Response to Imatinib Mesylate in Patients with Early Chronic Phase Chronic Myeloid Leukemia and Derivative Chromosome 9 Deletion or Clonal Evolution

Objectives: The significance of clonal evolution and derivative chromosome 9 in Philadelphia-positive CML is not fully characterized and studies have yielded conflicting results. After working on emergence of clonal evolution from our region, we continued to find out the response of Imatinib Mesylate on such cases of CML treated in our center. Materials and methods: We conducted a cross sectional, prospective analysis on response of Imatinib Mesylate on patients with Philadelphia positive chronic myeloid leukemia with clonal evolution treated from period of September 2007 till 2010. Patients were grouped on basis of cytogenetic analysis performed by conventional cytogenetic and fluorescence in situ hybridization (FISH) techniques and followed for three years to see the response rate of imatinib mesylate. Results: We reported here the response rate in one hundred and two previously untreated cases of chronic myeloid leukemia (Philadelphia positive). Twelve patients (11.7%) exhibit derivative chromosome 9, three had trisomy 8, one with addition 15 and one had deletion 16. At follow-up of 30 months 78 cases were evaluable and 45% and 61% showed complete and major cytogenetic response respectively. There is no significant association of derivative chromosome 9 with the response of imatinib mesylate in our group. Conclusion: Imatinib mesylate is the first line therapy in chronic phase of CML but the role in patients with clonal evolution need to be established by larger group of patients.