Imatinib
is superior to interferon-alfa and cytarabine as first-line therapy
for newly diagnosed chronic myeloid leukemia
Imatinib is superior to the current standard
of interferon-alfa and cytarabine for the first-line treatment of
newly diagnosed chronic-phase chronic myeloid leukemia, according
to trial results presented during the plenary session of the Annual
Meeting of the American Society of Hematology. The IRIS trial (International
Randomized Interferon versus STI571 study) is the largest clinical
trial to compare the two chemotherapy treatments. "Results
of our study showed that the use of imatinib resulted in a significantly
higher response rate and a longer period of time before the disease
progressed," said Richard Larson, M.D., study presenter. "This
is very encouraging news for patients and should be viewed as a
positive step forward in the treatment of chronic myeloid leukemia."
Imatinib therapy improved a number of clinical
outcomes: complete hematologic response (estimated at 97 percent
versus 69 percent with combination chemotherapy), major cytogenetic
response (87 percent versus 35 percent), complete cytogenetic response
(76 percent versus 14 percent) and progression-free survival (time
from diagnosis to disease progression or death, 92 percent versus
73 percent).
The 1,106 study participants were randomized
to imatinib 400 mg daily by mouth or to combination interferon-alfa
and cytarabine by injection. The target dose for interferon was
5 MU/m2/day subcutaneously, whereas target dose for cytarabine was
20mg/m2 subcutaneously for 10 days every month. The most recent
data were analyzed 18 months after the last patients were enrolled
in the phase III trial.
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