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May 21, 2007
Acambis issued positive results from two phase III trials of ACAM-2000, a vaccine for the treatment of smallpox. The primary endpoints in both trials were non-inferiority in cutaneous response and the strength of the neutralizing response (GMT) when compared to Dryvax, a licensed smallpox vaccine. The first trial, H-400-009, was a randomized, placebo controlled, double-blind design and enrolled 1,162 treatment-nave subjects aged 18-30 years. Results revealed that 96% of the subjects who received ACAM-2000 and 99% of the subjects receiving Dryvax had a major cutaneous response, establishing non-inferiority. By 30 days after vaccination, neutralizing antibody geometric mean titers (GMT) were 166 in the ACAM-2000 and 255 in the Dryvax group, again this established non-inferiority. The second trial, H-400-012, was a randomized, placebo controlled, double-blind design and enrolled 1,647 treatment experienced subjects aged 31-84 years. Of the subjects receiving ACAM-2000, 84% had a major cutaneous response compared to 98% receiving Dryvax. Non-inferiority was not established. By 30 days after vaccination, neutralizing antibody GMT were 286 in the ACAM-2000 group and 445 in the Dryvax group; this established non-inferiority. A BLA for ACAM-2000 is currently under review by the FDA.