Publication Date:
2008-11-16
Description:
Introduction Imatinib mesylate (IMT) dose escalation has been proposed as a therapeutic option in patients (Pts) with chronic myeloid leukemia (CML) who failed to achieve optimal response with standard dose IMT. We report the results of prospective multi-center single arm phase ¥≥study evaluating efficacy of escalated dose IMT. We intended to identify patterns of molecular change using serial quantitative RT-PCR and its relationship with clinical outcome. We also planned to find predictive markers for outcome with array comparative genomic hybridization (aCGH) and epigenetic study of bcr gene in addition to BCR/ABL mutation. Patient and methods Pts in chronic phase (CP) CML who failed to achieve optimal response by European LeukemiaNET with adequate organ function were enrolled. Pts in accelerated phase (AP) or blast crisis (BC) who failed to achieve complete hematologic response after 3 months of IMT were also eligible. CP Pts received 600mg daily, while Pts in AP or BC received 600 or 800mg IMT daily. Pts received IMT for at least 12 months or until the appearance of a progressive disease, intolerable toxicity. Along with cytogenetic response (CyR), molecular response (MR) was assessed with BCR-ABL/ABL gene ratio of peripheral blood or bone marrow aspirate. Baseline BCR/ABL gene mutation test was performed using Matrix-assisted laser desorption/ionization time of flight mass spectrometry. Genome-wide screening for regions of genetic gains and losses with baseline blood samples was performed for 38 Pts using aCGH. Methylation status of 4 CpG sites in bcr gene promoter region was tested for 40 Pts and average methylation level was used for analysis. Blood samples at baseline and 6 months after dose escalation were tested. 29 optimal responders to standard dose IMT and 38 healthy donors were also tested for bcr methylation status for additional comparison. Results 71 Pts (median age 49.0 years, M:F=50:21) received escalated dose IMT. Median time to treatment failure (TTTFx) was 18.0 months and toxicities were manageable. 44 and 52 Pts were evaluable for FISH at 6 months and 1 year, where 16 and 17 Pts showed complete CyR (CCyR) respectively. For 61 Pts with serial MR data, TTTFx was longer in Pts who achieved molecular reduction of more than 50% within 6 months (Molecular early responder: MER) than who didn’t (p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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