Positive results from phase 2, phase 3 trials of frozen smallpox vaccines

A phase 3 clinical trial of the liquid-frozen formulation of the Imvamune smallpox vaccine and a phase 2 trial of a freeze-dried version of the agent have demonstrated positive outcomes, according to a press release from the manufacturer, Bavarian Nordic.

These results would support a biologics license application for U.S. approval of the liquid-frozen vaccine as well as emergency use authorization for the freeze-dried form, according to the release.

The phase 3 trial included 4,000 participants; 3,000 received one of three unique manufacturing lots of the liquid-frozen formulation, and 1,000 participants were assigned placebo vaccine. Those who received liquid-frozen Imvamune demonstrated equivalent antibody responses between lots, with no serious adverse events reported. This safety profile is favorable to contemporaries such as the approved Acam2000 (SanofiPasteur Biologics) smallpox vaccine, which has shown high rates of cardiac complications.

In the phase 2 study, 650 enrolled participants were assigned the freeze-dried or liquid-frozen version of Imvamune. Observed safety and immunogenicity were equivalent between the vaccines, and, according to the release, provide enough clinical data to support stockpiling of the freeze-dried formulation in the U.S. Strategic National Stockpile.

“Completing this pivotal phase 2 study is a significant step in the transition to the freeze-dried version of the vaccine, which provides a number of advantages for the future procurement and stockpiling,” Paul Chaplin, president and CEO, Denmark-based Bavarian Nordic, said in the release. “We remain on track to complete the transfer of the manufacturing process which will enable us to start deliveries in 2016, as we look forward to continuing our successful long-standing collaboration with the U.S. government on their public health preparedness.”