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A
breakthrough Pfizer HIV drug linked to a diagnostic test
may soon be the next milestone along the path to
personalized medicine. Pfizer reported on pivotal trials
of maraviroc Tuesday, February 27 at the 14th
Conference on Retroviruses and Opportunistic Infections. According
to a Reuters report, results showed that adding the drug
to standard therapy doubled the number of patients
achieving viral suppression.
Maraviroc
is one of a new class of anti-HIV agents called CCR5
antagonists. These compounds work not by attacking the
virus but by blocking viral entry into T cells, a critical
step in the development of AIDS. The CCR5 co-receptor is
the T-cell gateway favored by HIV; however, over time, the
virus can also use an alternate route called CXCR4.
Patients are tested for “CCR5 tropism” to see whether
blocking the receptor will make any difference in their
condition.
Monogram
Biosciences’ Trofile test was used in the trials to
select CCR5-tropic patients.
The test was independently developed by Monogram,
because the company saw that several companies were
developing CCR5-targeting drugs. Now, Monogram is
collaborating with Pfizer to make the test available
internationally.
“If
you use this drug and the virus is using the other
receptor, then you are not helping the patient,” said
Monogram CEO William D. Young, speaking Tuesday night at a
special session during Cambridge Healthtech Institute (CHI)’s
Molecular Medicine Tri-Conference. The test is CLIA
approved and must be run at Monogram’s facility.
If
approved, maraviroc will be the first new type of oral
anti-HIV drug to reach the market in the last decade or
so. Because the drug’s use will be tied to a diagnostic,
it also represents a key development in personalized
medicine, which aims to tailor drug treatment more
specifically to individual biology. Biological variation
between patients is one reason why drugs don’t work in
certain people, or can cause side effects in some but not
others.
Maraviroc
is on the accelerated approval track in the
United States
and
Europe. Pfizer submitted the
US
and EU marketing applications in December 2006, and an FDA
Advisory Panel is scheduled for April 24 to review the
drug, which could possibly reach the market by this
summer. Pfizer is also pursuing regulatory approval for
maraviroc in other countries to enable broad access to the
drug.
"This
is the kind of targeted science that underscores our
commitment to research and development in a range of
infectious diseases where there is high human cost due to
drug resistance," said Ethan Weiner, senior vice
president, Pfizer Global Research and Development, in a
February 13 press release from the company.
“Doctors
treating AIDS are leading the world in personalized
medicine,” said Young, speaking at the CHI event.
Copyright
2007, Cambridge Healthtech Institute. All Rights Reserved.
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