Monitoring AML Disease Status with Next Generation Sequencing

Recent advance in next generation sequencing (NGS) have confirmed that AML is a heterogeneous malignancy harboring may many genetic mutations. These mutations have been studied for leukemia genesis, diagnosis and therapeutic targets. Monitoring minimal residual diseases has also been studied recently. We summarized our experience with NGS in morning AML disease status.

NGS data during 2014 and 2016 from patient with newly diagnosed or AML and/or AML follow-up patients along with bone marrow biopsy, FISH/cytogenetics, flow cytometric results were reviewed. Targeted sequencing was performed with customized panel (34 genes) on Ion PGM platform from Life Technology Inc.

41 AML patients with complete bone marrow work-up with bone marrow morphology, flow cytometry, FISH/cytogenetics (MFFC) and NGS were collected. At least one sample with complete work-up for each patient was included. Majority of the patients had several studies (2-8 samples). 15 out of 41 (36.6%) has complete remission based on bone marrow morphology, flow cytometry, FISH/cytogenetic studies. No mutations were detected among these 15 patients. 17 patients (41%) showed concordant result with other technologies, i.e. when the patient was in remission based on MFFC, No mutations were detected. When patient had recurrent AML or residual disease, mutations were detected. It worth to point out that 2 patients showed positive mutation without detectable increase in myeloblasts. These 2 patients had relapsed AML within 3 months. Different subclones were detected at different intervals in 1 patient. 2 (0.5%) patients (1 with newly diagnosed AML and 1 with early recurrent AML) showed no detectable mutations. Mutations were detected in 5 patients (12%) with AML remission by MFFC, additional follow-up is need for these patients. The most common mutations included TET2, ASXL1, DNMT3A, RUNX1, IDH1 and TP53.

NGS is valuable to assess the AML status despite of heterogeneous genetic abnormalities. Although the NGS results were concordant with bone marrow morphology, FISH/cytogenetics and flow cytometry in most of the cases (87.5%), persistent mutations may be detectable in cases without detectable residual AML by other modalities, which may be associated with minimal residual disease or early relapse, and need further evaluation. Clonal evaluation may occur at molecular level occasionally.