A Zika vaccine candidate co-developed by Emergent BioSolutions and Valneva has turned up positive early-stage results, laying the groundwork for a potential technology transfer to Emergent.

The alum-adjuvanted, inactivated vaccine candidate, dubbed VLA1601, was found to be safe in a phase 1 trial, meeting its primary endpoint. It also induced immune responses, as neutralizing antibodies against the Zika virus were observed in a dose- and schedule-dependent way, the pair reported on Monday.

Seroconversion rates reached as high as 85.7% on day 35 among all 67 adults who received either one of two different doses of the vaccine 7 or 28 days apart.

"The excellent safety profile supports further optimization of the elicited immune response to cover an unmet medical need in the most vulnerable populations," Wolfgang Bender, M.D., Ph.D., Valneva’s chief medical officer, said in a statement.

While the interim analysis cut data at Day 56, investigators will continue their study until Day 208 after first vaccination. The final results, expected in the first quarter of 2019, will include more immunogenicity data such as antibody concentration level, seroconversion rate and Zika-specific neutralizing antibodies titers versus baseline.

Valneva made the Zika vaccine based on the same manufacturing platform used in its FDA-approved Japanese encephalitis vaccine, Ixiaro. The French biotech reached an exclusive worldwide license agreement with Emergent back in July 2017.

The pair agreed to share all development costs through phase 1, but once full phase 1 data are in, Emergent could pay Valneva €5 million to take control of the vaccine for further development and, eventually, commercialization. Valneva will transfer the technology to Emergent’s facility in Baltimore, Maryland, and it will be eligible for additional milestones of up to €44 million.

Emergent has made several investments lately to strengthen its pipeline. It snatched up Sanofi’s smallpox vaccine ACAM2000 last July, bought out California-headquartered vaccine maker PaxVaxfor $270 million, and in August acquired the maker of opioid overdose-reversing drug Narcan, Adapt Pharma, for $635 million upfront.

Even though Zika has almost died down from an outbreak in 2015, the U.S. government and industry have continued with their search for potent vaccines. Another inactivated vaccine candidate, which Sanofi abandoned amid political pressure, is being developed by scientists at the Walter Reed Army Institute of Research. Companies large and small, including Takeda, Johnson & Johnson, Moderna, Inovio and Themis, among others, are all working in the field.

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