The effect of dose increase of imatinib mesylate in patients with chronic or accelerated phase chronic myelogenous leukemia with inadequate hematologic or cytogenetic response to initial treatment.
OBJECTIVE
Imatinib mesylate is a tyrosine kinase inhibitor with high affinity for the BCR-ABL fusion protein expressed by the hematopoietic cells in chronic myelogenous leukemia (CML). Some patients with chronic-phase or accelerated-phase CML either relapse after an initial response or are refractory to imatinib, prompting us to evaluate the efficacy of dose increase in such patients.


METHODS
Twelve chronic-phase patients initially receiving 400 mg/day and 4 patients with accelerated phase initially receiving either 400 mg/day (two patients) or 600 mg/day (two patients) had their dose increased (14 to 800 mg/day and 2 to 600 mg/day) because of progressive disease (usually clonal evolution) or inadequate cytogenetic response after at least 1 year of therapy.


RESULTS
Six patients had major cytogenetic responses after dose increase (3 complete and 3 partial). Two others had minor cytogenetic responses. Two patients with clonal evolution transiently lost the additional clonal aberrations. Almost all of the responses occurred within 6 months, and were typically 3-6 months in duration. However, 3 patients have continuing major cytogenetic responses of >18 months duration. Dose increase was well tolerated, with thrombocytopenia, mild leukopenia, and exacerbation of prior edema being the most common adverse events.


CONCLUSIONS
Although increasing the dose of imatinib can benefit a subgroup of patients with CML with either an inadequate cytogenetic response or disease progression, our results suggest the majority will not have a sustained meaningful response, and that other options, such as allogeneic stem cell transplant or investigational therapies, also need to be considered at the time of dose increase.
Zonder
Jeffrey A
JA
Karmanos Cancer Institute, Wayne State University, Detroit, Michigan 48201, USA. zonderj@karmanos.org
Pemberton
Pamela
P
Brandt
Helen
H
Mohamed
Anwar N
AN
Schiffer
Charles A
CA
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D001549:Benzamides; D005260:Female; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D015465:Leukemia, Myeloid, Accelerated Phase / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D010677:Philadelphia Chromosome; D010879:Piperazines / Q000008:administration & dosage* / Q000009:adverse effects; D011743:Pyrimidines / Q000008:administration & dosage* / Q000009:adverse effects
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate