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Scientist at the National Institutes of
Health (Bethesda, MD) have successfully treated metastatic melanoma
in two patients using killer T cells genetically retargeted to
attack the cancer cells. This study constitutes the first
demonstration that gene therapy can be effective in treating cancer.
The study results have been published in Science (October 2006).
In May 2006 a team of scientists led by Drs.
Luigi Naldini and Brian Brown from the San Raffaele Telethon
Institute for Gene Therapy (HSR-TIGET) in Milan, Italy reported a
breakthrough for gene therapy in which they developed a way to
prevent the immune system from rejecting a newly delivered gene.
Similar to organ transplanation, gene therapy has been plagued by
the problem of immune rejection. So far, delivery of the 'good' gene
has been difficult because the immune sytem does not recognize the
new gene and rejects the cells carrying it. To overcome this
problem, the HSR-TIGET group utilized a newly uncovered network of
genes regulated by molecules known as microRNAs. Dr. Naldini's group
reasoned that they could use this natural function of microRNA to
selectively turn off the identity of their therapeutic gene in cells
of the immune system and prevent the gene from being found and
destroyed. The researchers injected mice with the gene containing an
immune-cell microRNA target sequence, and spectacularly, the mice
did not reject the gene, as previously occurred when vectors without
the microRNA target sequence were used. This work will have
important implications for the treatment of hemophilia and other
genetic diseases by gene therapy.
In March 2006 an international group of
scientists announced the successful use of gene therapy to treat two
adult patients for a disease affecting myeloid cells. The study,
published in Nature Medicine, is believed to be the first to show
that gene therapy can cure diseases of the myeloid system
University of California, Los Angeles,
research team gets genes into the brain using liposomes coated in a
polymer called polyethylene glycol (PEG). The transfer of genes into
the brain is a significant achievement because viral vectors are too
big to get across the "blood-brain barrier." This method has
potential for treating Parkinson's disease. See Undercover genes
slip into the brain at NewScientist.com (March 20, 2003).
RNA interference or gene silencing may be a
new way to treat Huntington's. Short pieces of double-stranded RNA
(short, interfering RNAs or siRNAs) are used by cells to degrade RNA
of a particular sequence. If a siRNA is designed to match the RNA
copied from a faulty gene, then the abnormal protein product of that
gene will not be produced. See Gene therapy may switch off
Huntington's at NewScientist.com (March 13, 2003).
New gene therapy approach repairs errors in
messenger RNA derived from defective genes. Technique has potential
to treat the blood disorder thalassaemia, cystic fibrosis, and some
cancers. See Subtle gene therapy tackles blood disorder at
NewScientist.com (October 11, 2002).
Researchers at Case Western Reserve
University and Copernicus Therapeutics are able to create tiny
liposomes 25 nanometers across that can carry therapeutic DNA
through pores in the nuclear membrane. See DNA nanoballs boost
gene therapy at NewScientist.com (May 12, 2002).
Sickle cell is successfully treated in mice.
See Murine Gene Therapy Corrects Symptoms of Sickle Cell Disease
from March 18, 2002, issue of The Scientist.
The success of a multi-center trial for
treating children with SCID (severe combined immune deficiency or
"bubble boy" disease) held from 2000 and 2002 was questioned when
two of the ten children treated at the trial's Paris center
developed a leukemia-like condition. Clinical trials were halted
temporarily in 2002, but resumed after regulatory review of the
protocol in the United States, the United Kingdom, France, Italy,
and Germany. (V. Cavazzana-Calvo, Thrasher and Mavilio 2004; see
also 'Miracle' gene therapy trial halted at NewScientist.com,
October 3, 2002).
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