JUNE 27, 2018
Next
winter, there may be a new drug for people who contract influenza — one that
appears to be able to shut down infection quickly and, unlike anything else on
the market, can be taken as a single dose.
The Food
and Drug Administration on Tuesday said that it would give the drug, baloxavir
marboxil, a priority review, and
approval has the potential to upend the way influenza is treated.
Baloxavir
marboxil has already been licensed in Japan, where it is sold by Shionogi &
Co. under the brand name Xofluza. Roche bought most of the global rights to the
drugs — Shionogi retains the rights in Japan and Taiwan — and Genentech, a
Roche company, is developing the drug for the U.S. market.
GENENTECH
The FDA
has told Genentech that it will issue a decision on baloxavir marboxil within
six months — in other words, before Christmas.
The drug
has been shown to reduce the duration of flu symptoms by a little more than a
day — most uncomplicated flu infections only last a few days — and reduce the
duration of fever by nearly a day. It also substantially cut the length of time
people sick with influenza were coughing and sneezing out viruses — a potential
benefit for the people around those sick individuals.
Here’s
what you need to know about this drug.
Why the
buzz
A
single-dose drug that is potent and fast-acting is significant.
Any time
you can make a drug easier to take, the chances that people will actually take
it — and take it properly — go up. Public health authorities actually think flu
drugs are underutilized, so a drug that works well and has more appeal to
doctors and patients would be an advance.
The other
flu drug people might know about, Tamiflu, is given as two pills a day for five
days.
Secondly,
this drug works differently from all the other — and there aren’t that many
other — flu drugs on the market. It is an endonuclease inhibitor; this is the
first new class of influenza drugs to hit the market in over two decades.
There are
only two other classes of flu drugs, neuraminidase inhibitors (drugs like
Tamiflu, Relenza, Rapivab) and the adamantane drugs (amantadine and
rimantadine). The latter class is not recommended for use because flu viruses
quickly develop resistance to them.
New drug
classes are always a welcome development because they provide a hedge if flu
viruses develop resistance to existing drugs. “Just relying on essentially one
class of drug for something that can have the public health impact that
influenza can have is crazy,” said Richard Webby, head of the World Health
Organization’s influenza collaborating center at St. Jude Children’s Research
Hospital in Memphis. “So I think the more compounds we can have, the better.”
Another
class of flu drugs also opens up the possibility of using drugs in combination
to reduce the risk that viruses will develop resistance to the drugs, said
Webby, who has studied another experimental drug in this class but is not
involved in bringing baloxavir marboxil to market.
How it
works
The drug
interferes with a key step in the flu infection process. Flu viruses invade the
cells in the human respiratory tract and use those cells as mini factories to
pump out swarms of copies of themselves that then break out of those cells to
infect others.
Endonuclease
inhibitors stop that copying process.
Who it
will likely be licensed for
Mark
Eisner, Genentech’s vice president of product development for immunology,
infectious diseases, and ophthalmology, said the clinical trial used to prove
the drug worked enrolled subjects 12 years of age and older. So it’s likely if
the FDA approves the drug, it will be approved for the same patient population.
Additional
studies will be done to test the drug’s safety and effectiveness in younger
children. Others will test to see if the drug benefits people who are
hospitalized with severe influenza infections.
When it
will hit the market
If the
FDA approves baloxavir marboxil, will it be available next flu season? Maybe.
“We are
working very hard to make it available as soon as possible after approval. And
we will work with FDA to do everything we can to expedite [availability],”
Eisner said.
The big
unknown
The price
set for this drug will be crucial. How much are people willing to spend to cut
a day or so off of a bout of flu?
Genentech
said it’s too early to comment on what the cost of the drug might be. In
Japan, the drug sells for the equivalent of about $43.50.
A related
unknown
Tamiflu
and the other drugs in its class never got the market acceptance in the U.S.
that their manufacturers hoped and public health authorities expected them to
get.
The
reason: There has been a perception that the benefits — a little less time in
bed — don’t justify trying to get a doctor’s appointment, get to the doctor’s
office, and then find a pharmacy with the drug in stock. Many doctors also are
underwhelmed by the drugs, and aren’t inclined to prescribe them.
Then
there is the issue of the treatment window. Neuraminidase inhibitors work best
if treatment starts within 48 hours of symptom onset. After that, in cases of
uncomplicated flu, you’re into the realm of diminishing returns given that most
patients’ symptoms will begin to dissipate on their own.
Baloxavir
marboxil also needs to be taken within that 48-hour window — or at least that’s
what is known about the drug now, Eisner said.
The
question for the new drug will be: Does the prospect of a fast-acting, one-dose
treatment override skepticism over flu drugs? Webby said it’s possible the
“one-and-done” nature of the drug could increase usage.
Correction: An earlier version of this story
misspelled the drug name baloxavir marboxil.
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