A phase 2 study findings suggest that AV7909, a new vaccine for postexposure prophylaxis of anthrax disease, may work faster and require fewer vaccinations with fewer antigens when compared with BioThrax. The authors also speculate that AV7909 might require shorter stints with antimicrobial drugs than the 60-day regimen currently recommended along with the 3-dose series of BioThrax vaccine, which could lead to increased patients adherence.
The drug AV7909 combines BioThrax with CPG7909, a synthetic immunostimulatory oligonucleotide. Earlier trials identified a formulation that enhanced immune response without increasing adverse events (AEs). In a multicenter phase 2 trial that evaluated this formulation, researchers tested 3 vaccine schedules and 2 doses in 168 healthy volunteers. Serum samples were collected before the vaccination and on days 35, 42, 49, 63, and 84. Safety was assessed through Day 84.
The schedule of 2 full doses of AV7909, given 2 weeks apart, showed a comparable immune response to a 0/14/28-day BioThrax schedule but had a higher and earlier peak. The AV7909 vaccine was safe and well tolerated. Although the AV7909 group reported more AEs (79% for AV7909 vs 65% for BioThrax), no serious AEs were assessed as potentially vaccine related, and none were deemed of potential autoimmune etiology.