Moderna drops mRNA jab for CMV after phase 3 fail

Moderna has decided to halt the development of its mRNA-1647 vaccine for congenital cytomegalovirus (CMV) infections – once touted as a future blockbuster – after it failed the Phase 3 CMVictory trial.

CMV is a common virus, spread by close contact with bodily fluids, with upwards of half of all adults typically infected by middle age. It does not tend to cause any health problems in people who have healthy immune systems.

However, if a woman becomes infected with CMV while she is pregnant, she can pass the infection to her unborn baby – in fact, it is the most common infection transmitted during pregnancy. In some cases, this can cause the child to suffer long-term disability due to birth defects, including hearing loss, or even death in very severe cases.

That makes the case for immunisation of women of childbearing age. However, at the moment there is no approved vaccine.

Moderna's vaccine candidate was being tested in around 7,500 female subjects aged 16 to 40 who tested negative for CMV infections at the start of the trial, but revealed a very disappointing protective efficacy rate of between 6% and 23%, well below the hoped-for level of around 50%.

"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.

He noted that CMV does cause significant disease in other contexts - for example, in patients undergoing bone marrow transplantation - and said Moderna will continue to test mRNA-1647 in high-risk transplant patients in an ongoing phase 2 study.

There's no question that the demise of the vaccine for congenital CMV is a big setback for Moderna, given that the company had forecast sales could have been up to $5 billion a year if it reached the market and was adopted for routine use in immunisation campaigns.

It also adds to the pressure on Moderna's mRNA infectious disease vaccine business, which is facing an increasingly vaccine-sceptic environment in the US, declining sales of its COVID-19 vaccines, now being restricted by the HHS under the Trump administration, and negligible take-up of its new respiratory syncytial virus (RSV) vaccine mResvia.

In July, Moderna announced a plan to lay off 10% of its workforce – more than 800 employees – shortly before reporting a net loss in the second quarter of $800 million on sales that fell 41% to $142 million.

The company, which is due to report third-quarter results on 6th November, said it does not anticipate any impact of the CMV programme's end on its 2025 financial guidance or its plan to achieve breakeven in 2028.

Photo by Alicia Petresc on Unsplash