Novel flu drug that kills the virus in 1 day get clearance in Japan

Japanese pharmaceutical company Shionogi claims that treatment with baloxavir marboxil, effectively kills influenza A and B virus in just 24 hours as opposed to the current user oseltamivir (sold under the brand name Tamiflu), which takes 72 hours to kill the virus.

Japan’s health ministry recently approved the drug and will be sold under the brand name Xofluza.

This is a welcome announcement in healthcare and pharma industry, in the midst of worst Flu season that the USA has experienced. Probably it could make the next flu season safer.  

Baloxavir marboxil prevents the replication of the virus by cap-dependent endonuclease activity of the viral polymerase unlike the existing drug oseltamivir (Tamiflu, Genentech), which acts by inhibiting the neuraminidase enzyme.

It’s prescription as single dose treatment irrespective of age greatly improves patients’ compliance as opposed to the twice-daily dose of oseltamivir for 5 days.

Baloxavir marboxil was tested in a randomized, double-blind, parallel-group, multicenter, placebo- and active-controlled study (CAPSTONE-1), which enrolled 1,436 otherwise healthy patients diagnosed with influenza. 

These patients with age between 20-64 years were randomized in a ratio of 2:1:2 to receive a single 1-time oral dose of 40 or 80 mg of baloxavir marboxil based on body weight or a placebo, or 75 mg BID of oseltamivir for 5 days.

Patients between 12-19 years of age were given baloxavir marboxil based on body weight. Those who weighed less than 80 kg received 40 mg of the drug while patients weighing more than 80 kg were given 80 mg.

The trial results showed that:

•   Patients who received Baloxavir marboxil had significantly lower viral titer at 1, 2 and 4 days
• Viral shedding in Baloxavir marboxil group was significantly less at 24 hours as compared to 72 hours in patients on oseltamivir and 96 hours in patients on placebo.
• The patients in the study group were afebrile in 24 hours vs 42 hours in the placebo group.
• The time to alleviation of symptoms (TTAS) was significantly shortened in the study group (53.7 hours) vs (80.2 hours) in the placebo group (p<0.0001). 
• The new drug was also well tolerated with significantly fewer side effects (20.7%) as compared to placebo (24.6%) or oseltamivir (24.8%).  

Shionogi is currently conducting another phase 3 trials with the drug in patients who are at high risk for Influenza.

Following the approval by Japanese health ministry in February, the drug could be on sale in Japan as early as May.

The head of co-developer Roche's pharma unit, Daniel O'Day, told Bloomberg, "The advantage is that it's one pill once, versus a course of therapy, so particularly for pandemic planning, this could be an advantage, you don't have the potential resistance that comes with not completing your course of therapy."

Shionogi and the Tamiflu maker Roche share the rights to sell Baloxavir marboxil in international market, but it will be almost a year before the drug enters US market.

Shionogi News Release