For many, the name 'thalidomide'
conjures up the darker aspects of modern medicine. Once
prescribed for everything from insomnia to morning sickness
with disastrous results, the most notorious drug of the
last century has made something of a comeback as a breakthrough
medication for myeloma. Thalidomide's use today is hedged
with restrictions to prevent it from coming anywhere near
an unborn child, but even in adults thalidomide has a
side effect profile that would almost certainly rule out
its approval were it a new drug. But an analogue of thalidomide
may prove to be a good treatment for myeloma, bringing
the same benefits as current therapy without the adverse
effects.
SUPERIOR
ANALOGUE
Lenalidomide, more commonly referred to by its developmental
name CC-5013, is a cousin of thalidomide that's not
yet commercialized but appears to offer better response
rates with far fewer complications. Dr Vincent Rajkumar,
a Rochester, Minnesota Mayo Clinic hematologist/oncologist,
revealed the good news at the annual meeting of the
American Society of Hematology in San Diego this month.
According to him, CC-5013 in combination with the adrenocortical
steroid dexamethasone outperformed thalidomide plus
dexamethasone in newly diagnosed multiple myeloma patients.
The bulk of Dr Rajkumar's presentation
was devoted to reporting phase III findings on thalidomide
with dexamethasone, rapidly becoming a mainstream treatment,
which he said was "as effective as the standard intravenous
chemotherapy treatments commonly used as initial therapy
for myeloma." Following initial promising results reported
in 2002, he led a team that tested the combination versus
dexamethasone alone in 207 patients, and found a 63%
response rate from the two-pronged approach, compared
to a 41% response rate from the steroid alone.
"Based on this study, thalidomide
plus dexamethasone has probably become an appropriate
replacement for intravenous vincristine, adriamycin,
dexamethasone (VAD) chemotherapy, except for patients
with less aggressive disease for whom dexamethasone
alone may be adequate," said Dr Rajkumar.
THE
NO-CLOT COMBO
But thalidomide's potential side effects remains an
obstacle. In addition to dizziness, drowsiness, constipation,
rashes, hypothyroidism, leukocytopenia, peripheral neuropathy
and of course birth defects, thalidomide has an alarming
tendency to cause blood clotting, deep vein thrombosis
and pulmonary embolism. While only 3% of Dr Rajkumar's
dexamethasone patients developed blood clots, no fewer
than 18% of the combination therapy patients did.
Enter CC-5013, which appears to
boast all of the strengths of thalidomide with far fewer
of its weaknesses. "This regimen appears more effective
than the thalidomide-dexamethasone regimen, with fewer
side effects, and may in the future replace other regimens
including the thalidomide-dexamethasone combination
as initial treatment for myeloma," Dr Rajkumar says.
In 30 patients given a CC-5013 and dexamethasone combo,
response rates were a hefty 83% and no clotting was
seen. This finding, if confirmed in larger studies,
could allow thousands of patients currently judged unfit
for high-dose thalidomide to try a similar therapy.
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