Prognostic significance of FLT3-ITD length in AML patients treated with intensive regimens

FLT3-ITD mutations are detected in approximately 25% of newly diagnosed adult acute myeloid leukemia (AML) patients and confer an adverse prognosis. The FLT3-ITD allelic ratio has clear prognostic value. Nevertheless, there are numerous manuscripts with contradictory results regarding the prognostic relevance of the length and insertion site (IS) of the FLT3-ITD fragment. We aimed to assess the prognostic impact of these variables on the complete remission (CR) rates, overall survival (OS) and relapse-free survival (RFS) of AML patients with FLT3-ITDmutations. We studied the FLT3-ITD length of 362 adult AML patients included in the PETHEMA AML registry. We tried to validate the thresholds of ITD length previously published (i.e., 39 bp and 70 bp) in intensively treated AML patients (n = 161). We also analyzed the mutational profile of 118 FLT3-ITD AML patients with an NGS panel of 39 genes and correlated mutational status with the length and IS of ITD. The AUC of the ROC curve of the ITD length for OS prediction was 0.504, and no differences were found when applying any of the thresholds for OS, RFS or CR rate. Only four out of 106 patients had ITD IS in the TKD1 domain. Our results, alongside previous publications, confirm that FLT3-ITD length lacks prognostic value and clinical applicability. © 2021, The Author(s)

Design of anti- and pro-aggregation variants to assess the effects of methionine oxidation in human prion protein

Prion disease is characterized by the α→β structural conversion of the cellular prion protein (PrPC) into the misfolded and aggregated “scrapie” (PrPSc) isoform. It has been speculated that methionine (Met) oxidation in PrPC may have a special role in this process, but has not been detailed and assigned individually to the 9 Met residues of full-length, recombinant human PrPC [rhPrPC(23-231)]. To better understand this oxidative event in PrP aggregation, the extent of periodate-induced Met oxidation was monitored by electrospray ionization-MS and correlated with aggregation propensity. Also, the Met residues were replaced with isosteric and chemically stable, nonoxidizable analogs, i.e., with the more hydrophobic norleucine (Nle) and the highly hydrophilic methoxinine (Mox). The Nle-rhPrPC variant is an α-helix rich protein (like Met-rhPrPC) resistant to oxidation that lacks the in vitro aggregation properties of the parent protein. Conversely, the Mox-rhPrPC variant is a β-sheet rich protein that features strong proaggregation behavior. In contrast to the parent Met-rhPrPC, the Nle/Mox-containing variants are not sensitive to periodate-induced in vitro aggregation. The experimental results fully support a direct correlation of the α→β secondary structure conversion in rhPrPC with the conformational preferences of Met/Nle/Mox residues. Accordingly, sporadic prion and other neurodegenerative diseases, as well as various aging processes, might also be caused by oxidative stress leading to Met oxidation