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Updated: Jun 21, 2026
Comprehensive Protocol to Sample and Process Bone Marrow for Measuring Measurable Residual Disease and Leukemic Stem Cells in Acute Myeloid Leukemia
Published on: March 5, 2018
Minimal residual disease levels assessed by NPM1 mutation-specific RQ-PCR provide important prognostic information in
Susanne Schnittger1, Wolfgang Kern, Claudia Tschulik
1MLL Munich Leukemia Laboratory, Munich, Germany. susanne.schnittger@mll-online.com
Abstract:
Nucleophosmin (NPM1)-mutated acute myeloid leukemia (AML), which is recognized as a provisional entity in the World Health Organization 2008 classification of myeloid neoplasms, accounts for 30% of AML. We analyzed 1227 diagnostic and follow-up samples in 252 NPM1-mutated AML patients with 17 different NPM1 mutation-specific real-time quantitative polymerase chain reaction (RQ-PCR) assays. Paired diagnostic/relapse samples of 84 patients revealed stable NPM1 mutations in all cases, suggesting that they are pathogenetically early events and thus applicable for minimal residual disease detection. A total of 47 relapses were predictable because of an NPM1 mutation level (%NPM1/ABL1) increase of at least 1 log or in 15 cases because of NPM1 mutation levels not decreasing less than 3 log ranges. A high prognostic value of NPM1 levels was shown for 4 different intervals after therapy was initiated. Furthermore, thresholds of 0.1 and 0.01%NPM1/ABL1 during/after treatment discriminated between prognostic subgroups. Univariate analyses, including age, white blood cell count, blast count, CD34 positivity, FLT3 mutations status, FAB type, karyotype, NPM1 mutation type, and pretreatment NPM1 mutational level, showed that, besides NPM1 mutation level, only age and FLT3-LM mutation status were prognostically significant for EFS. Multivariate analysis, including age, FLT3-LM status, and NPM1 mutation level at different time points, demonstrated that NPM1 level was the most relevant prognostic factor during first-line treatment. Similar results were obtained in patients undergoing second-line chemotherapy or allogeneic stem cell transplantation.
Insights
Nucleophosmin (NPM1)-mutated acute myeloid leukemia (AML) levels are crucial for predicting relapse and patient outcomes. Monitoring NPM1 mutation levels post-treatment offers significant prognostic value for acute myeloid leukemia patients.
Area of Science:
- Hematology
- Molecular Oncology
Background:
- Nucleophosmin (NPM1)-mutated acute myeloid leukemia (AML) represents a significant subset of AML cases.
- NPM1 mutations are recognized as early pathogenetic events in AML development.
Purpose of the Study:
- To evaluate the prognostic significance of NPM1 mutation levels in NPM1-mutated AML.
- To assess the utility of NPM1 mutations for minimal residual disease detection and relapse prediction.
Main Methods:
- Analysis of 1227 diagnostic and follow-up samples from 252 NPM1-mutated AML patients.
- Utilized 17 NPM1 mutation-specific real-time quantitative polymerase chain reaction (RQ-PCR) assays.
- Paired diagnostic/relapse samples were analyzed to confirm mutation stability.
Main Results:
- NPM1 mutations remained stable in paired diagnostic/relapse samples, confirming their role in minimal residual disease monitoring.
- Relapses were predictable based on increases or insufficient decreases in NPM1 mutation levels (%NPM1/ABL1).
- NPM1 levels demonstrated high prognostic value across different post-therapy intervals, with specific thresholds (0.1% and 0.01%) discriminating prognostic subgroups.
Conclusions:
- NPM1 mutation level is the most significant prognostic factor in NPM1-mutated AML during first-line treatment.
- NPM1 mutation monitoring is valuable for predicting relapse and guiding treatment decisions in AML patients, including those undergoing second-line therapy or stem cell transplantation.
