DAVOS-Glimmers of hope but gene therapy still far off
Reuters North America
Montag, 29. Januar 2001 21:58:00
Copyright 2001 Reuters Ltd. All rights reserved.@bThe following news report may not be republished or redistributed, in whole or in part, without the prior written consent of Reuters Ltd.
By Ben Hirschler, European pharmaceuticals correspondent
DAVOS, Switzerland (Reuters) - After a decade of
research and $3 billion in investment by drug companies,
widespread use of gene therapy remains many years away, experts
at the World Economic Forum annual meeting said Monday.
The goal of replacing defective genes with normal ones
suffered a major setback in November 1999 when 18-year-old
Jesse Gelsinger became the first person to die during gene
therapy.
A number of programs were put on hold as a result and
investors dumped the stocks of companies involved in the
field.
Nonetheless, the past year has produced glimmers of hope
with preliminary success in treating French children suffering
from a rare genetic defect that destroys the immune system and
another group in the United States with hemophilia.
In addition, a gene therapy product developed by Introgen
and Aventis is currently in Phase III for head and neck
cancer.
But it is proving an uphill battle.
"Since the early 1990s, the amount of money spent by
commercial operations in developing this very exciting field is
at least $3 billion," said Henri Termeer, chief executive of
U.S. biotechnology firm Genzyme General Corp.
Genzyme itself has invested $200 million and conducted nine
clinical trials seeking a gene treatment for cystic fibrosis --
an inherited disease characterized by chronic lung infections
-- so far without success.
"Currently we at Genzyme have a number of trials going on.
... We have our fingers crossed every day but the earliest
something could come out of it is five years from now," Termeer
said.
DELIVERY A PROBLEM
Fred Gage, of the U.S.-based Salk Institute for Biological
Studies, said gene therapy held out great promise, not only in
treating cancer and rare inherited diseases caused by a single
gene defect, but also in degenerative brain diseases.
However, the technology for delivering genes into the body
is still not good enough, he said.
Scientists typically use a deactivated virus, such as the
one that causes the common cold, to carry genes into the body.
The problem is this can cause immune reactions, similar to
the one that is thought to have killed Gelsinger -- and many
viruses fail to get to all the right cells.
One option being considered is using a class of viruses
called lentiviruses, emptied of their own damaging genes, as
'vectors', since they are particularly effective at spreading
infections.
That poses a public relations challenge, since the best
known lentivirus is HIV.
For Irving Weissmann, professor of pathology at Stanford
University School of Medicine, the answer is to mend stem cells
in the laboratory and then reintroduce then into the patient,
thereby guaranteeing that all necessary cells are treated.
Stem cells are immature "master" cells which can be coaxed
into forming different types of tissue in the body.
"If you want to get genes to different parts of the body
you better hitch-hike on cells," he said.
REUTERS