New Method for Delivering Genes
in a Pill to Induce Production of Insulin
The first patent for a method of delivering normal
genes in a pill to induce the production of insulin
in people with diabetes was issued May 1 to the
University of California, San Francisco.
Sometimes referred to as a "gene pill,"
the oral delivery of normal genes has been a long-sought
and elusive technique. Now, UCSF researchers have
successfully demonstrated that raw DNA taken orally
can find its way inside cells lining the intestinal
tract and prompt those cells to express a protein,
such as insulin, even though they are not specialized
for that purpose.
The technique holds the potential for providing
patients with more than 50 proteins normally secreted
by the body into blood and which patients now
receive by injection into muscles - including
insulin, growth hormones, blood factors for treating
hemophilia, and erythropoietin for treating anemia.
Genteric, a biotechnology company in Alameda,
Calif. has an exclusive, worldwide license agreement
with the University to use the method for drug
development.
Oral delivery of genes differs from many of the
highly publicized gene therapy techniques now
under investigation in clinical trials at research
centers across the country. Gene therapy in those
studies attempts to correct disease at its root
by administering DNA to cells through the use
of a modified virus or other microscopic delivery
vehicle in order to provide a permanent or long-term
cure or treatment for the disease. Oral delivery
of genes is intended to provide short-term therapy
by placing a specifically-engineered therapeutic
gene with normal DNA in cells lining the intestinal
tract, causing those cells to express a desired
protein to be secreted into the blood - in the
case of this patent, insulin.
Cells containing the therapeutic gene would continue
to express the protein only for the few days they
remain on the wall of the intestine before the
body routinely sloughs them and replaces them
with new cells. In effect, the therapeutic genes
would remain "outside" the body on the
surface of the gastrointestinal tract as they
pass through the body, even as the protein drugs
that are manufactured are released into the blood
stream. As a consequence, the genes pass relatively
quickly through the body creating less opportunity
to access the blood stream or to enter other cells,
including those in the ovaries or testes.
"Regular oral delivery of new genes would
provide continuous production of insulin, and
the natural removal of the affected cells would
permit doses to be adjusted or stopped easily,"
said German, an expert on diabetes.
To demonstrate the validity of the method, the
UCSF research team had to show, among other obstacles,
that neither stomach acids nor intestinal enzymes
would destroy the DNA.
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FACT:
According to the results of the International
DECS Survey on global diabetes educational practices,
available soon in the Diabetes Atlas from IDF,
Physicians provided 74%, pharmacists 20% and nurse
educators 6% of diabetes education.
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