Although HIV
entry inhibitors--experimental drugs that aim to
prevent HIV from attaching to and infecting immune
system cells--are being touted as the next major
step forward in HIV treatment, some researchers are
beginning to worry that the drugs may pose safety risks, the
Associated Press reports.
Most of the drugs
in development work to jam a key receptor on the
surface of immune system cells, called CCR5, that HIV
attaches to. Previous research has showed that people
who naturally have non-working CCR5 cell receptors are
somewhat resistant to HIV infection and, if they do
become infected, are unlikely to experience HIV disease
progression to the point of developing AIDS.
But clinical
trials of some of the experimental entry inhibitors have
been called off when study participants began experiencing
severe drug-related side effects, including liver
damage and certain cancers. Worse yet, some
researchers worry that by jamming the CCR5 receptors on
immune system cells, HIV will be forced to adapt to use
another cell receptor, called CXCR4. Studies have
shown that HIV strains that have mutated to primarily
use CXCR4 receptors are much more virulent than CCR5
strains and progress much more quickly to AIDS diagnosis and
disease complications.
"It's a very exciting class and at the same
time, people are approaching it with some
trepidation," Tom Gegeny, executive director of The
Center for AIDS Information & Advocacy in Houston,
told the Associated Press.
"The
clinical development of this class has, in a word, been
challenging," Cornell University AIDS researcher Roy
Gulick told the news agency. (The Advocate)