for a progressive form of blindness. Other
gene therapies in development point to
a cure for hemophilia and relief from an
incapacitating skin disorder called epider-molysis bullosa.
Fixing rare diseases, impressive in
its own right, could be just the start.
Researchers are studying gene therapy in
clinical trials for about 40 to 50 different
diseases, says Maria-Grazia Roncarolo, a
pediatrician and scientist at Stanford Uni-
versity who led early gene-therapy experi-
ments in Italy that laid the foundation for
Strimvelis. That’s up from just a few con-
ditions 10 years ago. And in addition to
treating disorders caused by malfunctions
in single genes, researchers are looking to
engineer these therapies for more com-
mon diseases, like Alzheimer’s, diabetes,
heart failure, and cancer. Harvard geneti-
cist George Church has said that someday,
everyone may be able to take gene therapy
to combat the effects of aging.
Early gene therapies failed in part
because of the delivery mechanism. In
1990, a four-year-old girl with a form
of SCID was treated by scientists at
the National Institutes of Health, who
extracted white blood cells from her,
inserted normal copies of her faulty gene
into them, then injected her with the corrected cells. But patients later treated for a
different type of SCID went on to develop
leukemia. The new genetic material and
the virus used to carry it into cells were
delivered to the wrong part of the genome,
which switched on cancer-causing genes
in some patients. In Gelsinger’s case, the
virus used to transport functioning genes
into his cells made his immune system go
into overdrive, leading to multiple organ
failure and brain death.
Gene-therapy researchers have surmounted many of those early problems
by using viruses that are more efficient
at transporting new genetic material into
But several challenges remain. While
gene therapies have been developed for
several relatively rare diseases, creating
such treatments for more common diseases that have complex genetic causes
will be far more difficult. In diseases like
SCID and hemophilia, scientists know the
precise genetic mutation that is to blame.
But diseases like Alzheimer’s, diabetes,
and heart failure involve multiple genes—
and the same ones aren’t all involved in all
people with those conditions.
Nonetheless, for Kala and Philip Looks,
the success of gene therapy is already real.
A treatment they had never heard of rid
their child of a horrific disease.
2017 OR 2018
A gene therapy for an inherited
disease could be approved in the
U.S. for the first time.
European regulators approve
Strimvelis, the second gene
therapy for an inherited disease,
to treat a type of SCID.
Patients with an inherited
retinal disease called Leber’s
congenital amaurosis appear
to have improved vision
after treatment with a gene
therapy. However, years later,
researchers will report in the
New England Journal of Medicine
that some patients’ eyesight has
begun to wane.
The European Medicines
Agency approves the first gene
therapy for an inherited disease.
Called Glybera, the drug treats
lipoprotein lipase deficiency,
which causes fat to build up in