Right Idea, Wrong Drug, Stem Cell Study Shows
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STEM CELL CANCER RITUXIMAB CYCLOPHOSPHAMIDE LYMPHOMA ONCOLOGY
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Description
Preliminary data from one of the first clinical trials to test a stem
cell-targeting drug in cancer patients shows that while the drug did
not prolong survival, its suppressing effect on patients' stem cells
was impressive enough to send investigators looking for a better drug
to try.
The following summary is based on an abstract scheduled for
presentation at the American Association for Cancer Research (AACR)
Annual Meeting, April 12 - 16 in San Diego, CA.
Newswise — Preliminary data from one of the first clinical trials to
test a stem cell-targeting drug in cancer patients shows that while
the drug did not prolong survival, its suppressing effect on
patients' stem cells was impressive enough to send investigators
looking for a better drug to try.
As an emerging field of study in cancer research, stem cells are
believed to sprout cancer much like the hidden roots of weeds that
elude efforts to get rid of them.
Rituximab, a drug currently approved to treat B-cell lymphomas, plus
a common chemotherapy agent, cyclophosphamide, were given to 21
patients whose multiple myeloma, a cancer of the bone marrow, had
relapsed or was defined as high-risk first remission. A previous
study using the drug alone in multiple myeloma patients suggested
that the disease in some participants progressed more slowly.
During the study, the Johns Hopkins team examined the stem cells
under the microscope. "We found cancer stem cells coated with
rituxumab, but the drug wasn't killing them," said Carol Ann Huff,
M.D., assistant professor of oncology. "We think the idea is correct,
but the drug itself wasn't the right one." Rituximab is sold under
the trade name Rituxan.
Huff and her team believe that several therapies are required to kill
cancer - one to get rid of the bulk of the tumor, like mowing the
lawn, and another to hit the root of the cancer, its stem cells. "We
think one reason that cancer comes back is because stem cells, which
are resistant to chemotherapy, repopulate the body with new cancer
cells," says William Matsui, M.D., assistant professor of medicine at
the Johns Hopkins Kimmel Cancer Center.
Their test of the rituximab-cyclophos
1000-fold reduction in cancer stem cells during the initial
treatment. However, stem cell quantities eventually crept back up and
led to a progression of disease. Investigators were able to predict
when patients' disease would recur by tracking the number of stem
cells they had. The average advance notice was two months.
Since the study began in early 2005, four patients have died from
their disease, three remain progression-
disease that has progressed.
Matsui and Huff are currently testing drugs that block an enzyme
called telomerase, which may give cancer stem cells longevity, and
other drugs that block a stem cell-signaling pathway called hedgehog.
Other promising therapies, according to the scientists, include a
combination of the drugs, interleukin-
may prematurely age stem cells.
Funding for the study was provided by the National Cancer Institute,
American Society of Clinical Oncology, the Commonwealth Foundation,
and Genentech. In addition to Matsui and Huff, these Johns Hopkins
scientists participated in the study: Q Wang, K Rogers, M Jung,
Javier Bolanos-Meade, Ivan Borrello, and Richard Jones.
On the Web: http://www.hopkinsk
http://www.aacr.
http://www.newswise
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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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