Moderna has reported positive interim results from the Phase I clinical trial of its mRNA-1647 prophylactic vaccine for cytomegalovirus (CMV).
The vaccine is a combination of six mRNAs that encode for two antigens present on the virus surface. It is developed to induce an immune response aimed at preventing CMV infection.
The randomised, observer-blind, placebo-controlled, dose-ranging Phase I trial assessed the vaccine’s safety and immunogenicity at 30µg, 90µg, 180µg and 300µg dose levels in 169 healthy adults.
CMV-seronegative and CMV-seropositive individuals were enrolled in the trial.
The primary outcome of the study is solicited adverse events (AEs), while anti-CMV neutralising antibody titers against epithelial and fibroblast cell infections are secondary measures.
The interim analysis comprises safety and immunogenicity data of 30µg, 90µg and 180µg doses at three months.
For both seronegative and seropositive volunteers, the vaccine led to a dose-related rise in neutralising antibody titers in the epithelial cell, as well as fibroblast assay.
In the 12 sentinel seronegative subjects who received three doses of mRNA-1647 as part of an earlier arm, the vaccine led to comparatively higher neutralising antibody titers at seven months.
The antibodies were found sustain CMV-seropositive baseline levels for a minimum of 12 months in these participants.
Safety analysis showed the vaccine to be generally well-tolerated, without any associated serious adverse events (SAEs). The most common solicited local AE was injection site pain, while systemic AEs were headache, fatigue, myalgia, chills and fever.
Moderna CEO Stéphane Bancel said: “Given the urgent need for CMV prevention around the world, we believe mRNA-1647 has the potential to be a blockbuster commercial opportunity for Moderna.
“This is the sixth positive Phase I readout for a Moderna investigational prophylactic vaccine, and underscores why I believe our vaccine platform will be an important pillar of our future growth.”
Based on these results, the company will advance the vaccine to a dose-confirmation Phase II trial, which will assess the planned Phase III formulation.