Monday, Jun 3, 2019

Phase III Study Showed XOFLUZA (Baloxavir Marboxil) is Effective at Preventing Influenza Infection

Compared with placebo, XOFLUZA treatment significantly reduced the likelihood of people developing influenza (flu) after exposure to an infected household member

Data from the Phase III BLOCKSTONE study will be submitted to health authorities globally

South San Francisco, CA -- June 3, 2019 --

Genentech, a member of the Roche Group (SIX: RO, ROG; OTCQX: RHHBY), today announced that the Phase III BLOCKSTONE study, conducted by Shionogi & Co., Ltd., met its primary endpoint showing that people exposed to a household member with influenza (flu) and treated preventatively with XOFLUZA™ (baloxavir marboxil) were significantly less likely to develop the disease compared to those treated with placebo (1.9% versus 13.6%, p<0.0001). Furthermore, XOFLUZA was well tolerated with no safety signals identified. Full results from the BLOCKSTONE study will be presented at an upcoming medical meeting.

This positive Phase III study adds to robust existing clinical data for XOFLUZA, and is the first to show that a single treatment with XOFLUZA reduced the likelihood that people living with an infected household member would develop the flu,” said Sandra Horning, M.D., chief medical officer and head of Global Product Development. “Preventing otherwise healthy people from developing the flu virus will reduce the overall societal burden of disease, and we look forward to sharing these data with health authorities around the world.

XOFLUZA is the first and only one-dose oral medicine approved to treat the flu, and the first new flu medicine approved by the U.S. Food and Drug Administration (FDA) with a novel proposed mechanism of action in nearly 20 years. XOFLUZA is also the only flu treatment with a new mechanism of action shown to be efficacious in both otherwise healthy people with the flu (in the CAPSTONE-1 study) and people at high risk of flu complications (in the CAPSTONE-2 study).

XOFLUZA is currently approved in Japan for the treatment of influenza types A and B in children, adolescents and adults, and in the U.S. for the treatment of acute, uncomplicated influenza in people 12 years of age and older. In addition, the FDA recently accepted a supplemental New Drug Application (sNDA) for XOFLUZA as a one-dose oral treatment for people at high risk of 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 – for these people the flu can be particularly serious or deadly. The FDA is expected to decide on whether to approve this additional indication by November 4, 2019.


BLOCKSTONE is a Phase III, randomized, placebo-controlled, post-exposure prophylaxis study that evaluated a single dose of XOFLUZA compared with placebo in household members (adults and children) in Japan who are living with someone with an influenza infection confirmed by a rapid influenza diagnostic test (the ‘index patient’). The study was conducted by Shionogi & Co., Ltd. during the 2018-2019 flu season in Japan.

Participants enrolled in the study were household members of someone who had been diagnosed with influenza. The participants were randomized to receive a single dose of XOFLUZA (dose according to body weight) or placebo as a preventative measure against developing influenza. The primary endpoint of the study was to evaluate the proportion of participants who tested positive for the influenza virus and had fever, and one or more respiratory symptoms between day one and ten.

XOFLUZA showed a significant prophylactic effect on influenza infection after a single oral dose in people exposed to an infected family member. The proportion of household members who became symptomatically ill following infection with flu was significantly lower in those treated preventively with XOFLUZA compared to those treated with placebo (proportion of subjects with influenza virus infection, fever and other influenza symptoms in the 10-day observation period: 1.9% versus 13.6%, p<0.0001). The incidence of adverse events was 22.2% and 20.5% in XOFLUZA and placebo respectively. No serious adverse events were reported for XOFLUZA. Secondary objectives were clinical efficacy, pharmacokinetics and safety and tolerability.

About XOFLUZA (baloxavir marboxil)

XOFLUZA is a first-in-class, one-dose oral medicine with a novel proposed mechanism of action that has demonstrated efficacy in a wide range of influenza viruses, including in vitro activity against oseltamivir-resistant strains and avian strains (H7N9, H5N1) in non-clinical studies. Unlike other currently available antiviral treatments, XOFLUZA is the first in a new class of antivirals designed to inhibit the cap-dependent endonuclease protein, which is essential for viral replication.

XOFLUZA is being further studied in a Phase III development program, including pediatric populations and severely ill, hospitalized people with influenza, as well as to assess the potential to reduce transmission in otherwise healthy people.

XOFLUZA was discovered by Shionogi & Co., Ltd. and is being further developed and commercialized globally in collaboration with the Roche Group (which includes Genentech in the U.S.) and Shionogi & Co., Ltd. Under the terms of this agreement, Roche holds worldwide rights to XOFLUZA excluding Japan and Taiwan, which will be retained exclusively by Shionogi & Co., Ltd.

XOFLUZA U.S. Indication

XOFLUZA is a prescription medicine used to treat the flu (influenza) in people 12 years of age and older who have had flu symptoms for no more than 48 hours.

It is not known if XOFLUZA is safe and effective in children younger than 12 years of age or weighing less than 88 pounds (40 kg).

Limitations of Use : Influenza viruses change over time, and factors such as the virus type or subtype, emergence of resistance or changes in viral virulence could diminish the clinical benefit of antiviral drugs. Consider available information on drug susceptibility patterns for circulating influenza virus strains when deciding whether to use XOFLUZA. 

Important Safety Information

Do not take XOFLUZA if you are allergic to baloxavir marboxil or any of the ingredients in XOFLUZA.  

Before you take XOFLUZA, tell your healthcare provider about all of your medical conditions, including if you :

  • are pregnant or plan to become pregnant. It is not known if XOFLUZA can harm your unborn baby.
  • are breastfeeding or plan to breastfeed. It is not known if XOFLUZA passes into your breast milk.

Tell your healthcare provider about all the medicines you take , including prescription and over-the-counter medicines, vitamins and herbal supplements.

Talk to your healthcare provider before you receive a live flu vaccine after taking XOFLUZA.

Take XOFLUZA with or without food. Do not take XOFLUZA with dairy products, calcium-fortified beverages, laxatives, antacids or oral supplements containing iron, zinc, selenium, calcium or magnesium.

The most common side effects are diarrhea, bronchitis, nausea, common cold symptoms (nasopharyngitis) and headache.

XOFLUZA is not effective in treating infections other than influenza. Other kinds of infections can have symptoms like those of the flu or occur along with the flu and may need different kinds of treatment. Tell your healthcare provider if you feel worse or develop new symptoms during or after treatment with XOFLUZA or if your flu symptoms do not start to get better.

Please see the XOFLUZA full Prescribing Information for complete safety information.

You are encouraged to report side effects to Genentech by calling 1-888-835-2555 or to the FDA by visiting or calling 1-800-FDA-1088.

About Genentech in influenza

Influenza, or flu, is one of the most common, yet serious, infectious diseases, representing a significant threat to public health. Since 2010, the Centers for Disease Control and Prevention (CDC) estimates that the flu has resulted annually in 9.3 to 49 million illnesses, 140,000 to 960,000 hospitalizations and 12,000 to 79,000 deaths. Although vaccines are an important first line of defense in preventing the flu, there is a need for new medical options for prophylaxis and treatment. Current antiviral medicines have limitations with respect to efficacy, convenience of dosing and resistance. Genentech is committed to addressing the unmet need in this area through its agreement with Shionogi & Co., Ltd. to develop and commercialize XOFLUZA.

About Genentech

Founded more than 40 years ago, Genentech is a leading biotechnology company that discovers, develops, manufactures and commercializes medicines to treat patients with serious and life-threatening medical conditions. The company, a member of the Roche Group, has headquarters in South San Francisco, California. For additional information about the company, please visit