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 Takeda
Pharmaceutical Co Ltd plans to seek approval for the experimental
vaccine first in countries where the virus is endemic, rather than
starting with the United States or Europe, whose rigorous reviews
are often used as a benchmark worldwide, company executives told
Reuters.
The strategy mirrors one used by Sanofi SA, which licensed the
world's first dengue vaccine, Dengvaxia, in endemic markets in 2015
before attempting to get approval from Western regulators, and
forecast up to $1 billion in annual sales.
But the drugmaker failed to hit that target. In late 2017, Sanofi
disclosed that Dengvaxia could increase the risk of severe dengue in
children who had never been exposed to the virus, triggering a
government investigation in the Philippines where 800,000 school-age
children had already been vaccinated.
Fallout from Sanofi's vaccine has raised the bar for demonstrating
the safety of future dengue vaccines.
Takeda officials are banking on a different result, hopeful that
their approach will help avoid the setbacks that Sanofi experienced.
On Tuesday, Takeda said its vaccine was effective at preventing all
four types of dengue, meeting the main goal of its late-stage
clinical trial. The company said no significant safety concerns have
emerged, raising hopes it may be the next viable vaccine for the
tropical virus that kills up to 25,000 people each year.
Takeda will first seek approval in each of the eight countries where
its clinical trial took place: Brazil, Colombia, Panama, Dominican
Republic, Nicaragua, Philippines, Thailand and Sri Lanka.
"We're still expecting to go first to dengue-endemic countries with
a dossier because we think this is where the vaccine's most
important use is," Derek Wallace, who runs Takeda's global dengue
vaccine program, told Reuters.
VACCINE FUTURE
The success of TAK-003 is crucial to Takeda's vaccine ambitions as
the Japan-based drugmaker integrates its $59 billion purchase of
Shire Plc.
"The global business was predicated on global products and a global
pipeline," Dr. Rajeev Venkayya, president of Takeda's vaccines
business, said in a telephone interview.
Under pressure to cut costs after the Shire deal, Takeda needs a
strong performance from both its dengue and norovirus experimental
vaccines to prove the viability of the global vaccines business.
"Once those two programs declare themselves, we’ll then map out what
our future looks like," Takeda research chief Andy Plump said in an
interview last month. Venkayya said he is encouraged by the results
so far.
Dengue experts have questioned whether Takeda's vaccine may pose
similar risks to Dengvaxia, and the results released on Tuesday were
not detailed enough to provide answers.
Takeda executives said they had taken steps to ensure their vaccine
did not run into the same issues.
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Takeda's TAK-003 is based on a dengue 2 virus, with genes from the
remaining three dengue viruses added in. Dengvaxia is based on a
yellow fever virus with dengue genes added in. Takeda hopes the
all-dengue design will trigger a more robust immune response.
Unlike Sanofi, Takeda researchers took blood samples from all 20,000
trial participants before they received the vaccine. That should
allow them to see differences in the vaccine's performance in people
who had a previous dengue infection versus those who had not,
according to dengue experts.
Takeda delayed the release of its trial results for several weeks to
characterize the immune responses of all participants. The company
expects some of that data will soon be published in a peer-reviewed
medical journal.
SANOFI'S REGRET
Earlier this month, Sanofi vaccines chief David Loew told
FiercePharma that the company regretted launching Dengvaxia in
emerging markets before it was reviewed by the U.S. Food and Drug
Administration or the European Medicines Agency. It was the first
time Sanofi had taken such an approach with a vaccine, he said.
"Other regulatory authorities often look to the FDA and EMA for
their own guidelines," Loew told Reuters via email.
To share its data with endemic countries and answer questions on
Dengvaxia, Sanofi took part in a three-day meeting hosted by the
World Health Organization and the Dengue Vaccine Initiative in July
2015. Regulators from seven countries where dengue poses the biggest
threat, including the Philippines, were there.
Dengvaxia has since won European approval for people living in
endemic areas who have a documented prior infection. The vaccine is
also under FDA review.
Dr. Joachim Hombach, senior health adviser in WHO's vaccine
department, said that governments in dengue-endemic countries in
Latin America and Asia are now "highly sensitized" to the potential
risks in the wake of Dengvaxia.
"We will be looking at this very carefully," Hombach said of
Takeda's data.
Takeda is undeterred.
The company plans to file in the U.S. and Europe within a year of
filing in dengue-endemic countries, Venkayya said. Takeda and dengue
experts are already planning ways to review the latest vaccine data
with those regulators.
The Global Dengue & Aedes-Transmitted Diseases Consortium (GDAC), a
group funded in part by drugmakers that works closely with WHO,
scheduled a meeting for early March in Bangkok with regulators from
at least six countries to take a first look at Takeda's results,
said Dr. In-Kyu Yoon, director of GDAC.
Yoon said the meeting will be paid for by the International Vaccine
Institute, funded largely by charities and the Korean government. He
plans to ask countries whether they want a joint regulatory review
similar to the one Sanofi attended in 2015.
"Right now, there is clearly some caution," Yoon said.
(Reporting by Julie Steenhuysen; Editing by Michele Gershberg and
Edward Tobin)
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