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Back to Oncology Articles
Monday June 7, 2004 4:24 PM GMT
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There had previously been no approved therapies for
MDS. Vidaza
is the first FDA approved drug for MDS.
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The FDA announced on May 20, 2004, the approval of Vidaza injection,
the first effective treatment for a rare and difficult-to-treat bone
marrow disease.
Vidaza will be used to treat patients with myelodysplastic syndrome.
The product was given "fast track" status and a priority review.
Priority Review status of the application reduces the standard agency
response time to six months.
By restoring normal growth and differentiation of bone marrow cells,
this new treatment will offer a much-needed option for patients
suffering from this incurable illness that, in some cases, has been
found to progress to leukemia.
Myelodysplastic syndrome
Myelodysplastic syndrome is a collection of conditions in which the
bone marrow does not function normally. These conditions show
abnormalities in the production of one or more of the cellular
components of blood (red cells, white cells (other than lymphocytes) and
platelets (or their progenitor cells, megakaryocytes).
Myelodysplastic syndrome patients have an increased risk of developing acute leukaemia, which is notoriously resistant to treatment ("secondary
leukaemia"). In RA and RARS the risk is relatively low and the
condition
may persist for many years (e.g. 10 years). In RAEB and CMML the time course is
typically quicker.
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Epidemiology
It is estimated that 7,000 to 12,000 new cases of
myelodysplastic syndrome are diagnosed each year in the U.S.
These are mostly conditions of the elderly. However, there is an
increased risk in those people who have had chemotherapy for other
tumors.
Symptoms
Anaemia - chronic tiredness (in this condition blood transfusion is the
only effective treatment, which can carry on for years)
Neutropenia (low white cell count) - increased susceptibility to
infection
Thrombocytopenia (low platelet count) - increased susceptibility to
bleeding
Because the cellular function is impaired the effects of low cell counts
may be greater than in other conditions with a similar cell count be
less impairment of normal function.
Vidaza the first approved treatment of MDS
There are currently no approved therapies for
MDS. Vidaza (azacitidine for injectable suspension) manufactured by Pharmion
is the first FDA approved drug for MDS.
Azacitidine is a pyrimidine nucleoside analog
of cytidine. Besides its cytotoxic effects, azacitidine is a member of a
class of drugs in development known as "hypomethylating" or "demethylating"
agents. Methylation of DNA is a major mechanism regulating gene
expression. Researchers have found that an increase in methylation of
DNA can result in blockage of the activity of genes that regulate cell
division and differentiation, known as "suppressor genes." With
suppressor gene expression blocked, cell division becomes unregulated,
allowing or promoting cancer. In in-vitro studies, researchers have
found that azacitidine can reverse the methylation of DNA, leading to
reexpression of suppressor genes and a resulting differentiation and
maturation of cells. Vidaza is thought to work by restoring normal growth and development
of bone marrow cells.
The three trials
The safety and effectiveness of Vidaza, in the treatment of all
subtypes of myelodysplastic syndrome, were established in studies
involving a total of 268 patients. About 15% of patients in the three
trials had complete or partial responses to Vidaza. Responses consisted
of complete or partial normalization of blood in the bone marrow and
normal levels of blood cells. In responders the need for blood
transfusions was eliminated.
The most common side effects reported in clinical trials included
nausea, anemia, low platelets in blood, diarrhea, fatigue, irritation at
the injection site, and constipation.
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