FDA delays approval of Dynavax' Heplisav, issuing CRL

Dynavax Technologies ( Nasdaq: DVAX) saw its shares plunge as much as 38% to $1.84 in pre-market trading on February 25, when the firm revealed that it received a Complete Response Letter (CRL) from the US. Food and Drug Administration regarding its Biologic License Application for Heplisav, an investigational adult hepatitis B vaccine for which it has previously estimated potential sales of $700 million a year.

In the CRL, the FDA specified that the indication in adults 18-70 years of age cannot be approved without further evaluation of safety in this broad age group. The FDA also continues to express concern that novel adjuvants may cause rare autoimmune events. However, the Agency indicated its willingness to continue discussions regarding a more restricted use of Heplisav. Dynavax plans to discuss the CRL with the FDA to identify the most expeditious path to approval for the drug, particularly in adults who may receive the greatest benefit from Heplisav.

Requests additional data on validation program