US group Dynavax Technologies Corp saw its shares reach an all-time high this week, after shooting up 32% on news that the group’s hepatitis B vaccine Heplisav outperformed a rival in a late-stage trial.

Results of the Phase III study, which enrolled more than 400 subjects aged 40 to 70 years in Singapore, Korea and the Philippines, showed that after three doses Heplisav provided seroprotection to 100% of subjects, compared to 73.1% in the group given GlaxoSmithKline’s Engerix-B.

The greatest difference in seroprotection after three doses was seen in subjects 56 to 70 years of age, where Heplisav provided 100% protection versus 56.1% with Engerix-B. Furthermore, data for the entire study population demonstrate that, after two doses, Heplisav provided 98.5% seroprotection against Engerix-B's 25%, the group said.

Dynavax says it plans to go for approval of a two-dose regimen administered at zero and one month, and hopes to initiate multicentre, international Phase III trials in Europe, Canada and the USA before the end of the year, to assess the two-dose regimen against Engerix-B in patients from 11 to 55 years of age. Trials are expected to complete in 2008.

Commenting on the findings, Dino Dina, President and Chief Executive of the firm, said: “These results once again demonstrate Heplisav’s superior effectiveness over conventional hepatitis B vaccine. The most striking outcome from the trial is the vaccine's ability to generate 98.5% protection after two doses in older difficult-to-immunize adults. This has the potential to drive an important change in the way people are immunized against hepatitis B."