Analyst: Dynavax hep B vaccine positioned to grab market share from GSK's Engerix-B

Initially approved by the FDA in 1989, GlaxoSmithKline's ($GSK) Engerix-B has been the standard-of-care against hepatitis B. But an analyst thinks that if it's approved, Dynavax's ($DVAX) experimental Heplisav is poised to swipe some market share. Dynavax previously submitted the candidate for approval in February 2013, when it was rejected due to safety concerns.

The company will report data from its third Phase III trial of Heplisav in Q1 2016. Assuming there are no red flags for safety, RBC Capital Markets' Simos Simeonidis expects a regulatory filing based on these data to follow.

In an analyst note, Simeonidis wrote that Heplisav is a "stronger and more convenient" vaccine than Engerix-B, which will allow it to gain the majority of the $270 million U.S. hepatitis B market. In two Phase III trials, Dynavax's candidate demonstrated both noninferiority and superiority over the standard-of-care, including higher seroprotection (95% compared to Engerix-B's 81%) using fewer doses (two vs. three). It also achieved protection in one month, compared to Engerix-B's 6.

A 2011 Centers for Disease Control and Prevention recommendation for diabetics to receive a hep B vaccine can also help expand the market for the vaccine, Simeonidis said.

In its 2013 bid, Dynavax sought approval for Heplisav in adults aged 18 to 70. The FDA rejected it, saying it would meet to discuss a narrower indication in 6 weeks.

Dynavax shares dropped again in mid-2013 when the agency requested more data. In February 2014, the European Medicines Agency followed suit, requesting further safety data, which caused Dynavax to pull its European regulatory application while it worked to generate the data. Two months later, it launched a new Phase III trial in the hopes of allaying these safety concerns.