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Oral decitabine/cedazuridine has been studied in chronic myelomonocytic leukemia (CMML) recently but the molecular changes during this treatment have not been reported so far. We report a CMML patient who was treated with oral decitabine/cedazuridine and showed a stepwise loss of KRAS mutation and trisomy 8 while the TET2 mutated clone gradually increased eventually resulting in clonal hematopoiesis. This case report highlights the disease modifying potential of this treatment in single CMML patients.

The analytically sensitive detection of D816V in blood and bone marrow is important for diagnosing systemic mastocytosis (SM). Additionally, precise quantification of the D816V variant allele fraction (VAF) is relevant clinically because it helps to predict multilineage involvement and prognosis in cases of advanced SM. Digital PCR (dPCR) is a promising new method for sensitive detection and accurate quantification of somatic mutations. We performed a validation study of dPCR for D816V on 302 peripheral blood and bone marrow samples from 156 patients with mastocytosis for comparison with melting curve analysis after peptide nucleic acid-mediated PCR clamping (clamp-PCR) and allele-specific quantitative real-time PCR (qPCR). dPCR showed a limit of detection of 0.01% VAF with a mean CV of 8.5% and identified the mutation in 90% of patients compared with 70% for clamp-PCR ( < 0.001). Moreover, dPCR for D816V was highly concordant with qPCR without systematic deviation of results, and confirmed the clinical value of D816V VAF measurements. Thus, patients with advanced SM showed a significantly higher D816V VAF (median, 2.43%) compared with patients with indolent SM (median, 0.14%; < 0.001). Moreover, dPCR confirmed the prognostic significance of a high D816V VAF regarding survival ( < 0.001). dPCR for D816V provides a high degree of precision and sensitivity combined with the potential for interlaboratory standardization, which is crucial for the implementation of D816V allele burden measurement. Thus, dPCR is suitable as a new method for D816V testing in patients with mastocytosis.

Standardized monitoring of BCR::ABL1 mRNA levels is essential for the management of chronic myeloid leukemia (CML) patients. From 2016 to 2021 the European Treatment and Outcome Study for CML (EUTOS) explored the use of secondary, lyophilized cell-based BCR::ABL1 reference panels traceable to the World Health Organization primary reference material to standardize and validate local laboratory tests. Panels were used to assign and validate conversion factors (CFs) to the International Scale and assess the ability of laboratories to assess deep molecular response (DMR). The study also explored aspects of internal quality control. The percentage of EUTOS reference laboratories (n = 50) with CFs validated as optimal or satisfactory increased from 67.5% to 97.6% and 36.4% to 91.7% for ABL1 and GUSB, respectively, during the study period and 98% of laboratories were able to detect MR4.5 in most samples. Laboratories with unvalidated CFs had a higher coefficient of variation for BCR::ABL1IS and some laboratories had a limit of blank greater than zero which could affect the accurate reporting of DMR. Our study indicates that secondary reference panels can be used effectively to obtain and validate CFs in a manner equivalent to sample exchange and can also be used to monitor additional aspects of quality assurance.