Detailed Phase III SUPPRESS data for CMX 001 (brincidofovir) in cytomegalovirus- Chimerix

Chimerix has announced detailed results from its Phase III SUPPRESS trial of CMX 001 (brincidofovir) for the prevention of cytomegalovirus (CMV) in patients undergoing hematopoietic cell transplantation (HCT). As reported in December 2015, the SUPPRESS trial did not meet the primary endpoint of prevention of clinically significant CMV infection at Week 24 following HCT; however, a clear antiviral effect was seen at the end of the on-treatment period at Week 14, with patients who received brincidofovir experiencing fewer clinically significant CMV infections than patients in the placebo group (24 percent versus 38 percent). At the Week 24 primary endpoint assessment, the proportion of patients with clinically significant CMV infection on brincidofovir (51 percent) was similar to placebo (52 percent).

The failure to meet the SUPPRESS trial’s endpoint of prevention of CMV infection at Week 24 appears to be associated with CMV events in the post-treatment period among subjects on the brincidofovir arm, driven by higher use of corticosteroids and other immune suppressing therapies for the treatment of presumptive graft versus host disease (GVHD). Among the secondary efficacy endpoints, brincidofovir was not shown to prevent infection with non-CMV DNA viruses, such as BK virus. There were no statistically significant differences in all-cause mortality in the trial (15.5 percent in the brincidofovir arm, 10.1 percent in the placebo arm); the numerical differences appear to be driven by higher use of corticosteroids and other immunosuppressive therapies in the subjects who received brincidofovir. These data were presented at the BMT Tandem Meetings.

Comment: Chimerix will discuss the SUPPRESS data in full with the FDA and foreign regulators to determine next steps for the brincidofovir clinical programs. The development of an intravenous (IV) formulation of brincidofovir is progressing toward clinical testing, and has the potential to avoid the gastrointestinal side effects of orally-administered brincidofovir.