Detection of hotspot mutations in IDH1/2 in patients withacute myeloid leukemia using Droplet Digital PCR

Sammanfattning: IntroductionAcute myeloid leukemia (AML) is caused by a wide range of genetic aberrations, includingmutations within the genes that encode the enzymes isocitrate dehydrogenase 1 and 2(IDH1/2). Drugs that target mutant IDH1/2 are now available, which makes assessment of themutational status of IDH1/2 important in clinical diagnostics of AML. A promising method todetect these mutations is the droplet digital polymerase chain reaction (ddPCR), which showsadvantages of a high sensitivity and a simple workflow.AimTo evaluate ddPCR as method of choice to detect hotspot mutations in IDH1 (codon R132)and IDH2 (codon R140 and R172) in patients with AML.MethodsFifteen AML patients known to be positive for IDH1/2 diagnosed by a previously performednext generation sequencing (NGS) were selected for evaluation of ddPCR. Diagnosticsamples were tested for 14 patients, whereas follow-up samples were tested for one patient.ddPCR was performed using QX200™ Droplet Digital PCR system and data were presentedas fractional abundance of mutant allele.ResultsThe amount of mutant IDH1/2 in samples reported by ddPCR correlated well with the resultsfrom NGS when using probes that target their specific mutation. The detection limit formutant allele in the background of wild type IDH1/2 was 0,5% for IDH2 p.R140Q and 0.1%for IDH1 p.R132C/H.ConclusionddPCR that target specific mutations shows a great potential in measuring minimal residualdisease during follow-up. However, its use in screening for mutant IDH1/2 at the time ofdiagnosis is limited and alternative approaches should be considered.