Takeda’s Zika vaccine candidate wins FDA fast-track status

Takeda’s Zika vaccine candidate, TAK-426, received FDA fast-track designation. (Image: Health.mil)

For years, experts have expressed worries about the reactive nature of emerging disease vaccine development, most recently with the Zika outbreak. But even after the WHO stopped classifying Zika as an "emergency" in late 2016, Takeda pressed ahead with its program, this week winning the FDA's fast-track designation.

FDA granted the designation to TAK-426, a purified, inactivated, alum-adjuvanted vaccine with whole Zika virus. Last November, Takeda advanced the candidate into a 240-subject phase 1 study in the continental U.S. and Puerto Rico.

From the FDA's perspective, granting the fast-track label means the agency deems Zika a serious condition with an unmet medical need. There are no approved vaccines or drugs against the infection, which can cause microcephaly and other congenital brain abnormalities in infants born to infected mothers

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For Takeda, the designation means more frequent interactions with the agency and eligibility for accelerated approval and a priority review.

“We recognize the public health threat posed by the Zika virus,” Laurence De Moerlooze, Ph.D., Takeda’s global Zika program lead, said in a statement on Monday. She said the Japanese pharma prioritized development of the candidate after the Biomedical Advanced Research and Development Authority (BARDA) committed $19.8 million to cover development costs through phase 1 and promised up to $312 million in assistance through a potential FDA approval.

The Zika virus has significantly died down after an outbreak caught the world off guard in late 2015 and through 2016. Symptomatic cases reported to the CDC from U.S. states and territories were 418 and 637, respectively in 2017, compared to 5,102 and 36,079 for 2016, according to the most recent agency data.

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Back in November 2016, the WHO changed its classification for Zika from a “public health emergency " to a “long-term commitment." Some experts voiced their concern that the decision would dampen enthusiasm for vaccine development, and as a consequence, a lack of preparedness if the disease spreads again. Some have also warned of the reactive nature of vaccine R&D could shift developers’ attention every time a new outbreak emerges, drawing comparisons with how Zika replaced Ebola on the international community’s agenda.

Although the waning epidemic means fewer people are falling ill, the decrease in cases also makes it tougher to conduct late-phase clinical studies to prove vaccine efficacy. Sanofi cited that as one of the reasons behind its decision to drop out of an agreement to license a Zika vaccine candidate developed by the U.S. Army.