[AI] Landmark Gene Therapy Provides Vision to Nearly Blind Young Adults

Varun Khosla varun.enjoy at gmail.com
Wed Apr 30 14:46:47 EDT 2008

Breaking News from the Foundation Fighting Blindness


Now They See
Landmark Gene Therapy Provides Vision to Nearly Blind Young Adults

Jean Bennett, M.D., Ph.D.,
lead investigator of the study, with her husband, Albert Maguire, M.D.,
the study's lead surgeon.

Three young adults with virtually no vision can now read several lines
on an eye chart and see better in dimly lit settings thanks to an
innovative gene
therapy aiming to reverse blindness in a severe form of retinitis
pigmentosa known as Leber congenital amaurosis or LCA. One person was
even able to better
navigate an obstacle course several weeks after receiving the therapy.

The three individuals are participating in a Phase I clinical trial at
The Children's Hospital of Philadelphia, which is funded in part by
the Foundation
Fighting Blindness.

"I am overwhelmed with delight. We are delivering vision to people who
were blind. This is the biggest advancement in the 37-year history of
the Foundation
Fighting Blindness," says Gordon Gund, Co-Founder and Chairman of the
Foundation Fighting Blindness. "We have achieved an incredible
milestone in curing
blindness, and this advancement will help pave the way for the
development of gene therapies to treat and cure a variety of retinal
diseases including:
retinitis pigmentosa, Stargardt disease, Usher syndrome, and macular
degeneration. This is a great day for the Foundation and all people
affected by blinding
retinal diseases."

The development of the approach began when a form of LCA was linked to
the RPE65 gene in 1997. Three years later, researchers began giving
vision to dogs
born blind from LCA, including the world-famous Lancelot. More than 50
dogs have been treated and all continue to see well. The Foundation
Fighting Blindness
has been funding this research virtually every step of the way.

Though the Phase I studies are primarily focused on safety, the first
dose used in this study resulted in improved vision. An additional six
will be enrolled in a continuation of this study to evaluate safety
and efficacy of differing doses. The vision improvement in young
adults seen so far
at the lowest dose gives researchers optimism that the treatment may
provide near-normal vision to children in Phase II studies.

Results of the clinical trials, funded in part by the Foundation, were
published on April 28, 2008 in the New England Journal of Medicine.
The journal published
the results of gene therapy trials taking place at CHOP and Moorfields
Eye Hospital in London. A third trial of the gene therapy, sponsored
by the NEI,
is also taking place at the University of Pennsylvania and the
University of Florida.

Jean Bennett, M.D., Ph.D., lead investigator of the CHOP trial,
reports that the team studied three participants, who ranged in age
from 19 to 26. All three
had one eye treated.

Bennett says that all three individuals reported improved vision in
dimly lit environments and in visual acuity in their injected eyes
starting two weeks
after treatment. Nystagmus- the roving eye movement associated with
severe vision loss from LCA- was also reduced in all three

The treatment developed by this team of investigators involves
delivery of a normal RPE65 gene to the retina to augment function of
the defective RPE65
gene that leads to one form of LCA. Twelve different genes that lead
to LCA have been identified.

The gene is delivered using a therapeutic virus known as an
adeno-associated vector or AAV.

Researchers believe the vision improvement from a single injection
will last for many years. In earlier laboratory studies, a single
AAV-based gene therapy
in more than 50 dogs born blind from LCA has been effective for more
than seven years.

This study is being carried out by an international team led by The
University of Pennsylvania, The Children's Hospital of Philadelphia,
the Second University
of Naples and the Telethon Institute of Genetics and Medicine (both in
Italy), and several other American institutions.


Varun Khosla

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