Natural killer cell activity for IFN-gamma production as a supportive diagnostic marker for gastric cancer Natural killer cell activity for IFN-gamma production as a supportive diagnostic marker for gastric cancer

Monitoring minimal residual disease (MRD) provides important information during treatment of hematologic malignancies. Chimerism analysis also provides key information after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Recent advances in next-generation sequencing (NGS) have enabled identification of various mutations and quantification of mutant allele burden. In this study, we developed a new analytic algorithm to monitor chimerism applicable to NGS multi-gene panel in use to identify mutations of myelodysplastic syndrome (MDS). We enrolled patients who were diagnosed with MDS and received allo-HSCT and their corresponding donors. Monitoring MRD by NGS assay was performed using 53 DNA samples by calculating mutant allele burden after treatment. For monitoring chimerism by NGS, we selected 121 single nucleotide polymorphisms (SNPs) after careful stepwise evaluation and calculated average donor allele burden. Data obtained from NGS were compared with bone marrow findings, chromosome analysis and short tandem repeat (STR)-based chimerism. SNP-based NGS chimerism analysis was accurate and even superior to conventional STR method by overcoming the various technical limitations of STR. In addition, simultaneous monitoring of mutation and chimerism using NGS could implement comprehensive pre- and post-HSCT monitoring of various clinical conditions such as complete donor chimerism, persistent mixed chimerism, early relapse, and even donor cell-derived diseases.

The in-frame internal tandem duplication (ITD) of the FMS-like tyrosine kinase 3 (FLT3) gene is an important negative prognostic marker in acute myeloid leukemia (AML). FLT3-ITD monitoring is essential for patients at relapse or those receiving FLT3-targeted therapies. Fragment analysis (FA) is commonly used to detect and quantify FLT3-ITDs; however, detecting low-burden FLT3-ITDs after a treatment is challenging. We, therefore, developed a customized, next-generation sequencing (NGS)-based FLT3-ITD assay that includes a new ITD-tracing algorithm, “SEED”, optimized for measurable residual disease (MRD) monitoring. NGS-SEED showed an enhanced sensitivity (0.001%) and has a superior performance over conventional fragment analysis. We further investigated the prognostic impact of MRD analyzed by NGS-SEED in AML patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT). Our assay showed that the MRD assessed before and after HSCT were significantly associated with a risk of relapse and a poor overall survival, respectively, in a time-dependent analysis. Thus, this report highlighted the prognostic value of serial MRD monitoring using a sensitive method in a clinical setting of AML patients with FLT3-ITD.

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries. However, CLL is relatively rare in Asia; its genetic features are rarely studied. Here, we aimed to genetically characterize Korean CLL patients and to elucidate the genetic and clinical associations based on data obtained from 113 patients at a single Korean institute. We used next-generation sequencing to explore the multi-gene mutational data and immunoglobulin heavy chain variable gene clonality with somatic hypermutation (SHM). MYD88 (28.3%), including L265P (11.5%) and V217F (13.3%), was the most frequently mutated gene, followed by KMT2D (6.2%), NOTCH1 (5.3%), SF3B1 (5.3%), and TP53 (4.4%). MYD88-mutated CLL was characterized by SHM and atypical immunophenotype with fewer cytogenetic abnormalities. The 5-year time to treatment (TTT) of the overall cohort was 49.8% ± 8.2% (mean ± standard deviation) and the 5-year overall survival was 86.2% ± 5.8%. Patients with SHM, isolated del(13q), TP53-wild type, and NOTCH1-wild type showed better results than those without these conditions. In the subgroup analyses, patients with SHM and L265P presented shorter TTT than patients with SHM but not L265P. In contrast, V217F was associated with a higher SHM percentage and showed a favorable prognosis. Our study revealed the distinct characteristics of Korean CLL patients with high frequencies of MYD88 mutations and their clinical relevance.

Lee JM, et al. Ann Lab Med. 2018 Sep;38(5):492-494. https://doi.org/10.3343/alm.2018.38.5.492

Lee JM, et al. Ann Lab Med. 2020 Jan;40(1):84-87. https://doi.org/10.3343/alm.2020.40.1.84