Japan's Love for Genentech’s Xofluza Flu Treatment May Be Waning
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When the U.S. Food and Drug Administration (FDA) approved Genentech’s Xofluza, a single-dose treatment for the flu, it was met with great fanfare, particularly in Japan, where the treatment was first discovered.
Since its approval in October 2018, the first new flu treatment approved by the FDA in nearly 20 years, the treatment has been slow to be adopted in the United States. From the time it was approved to the end of the year, Xofluza earned Genentech about $13 million in the United States. Many doctors are still prescribing Tamiflu, Genentech’s other leading flu treatment.
But, it’s a different story in Japan. During the same three month period of 2018, Xofluza garnered about $90 million in revenue. In Japan, the medication has been embraced as a one-shot treatment that can turn symptoms around in about 24 hours. Many doctors in Japan have billed the drug as something of a “silver bullet,” according to the Wall Street Journal. There is anecdotal evidence of people feeling better within hours of taking Xofluza, the Journal said.
However, there’s no real silver bullet when it comes to treating an illness. And researchers in Japan have already announced the discovery of several flu strains that seem to be resistant to Xofluza’s efficacy. That announcement has led several doctors to either slow down or halt prescribing the drug to patients during the flu season, according to the report.
The Journal reached out to Genentech about the concerns of the Japanese physicians. The South San Francisco-based Genentech, a subsidiary of pharma giant Roche, said the strains of the flu that seem to be resistant to the medication had “reduced susceptibility” to Xofluza. However, by U.S. regulatory standards, Xofluza still had an effect on those strains of the flu, the Genentech spokesperson told the Journal. The company did say that further study is needed “to determine the extent of the problem and the transmissibility of the mutant strains.” A study on how Xofluza can affect the spread of the flu is beginning this year, the Journal reported.
When Xofluza was approved in the U.S., Sandra Horning, Roche’s chief medical officer and head of global product development, said that if patients see their doctors within 48 hours of symptom onset, “one dose of Xofluza can significantly reduce the duration of flu symptoms.”
The FDA approved Xofluza based on data from the CAPSTONE-1 study. In that clinical trial, Xofluza demonstrated a clinically significant benefit over placebo in otherwise healthy people with influenza. Xofluza (baloxavir marboxil) reduced the time that the virus continued to be released, called viral shedding, and also reduced viral levels in the body. In non-clinical studies, Xofluza demonstrated efficacy against a number of flu viruses, including oseltamivir-resistant strains and avian strains (H7N9, H5N1).