New Phase 1 Zika Vaccine Trial Meets Primary Endpoint

Emergent BioSolutions Inc. and Valneva SE (VLA) recently announced positive interim results for the Phase 1 study evaluating VLA1601, their vaccine candidate against the Zika virus.  The highly purified inactivated vaccine candidate, VLA1601, met the study’s primary endpoint showing a favorable safety profile in all doses and schedules tested.

VLA1601 was also immunogenic in all treatment groups and induced both dose- and schedule- dependent neutralizing antibodies against the Zika virus with the kinetics expected for an inactivated, alum-adjuvanted whole-virus vaccine. Seroconversion Rates (SCR) reached up to 85.7% on Day 35 (Interim Analysis of Data up to Day 56).

The Phase 1 study was designed to assess safety and immunogenicity. It is being co-financed by Emergent and Valneva as part of an exclusive, worldwide license agreement signed in July 2017. The agreement includes pre-defined post-Phase 1 opt-in rights for Emergent.

 Wolfgang Bender, MD, PhD, Chief Medical Officer of Valneva said, “We are pleased to see progress of this promising vaccine candidate for the prevention of infections caused by the Zika virus and their serious implications during pregnancy. The excellent safety profile supports further optimization of the elicited immune response to cover an unmet medical need in the most vulnerable populations.”

Kelly Lyn Warfield, PhD, Vice President, Vaccines and Anti-Infectives Research and Development at Emergent BioSolutions, added “Emergent’s continued focus on the development of prevention and treatment strategies for emerging infectious diseases is part of its broader mission – to protect and enhance life. Through our work, we are committed to making a positive impact on public health across the globe.”

VLA1601-101 is a first-in-human, randomized, placebo-controlled and observer-blinded study. It is assessing the safety and immunogenicity of two different dose levels of the alum adjuvanted, inactivated whole virus Zika vaccine candidate VLA1601 in 67 healthy, flavivirus- naïve adults aged 18-49 years. The study is being conducted in Knoxville, TN. Participants received two vaccinations with a lower (3AU) or higher dose (6AU) – either 7 or 28 days apart. The current analysis includes full, final data for all analyses (safety and immunogenicity) up to day 56 after the first vaccination.

The final analysis at day 208 after first vaccination, which is expected in the first quarter 2019, will include additional immunogenicity data such as Geometric Mean Titres (GMTs), rate of subjects with seroconversion and fold-increase of ZIKA virus specific neutralizing antibodies titres as compared to base-line, measured by PRNT. Additional information, including a detailed description of the study design and eligibility criteria is available at ClinicalTrials.gov using identifier NCT03425149.

The Zika virus is a mosquito-borne flavivirus that was first discovered in 1947. The first human cases were detected in 1952. Since then, outbreaks have been reported in tropical Africa, Southeast Asia, the Pacific Islands, and, in 2015, in the Americas.

According to the World Health Organization, there is scientific consensus that ZIKV is a cause of microcephaly and Guillain-Barré syndrome. Since 2013, 31 countries and territories have reported cases of microcephaly and other central nervous system malformations associated with ZIKV infection.

VLA1601 is a highly purified inactivated vaccine candidate against the Zika virus, developed using the same manufacturing platform as Valneva’s IXIARO (JESPECT) Japanese Encephalitis (JE) vaccine. In pre-clinical development, VLA1601 demonstrated excellent purity and had an overall biological, chemical and physical profile comparable to the commercially produced JE vaccine. Valneva has an established manufacturing process in its dedicated clinical JE vaccine facility.