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ViroLogic
Assays Characterize and Identify Potential Treatments for Virulent
Multi-Drug Resistant Strain of HIV
The highly
pathogenic isolate of HIV recently identified in a New
York City resident was characterized at ViroLogic, Inc using its
PhenoSense™, GeneSeq™, and Entry Assays to assess resistance to
all currently available antiretroviral drugs, according to an announcement
from the company.
The isolate
was sent to ViroLogic for more extensive testing after initial evaluation
at the Aaron Diamond AIDS Research Center (ADARC) in New York suggested
that the recently transmitted virus was resistant to three of the
four classes of standard antiretroviral therapy. ViroLogic’s analysis
confirmed the data from ADARC, and importantly, revealed therapeutic
options that informed the selection of a drug regimen for the patient.
Additional
testing was performed using several newer assays developed at Virologic.
The Entry Assay
demonstrated that the virus was susceptible to enfuvirtide
(Fuzeon®), the only commercially available
entry inhibitor drug. The analysis at ViroLogic also identified
the cellular receptors that this virus uses to enter CD4 cells,
the targets of viral infection. The test results indicate that
the virus uses a receptor that has been linked to accelerated immune
destruction and rapid
progression to clinical AIDS.
Viruses with
significant resistance often replicate less well than wild-type
viruses. In this case however, the ViroLogic Replication
Capacity (RC) assay indicated that virus replication
was comparable to most wild-type strains. Replication Capacity
is the focus of intensive study at ViroLogic and preliminary data
indicate that viruses with high RC values are associated with more
rapid
immunosuppression.
“This episode
serves as a sobering reminder of the potential danger of transmitted
resistant viruses,” said David D. Ho, M.D., Scientific Director
and Chief Executive Officer of ADARC in New York and a Professor
at The Rockefeller University.
“This is an
interesting case because it has features that we often see, although
not typically in the same virus. While we see triple-class resistance
fairly commonly in patients with a long history of antiretroviral
drug experience, this case is noteworthy in that a single virus
harbors triple-class resistance, a high RC, and CXCR4 receptor tropism
in the setting of recent infection. The value of having access
to comprehensive drug resistance testing technologies helped to
clarify this patient’s best treatment options.”
“While the
receptor tropism and RC of this virus suggest possible explanations
for the rapid pace of disease progression in this patient, additional
clinical tests regarding the individual patient’s genetic make-up
need to be conducted and are underway. Nonetheless, this appears
to be a virus that is resistant to most antiretroviral drugs, replicates
efficiently, and has led to the rapid onset of AIDS in this patient,”
continued Dr. Ho.
“This case
reinforces the importance of resistance testing in the management
of HIV patients, including those individuals who have not received
prior antiretroviral treatment,” said Michael Bates, M.D., Vice
President of Clinical Research at ViroLogic.
“At ViroLogic, we’re focused on understanding how to use parameters
like resistance, RC and tropism more effectively in patient management.
We continue to define and broaden the clinical utility of ViroLogic's
technology, improving the clinician's ability to optimize the management
of antiretroviral therapy for their patients, and assisting our
pharmaceutical colleagues in developing novel drugs to treat HIV
infection.”
ViroLogic’s
drug resistance test PhenoSense
GT™ combines phenotypic and
genotypic testing into
one assay that is performed using a single patient sample, and is
reported on a single form. This combination assay was developed
to provide physicians with a more comprehensive look at an individual’s
drug susceptibility profile.
Understanding
the clinical utility of Replication Capacity in the management of
HIV-infected patients is currently the subject of a $1.5M grant
awarded to ViroLogic by the National Institutes of Health. The
Tropism Assay is currently being utilized in multiple pharmaceutical
sponsored phase 2 and phase 3 clinical development programs designed
to evaluate the efficacy and safety of inhibitors that block the
ability of HIV to infect new cells.
02/16/05
Source
Virologic,
Inc. ViroLogic Assays Used to Characterize and Identify Potential
Treatments for Virulent Multi-Drug Resistant Strain of HIV. Press
Release. February 16, 2005.
www.virologic.com
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