Government FDA Okays Amgen’s Nplate for treating rare blood disorder
By Ben Wasserman
Aug 23, 2008 - 1:36:41 PM
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Saturday August 23, 2008 (foodconsumer.org) -- The Food
and Drug Administration on Friday Aug. 22 announced its approval of Nplate
(romiplostim) manufactured by Amgen, Inc. of Thousand Oaks, California as a bone
marrow stimulator to treat immune-related low platelet counts.
Nplate is the first of its kind ever approved by the FDA
to stimulate the bone marrow to produce platelets that patients with a rare
blood disorder need to prevent serious bleeding due to low counts of platelets.
The blood disorder of concern is known as chronic immune
thrombocytopenic purpura or ITP, which develops in adults resulting in a low
number of platelets. The drug helps with clotting and prevents bleeding,
according to the FDA.
In patients with chronic ITP, the immune system destroys
platelets and the bone marrow is not able to compensate the loss, leading to increased
risk of serious bleeding.
An estimated
140,000 people in the U.S. suffer chronic ITP.
"This product is important in that it offers a new
approach to the treatment of patients with an uncommon blood disorder who are
often very ill," said Janet Woodcock, M.D., director, Center for Drug
Evaluation and Research, FDA.
The treatments available currently include
corticosteroids and immunoglobulin. Splenectomy, a procedure to remove the
spleen, may also help some patients.
But Nplate is approved only for chronic ITP patients who
do not respond to current treatments.
The FDA approval was based on two clinical trials of about
125 patients who had received at least one treatment prior to the trials with
one study on patients who still had their spleen and another on patients who had
had their spleen removed.
Results from six months of treatment showed patients who
received Nplate had significantly higher counts of platelets and maintained
higher counts than those who did not receive the medication.
The efficacy was good mostly among those who still kept their
spleen.
Of those who underwent a
splenectomy, only one experienced maintained an increased in platelet counts.
However, higher platelets counts needed to be maintained
by taking Nplate.
Once the treatment was
stopped, platelet counts dropped even below the beginning counts. Another side
effect is that the drug caused fibrous deposits in the bone marrow and blood
clots due to excessive increases in platelets.
Nplate also predisposed some patients with a blood
disorder known as myelodysplasia to leukemia, a blood cancer.
A study showed of 44 patients with
myelodysplasia, four developed leukemia. But the FDA said further research is
needed to determine whether it is Nplate that causes increased risk of
leukemia.
Because of these adverse effects, Nplate is only approved
for patients who have chronic ITP but do not respond sufficiently to current
treatments.
Herbchina2000.com reported that an herbal
remedy based on Chinese herbs has been proved to be very successful in treating
Primary thrombocytopenic purpura. The source cites a study saying that
of 52 cases, 39 patients who were treated with the remedy were recovering and
free of symptoms while another 11 improved their conditions.
Another study also showed the remedy is also
equally effective at treating Secondary thrombocytopenic purpura. No
side effects were observed.
Analysts expect the sales from about 60,000 U.S. patients
with chronic ITP to be at anywhere between $66 and $117 million in 2009,
Reuters reported.
Also Amgen will face competition
from GlaxoSmithKline which also expects to get FDA approval for its Promacta or
eltrombopag in September.