Contributions
Type: Publication Only
Background
Minimal residual disease (MRD) tests provide early identification of hematologic relapse and timely management of acute myeloid leukemia(AML)patients. Approximately 50% of AML patients do not have clonal chromosomal aberrations and categorize as a cytogenetically normal acute myeloid leukemia (CN-AML). Molecular markers are useful in the dissection of this heterogeneous group of AML patients into prognostically different subgroups. About 60% of adult CN-AML have a mutationin exon 12 of the NPM1 gene. This mutation is specific for malignant clone and potentially is a good marker of MRD.
Aims
In this retrospective study, we set up a NPM1quantitative test and then AML patients carrying NPM1mut were followed up for MRD monitoring.
Methods
In this study, we prepared plasmids containing a cDNA fragment of the NPM1 and ABL genes by PCR cloning. ABL served as a control to compensate for variations in the quality of the RNA and for differences in the efficiency of the reverse transcription reaction the plasmids were used to construct standard curves quantitation of each of the target and control genes. Eleven patients were analyzed using established method. Serial PB /and or BM samples ( 71 samples ) were taken in1-3 month intervals (mean 1.5-month intervals) and median follow up duration after chemotherapy was 11 months ( 5- 28.5 months ).
Results
In this study, we developed RNA-based RQ-PCR to quantitation of NPM1 mutation A with sensitivity of 10(-5). NPMmut transcript levels were expressed as a percentage ratio of NPMmut to ABL transcripts. The percent of NPMmut/ ABL level showed a range between 132 and 757 with a median of 383.5 in samples at diagnosis. The median NPMmut transcript level log reduction was 3 log.Relapse occurred in 45% of patients ( 5 cases), All cases at diagnosis demonstrated the same mutation at relapse. In patients who experienced relapse, Log reduction levels of NPM1 mRNA transcript after therapy were 4(2 patients),3(two patients) and 1 log(1 patient). Totaly NPMmut level showed less than 5 log reduction in all of them, Whereas this reduction was 5 - 6 log in other patients.
Summary
Despite the limitations of this study in terms of sample size and duration of follow up, it showed the accuracy of set up for detection of mutation and this marker has worth for following up at different stages of disease. Because of high frequency, stability, specificity to abnormal clone and high sensitivity, NPM1 is a suitable marker for monitoring of NPMc+ AML patients.
Keyword(s): Acute myeloid leukemia, MRD
Session topic: Publication Only
Type: Publication Only
Background
Minimal residual disease (MRD) tests provide early identification of hematologic relapse and timely management of acute myeloid leukemia(AML)patients. Approximately 50% of AML patients do not have clonal chromosomal aberrations and categorize as a cytogenetically normal acute myeloid leukemia (CN-AML). Molecular markers are useful in the dissection of this heterogeneous group of AML patients into prognostically different subgroups. About 60% of adult CN-AML have a mutationin exon 12 of the NPM1 gene. This mutation is specific for malignant clone and potentially is a good marker of MRD.
Aims
In this retrospective study, we set up a NPM1quantitative test and then AML patients carrying NPM1mut were followed up for MRD monitoring.
Methods
In this study, we prepared plasmids containing a cDNA fragment of the NPM1 and ABL genes by PCR cloning. ABL served as a control to compensate for variations in the quality of the RNA and for differences in the efficiency of the reverse transcription reaction the plasmids were used to construct standard curves quantitation of each of the target and control genes. Eleven patients were analyzed using established method. Serial PB /and or BM samples ( 71 samples ) were taken in1-3 month intervals (mean 1.5-month intervals) and median follow up duration after chemotherapy was 11 months ( 5- 28.5 months ).
Results
In this study, we developed RNA-based RQ-PCR to quantitation of NPM1 mutation A with sensitivity of 10(-5). NPMmut transcript levels were expressed as a percentage ratio of NPMmut to ABL transcripts. The percent of NPMmut/ ABL level showed a range between 132 and 757 with a median of 383.5 in samples at diagnosis. The median NPMmut transcript level log reduction was 3 log.Relapse occurred in 45% of patients ( 5 cases), All cases at diagnosis demonstrated the same mutation at relapse. In patients who experienced relapse, Log reduction levels of NPM1 mRNA transcript after therapy were 4(2 patients),3(two patients) and 1 log(1 patient). Totaly NPMmut level showed less than 5 log reduction in all of them, Whereas this reduction was 5 - 6 log in other patients.
Summary
Despite the limitations of this study in terms of sample size and duration of follow up, it showed the accuracy of set up for detection of mutation and this marker has worth for following up at different stages of disease. Because of high frequency, stability, specificity to abnormal clone and high sensitivity, NPM1 is a suitable marker for monitoring of NPMc+ AML patients.
Keyword(s): Acute myeloid leukemia, MRD
Session topic: Publication Only