December 28, 2015
By Alex Keown, BioSpace.com Breaking News Staff
DURHAM, N.C. – Chimerix plunged nearly 80 percent in early trading this morning after the company announced its experimental oral antiviral drug brincidofovir failed to achieve its primary endpoint during a Phase III trial.
Brincidofovir is being developed to prevent infection in patients undergoing hematopoietic cell transplantation. The Phase III results showed patients did not see a significant reduction in cytomegalovirus (CMV) infection through Week 24 after transplant, the company announced this morning. The company reported that during the 14 week period patients received brincidofovir for CMV, there were fewer reports of infection. However, during the 10 weeks off-treatment, there was an increase in CMV infections, the company said.
Chimerix said its lead drug failed to achieve efficacy due to cases of graft-versus-host-disease (GVHD), a complication that occurs when transplanted donor cells attack the recipient’s body. That resulted in a “significantly higher” use of corticosteroids. Both GVHD and use of corticosteroids are risk factors for “late” CMV infection that occurs after discontinuation of the antiviral in HCT recipients, Chimerix said
Cytomegalovirus is one of the herpes viruses and is usually harmless. However, transplant patients are highly susceptible to viral, bacterial and fungal infections. These complications are a significant cause of morbidity and mortality in the months following the transplant, and too often the high risk of infection in the first year after transplant results in patients and their families deciding to not undergo a potentially curative transplant, Chimerix said. Currently there are no approved therapies for the prevention of CMV in HCT recipients because of known toxicities associated with available CMV antivirals, including bone marrow suppression and renal impairment.
Despite the failure of brincidofovir in the Phase III trial, Chimerix said it remains committed to continue the programs testing brincidofovir in serious adenovirus infections and in smallpox. Brincidofovir has received Fast Track designation from the FDA for CMV, adenovirus, and smallpox.
W. Garrett Nichols, Chimerix’s chief medical officer, said the company will evaluate the sub-groups of patients in the Phase III Suppress Trial, including “T-cell depleted transplant recipients who have a lower risk of GVHD, to better understand these results and inform our next steps.” Chimerix will continue talks with the U.S. Food and Drug Administration and other regulatory bodies as the company continues to move forward with studies of brincidofovir, Nichols said.
“While we are clearly disappointed in the top-line results from SUPPRESS, we remain committed to better understanding the full data set as we consider potential paths forward for brincidofovir,” M. Michelle Berrey, president and chief executive officer of Chimerix, said in a statement. “With a strong cash position, an experienced leadership team, and brincidofovir patent exclusivity through 2034, we continue to believe there is a viable path forward for the development of brincidofovir.”
