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 HIV drugs called nucleoside reverse transcriptase inhibitors
(NRTIs), including AZT and three others, blocked age-related macular
degeneration in mice and worked well in experiments involving human
retinal cells in the laboratory, researchers said on Thursday.
In HIV-infected people, NRTIs block an enzyme the virus uses to
create more copies of itself. The new research shows the drugs also
block the activity of a biological pathway responsible for
activating inflammatory processes in the body.
It is that previously unrecognized quality that makes NRTIs
promising for treating macular degeneration as well as
graft-versus-host disease, a rarer ailment that can occur after a
stem cell or bone marrow transplant, the researchers said.
University of Kentucky ophthalmologist Dr. Jayakrishna Ambati, who
led the study published in the journal Science, said macular
generation affects an estimated 50 million people worldwide.
"With the aging of the population, it is projected to affect 200
million people by the year 2020. It is therefore critical that we
develop new and improved treatments for this disease, which is
growing like an epidemic," Ambati said.
Macular degeneration causes cells to die in the macula, a part of
the eye located near the center of the retina that permits vision in
fine detail.
The chronic disease has two forms: "dry" and "wet." Several
treatments exist for "wet" macular degeneration but only about a
third of patients get significant vision improvement. There are no
approved treatments for the "dry" form, which is much more common
but less severe.
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The "wet" type occurs when abnormal blood vessels grow under the
macula and leak blood and fluid. The "dry" form occurs when cells in
the macula break down.
In the new study, the NRTIs blocked a powerful collection of
proteins that can kill cells in the retina, preserving vision in
mice.
Researchers are planning for clinical trials in the coming months
and it could be known in as soon as two to three years whether the
drugs are effective in treating macular degeneration in people,
Ambati said.
Because these inexpensive drugs are already approved by the U.S.
Food and Drug Administration and have a good safety record, they
could be "repurposed" rapidly to treat other illnesses, he added.
(Reporting by Will Dunham; Editing by Frances Kerry)
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