FDA Rejects Dynavax’s Heplisav Hepatitis B Vaccine Citing Safety Concerns

Dynavax Technologies Corp. (DVAX) said early Monday morning that it has received a Complete Response Letter from the U.S. Food and Drug Administration pertaining to its Biologic License Application for Heplisav, the company’s investigational adult hepatitis B vaccine.

Heplisav, which combines hepatitis B surface antigen with a proprietary Toll-like Receptor 9 agonist to enhance the immune response, is Dynavax’s lead product candidate.

The FDA said that it requires further safety evaluation studies in the broad group of adults 18 – 70 years of age before it can approve Heplisav. The regulatory agency is concerned about rare autoimmune events occurring because of novel adjuvants contained in Heplisav. The FDA also requested additional data from Dynavax’s process validation program and more information on the manufacturing controls and facilities to assure quality of the product.

Dynavax expressed that the FDA is willing to continue discussions regarding more restricted use of Heplisav, a course that the Berkeley, California-based company says that it plans to pursue in order to “identify the most expeditious path to approval” for the new vaccine. Dynavax believes that the first meeting to discuss the necessary steps to work towards marketing approval can happen within six weeks.

The application for Heplisav was accepted for FDA review last June. In November, the FDA’s Vaccines and Related Biological Products Advisory Committee voted 8 to 5 (with one abstention) to not recommend approval based upon insufficient safety data for Heplisav, although the committee did vote 13 to 1 that research data showed Heplisav demonstrated immunogenicity.

Dynavax is looking to bring its first product to market with Heplisav and capture some of the hepatitis B market that is primarily controlled by Merck & Co., Inc.’s (MRK) Recombivax HB vaccine and GlaxoSmithKline Plc.’s (GSK) Engerix B vaccine. The FDA has approved a total of five hepatitis vaccines to date.

Research firm GlobalData estimated the global hepatitis B vaccine market to be valued at about $1 billion in 2010. Hepatitis is the leading cause of liver cancer and cirrhosis worldwide with the Centers for Disease Control and Prevention estimating that about 500 million people globally have chronic viral hepatitis, although most don’t know they are infected.

Shares of DVAX were halved in value in November from around $5 to lows of $2.22 with the news from the FDA advisory committee. Shares have slowly lumbered upward and closed Friday at $2.97, representing about 26 percent depreciation in the past 52 weeks.