Brincidofovir fails in Phase III trial to prevent cytomegalovirus- Chimerix

Chimerix announced that its Phase III SUPPRESS trial of brincidofovir in patients undergoing haematopoietic 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.

Preliminary analysis suggests that the primary endpoint failures in both the prevention of CMV infections and mortality in the brincidofovir arm were driven by confirmed cases of graft-versus-host-disease (GVHD), which resulted in a significantly higher use of corticosteroids than in the control arm. Both GVHD and use of corticosteroids are risk factors for 'late' CMV infection that occurs after discontinuation of the antiviral in HCT recipients.