Dynavax's experimental hepatitis B vaccine Heplisav-B hits late-stage study goals

Dynavax Technologies reported Thursday that a Phase III study of its investigational hepatitis B vaccine Heplisav-B met both of its co-primary endpoints versus GlaxoSmithKline's Engerix-B. "We are delighted to report these topline results from HBV-23 and confirm our intention to resubmit [Heplisav-B for FDA approval] by the end of March," remarked CEO Eddie Gray adding "these results support our belief that Heplisav-B, if approved, could offer benefits to adults at risk for hepatitis B, particularly given that these significant differences in seroprotection were demonstrated in a controlled setting, where compliance is optimised."

In the study, adults aged 18 to 70 were randomised to immunisation with two doses of Heplisav-B, given at months zero and one, or three doses of Engerix-B, given at months zero, one and six. Patients in the Heplisav-B arm were followed for 52 weeks after the last dose, while those in the Engerix-B arm were followed for 28 weeks after the last dose. The main goals comprised the rates of clinically significant adverse events and non-inferiority of seroprotection in participants with diabetes mellitus.

According to Dynavax, results from the study showed that 22 patients in the Heplisav-B group experienced an adverse event of special interest, compared to 11 patients in the Engerix-B group. Of these events, 11 events in Heplisav-B-treated patients and 10 events in Engerix-B-treated subjects were determined to be autoimmune events. Dynavax noted that as a secondary safety endpoint, no cases of Wegener's Granulomatosis or Tolosa Hunt syndrome were observed in either arm.

Regarding seroprotection, the peak seroprotection rates (SPRs) among patients with type 2 diabetes mellitus were 90 percent in the Heplisav-B arm and 65.1 percent in the Engerix-B arm. Meanwhile, the peak SPR for all patients was 95.4 percent for the Heplisav-B group, versus 81.3 percent for patients who received Engerix-B. Dynavax indicated that the peak SPR was statistically significantly higher in the Heplisav-B arm than in the Engerix-B arm for each age decile as well as in each pre-specified subpopulation analysed.

The FDA declined to approve Heplisav-B in February 2013 citing, amongst other things, the need for more safety information. The FDA later affirmed that Dynavax would need to submit additional safety data prior to resubmission of the vaccine.

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