Dynavax shares fall as FDA cancels vax adcomm
- The Food and Drug Administration has canceled a November advisory panel meeting scheduled to review Dynavax’s recombinant hep B vaccine, Heplisav-B. The target action date for a final regulatory decision is still set for December 15, and the FDA will call another meeting if necessary.
- Heplisav-B is an adult hepatitis B vaccine which combines hepatitis B surface antigens with a Toll-like receptor 9 agonist to enhance immune response. The drug has completed Phase 3 testing, but has been previously knocked back by the regulator due to concerns over immunogenicity.
- Around 20,000 people get infected with the hepatitis B virus every year. There is no cure, so vaccination is the only way to stop the disease’s spread.
Dynavax only announced the news of the advisory panel meeting for Heplisav-B in late August. The public meeting was supposed to review the biologics license application for the vaccine. Instead, the FDA has scrapped the meeting altogether to allow itself time for review of "several outstanding issues." A statement from the company indicated remaining questions on the drug would be addressed through the normal process.
"Our dialogue with the FDA has been very open and productive, and we look forward to providing the review team with any additional information they may need to complete their review," said Eddie Gray, chief executive officer of Dynavax.
Vaccination against hepatitis B requires three doses over six months, and only around 54% of adults complete the vaccination program. Hepsilav-B’s advantage would require only two doses over one month, which could improve compliance and therefore cut levels of infection.
This isn’t the first time the FDA has put the brakes on Heplisav-B.
In 2013, the FDA requested additional safety data in a complete response letter because of concerns about immunogenicity. In reply, Dynavax set up its most recent Phase 3 trial, aiming to create a database of safety data from 8000 subjects given either Heplisav-B or Engerix-B.
The trial included a subset of people with type 2 diabetes. The overall immunogenicity data from this study will be reviewed by the FDA, but Dynavax has been asked to submit the diabetes data as part of a supplemental BLA as it wasn’t a direct response to the complete response letter.
Heplisav-B's target action date had been extended by three months to December 15 in response to the submission of large individual trial data sets, which the FDA regarded as a major amendment to the BLA.
Dynavax stock dropped by nearly 32% when the FDA first announced the meeting cancelation last week.
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