Solid PhIII brings Sanofi closer to blockbuster dengue sales

A new batch of results from a large-scale Phase III trial of Sanofi's ($SNY) dengue candidate holds mostly good news for the French drugmaker, which is on track to produce the world's first vaccine for the deadly disease. But while the candidate showed itself to be by and large safe and effective, it once again faltered against serotype 2, the same variant that tripped it up in an earlier trial.

In a study of 10,275 children aged 2 to 14 across Asia, Sanofi's jab reduced the incidence of dengue by 56.6%, results published in The Lancet show. A three-shot regimen also cut hemorrhagic fever, a severe form of the disease, by 88.5% and reduced hospitalizations by 67%, hitting statistical significance.

But while the vaccine successfully fought off dengue serotypes 1, 3 and 4, it posted just 34.7% efficacy in serotype 2, falling short of the statistical significance mark in one of the continent's more common forms of the disease. It's not the first time serotype 2 has given the company fits, either. Back in 2012, results from a Phase IIb trial revealed the vaccine had put up about 30% overall efficacy against it--way short of the estimate above 70% that Sanofi had banked on.

Still, considering the vaccine's high safety marks and ability to cut down the overall risk of contracting dengue--which affects up to 100 million people per year--the results show its potential to have "a significant impact on public health," lead researcher Dr. Maria Rosario Capeding said in a statement.

John Shiver

Next up will be results from another Phase III study, which Sanofi will wait for before heading down the regulatory pathway. And if it makes it to the end, there could be $1.4 billion in peak sales in the vaccine's future--a payoff that's been a long time coming for the pharma giant.

"These pivotal phase III vaccine efficacy study results take us closer to our ambition to bring the first vaccine against dengue to the world," John Shiver, R&D SVP at Sanofi Pasteur, said in a statement. "After more than 20 years of commitment in collaboration with the scientific community, we are on course to make dengue the next vaccine-preventable disease."

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