Heplisav-B, the hepatitis B vaccine developed by Dynavax Technologies Corporation (NASDAQ:DVAX) has been found to be effective though serious heart problems and more deaths were recorded in the patients who were given the vaccine compared to those given a competing product. This is according to a preliminary report published by the U.S. Food and Drug Administration.

The review by the FDA, however, concluded that the overall rates and numbers of the cardiac events were not high. Posted on the website of the FDA, the review comes days before an outside advisors’ meeting is convened to discuss Heplisav-B and issue recommendations on whether or not an approval should be given. While the FDA typically follows the recommendations of the advisory panels, it is not duty bound to follow such advice.

Two rejections

Heplisav-B has twice been rejected by the U.S. Food and Drug Administration over unresolved safety concerns. The most recent rejecttion was last year in November. At the time the shares of Dynavax fell by approximately 70% to hit a one-year low.

According to Anupam Rama, a JPMorgan analyst, the chances of Heplisav-B getting approved is 40%. This is because of the previous rejections as well as the mixed opinions that are contained in the briefing documents of the FDA. However, the position may change after the advisory panel meets.

Plausible argument

In Dynavax’s arguments the reason the rate of heart problems was higher in patients who were taking Heplisav-B was because of fewer than expected instances happening in patients who were given Engerix-B, the competing product.

Some cardiologists who were consulted by the Food and Drug Administration agreed with the argument adding that safety monitoring should not be discontinued after Heplisav-B hits the market and that the imbalance ought to be noted on the label of the product. There were also those cardiologists who were less certain about the plausibility of the argument.

“While the finding could be attributable to chance, I cannot confidently say that there is no increased cardiovascular risk with Heplisav,” one cardiologist said.

On Wednesday shares of Dynavax Technologies Corporation rose by 5.05% to close the day at $10.40.