Moderna cries foul as FDA blocks filing of mRNA flu shot

 The FDA has refused to accept Moderna's marketing application of an mRNA-based seasonal influenza vaccine, and said the decision is "inconsistent" with its prior interactions with the regulator about the programme.

The refusal-to-file (RTF) letter is the strongest signal yet of the seismic impact that changes in US federal government policy are having on vaccine developers – and particularly those focused on mRNA shots – under the leadership of vaccine-sceptic HHS Secretary Robert F Kennedy Jr.

According to Moderna, which used a valuable priority review voucher to speed up the FDA's review, the agency has said that the choice of a licensed standard-dose seasonal influenza vaccine comparator in its main clinical trial of the mRNA-1010 vaccine was "the sole reason for the refusal to initiate the review."

Signed by Vinay Prasad, director of the FDA's Center for Biologics Evaluation and Research (CBER), the RTF suggested that use of the active comparator meant that it was not an "adequate and well-controlled" trial as it included a comparator arm that "does not reflect the best-available standard of care."

Kennedy – who cut $500 million in federal funding for mRNA vaccines last year and questioned their efficacy and safety – said last year that he planned to require placebo-controlled safety testing of all new vaccines before licensing, calling this a "radical departure from past practices."

That triggered debate about the scope of the plan and the potential for it to include annually updated vaccines like COVID-19 and flu, moving the goal posts for jabs that for many years have been tested on the basis of non-inferiority to current options.

Emboldened by Kennedy's stance, several US states have introduced legislation to ban or restrict mRNA vaccines.

In its statement, Moderna points out that there is nothing in US regulations or FDA guidance that contains "any reference to the use of a comparator reflecting the 'best-available standard of care'," and the agency raised no concerns about safety or efficacy. It also said that the RTF runs counter to advice it had from the regulator in 2024 and 2025.

"It should not be controversial to conduct a comprehensive review of a flu vaccine submission that uses an FDA-approved vaccine as a comparator in a study that was discussed and agreed on with CBER prior to starting," said Moderna CEO Stéphane Bancel. The company has published a redacted version (PDF) of the letter on its website.

In clinical trials, mRNA-1010 was shown to be 26.6% more effective than the comparator flu shot in adults aged 50 years and older. mRNA-based flu vaccines, which can be produced rapidly, have the potential advantage of more precisely matching circulating strains.

Moderna has requested a meeting with the FDA to discuss the RTF and said that mRNA-1010 remains under regulatory review in the EU, Canada, and Australia.

https://pharmaphorum.com/news/moderna-cries-foul-fda-blocks-filing-mrna-flu-shot