FDA Approves Flu Treatment for Preventative Use After Exposure

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Genentech’s influenza treatment Xofluza® (baloxavir marboxil) has been granted approval by the U.S. Food and Drug Administration for use in people 12 years and older, making it the first single-dose post-exposure prophylaxis strategy approved by the agency.

Xofluza, a first-in-class, single-dose oral medicine, has proven itself effective against several influenza viruses. The drug is the first in a class of antivirals that has been shown to inhibit the cap-dependent endonuclease protein, an essential component of viral replication. Non-clinical, in vitro studies have observed the medicine’s activity against oseltamivir-resistant strains and avian strains, including H7N9 and H5N1.

The FDA gave Xofluza the greenlight as a post-exposure prophylaxis, a treatment strategy that can prevent the flu in people aged 12 and older following immediate contact with someone infected with influenza. Approval was based on findings from the Phase III BLOCKSTONE trial, published in The New England Journal of Medicine.

In the BLOCKSTONE trial, researchers compared Xofluza with placebo as a preventative treatment for adults and children living in the same household as someone with influenza. Treatment with Xofluza was associated with a significantly greater prophylactic effect after only a single oral dose. In fact, only 1% of participants in the Xofluza developed the flu compared with 13% of participants in the placebo arm. Common adverse events associated with Xofluza were diarrhea (3%), bronchitis (3%), nausea (2%), sinusitis (2%) and headache (1%).

The FDA previously approved Xofluza for the treatment of acute uncomplicated influenza in people 12 years of age and older who have experienced the onset of influenza symptoms within 48 hours or less. Genentech is also currently looking for ways to obtain FDA approval for its influenza drug as a treatment for acute uncomplicated influenza in otherwise healthy children up to 12 years of age as well as for the prevention of the flu children who have been recently exposed to influenza.

Genentech hopes the approval of the new treatment will reduce the flu’s impact on the healthcare system during the COVID-19 pandemic.

“With today’s approval, Xofluza is now available as the first single-dose, post-exposure preventive treatment for influenza,” said Genentech’s chief medical officer and head of Global Product Development, Levi Garraway, M.D., Ph.D., in a statement. “We’re hopeful that reducing the burden of influenza may help to mitigate the strain on our healthcare system amid the COVID-19 pandemic.”

The newly approved Genentech treatment, however, is not effective against SARS-CoV-2, the coronavirus that causes COVID-19.

"This expanded indication for Xofluza will provide an important option to help prevent influenza just in time for a flu season that is anticipated to be unlike any other because it will coincide with the coronavirus pandemic," according to a statement made by Debra Birnkrant, M.D., director of the Division of Antiviral Products in the FDA's Center for Drug Evaluation and Research. "Americans will have to be more vigilant than ever as these viruses spread concurrently."

Meanwhile, the global race to approve and distribute a COVID-19 vaccine has started to heat up, with Moderna as well as Pfizer and BioNTech’s vaccines showing approximately 95% efficacy rates against SARS-CoV-2. Pfizer and BioNTech most recently submitted their COVID-19 vaccine trial data to the FDA, hoping to be the first in a series of companies to get an emergency use approval. Both companies have said they can produce up to 50 million vaccine doses by the end of the year and up to 1.3 billion doses by the end of 2021.

Also, the European Medicines Agency has started a rolling review process of Moderna’s mRNA COVID-19 vaccine candidate, following promising findings from the company’s late-stage clinical trial. AstraZeneca’s COVID-19 vaccine has also demonstrated an up to 90% efficacy rate against the virus. As the world watches these vaccines closely, it’s only a matter of time before the FDA reaches a decision as to which candidate will likely receive approval for widescale public distribution.

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