Ivo Palásek

Monitoring of minimal residual disease in acute myeloid leukemia with frequent and rare patient‐specific NPM1 mutations

Nucleophosmin (NPM1) mutations in exon 12 are the most common genetic alternation in cytogenetically normal AML (CN‐AML). Although mutation types A, B, and D represent the majority of cases, rare mutation variants of the NPM1 gene in individual patients do occur. In this study, we have evaluated a novel, DNA‐based real‐time quantitative polymerase chain reaction (RQ‐PCR) for the detection of three of the most commonly occurring mutations and for six rare patient‐specific mutation types, which represent 28% of all of the NPM1 mutations in our group of 25 CN‐AML patients. Furthermore, the prognostic relevance of NPM1‐based monitoring of minimal residual disease (MRD) in peripheral blood (PB), bone marrow (BM), and in specific cell subsets (CD34+, CD34−, CD34dim) of BM were evaluated. In 80% of the evaluable patients, a molecular relapse preceded a hematological relapse. Moreover, in this subset of patients, the molecular relapse occurred at a median of 97 days before the hematological relapse. Our compartment analysis showed a strong correlation between BM and PB (r = 0.907, P < 0.001) as well as a high copy number of mutated NPM1 in CD34+ BM cells. In conclusion, we have demonstrated applicability of our presented RQ‐PCR method for a large percentage of mutated NPM1 patients with CN‐AML as well as the usefulness for long‐term follow‐up monitoring of MRD and the prediction of hematological relapse. Am. J. Hematol., 2010.

A novel quantitative assessment of minimal residual disease in patients with acute myeloid leukemia carrying NPM1 (nucleophosmin) exon 12 mutations

Acute myeloid leukemia (AML) is a heterogeneous group of diseases affecting hematopoietic stem cells. In recent years, several novel molecular abnormalities have been identified in patients with AML, particularly in cases with normal karyotype. Among these, mutations of the nucleophosmin gene (NPM1) have been established as currently the most common abnormality in AML, found about half of all AML patients with normal karyotype. For the detection of NPM1 mutations on the molecular level, several different assays have been described, including direct sequencing, fragment analysis or high resolution melt analysis or high-performance liquid chromatography. NPM1 mutations might be also suitable as target structure for minimal residual disease monitoring. Here, we describe a novel quantitative assessment based on allelic discrimination assays and real-time PCR with mutation-specific minor groove binding (MGB) probes. This method offers an alternative to the standard routine laboratory evaluation and representing an efficient approach to the specific detection of NPM1 mutations without any false positivities caused by amplification on the wild-type alleles.

Acute myeloid leukemias with recurrent genetic abnormalities: frequent assessment of minimal residual disease and treatment of molecular relapse with chemotherapy.

Acute myeloid leukemias with recurrent genetic abnormalities: frequent assessment of minimal residual disease and treatment of molecular relapse with chemotherapy