Valneva’s Shigella vaccine has been shown to reduce cases of intestinal infection, hitting the key endpoint of a phase 2 trial.
The French vaccine company paid 10 million euros ($10.7 million) upfront to LimmaTech back in 2024 for the rights to the tetravalent bioconjugate vaccine, called Shigella4V2.
In the phase 2 controlled human infection model (CHIM) study in the U.S., which was sponsored by LimmaTech, 120 healthy adults aged 18 to 50 years received two doses of S4V2 or placebo one month apart. Around a month after the second dose, participants were challenged with the Shigella sonnei 53G strain.
The results demonstrated a statistically significant reduction in cases of shigellosis—the intestinal infection caused by Shigella bacteri—among participants who received S4V2 compared to placebo, hitting the study’s primary endpoint.
Valneva didn’t offer detailed data on the win, instead saying that it is conducting additional analysis of the vaccine’s efficacy and immunogenicity.
The Lyon, France-based company announced the results alongside another mid-stage study, this time in Kenya, which evaluated two dose of levels of S4V2 against a meningococcal vaccine in 110 infants aged nine months. That trial showed a “favorable safety and tolerability profile across both dose levels” with adverse events tending to be mild to moderate in severity and at similar rates across the control groups, Valneva said.
Data from that study provided “encouraging evidence of immunogenicity and antibody persistence while highlighting the need for further evaluation of dose selection and vaccination scheduling to optimize the breadth and robustness of the immune response,” the company concluded.
There are no approved Shigella vaccines, despite shigellosis being the second leading cause of fatal diarrheal disease worldwide.
S4V2 is the world’s most clinically advanced tetravalent bioconjugate vaccine candidate against shigellosis, noted Valneva, which said it is evaluating the complete datasets of the phase 2 studies to “determine the most appropriate path forward for the potential first-in-class vaccine candidate.”
“These studies provide important clinical data on the safety, immunogenicity and preliminary efficacy of the S4V2 vaccine candidate,” Valneva CEO Hanneke Schuitemaker, Ph.D., said in a Nov. 9 release.
“The favorable safety profile observed across both studies, together with the immune responses seen in infants and the achievements of the predefined primary endpoint in the CHIM study, represent positive and encouraging results while underscoring the need for further clinical evaluation and optimization,” Schuitemaker said. “We will complete the assessment of the full datasets to inform the design of the next steps of clinical development for the vaccine candidate.”
Shigella4V2’s story began at LimmaTech, which spun out from GlycoVaxyn after its 2015 acquisition by GSK. When GSK acquired GlycoVaxyn, the candidate was added to the pipeline and LimmaTech was offered a research agreement to develop new bioconjugate antigen-based vaccines in partnership with the U.K.'s non-profit Wellcome Trust. GSK handed back the candidate in 2023, citing plans to prioritize its own vaccine for the bacteria, before Valneva picked the vaccine up the following year.
Valneva —whose products include the Japanese encephalitis shot Ixiaro and the cholera vaccine Dukoral—laid off 15% of its workforce earlier this year as the company navigated a drop in travel vaccine uptake. The biopharma remains hopeful for a positive FDA decision for its FDA-partnered Lyme disease vaccine, despite mixed phase 3 data.