WHO/ICC Classification for Myelodysplastic Neoplasms/Syndromes Performs Better for Subtype Cytomorphological Diagnosis?

The International Consensus Classification of Myeloid Neoplasms and Acute Leukemias (ICC) and the 5th edition of the WHO classification (WHO 2022) have refined the diagnosis of myelodysplastic syndromes (MDS). Both classifications segregate MDS subtypes based on molecular or cytogenetic findings but rely on the subjective assessment of blast cell percentage and dysplasia in hematopoietic cell lineages. This study aimed to evaluate interobserver concordance among 13 cytomorphologists from eight hospitals in assessing blast percentages and dysplastic features in 44 MDS patients. The study found fair interobserver agreement for the PB blast percentage and moderate agreement for the BM blast percentage, with the best concordance in cases with <5% BM blasts and >10% BM blasts. Monocyte count agreement was fair, and dysplasia assessment showed moderate concordance for megakaryocytic lineage but lower concordance for erythroid and granulocytic lineages. Overall, interobserver concordance for MDS subtypes was moderate across all classifications, with slightly better results for WHO 2022. These findings highlight the ongoing need for morphological evaluation in MDS diagnosis despite advances in genetic and molecular techniques. The study supports the blast percentage ranges established by the ICC but suggests refining BM blast cutoffs. Given the moderate interobserver concordance, a unified classification approach for MDS is recommended.

Design and Validation of a Custom Next-Generation Sequencing Panel in Pediatric Acute Lymphoblastic Leukemia.

The molecular landscape of acute lymphoblastic leukemia (ALL) is highly heterogeneous, and genetic lesions are clinically relevant for diagnosis, risk stratification, and treatment guidance. Next-generation sequencing (NGS) has become an essential tool for clinical laboratories, where disease-targeted panels are able to capture the most relevant alterations in a cost-effective and fast way. However, comprehensive ALL panels assessing all relevant alterations are scarce. Here, we design and validate an NGS panel including single-nucleotide variants (SNVs), insertion-deletions (indels), copy number variations (CNVs), fusions, and gene expression (ALLseq). ALLseq sequencing metrics were acceptable for clinical use and showed 100% sensitivity and specificity for virtually all types of alterations. The limit of detection was established at a 2% variant allele frequency for SNVs and indels, and at a 0.5 copy number ratio for CNVs. Overall, ALLseq is able to provide clinically relevant information to more than 83% of pediatric patients, making it an attractive tool for the molecular characterization of ALL in clinical settings.

Results of treatment with azacitidine in patients aged ≥ 75 years included in the Spanish Registry of Myelodysplastic Syndromes.

The tolerability of azacitidine (AZA) allows its administration in elderly patients. The objective of this study was to analyze the clinical and biological characteristics, transfusion independence (TI), overall survival (OS) and toxicity in a series of 107 patients ≥ 75 years of age from the Spanish Registry of Myelodysplastic Syndromes (MDS) treated with AZA. The median age (range) was 78 (75-90) years. According to the World Health Organization (WHO) classification, 86/102 (84%) had MDS, 10/102 (10%) had mixed myeloproferative/myelodysplastic disorder and 6/102 (6%) had acute myeloblastic leukemia. Regarding MDS by the International Prognostic Scoring System on initiation of AZA, 38/84 (45%) were low-intermediate-1 risk and 46/84 (55%) were intermediate-2-high risk. Ninety-five patients (89%) were red blood cell or platelet transfusion dependent. The AZA schedule was 5-0-0 in 39/106 (37%) patients, 5-2-2 in 36/106 (34%) patients and 7 consecutive days in 31/106 (29%) patients. The median number of cycles administered was 8 (range, 1-30). Thirty-eight out of 94 (40%) patients achieved TI. Median OS (95% confidence interval [CI]) was significantly better in patients achieving TI (n = 38) compared to patients who did not (n = 56) (22 [20.1-23.9] months vs. 11.1 [4.8-17.5] months, p = 0.001). No significant differences were observed in TI rate and OS among the three different schedules. With a median follow-up of 14 (min-max, 1-50) months, the median OS (95% CI) of the 107 patients was 18 (12-23) months and the probability of OS (95% CI) at 2 years was 34% (22-46%). Cycles were delayed in 31/106 (29%) patients and 47/101 patients (47%) were hospitalized for infection. These results show that treatment with AZA was feasible and effective in this elderly population, with 40% achieving TI, having a better OS than patients not achieving it. The schedule of AZA administration did not affect efficacy and toxicity.

New colorimetric screening assays for the directed evolution of fungal laccases to improve the conversion of plant biomass.

BACKGROUND: Fungal laccases are multicopper oxidases with huge applicability in different sectors. Here, we describe the development of a set of high-throughput colorimetric assays for screening laccase libraries in directed evolution studies. RESULTS: Firstly, we designed three colorimetric assays based on the oxidation of sinapic acid, acetosyringone and syringaldehyde with λmax of 512, 520 and 370 nm, respectively. These syringyl-type phenolic compounds are released during the degradation of lignocellulose and can act as laccase redox mediators. The oxidation of the three compounds by low and high-redox potential laccases evolved in Saccharomyces cerevisiae produced quantifiable and linear responses, with detection limits around 1 mU/mL and CV values below 16%. The phenolic substrates were also suitable for pre-screening mutant libraries on solid phase format. Intense colored-halos were developed around the yeast colonies secreting laccase. Furthermore, the oxidation of violuric acid to its iminoxyl radical (λmax of 515 nm and CV below 15%) was devised as reporter assay for laccase redox potential during the screening of mutant libraries from high-redox potential laccases. Finally, we developed three dye-decolorizing assays based on the enzymatic oxidation of Methyl Orange (470 nm), Evans Blue (605 nm) and Remazol Brilliant Blue (640 nm) giving up to 40% decolorization yields and CV values below 18%. The assays were reliable for direct measurement of laccase activity or to indirectly explore the oxidation of mediators that do not render colored products (but promote dye decolorization). Every single assay reported in this work was tested by exploring mutant libraries created by error prone PCR of fungal laccases secreted by yeast. CONCLUSIONS: The high-throughput screening methods reported in this work could be useful for engineering laccases for different purposes. The assays based on the oxidation of syringyl-compounds might be valuable tools for tailoring laccases precisely enhanced to aid biomass conversion processes. The violuric assay might be useful to preserve the redox potential of laccase whilst evolving towards new functions. The dye-decolorizing assays are useful for engineering ad hoc laccases for detoxification of textile wastewaters, or as indirect assays to explore laccase activity on other natural mediators.

Development of chimeric laccases by directed evolution.

DNA recombination methods are useful tools to generate diversity in directed evolution protein engineering studies. We have designed an array of chimeric laccases with high-redox potential by in vitro and in vivo DNA recombination of two fungal laccases (from Pycnoporus cinnabarinus and PM1 basidiomycete), which were previously tailored by laboratory evolution for functional expression in Saccharomyces cerevisiae. The laccase fusion genes (including the evolved α-factor prepro-leaders for secretion in yeast) were subjected to a round of family shuffling to construct chimeric libraries and the best laccase hybrids were identified in dual high-throughput screening (HTS) assays. Using this approach, we identified chimeras with up to six crossover events in the whole sequence, and we obtained active hybrid laccases with combined characteristics in terms of pH activity and thermostability.