Genentech announces Phase III study results of baloxavir marboxil in people at high risk of flu

Reviewed by James Ives, M.Psych. (Editor)Oct 4 2018

Genentech, a member of the Roche Group, today announced that the Phase III CAPSTONE-2 study showed treatment with baloxavir marboxil significantly reduced the time to improvement of influenza symptoms versus placebo (median time of 73.2 hours versus 102.3 hours; p<0.0001) in people at high risk of serious complications from the flu, which includes adults 65 years of age or older, or those who have conditions such as asthma, chronic lung disease, morbid obesity, or heart disease. Baloxavir marboxil was well-tolerated and no new safety signals were identified. Results of the study will be presented as a late-breaking oral presentation during IDWeek 2018 in San Francisco, California on Saturday, October 6, 2018 (Abstract #LB16). Baloxavir marboxil was discovered and developed by Shionogi & Co., Ltd., and is sold in Japan under the trade name Xofluza^®.

"This is the first Phase III trial to demonstrate a significant, clinically meaningful benefit in people at high risk for complications from the flu for which there are no currently approved medicines," said Sandra Horning, M.D., chief medical officer and head of Global Product Development. "This study adds to the growing body of evidence supporting baloxavir marboxil as a potential first-in-class antiviral flu treatment, and we plan to discuss these data with health authorities around the world."

The CAPSTONE-2 study also showed that baloxavir marboxil demonstrated efficacy (reduced time to improvement of influenza symptoms) in influenza type A/H3N2 (median time of 75.4 hours and 100.4 hours; p<0.05) and type B (median time of 74.6 hours and 100.6 hours; p<0.05) versus placebo. In addition, results for the overall patient population of the study showed numerically shorter time to improvement of influenza symptoms of baloxavir marboxil versus oseltamivir with a median time to improvement of symptoms of 73.2 hours for baloxavir marboxil compared with 81.0 hours for oseltamivir (p=0.8347). In the subpopulation of people with influenza type B, a subgroup where some antiviral treatments have shown only limited efficacy or inconclusive data, baloxavir marboxil was significantly more efficacious than oseltamivir in reducing the time to improvement of symptoms (median time of 74.6 hours versus 101.6 hours; p<0.05).

Baloxavir marboxil demonstrated efficacy compared to placebo and oseltamivir for key secondary endpoints, including reducing the time that the virus continued to be released from the body (viral shedding; median time of 48.0 hours for baloxavir marboxil versus 96.0 hours for both placebo and oseltamivir; p<0.0001). Baloxavir marboxil also reduced the use of antibiotics and incidence of influenza-related complications (3.4 percent and 2.8 percent respectively) compared to placebo (7.5 percent and 10.4 percent; p=0.01 and p<0.05). Baloxavir marboxil had a numerically lower overall incidence of reported adverse events (25.1 percent) compared with placebo (29.7 percent) or oseltamivir (28.0 percent).

Baloxavir marboxil is a single-dose, investigational oral medicine that represents the first of a new class of antivirals with a novel proposed mechanism of action that differs from other currently available treatments. Baloxavir marboxil has already demonstrated a clinically significant benefit over placebo in otherwise healthy people with influenza in the Phase III CAPSTONE-1 study. The U.S. Food and Drug Administration (FDA) accepted a New Drug Application (NDA) and granted Priority Review to baloxavir marboxil as a single-dose, oral treatment for acute, uncomplicated influenza in people 12 years and older based on the results from CAPSTONE-1 and an earlier Phase II study. The FDA is expected to make a decision on approval by December 24, 2018. If approved, baloxavir marboxil will be the first single-dose oral antiviral, and the first medicine with a novel proposed mechanism of action to treat the flu in nearly 20 years.

Genentech also announced that they have entered into a private-public partnership with the Biomedical Advanced Research and Development Authority (BARDA) of the U.S. Department of Health and Human Services (HSS), to advance the development of medicines for infectious diseases for which there is a significant unmet need. As part of the agreement, BARDA will provide funding that will support the development of baloxavir marboxil for severely ill hospitalized people with influenza, with the potential for funding of other studies.