Moderna has dosed the first subject in the pivotal Phase III CMVictory clinical trial of its cytomegalovirus (CMV) vaccine candidate, mRNA-1647.
mRNA-1647 merges six messenger ribonucleic acids (mRNAs) in a single vaccine that encode for two proteins found on the CMV surface.
Five mRNAs encode the subunits that form the membrane-bound pentamer complex while one encodes the complete membrane-bound glycoprotein B (gB).
CMV requires both the pentamer and gB to infect barrier epithelial surfaces and enter the body, which is the initial stage in CMV infection.
mRNA-1647 can potentially induce an immune response against the pentamer and gB to avert the infection.
The Phase III trial will assess the safety and efficacy of the vaccine against primary CMV infection in women aged 16 to 40 years.
Starting in the US, Moderna intends to recruit roughly 8,000 subjects, including 6,900 women of childbearing age, from nearly 150 centres worldwide.
Moderna has set a target of recruiting a broad group of people from the US in the trial, with 42% of subjects being people of colour.
Functional antigen-specific responses were observed in Phase I and II trials of the vaccine, indicating its potential to avert CMV.
According to the interim, seven-month results from the Phase II trial, the vaccine at dose levels of 50μg, 100μg and 150μg, mRNA-1647 was generally well tolerated.
Furthermore, the 100μg dosage for the Phase III trial was selected based on the data from the interim analysis of the Phase II trial.
Moderna CEO Stéphane Bancel said: “CMV is a complex, latent virus and represents a significant unmet medical need.
“The CDC estimates that one in 200 babies are born with CMV, and approximately one in five of them will have devastating sequelae such as hearing loss, seizures, and blindness.
“This study will allow us to get closer to our goal of addressing this unmet need with a preventative mRNA vaccine against primary CMV infection.”
Earlier this month, Denmark and Sweden decided to suspend the use of Moderna’s Covid-19 vaccine, Spikevax, for younger age groups.