Chimerix says Phase III brincidofovir trial fails to meet goals

Shares of US antiviral biopharma company Chimerix (Nasdaq: CMRX) plunged more than 77% in premarket trading on Monday, after it announced disappointing clinical results with its brincidofovir. The shares fell further to $7.37 shortly after the markets opened.

Chimerix said that its Phase III SUPPRESS trial of brincidofovir in patients undergoing hematopoietic cell transplantation (HCT) did not achieve its primary endpoint for the prevention of clinically significant cytomegalovirus (CMV) infection through Week 24 after transplant.

During the on-treatment period through Week 14 after HCT, fewer patients in the brincidofovir arm had a CMV infection, consistent with the positive antiviral effect of the compound seen in the Phase II study. However, during the 10 weeks off treatment from Week 14 to Week 24, there was an increase in CMV infections in the brincidofovir arm compared to the control arm. There was also a non-statistically significant increase in mortality in the brincidofovir arm compared to the control arm.