Imatinib Treatment Experience in a Public Health System, Minority Patient Population with Chronic Myelogenous Leukemia (CML).

Abstract

Introduction: Imatinib (STI571/ Gleevec) is a tyrosine kinase inhibitor that functions by blocking the binding of ATP to the bcr-abl tyrosine kinase, inhibiting its activity and preventing myeloid proliferation, a characteristic of CML. We report our experience with imatinib use in a minority patient population.Methods: Data from 67 patients (pts) with CML treated at Cook County Hospital, Chicago, Illinois over a 4 year period were collected. Demographics, presentation, dosage schedule, tolerability and response were analyzed. Continuous data were analyzed via Student's T test and categorical data via Fisher's Exact test.Results: 57 pts with complete data [mean age at diagnosis 42.8 yrs, range 19–72 yrs, 46 (80.7%) males and 11 (19.3%) females] were identified and analyzed as a retrospective cohort. 41 pts (71.9%) were between 30 and 60 yrs of age and 17 pts (29.8%) had ≥ 1 major comorbidity at presentation. 28 (49.1%) were African American (AA), 4 (7%) Asian, 5 (8.8%) Eastern European, 17 (29.8%) Hispanic, and 3 (5.3%) Middle Eastern. 50 pts (87.7%) were in chronic phase, 5 (8.8%) in accelerated phase, 2 (3.5%) in blast phase, 2 (3.5%) had granulocytic sarcomas and 5 pts (8.8%) had second malignancies at presentation. 54 pts (94.7%) were started on 400mg of imatinib. 19 pts (33.3%) had imatinib-related toxicities including skin rash, cytopenias and nausea. 17 pts (29.8%) were non-compliant with imatinib therapy. AA pts were as old as the non-AA pts [44.8 ± 12.6 yrs vs 40.9 ± 13.8 yrs, p 0.27]. Non-AA pts were predominantly male. Following imatinib therapy a hematologic response (HR) was noted in 45.7± 54.6 days (d) in AA vs 31.3 ± 23.9 d in non-AA (p= 0.27), a major cytogenetic response (MCR) in 351 ± 342.6 d in AA pts vs 289±132.7 d in non-AA (p=0.58) and a complete cytogenetic response in 664±265.1 d in AA vs 642±292.5 d in non-AA pts (p=0.87). 11 AA pts failed imatinib therapy vs 8 non-AA pts. These pts were then subjected to imatinib dose escalation (600mg or 800mg) with only 4 pts in the AA group attaining MCR and 1 pt in the non-AA group attaining CCR. 4 AA pts then received Dasatanib and 2 went on to Allogeneic Stem Cell Transplant (ASCT) and 3 pts in the non-AA group received Nillotinib or Dasatanib and 2 went on to ASCT. There were 3 deaths in the AA group vs 1 in the non-AA group.Conclusion: In this primarily minority-based cohort there appears to be no significant difference in the age or gender distribution of the AA or non-AA pts although there appeared to be a male preponderance amongst the non-AA pts. The ethnic background does not appear to affect the time to significant hematologic response, major cytogenetic response or complete cytogenetic response to imatinib therapy in the AA or non-AA pts. Since the number of patients is small, definitive conclusions in either cohort cannot be made. Further investigation in minority patients is warranted.