Moderna, Inc. (NASDAQ:MRNA) revealed topline results on Wednesday from a Phase 3 trial evaluating the efficacy of mRNA-1647, the company’s investigational cytomegalovirus (CMV) vaccine. CMV is a herpes virus. Those who are pregnant or have compromised immune systems are most at risk from CMV.
The study did not meet its primary efficacy endpoint of preventing CMV infection in seronegative female participants of childbearing age (16-40 years of age).
Moderna will discontinue its congenital CMV clinical development program.
Also Read: Moderna Reports Promising Response Rates For Skin Cancer Combo Therapy In Resistant Patients
The Phase 3 trial included approximately 7,500 women. Vaccine efficacy against primary CMV infection in healthy women was well below the company’s target, ranging from 6% to 23% depending on the case definition used.
“We are clearly disappointed by the failure to prevent primary infection because it means there is still no vaccine for the prevention of congenital CMV despite the many decades of work by the field,” said Stephen Hoge, president of Moderna. “We will continue to explore the potential of mRNA-1647 to suppress disease associated with reactivation in those high-risk patients through our ongoing Phase 2 study.”
mRNA-1647 was generally well-tolerated regardless of CMV serostatus, with a safety profile consistent with earlier studies.
The Data and Safety Monitoring Board has raised no safety concerns.
The company plans to continue its study of mRNA-1647 in bone marrow transplant patients, which is currently in a Phase 2 trial.
Moderna does not anticipate any impact on its 2025 financial guidance or its expectation of achieving breakeven in 2028.
Moderna anticipated minimal initial revenue contribution from mRNA-1647, given the necessary investments in market building and launch, and expected the product to be cash flow negative in 2028.
William Blair sees the trial’s failure as an incremental setback for Moderna, given low investor expectations following its prior interim analysis miss.
Ironically, this product would have been cash flow negative toward Moderna's maintained breakeven guidance in 2028, which remains a key focus for investors and is something analyst Myles Minter remains cautious about.
William Blair reiterates a Market Perform rating for Moderna.
Price Action: MRNA stock is down 4.15% to $25.74 in the premarket at the last check on Thursday.
Read Next:
Photo: Shutterstock
© 2025 Benzinga.com. Benzinga does not provide investment advice. All rights reserved.
