GlaxoSmithKline said Thursday that a pivotal late-stage trial of the experimental vaccine HZ/su for the prevention of shingles met its primary endpoint. HZ/su combines gE, a protein found on the virus that causes shingles, with the AS01B adjuvant system, which contains Agenus' QS-21 Stimulon adjuvant.
In the ZOE-50 trial, 16 160 adults aged 50 and older were randomised to receive HZ/su or placebo on a two-dose schedule at zero and two months. The primary endpoint of the study was the efficacy of the vaccine versus placebo across all age cohorts. Study results demonstrated that HZ/su lowered the risk of shingles by 97.2 percent compared to placebo.
GlaxoSmithKline noted that full safety data from the study is currently being analysed and will be disclosed in the coming months. The company added that the trial's independent Data Monitoring Committee, in its ongoing review of the safety information up to 31 May, raised no concerns regarding the continuation of the study.
Alain Brecx, head of vaccine development at GlaxoSmithKline, remarked "we look forward to sharing these compelling results and additional data from the ZOE-50 study and the broader HZ/su clinical development programme." The drugmaker indicated that full data from the trial will be presented at a future medical conference and submitted for publication in a peer-reviewed journal.
At present, Merck & Co.'s Zostavax, which was cleared  by the FDA in 2006 for patients 60 years and older, and later expanded  to include those aged 50 to 59 years, is currently the only marketed shingles vaccine. The product generated $758 million in revenue last year, while analysts project sales of $1.1 billion for the vaccine by 2019. Analysts at USB estimated that with its potentially superior efficacy, HZ/su could amass annual sales in excess of $1 billion.
GlaxoSmithKline is also evaluating the ability of HZ/su to prevent shingles in patients aged 70 and older and in immunocompromised people. If approved, Agenus is entitled to receive royalties on sales of the vaccine.