Acambis announces halt of smallpox vaccine trial

Journal of Drugs in Dermatology, Sept-Oct, 2004

Acambis has announced suspension of additional recruitment of subjects into a phase III trial of ACAM2000 smallpox vaccine after three suspected myopericarditis cases were discovered. An ongoing investigation is occurring to determine if there is any relationship between this smallpox vaccine and myopericarditis. Once the investigation is complete, Acambis will meet with the FDA and CDC to determine the next step in development. Smallpox vaccines contain live vaccinia virus, a virus closely related to the variola (smallpox) virus. Results from the U.S. smallpox vaccination program revealed data supporting a causal association between myopericarditis and smallpox vaccinations.

Acambis had been given a contract from the Center for Disease Control and Prevention (CDC) for 209 million doses of the ACAM2000 vaccine with plans to apply for FDA licensure in 2004. Acambis is also focused on the development of a smallpox vaccine that can be used in immunosuppressed individuals (the MVA--Modified Vaccinia Ankara smallpox vaccine). Immunosuppressed individuals are more at risk of adverse reactions to the smallpox vaccine. MVA is a more attenuated form of the current generation of smallpox vaccines. Acambis was awarded a contract by the National Institute of Allergy and Infectious Diseases to further develop its MVA smallpox vaccine.

The smallpox vaccine that is currently available (Dryvax) exists from a stockpiled source from 1982 when Wyeth stopped manufacture of the vaccine. The doses available of this vaccine are insufficient to vaccinate the US population in the event of a bioterrorist attack with smallpox virus.