Pulkit Rastogi¹, Chandan Bhatia¹, Manupdesh Singh Sachdeva¹, Shano Naseem¹, Jogeshwar Binota¹, Nabhajit Mallik¹, Deepak Bansal², Arihant Jain, Pankaj Malhotra³

¹Department of Haematology, ²Department of Paediatrics, ³Department of Clinical Hematology & Medical Oncology, Postgraduate Institute of Medical Education and Research, Chandigarh, India 

Introduction: Measurable residual disease (MRD) monitoring in core-binding factor acute myeloid leukemia (CBF-AML) has traditionally relied on qRT-PCR, though its consistency is limited by lack of standardization.¹ Droplet digital PCR (ddPCR), offering precise quantification without the need for external standards, emerges as a promising alternative.² This study compares ddPCR versus multi-parameter flow cytometry (MFC) for MRD assessment in CBF-AML.

Materials and Methods: We followed 25 CBF-AML patients across 41 therapy time-points, using ddPCR and MFC. Paired assessments were conducted at 33 time-points to evaluate concordance. Fusion transcript copy numbers (ddPCR), % ratios (ddPCR), and MRD% (MFC) were analyzed to compare the two methods.

Results: MRD assessments revealed 66.7% concordance and 33.3% discordance between ddPCR and MFC. ddPCR demonstrated higher sensitivity (91.4% MRD positivity vs. 56.4% for MFC). In two relapsed cases, ddPCR detected positivity 268 and 113 days before MFC. A Cohen’s Kappa score of 0.124 indicated minimal agreement between methods, with no significant survival differences between MRD-positive groups.

Conclusion: While ddPCR offers enhanced sensitivity and early relapse detection, both ddPCR and MFC are similarly effective for MRD monitoring in terms of predicting overall and relapse-free survival. Clinicians may choose either method based on availability, cost, and specific patient needs, as both provide reliable survival insights. 

1. Liu Yin JA, O’Brien MA, Hills RK, et al. Minimal residual disease monitoring by quantitative RT-PCR in core binding factor AML allows risk stratification and predicts relapse: Results of the United Kingdom MRC AML-15 trial. Blood 2012;120:2826– 2835.

2. Ip BBK, Wong ATC, Hei J, et al. Application of droplet digital PCR in minimal residual disease monitoring of rare fusion transcripts and mutations in haematological malignancies. Scientific Reports | 123AD;14:6400.

Statement of originality: The design and implementation of the comparative evaluation of ddPCR and MFC for MRD monitoring and their potential in early relapse detection, were authors’ original contribution to this study.