FDA rejects Dynavax hepatitis B vaccine

The U.S. Food and Drug Administration rejected Dynavax Technologies Corp's hepatitis B vaccine for the second time in three years, casting doubts on the drug developer's ability to bring its main drug to the market on its own.

Shares of the company, which has no drug on the market, plunged as much as 72 percent to $3.20, their lowest since late 2008.

Dynavax Chief Executive Eddie Gray said the company would meet with the FDA "as soon as possible" to discuss concerns raised by the agency in a "complete response letter".

"However, the time and resources that will be required to gain approval leads us to consider that we may not be able to advance this program on our own and we are moving swiftly to identify a potential pharmaceutical or financial partner," Gray said.

The company said the FDA, in its letter, sought information about certain "adverse events" during clinical trials, among other clarifications.

Dynavax, which had $109.6 million in cash, cash equivalents and marketable securities as of Sept. 30, had an earlier marketing application for the vaccine, Heplisav-B, rejected in February 2013.

A positive late-stage study in January paved the way for Dynavax to resubmit its application for the vaccine.

However, the FDA in September had canceled an advisory committee meeting meant to discuss Dynavax's vaccine, in order to provide the agency more time to review pending issues.

Investors interpreted the cancellation of the meeting as a sign that there were unresolved issues with Heplisav's application that could jeopardize its approval.

The FDA acknowledged in its letter that it had not yet fully reviewed Dynavax's responses to the agency's clarifications, the company said.

There was no request from the FDA for additional clinical trials and there were no apparent concerns about rare serious events, the company said.

Dynavax said it expects the review period for a possible resubmission of its application would be six months.

The U.S. Centers for Disease Control and Prevention (CDC) estimates that about 850,000-2.2 million people in the United States suffer from chronic hepatitis B virus infection.

About 786,000 people worldwide die each year from hepatitis B virus-related liver disease, according to the CDC.

Dynavax reported encouraging early-stage data for its cancer immunotherapy last week. The company is also developing a treatment for asthma.

Up to Friday's close of $11.60, Dynavax's shares had dropped about 52 percent this year.