February 22, 2016
By Alex Keown, BioSpace.com Breaking News Staff
DURHAM, N.C. – Shares of North Carolina-based Chimerix are down more than 30 percent this morning after the company announced it was shutting down two Phase III trials of its antiviral brincidofovir following the release of data from a Phase III trial that was scuttled in December.
On Sunday, Chimerix presented data at the combined annual meetings of the Center for International Blood and Marrow Transplant Research and the American Society of Blood and Marrow Transplantation. The company said although the trial that was shut down in December did not meet its endpoints, the study showed “a clear antiviral effect was seen at the end of the on-treatment period at Week 14.” By week 24 though, the company said the antiviral effect was similar to placebo. As a result, Chimerix said it will step back from its Phase III efforts and concentrate on a Phase II trial that focuses on the intravenous formulation of the treatment. Preclinical data has shown that an IV version of brincidofovir may help patients avoid the gastrointestinal side effects of orally-administered version of the drug.
“We remain committed to establishing the best path forward for the evaluation of brincidofovir in solid organ transplant patients, including kidney transplant recipients,” W. Garrett Nichols, Chimerix’s chief medical officer, said in a statement. “It is important that we take the appropriate steps to ensure the success of our clinical program evaluating brincidofovir in the prevention of viral infections in the solid organ setting, including potentially CMV, BK virus and adenovirus infections.”
During its presentation, Chimerix said there was an increase in reports of diarrhea in patients taking brincidofovir, which is associated with graft-versus-host-disease (GVHD), as well as being a known side effect for the Chimerix drug. As a result, there was an increase in the amount of corticosteroids and other immune suppressing therapies given to those patients. GVHD is a potentially life-threatening condition in which donated bone marrow or stem cells view the recipient’s body as foreign and attack the host. The use of corticosteroids and other immunosuppressive therapies for the treatment of GVHD is known to increase the risk of infections, including CMV infections that occur when patients discontinue antiviral therapy. 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.
Additionally, Chimerix said brincidofovir was not shown to prevent infection with non-CMV DNA viruses, such as BK virus.
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.
