Roche's Xofluza wins FDA nod to prevent flu but hits a snag with bid to reach younger patients

The FDA has approved Xofluza to prevent influenza in people ages 12 years and older following contact with an infected person. (Roche)

Roche’s Xofluza has been approved in the U.S. to treat the flu for two years now, but sales have been languishing as it battles cheap generics of its predecessor Tamiflu. Now, a new FDA green light could add some extra oomph to the drug’s market performance.

As the Northern Hemisphere undergoes a new flu season while fighting the COVID-19 pandemic, the FDA has approved Xofluza to prevent influenza in people ages 12 years and older following contact with an infected person, Roche’s Genentech said Monday. But the company was simultaneously hoping for an approval of a granules formulation to reach younger patients. That didn't come as expected.

The new post-exposure prophylaxis use adds onto Xofluza’s two existing indications in the treatment setting—for uncomplicated influenza and for symptomatic patients who are at high risk of developing flu-related complications.

“With today’s approval, Xofluza is now available as the first single-dose, post-exposure preventive treatment for influenza,” Levi Garraway, Genentech’s chief medical officer, said 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.”

Xofluza’s prophylaxis power was proven in the phase 3 Blockstone study, which was conducted by the drug’s original developer and marketer in Japan, Shionogi. Among about 750 people who were household contacts of 545 influenza patients in Japan, a single dose of Xofluza significantly cut the risk of developing the flu by 86% compared with placebo, according to data published in The New England Journal of Medicine.

Even under more stringent criteria for flu, the drug was still linked to a major 76% reduction. The benefit was also significant in subgroup analyses in people at high risk of developing complications and children under 12 years of age, though the current FDA go-ahead doesn’t include the latter population.

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Since its introduction in October 2018 as the first new flu antiviral with a novel mechanism of action in about 20 years, Xofluza hasn't gained as much traction as Roche would like. In the first quarter, the drug only sold CHF 28 million ($31 million), a far cry from the annual blockbuster level Tamiflu enjoyed before generics launched.

The new label expansion could give Roche a much-needed boost to Xofluza sales. As shown in the Blockstone trial, one confirmed flu patient might come in contact with more than one person in a household, meaning the potential post-exposure prophylactic market could be larger.

However, as Timothy Uyeki, M.D., chief medical officer at the CDC’s influenza division, noted in an editorial accompanying the NEJM study on Blockstone while Japanese patients typically seek medical care for influenza testing soon after symptom onset, in the U.S., “even high-risk patients with influenza may not present within two days” of illness onset or seek treatment at all.

Tamiflu, as a treatment for symptomatic patients, must start within 48 hours, which could at least partly explain its lackluster U.S. sales so far. That low in-time treatment rate also put into question the potential of people seeking it as a prophylactic option.

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Meanwhile, about 74% of the symptomatic patients Blockstone participants contacted were younger than 12 years of age—a population that Xofluza is not yet approved in the U.S.—indicating pediatric use could be a larger market for Xofluza.

Back in March, the FDA accepted a new drug application for Xofluza as granules for mixing with water in patients as young as 1 year of age. Monday, the FDA said it had approved the granules formulation, but apparently only in the tablet form’s existing patient population. 

According to the CDC, each year, millions of children get sick with seasonal flu; thousands are hospitalized, and some children die from the flu. Children and people older than 65 years of age are two large groups of people at higher risk of suffering from severe diseases after influenza infection.

A Genentech spokesperson confirmed to Fierce Pharma that the granules approval is only for patients 12 years of age and older who are unable to swallow or have difficulty swallowing tablets, or who require enteral administration. The company said it’s working on a path forward with the FDA to expand Xofluza’s use for uncomplicated influenza and for post-exposure prophylaxis in children 1 to 12 years of age.

Earlier this month, the European Medicines Agency’s Committee for Medicinal Products for Human Use recommended approving the drug in uncomplicated influenza in patients aged 12 years and older.