Sanofi's dengue shot Dengvaxia wins FDA priority review despite controversial past

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Sanofi's Dengvaxia picked up an FDA priority review, the company said Tuesday. (Sanofi on Flickr)

Sanofi has weathered controversy with its world-first dengue vaccine, Dengvaxia, but the company is pressing ahead, and on Tuesday said the FDA had not only accepted its application for approval, but also granted a priority review. 

The FDA is set to decide on Sanofi’s vaccine by May 1, 2019. In granting the priority review, the FDA determined the vaccine could be the first medical tool to prevent a serious disease with unmet need. Recipients would need to have confirmation of a prior dengue infection because of safety risks in those who haven't, a Sanofi executive said, a factor that could complicate a broad rollout.

With an approval, officials could use the vaccine in the U.S. Virgin Islands and Puerto Rico, where the dengue burden is high, according to the company. 

The vaccine's history is complicated. Dengvaxia won initial approvals in late 2015 and has now secured licenses in 20 markets. But in late 2017, the company released an analysis that showed it can cause more serious infections if given to people who haven’t had a prior infection. 

The revelation caused a safety scandal in the Philippines, the first country to adopt the vaccine for a national immunization campaign. Officials there demanded refunds and started an investigation. All told, the episode cost Sanofi €158 million last year, the company reported.

In an interview, Sanofi Pasteur North American regional medical head David Greenberg said that if the vaccine wins U.S. approval, potential recipients would need to be tested for a prior dengue infection by their healthcare providers. The test takes about a week, he said. Only those with a confirmed infection should be vaccinated, he said.

“We stand behind this vaccine because it is an extremely important public health measure,” he said. 

While Dengvaxia hasn’t met early commercial projections—which ranged into blockbuster territory—Sanofi recently scored a win for the vaccine. This month, the European Medicines Agency’s Committee for Medicinal Products for Human Use recommended the shot for approval, setting up a likely European nod by the end of the year.  

In 2016, its first year on the market, Sanofi execs said Dengvaxia could deliver sales of up to €200 million, but the vaccine generated sales of just €55 million. In 2017, sales sank to €3 million. The company spent 20 years and €1.5 billion to develop the vaccine.

As Sanofi presses ahead with Dengvaxia, Takeda is testing a potential rival in phase 3.