Moderna Halts Development of Congenital CMV Vaccine After Phase 3 Failure

Moderna, the biotechnology giant known for its mRNA vaccine technology, has announced the discontinuation of its congenital cytomegalovirus (CMV) vaccine program following disappointing results from a large-scale phase 3 trial. The decision marks a significant setback in the company's efforts to expand its vaccine portfolio beyond COVID-19 and highlights the challenges in developing effective preventions for complex viral infections.

Phase 3 Trial Results and Program Discontinuation

The phase 3 trial, which enrolled 7,454 women aged 16 to 40 from 13 countries, aimed to prevent primary CMV infection in women. Despite being well-tolerated, the mRNA-1647 vaccine demonstrated low efficacy, with protection rates ranging from 6% to 23% depending on how CMV cases were defined. These figures fell far short of Moderna's target, leading to the program's termination.

Dr. Stephen Hoge, Moderna's President, expressed disappointment in the outcome, stating, "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." He further elaborated on the unique challenges of the trial, noting that it was "particularly challenging" as it aimed to prevent primary infection from a latent virus rather than preventing symptomatic disease.

Ongoing CMV Research and Financial Implications

While Moderna is halting the congenital CMV program, the company will continue to explore the vaccine's potential in other contexts. A phase 2 trial investigating the vaccine's efficacy in protecting against reactivated CMV in bone marrow transplant patients is ongoing, with results expected by August 2026.

Moderna has assured investors that the discontinuation of the congenital CMV program will not impact its financial guidance for 2025 or its plans to break even in 2028. This statement aims to mitigate concerns about the company's financial stability and long-term prospects in the wake of this setback.

Shifting Focus to Oncology

In light of the CMV program's failure and increasing government scrutiny of mRNA vaccines, Moderna is placing greater emphasis on its oncology pipeline. Dr. Kyle Holen, Moderna's oncology head, recently revealed that the majority of the company's upcoming investigational new drug applications will be in cancer indications rather than infectious diseases.

At the European Society of Medical Oncology (ESMO) meeting, Moderna presented promising phase 1/2 data for its cancer vaccine mRNA-4359 in combination with Merck & Co.'s Keytruda. The results showed an objective response rate of 24% in evaluable patients, encouraging the company to expand its research into lung cancer applications.

As Moderna navigates this strategic pivot, the pharmaceutical industry watches closely to see how the company will leverage its mRNA technology platform to address the complex challenges in oncology and maintain its position as a leader in innovative therapeutics.