, brincidofovir was in phase iii clinical trials for use in humans against cytomegalovirus and adenovirus, after testing for safety in over 1,000 human subjects, and has received fda fast track designation for treatment of cytomegalovirus, adenovirus, and smallpox. chimerix announced in december 2015 that the phase iii trials for use of the drug in preventing cytomegalovirus infection in stem cell transplant patients had failed, and in february 2016 shut down two other late-stage trials for use of the drug in preventing infection after kidney transplants.