FDA Accepts NDA & Grants Priority Review to Baloxavir Marboxil to Treat Influenza

The US Food and Drug Administration (FDA) has accepted a New Drug Application (NDA) and granted Priority Review for Genentech’s baloxavir marboxil for the treatment of acute, uncomplicated influenza in individuals aged 12 and older.

“The severity of the recent flu season underscores the need for new options beyond current treatments, and if approved, baloxavir marboxil would be the first flu medicine with a novel proposed mechanism of action in nearly 20 years,” Sandra Horning, MD, Genentech’s chief medical officer and head of Global Product Development, stressed in a recent statement.

A first-in-class, investigational oral medication, baloxavir marboxil, has been developed to hinder the cap-dependent endonuclease protein within the flu virus which is a key player in the virus’ ability to replicate. The drug has been designed to target the flu virus, including resistant strains such as H7N9 and avian strains, such as H5N1.

“Baloxavir marboxil has been shown in clinical trials to decrease the duration of symptoms with 1 dose and demonstrated a significant reduction in viral shedding in just 1 day,” Dr. Horning added. “We look forward to working with the FDA during this review process.”

The acceptance of the NDA was based on promising results yielded in the phase 3 CAPSTONE-1 study, which was a multicenter, randomized, double-blind, placebo-controlled study that assessed the safety and effectiveness of the drug in 1436 participants in the United States and Japan.

Investigators defined the study’s primary endpoint as time to alleviation of symptoms; secondary endpoints consisted of the following: time to resolution of fever, time to cessation of viral shedding, and proportion of participants who were positive for influenza virus titer, or virus levels in the body, by time point.

Compared with placebo, baloxavir marboxil was found to meet the study’s primary and secondary endpoints in that it significantly reduced the duration of flu symptoms by more than 1 day; it significantly reduced duration of fever by more than 1 day; it significantly cut the length of time of viral shedding; and it reduced viral levels in than nose and throat significantly, from 24 hours through 120 hours.

Although similar efficacy results were noted between treatment with baloxavir marboxil and oseltamivir, when it came to duration of symptoms and fever reduction, significant differences were reported regarding reducing the length of time of viral shedding (24 hours versus 72 hours), favoring baloxavir marboxil.

Overall, the drug was found to be well-tolerated in participants and to have less overall incidence of associated adverse events (20.7%) compared with placebo or oseltamivir (24.6%, 24.8%, respectively). The investigators note that diarrhea, bronchitis, nausea, and sinusitis were among the most frequently reported adverse events, but all of them occurred at a lower frequency than those noted with placebo.

Data yielded from a placebo-controlled phase 2 study conducted in otherwise healthy individuals with the flu were also used to support the NDA.

The FDA is expected to make a decision on approval toward the end of this year, December 24, 2018.