Detecting minimal residual disease in patients with chronic lymphocytic leukemia using 8-color flow cytometry protocol in routine hematological practice.

Introduction: Minimal residual disease (MRD) detection has become increasingly important for the assessment of therapy response in chronic lymphocytic leukemia (CLL). However, current MRD analysis methods, both molecular genetic and flow cytometric, are time-consuming and require experienced laboratory staff.

Methods: To reduce the demands of flow cytometric MRD detection in CLL, we have introduced a novel flow cytometric 8-color protocol. The MRD analysis results using this protocol were then compared with the commonly employed 4-color protocol and the molecular genetic (real-time quantitative allele-specific oligonucleotide IGH polymerase chain reaction; RQ-ASO IGH PCR) approach.

Results: Forty-two CLL patient samples were repeatedly analyzed after allogeneic stem cell transplantation (n = 20) or after fludarabine-based therapy (n = 22), and 100% concordance was found using both flow cytometric protocols. Furthermore, there was a strong correlation (r = 0.94) between flow cytometric and RQ-ASO IGH PCR results in MRD detection.

Conclusion: Flow cytometry is less time-consuming, less financially demanding, and moreover, MRD assessment using our novel 8-color protocol is less complicated than the 4-color approach and molecular methods.