Apparent decrease and elimination of BCR/ABL mRNA-expressing residual cells in patients with chronic myelogenous...

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia (CML) is a hematologic malignancy.
• Allogeneic bone marrow transplantation (BMT) is a curative treatment for CML.
• Monitoring minimal residual disease (MRD) post-BMT is crucial for predicting relapse.

Purpose of the Study:

• To evaluate the sensitivity of a modified two-step polymerase chain reaction (PCR) for detecting BCR/ABL mRNA in CML patients after BMT.
• To correlate the presence of BCR/ABL mRNA with clinical outcomes, including relapse.

Main Methods:

• A modified two-step PCR assay was developed to amplify BCR/ABL mRNA.
• Sixteen patients with Ph+ CML undergoing allogeneic BMT were monitored at various intervals post-transplant.
• The assay's sensitivity was enhanced to detect one Ph+ cell in 10(5-6).

Main Results:

• Eight of 16 patients became negative for BCR/ABL mRNA by two-step PCR 1-39 months post-BMT.
• Five patients negative by one-step PCR were positive with nested primers, indicating significantly reduced BCR/ABL mRNA levels.
• Persistence of BCR/ABL mRNA correlated with relapse only in patients transplanted during blast crisis.
• Patients transplanted in chronic phase remained in remission, irrespective of PCR results.

Conclusions:

• The modified two-step PCR is a highly sensitive method for detecting MRD in CML patients post-BMT.
• BCR/ABL mRNA detection post-BMT can predict relapse risk, especially in blast crisis cases.
• While aggressive treatments may not eradicate the malignant clone, graft-versus-leukemia effects may contribute to long-term remission.