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 If mid-stage trial data proves positive, Novavax Inc will be closer
than any drug developer to a vaccine for respiratory syncytial
virus, or RSV, which affects those most with compromised immune
systems - including young infants and the elderly.
An effective vaccine would represent a $1 billion opportunity in the
United States and potentially double that worldwide, said Heather
Behanna, an analyst at Wedbush Securities.
But the complex molecular structure of the virus has proven to be an
issue for drug developers in the nearly 60 years since its
discovery. If the mid-stage trial data disappoints, Novavax will
join a handful of other developers that have failed at this stage.
Most children in the United States will suffer an RSV infection
before their second birthday, according to the Centers for Disease
Control and Prevention.
For most older healthy children and adults, it causes little more
than a common cold, but in high-risk groups it can lead to more
serious lung and airway infections.
It is the leading cause of bronchiolitis, an inflammation of the
small airways, as well as pneumonia in children less than a year
old.
On average, RSV kills fewer people than influenza - between 10,000
and 15,000 elderly Americans a year, compared with 20,000 to 50,000
older adults for flu deaths, according to researcher Dr. Pedro
Piedra of the Baylor College of Medicine, who also serves on
Novavax's scientific advisory board.
However, RSV is the major viral pathogen in infants, killing about
500 infants every year in the United States, Piedra said.
RSV is also responsible for more than 2 million outpatient visits a
year by children under the age of five - a huge drain on the
country's healthcare resources. Novavax estimates hospital costs
associated with RSV in older adults alone costs the U.S. healthcare
system about $23 billion.
With so many cases, Chief Executive Stanley Erck says Novavax's drug
has the potential to be "the largest selling vaccine in the history
of vaccines in terms of revenue". It could be ready as early as
2017, he told Reuters.
Novavax's mid-stage data in the elderly, expected this quarter, aims
to prove that the vaccine can prevent RSV infection in this
population. Meanwhile, the company is also immunizing mothers in a
separate mid-stage trial in an attempt to jumpstart infant immunity.
Data from this study is expected in the third quarter.
SEASONAL VIRUS, BUT NOT THE FLU
In the mid-1960s, developers followed the same strategy that had
worked with influenza: they grew the virus in a lab, killed it and
used the dead cells to develop a vaccine.
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Like the flu, RSV is a seasonal virus. But it proved far different
than the flu. Those exposed in early testing fell sick; a trial in
1966 resulted in the deaths of two toddlers. (http://bit.ly/1h32MRW)
That episode halted trials for many years, said Dr. Leonard Krilov,
Chief of Pediatric Infectious Diseases at Winthrop-University
Hospital in Mineola, New York. As researchers developed a better
molecular understanding of RSV, testing resumed.
Several big companies, including Novartis AG, GlaxoSmithKline Plc
and Bavarian Nordic A/S, are also conducting clinical trials but
Behanna of Wedbush expects Novavax to reach later stages of
development earlier.
MedImmune, now part of AstraZeneca Plc, developed a drug, Synagis,
that can prevent lung infections caused by RSV. It has been used to
treat more than 2 million babies worldwide since 1998, but it cannot
prevent the RSV infection itself.
It is also expensive. The average seasonal cost per patient during
the 2013-2014 RSV season was about $6,400, AstraZeneca said.
Behanna estimated the Novavax vaccine might have a retail cost about
$40 a shot for the elderly and $100 for pregnant American women.
Erck said Novavax was considering tiered global pricing for its
vaccine but that it was too early to provide details.
The mid-stage data could allow Novavax to determine dosage strength
for the elderly and to help design a late-stage trial planned for
this RSV season, which corresponds roughly with winter.
(Reporting by Natalie Grover in Bengaluru; Editing by Robin Paxton
and Bernard Orr)
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