Dynavax tanks on feds' Heplisav stance

Shares of Dynavax Technologies plunged 75 percent after company officials announced that U.S. regulators were asking for more information on its hepatitis B Vaccine and was continuing its clinical hold on the program. The FDA placed the clinical hold on Heplisav seven months ago after a patient in a study contracted Wegener's granulomatosis, a disease in which blood vessels get inflamed. Regulators say the balance of risk versus potential benefit no longer favors continued clinical evaluation of Heplisav in healthy adults and children. That's something 24/7 Wall Street characterized as "the kiss of death for a trial program."

The FDA did say that there may be potential for an acceptable risk versus benefit profile for Heplisav in patients with renal failure.  And the agency requested additional information from the companies before considering further clinical studies in those patients. Dynavax and Merck, which is partnered on the vaccine, say they will study the FDA's position before deciding how to proceed.

- see Dynavax's release
- read the report from 24/7 Wall Street