IDH1 and IDH2 mutations in patients with acute myeloid leukemia: Suitable targets for minimal residual disease monitoring?

Objectives: Molecular screening plays a major role in prognostic categorization and subsequent definition of treatment strategies for acute myeloid leukemia. The possibility of using IDH1/2 mutations as a marker for the monitoring of minimal residual disease (MRD) is still under investigation and remains unclear. Methods: In this retrospective study, we evaluated 90 patients with de novo AML using Sanger sequencing (exon 4, IDH1 and IDH2). For subsequent MRD monitoring were used both methods, massive parallel sequencing and droplet digital PCR (ddPCR). Results: We identified 22 patients (24%) who harboured mutations in IDH1 or IDH2 genes. Fourteen (64%) of them had other commonly used MRD markers (insertion in NPM1 and partial tandem duplication of MLL, MLL-PTD). Eight of the 22 patients had IDH1 mutations, 13 had IDH2 mutations and 1 had both IDH1 and IDH2 mutations. In our cohort, this IDH1/2 marker responded to the treatment in all of the patients and reflected the onset of the relapse very well. NPM1 mutation based MRD monitoring was more sensitive and predicted relapse earlier but IDH1/2 based monitoring was more sensitive than a method based on MLL-PTD. Both massive parallel sequencing and ddPCR were competent to monitor MRD using IDH1/2. Nevertheless, ddPCR was able to achieve a higher sensitivity in some cases and moreover this method can analyse a single sample without significant price increases. Conclusion: Given these data, we conclude that IDH1/2 mutations can be used as a reliable and cost-effective marker for MRD monitoring.