significant reduction in cytomegalovirus (CMV) infection through week 24 after transplant.
CMV is a member of the herpes virus family and remains a significant cause of viral infections in transplant recipients.
While the drug initially appeared to reduce rate of CMV infection during the treatment period, there was a rebound after the patients went off the treatment, leading to the trial's failure.
Chimerix said the rebound was due to cases of graft-versus-host-disease (GVHD), a complication that occurs when transplanted donor cells attack the recipient's body.
Piper Jaffray analyst Joshua Schimmer said he was stripping CMV prevention from his estimates for the drug and slashed the price target on the stock to $10 from $63.
Chimerix said pending the availability of complete data from late-stage trial of the drug, it has paused further enrollment of kidney transplant patients.
The company, which will present full data on the trial in a medical conference next year, said it would consult the United States Food and Drug Administration to decide on the future of the drug.
The Durham, North Carolina-based company plans to continue testing brincidofovir for serious DNA virus infections and smallpox.