Monitoring of response to therapy with imatinib mesylate in Chronic Myeloid Leukemia in chronic phase (CML-CP).

BACKGROUND: The BCR-ABL tyrosine kinase is a well validated therapeutic target in Chronic Myeloid Leukemia (CML). Imatinib mesylate (IM), a tyrosine kinase inhibitor is highly effective in the treatment of chronic phase CML. BCR - ABL transcripts have been well established as a molecular marker to document response to therapy in CML. Periodic monitoring of this marker helps in evolving therapeutic strategies with IM and also in diagnosing early relapse. This study was undertaken to monitor therapeutic response to IM in CML in chronic phase (CML-CP) by assessing BCR-ABL by real time quantitative PCR (RQ-PCR) techniques and to determine the effectiveness of the Indian generic IM.

METHODS: One hundred consecutive patients of CML in chronic phase (CML-CP) were treated with an Indian generic of IM. Eighty-five patients were evaluable at 12 months of therapy. At entry, diagnosis of CML-CP was confirmed by FISH and RQ-PCR. Response to therapy was monitored by assessing BCR-ABL levels by RQ-PCR at 6 and 12 months of therapy. Regular follow up of patients was done to evaluate the safety profile of IM used in these patients.

RESULTS: Complete hematological response (CHR) rates at 3, 6, 9 and 12 months were 92%, 94%, 100% and 100% respectively. The total molecular response at 12 months was 43.52% of which complete molecular response (CMR) was noted in 17.64% and major molecular response (MMR) was observed in 25.88%. A cumulative survival probability of 0.8 was observed.

CONCLUSION: The Indian generic molecule of IM is effective in the treatment of CML-CP. The cost of Indian generic molecule is less than Rs. 10,000 per month there by making this affordable for large number of CML-CP patients in India.