Clinical Trials of Stem Cells: Proceed with Caution
Regulators debate what kinds of tests are needed to begin.
Friday, April 11, 2008
By Emily Singer
With three biotech companies gearing up to begin clinical trials of
their embryonic stem cell therapies, the FDA convened a panel
yesterday to debate the safety of these therapies, the biggest
concern being that these novel cell therapies carry a risk of cancer.
According to a stem cell blog called The Niche:
Three companies, Geron, Advanced Cell Technology, and Novocell,
described their work bringing embryonic-derived cells in
(respectively) acute spinal cord injury, visual impairment, and
diabetes. One expert who wasn't on the committee said that the
discussions had been impressively grounded in science, even getting
into specifics about what assays might be considered. Attendees were
surprised that no opponents of embryonic stem cell research showed
up, but the FDA's announcement said explicitly that it was only the
cells' safety that was under consideration.
The dark shadow of gene therapy looms over the regulators--
suffered a major setback in 1999 when a patient died of cancer linked
to the therapy. Scientists know that undifferentiated stem cells can
form into a benign mass known as a teratoma when injected into
animals, and they fear that a safety incident in the first round of
clinical trials could devastate the already-troubled field. The cell
therapies under development use differentiated cells, but the
possibility remains that some undifferentiated cells may be left in
the mix.
According to The Niche, major questions need to be answered to assess
that risk:
How do we know what cells we have? How do we know what the cells will
do in the body? Where do you put cells? Where do they go? What do
they do? How many cells might be dangerous? How many can be useful?
What can animals tell us? If the cells "go rogue" in a human
participant, will we be able to stop them or even to track them?
What's the best way to balance risk and benefit?
The committee declined to speculate when it would release its
guidance statement. But Geron has said it plans to begin trials of
its cell therapy for spinal cord injury this summer.
http://www.technolo
FDA Signals High Bar for Stem Cell Treatments
Posted by Jacob Goldstein
Yes, human embryonic stem cells are full of scientific promise. But
there's still a lot of mystery about how therapies derived from cells
will actually work in the body, and the FDA may require unusually
compelling evidence in evaluating the treatments.
At a meeting yesterday, the chief of the FDA's cell and tissue
therapy branch said data from clinical trials of the treatments may
need to be "particularly strong" to persuade the agency, Dow Jones
Newswires reports.
No one's testing the therapies in people yet, but Geron plans to
start human trials this year, and Novocell and Advanced Cell
Technology are also working on bringing treatments to the clinic,
Bloomberg reports. Experimental treatments could apply to a wide
range of problems, including diabetes, spinal cord injury and macular
degeneration.
Unanswered questions include whether the cell therapies may cause the
growth of tumors, how the cells will travel through the body and
whether patients will need to take immune-suppressing drugs in order
for the therapies to work.
"We've talked about how long we need to monitor people for, and the
answer is forever," Gordon Weir, a Harvard med school professor on
the FDA advisory committee, reportedly said during yesterday's
meeting. "We're putting in these cells, and we don't know what
they're going to cause in terms of trouble."
Today the meeting will tackle adult stem cells as therapy.
http://blogs.
cell-treatments/
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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