Death Count Rises for Patients on Dynavax's Hep B Vaccine But Overall Rate Was Low, Says the FDA

July 26, 2017
By Alex Keown, BioSpace.com Breaking News Staff

BERKELY, Calif. – Shares of Dynavax Technologies Corporation are down this morning after a preliminary advisory committee report by the U.S. Food and Drug Administration once again pointed to some serious safety issues with its troubled Hepatitis B treatment, Heplisav-B.

According to a Reuters report, the FDA said Heplisav-B was effective in treating hepatitis B, but there were “more deaths and serious cardiac events in patients given the vaccine than in those given a rival product.” That rival drug is GlaxoSmithKline ’s Engerix-B. In Phase III trials, Heplsav-Bs showed non-inferiority against the GSK drug. While the advisory committee pointed to the safety concerns, Reuters noted the members said the “overall numbers and rates of events were low.”

“In summary, Heplisav was shown to have a robust immune response in healthy adults 18-70 years of age in Studies DV2-HBV-10 and -16. Heplisav met pre-specified non-inferiority criteria to an active comparator vaccine, Engerix-B, in these two Phase III clinical trials. Regarding safety, there appears to be imbalances in deaths and SAEs of MI in DV2-HBV-23, and imbalances in AESIs in DV2-HBV-16 and -23 (the studies that prospectively evaluated these events). Numbers and rates of events are low, and the lack of prospectively defined monitoring and evaluation of cardiac events limits the causal interpretation of these observations,” the committee said in its summary.

The FDA’s review comes two days before the advisory committee is set to vote on whether or not it recommends approval of the treatment. The FDA is scheduled to issue a ruling on Heplisav-B later this year.

The FDA advisory committee preliminary report comes less than a year after the agency rejected the company’s bid for approval of Heplisav-B, its hepatitis B vaccine for adults. That marked the second time the hepatitis drug was rejected by the FDA. The FDA also rejected the drug in 2013, in part due to insufficient size of the safety database. Most recently, in December 2016 the FDA sent Dynavax a Complete Response Letter saying the regulatory agency wanted additional information before the approval process could move forward. At the time, Dynavax said the FDA wanted clarification “regarding specific adverse events of special interest (AESIs), a numerical imbalance in a small number of cardiac events in a single study (HBV-23), new analyses of the integrated safety data base across different time periods, and post-marketing commitments.”

Following the posting of the advisory committee review and reports of its content, Dynavax investors are more than wary of the FDA. Shares of Dynavax are down more than 7 percent as of 10:12 a.m., trading at $9.15. Still, if the FDA does approve Heplisav-B, Katherine Xu, an analyst at William Blair, said in a research note that stock prices could climb to as high as $30 per share. Furthermore, Reuters noted Xu believes Heplisav-B could become the standard of care for patients.

That would be quite a turnaround for the company, which in January initiated a corporate restructuring that included terminated 38 percent of the company’s workforce. That reorganization was done with the primary intent of guiding Heplisav-B through the regulatory process.