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Erythropoietic Therapy Does Not Interfere With Response to Imatinib in CML Patients

Erythropoietic Therapy Does Not Interfere With Response to Imatinib in CML Patients

PORTLAND, Oregon—Giving erythropoietic therapy to chronic myelogenous
leukemia (CML) patients does not appear to interfere with their response to
imatinib mesylate (STI571, Gleevec) therapy, according to a retrospective
study of 37 patients treated in the Leukemia Center at Oregon Health and
Science University in Portland (ASCO abstract 106).

Michael J. Mauro, MD, and his colleagues reported that 58% of the
patients responded to erythropoietic therapy with rises in hemoglobin counts
of 2 g/dL or more. The study group also had treatment response rates in line
with previous phase I and phase II trials of imatinib in CML patients. Among
the chronic-phase patients treated with erythropoietic therapy, 44% had a
major cytogenetic response, including 19% who had a complete cytogenetic
response.

The 19 patients with accelerated-phase disease caused the most concern,
according to Dr. Mauro. Yet these patients had the best responses to
erythropoietin therapy (68%) and to imatinib. Nearly half (47%) achieved a
major cytogenetic responses, including 37% who had a complete cytogenetic
response. One of two patients with blast crisis responded to erythropoietic
therapy, but neither responded to imatinib.

"The numbers are still fairly small, but it’s encouraging,"
Dr. Mauro told ONI, suggesting that erythropoietic therapy might allow
advanced CML patients to receive more intensive therapy with imatinib, an
ABL-tyrosine kinase inhibitor. At the time the patients received
erythropoietic therapy, the mean dose of imatinib was 546 mg, reflecting the
large proportion of accelerated-phase patients in the trial.

Anemia Is Common Problem

Anemia is a common problem for CML patients receiving imatinib,
especially in the accelerated and blast phases of disease, according to Dr.
Mauro. In previous trials, between 29% and 77% of these patients developed
grade 3 or grade 4 anemia. Though the condition was nowhere as widespread in
chronic-phase patients treated with imatinib, previous studies have also
characterized anemia as a poor prognostic factor at any phase for any
patient receiving imatinib therapy for CML.

Among the concerns about adding erythropoietin to imatinib was the
possibility that the disease affects erythropoietic receptors. Another was
the possibility that the growth factor would send growth or survival signals
to malignant blood cells. Dr. Mauro and his coauthors theorized, however,
that erythropoietic therapy would support nonmalignant erythropoiesis.

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