On Mar. 3, 2020, Moderna announced that enrollment was complete for all three dose cohorts of the Phase 2 dose-confirmation study of its investigational cytomegalovirus (CMV) vaccine (mRNA-1647). mRNA-1647, the first mRNA vaccine for an infectious disease to enter a Phase 2 study, was a wholly owned program in Moderna’s prophylactic vaccines portfolio.

On January 9, the Company announced positive seven-month interim safety and immunogenicity data after the third and final vaccination of the 30, 90, and 180 μg dose level cohorts of the Phase 1 study, which built on the previously reported three-month interim analysis, after two vaccinations. The first interim analysis of the Phase 2 study is expected in the third quarter of 2020.

mRNA-1647 comprises six mRNAs encoding two antigens in one vaccine and is designed to protect against CMV infection. Of the six mRNAs, five encode the subunits of the CMV pentamer complex and one mRNA encodes the glycoprotein B (gB) protein, both of which are highly immunogenic. Both pentamer and gB proteins are essential for CMV to enter epithelial cells, which is the first step in CMV infection. mRNA-1647 is designed to produce an immune response to both pentamer and gB antigens to prevent CMV infection. There is no approved vaccine for CMV.