(Reuters) - U.S. health regulators denied approval to Dynavax Technologies Inc's adult hepatitis B vaccine in its current form and asked for more data to evaluate the vaccine's safety. The U.S. Food and Drug Administration indicated it was willing to have discussions for a more restricted use of the vaccine Heplisav, Dynavax said in a statement. (Reporting by Zeba Siddiqui in Bangalore; Editing by Roshni Menon)