(Reuters) - U.S. health regulators denied approval for Dynavax Technologies Inc's adult hepatitis B vaccine pending additional data to evaluate its safety, potentially delaying the U.S. market entry of the company's first promising product.
The U.S. Food and Drug Administration, however, indicated it was willing to have discussions for a more restricted use of the vaccine Heplisav, Dynavax said.
The company also said the FDA continues to express concern that novel adjuvants that Heplisav contains may cause rare autoimmune events.
Adjuvants are added to vaccines to improve their ability to trigger an immune response, but they carry the risk of causing several potentially fatal adverse reactions.
Advisors to the U.S. FDA had flagged safety concerns on Heplisav in November, even as they voted unanimously to support the efficacy of the vaccine.
"Furthermore, the FDA requested additional data ... clarifying information on the manufacturing controls and facilities related to the assurance of the quality of the commercial product," Dynavax said in a statement.
The company said it expects to meet with the FDA within six weeks to discuss the steps required for Heplisav's approval.
The rejection brings into question the future Dynavax, which has no drugs on the market. The company has been generating revenue so far through its research and development alliances.
An estimated 3.5 million to 5.3 million people are living with viral hepatitis in the United States, and vaccination is crucial as it prevents progression of the infection, which is the leading cause of liver cancer.
Dynavax pitched Heplisav for use in patients between 18 and 70 years of age. The company estimates the global market for adult hepatitis B vaccines at about $700 million annually.
The hepatitis B market is currently dominated by GlaxoSmithKline Plc's Engerix B and Merck & Co's Recombivax HB vaccines.
(Reporting by Zeba Siddiqui in Bangalore; Editing by Roshni Menon)