Association between molecular monitoring and long-term outcomes in chronic myelogenous leukemia patients treated with first line imatinib.

OBJECTIVE: Molecular monitoring using quantitative polymerase chain reaction (qPCR) of BCR-ABL mRNA transcripts using the international scale (IS) is recommended by the National Comprehensive Cancer Network and the European LeukemiaNet for patients with chronic myelogenous leukemia in chronic phase (CML-CP). This study assessed the impact of the frequency of qPCR testing on progression-free survival (PFS). RESEARCH DESIGN AND METHODS: This retrospective chart review of 402 CML-CP patients on first line imatinib therapy, performed by 38 community-based US physicians, analyzed the impact of the frequency of molecular monitoring on the risk of progression and PFS. MAIN OUTCOME MEASURES: Time to progression and progression-free survival.
RESULTS: Over the 3 year study, 13.2% of patients did not have any qPCR monitoring and 46.3% had 3-4 qPCR tests per year; 5.7% of CML-CP patients progressed to accelerated/blast phase or died. Compared to patients with no qPCR monitoring, those with 3-4 qPCR tests per year had a lower risk of progression (HR = 0.085; p = 0.001) and longer PFS (HR = 0.088; p = 0.001) after adjusting for potential confounders, as did those patients with 1-2 qPCR tests per year (both p < 0.02). Results were consistent after adjusting for Sokal score when available.
CONCLUSION: This is the first study to document the clinical impact of frequent molecular monitoring, and the findings underscore the importance of regular molecular monitoring in delivering quality care for CML. These findings could be subject to unobserved confounders.