GlobeImmune and partner Gilead suffered a setback this week after its new hepatitis B vaccine GS-4774 missed its mid-stage trial target.

The phase II trial was looking at patients with chronic hepatitis B on long-term viral suppression with an oral antiviral treatment. 

In this study, patients treated with the highest dose of GS-4774 plus on-going oral antiviral therapy (OAV) did not show a reduction in hepatitis B surface antigen (HBsAg) at week 24, the primary endpoint of the study.

GlobeImmune added that in the trial patients at 48 weeks had a mean -0.17 log reduction of HBsAg compared with a -0.04 log reduction in the OAV alone group.

Three patients receiving the highest dose of GS-4774 had HBsAg reductions between -0.94 and -3.89 log at 48 weeks. 

There was however no difference in HBsAg reductions between the two lowest dose groups versus the control arm at 48 weeks. Further characterisation of the T-cell response to GS-4774 and association with HBsAg changes are on-going., according to the firm. 

GS-4774 was found to be generally safe and well tolerated, with injection site reactions identified as the primary adverse event. Data from this trial are expected to be submitted for future presentation and publication.

Timothy Rodell, president and CEO of GlobeImmune, said: “We believe that this first phase II trial of GS-4774 in virally-suppressed patients suggests initial biologic activity at the highest dose tested.

“We look forward to collaborating with our partner Gilead Sciences to identify potential next steps for GS-4774 in this patient population as well as to seeing the results from the second on-going phase II trial of GS-4774 in HBV treatment-naïve patients.”