Heterogeneity in detecting Abl kinase mutations and better sensitivity using circulating plasma RNA

Area of Science:

• Molecular Biology
• Hematology
• Oncology

Background:

• Chronic myeloid leukemia (CML) management often involves monitoring mutations in the ABL gene.
• Peripheral blood (PB) cells are commonly used, but disease progression can increase blasts in bone marrow (BM), not PB.
• Imatinib resistance in CML necessitates accurate mutation detection for effective treatment.

Purpose of the Study:

• To evaluate the reliability of circulating plasma mRNA as an alternative to BM cells for detecting ABL mutations in imatinib-resistant CML.
• To compare mutation detection rates between PB cells, BM cells, and plasma in CML patients.

Main Methods:

• Simultaneous analysis of plasma, PB cells, and BM cells from 41 imatinib-resistant CML patients.
• Detection of ABL kinase domain mutations.
• Analysis of plasma from 45 previously untreated CML patients.

Main Results:

• ABL mutations were detected in 63% of PB cells and 68% of plasma or BM cells (P = 0.04) in resistant CML.
• In discordant cases, mutations were found more frequently in plasma (13) and BM (11) than in PB cells (9).
• The T315I mutation was detected in plasma and BM but not PB cells in one patient. No mutations were found in the plasma of previously untreated patients, but some developed plasma mutations on therapy.

Conclusions:

• Circulating plasma mRNA is a reliable alternative to BM mRNA for detecting ABL mutations in CML.
• Plasma analysis can identify mutations missed by PB cell analysis, particularly in advanced or resistant disease.
• This approach may improve monitoring and treatment strategies for CML patients.