At Day 28, 100% seroconversion rate was achieved in a pooled analysis of all participants who received a single vaccination of VLA1553.
As of 2017, there have been more than 1 million reported cases of chikungunya in the Americas. There are no approved treatments or vaccines for the mosquito-borne viral disease, but Valneva SE recently reported favorable phase 1 interim results for their vaccine candidate VLA1553.
VLA1553 is a monovalent, single dose, live-attenuated vaccine being developed to protect against chikungunya and was granted Fast Track designation by the US Food and Drug Administration in December 2018.
The phase 1 clinical trial to assess the safety and immunogenicity profile of the candidate was launched in March 2018. The trial is a randomized, observer-blinded, multicenter dose-escalation phase 1 clinical trial that is assessing 3 dose levels of the candidate following a single immunization.
The interim results include data from the first 28 days following vaccination.
A total of 120 healthy volunteers from the United States who were between the ages of 18 and 45 were enrolled in the trial. At enrollment, participants were randomly assigned into 1 of 3 different study groups. Half of the participants (n = 60) were randomized into either the low dose or medium dose groups, and the other 60 participants were randomized into the high dose group.
The interim results indicated that 100% seroconversion rate was achieved at Day 28 in a pooled analysis of all vaccinated groups. Additionally, the company reported that 96.5% of the subjects achieved at least a “15-fold increase in antibody titers and a high geometric mean titer, supporting the candidate’s differentiated target product profile.”
Some of the study participants reported systemic adverse events, including short-term fever, headache, and fatigue. “[T]ransient cases of reduced levels of neutrophils, lymphocytes, or leucocytes without clinical symptoms,” were also reported, according to a statement from Valneva SE.
Overall, the study investigators reported that the vaccine was well tolerated and no serious adverse events or adverse events of special interest were reported at Day 28.
The trial protocol includes revaccination at month 6 or month 12 to confirm that a single vaccination will be sufficient to induce high titer neutralizing antibodies and protect subject from chikungunya infection.
Study participants will be followed for 13 months after initial vaccination.
According to a statement issued by the company, phase 1 revaccination data following month 6 is expected by mid-2019. These data will include additional information on whether the clinical trial participants are protected from chikungunya viremia, which will allow the company to determine the final dose for development.
VLA1553 is being designed for prophylactic, active, single-dose immunization against chikungunya in humans 1 year or older. The objective for the vaccine is to provide lasting protection and an anticipated safety profile similar to licensed vaccines for active immunization in adults and children.
According to the company, the target populations for this vaccine are travelers, military personnel, and individuals who live in regions where chikungunya is endemic.
In pre-clinical development, a single-vaccination of VLA1553 was shown to be highly immunogenic in vaccinated nonhuman primates. Additionally, the company reported an antibody response that was measured to last more than 300 days, along with a good safety profile.