Reporting bone marrow biopsies for myelodysplastic neoplasms and acute myeloid leukaemia incorporating WHO 5th edition and ICC 2022 classification systems: ALLG/RCPA joint committee consensus recommendations.

The classification of myeloid neoplasms continues to evolve along with advances in molecular diagnosis, risk stratification and treatment of disease. An approach for disease classification has been grounded in international consensus that has facilitated understanding, identification and management of molecularly heterogeneous entities, as well as enabled consistent patient stratification into clinical trials and clinical registries over time. The new World Health Organization (WHO) and International Consensus Classification (ICC) Clinical Advisory Committee releasing separate classification systems for myeloid neoplasms in 2022 precipitated some concern amongst haematopathology colleagues both locally and internationally. While both classifications emphasise molecular disease classification over the historical use of morphology, flow cytometry and cytogenetic based diagnostic methods, notable differences exist in how morphological, molecular and cytogenetic criteria are applied for defining myelodysplastic neoplasms (MDS) and acute myeloid leukaemias (AML). Here we review the conceptual advances, diagnostic nuances, and molecular platforms required for the diagnosis of MDS and AML using the new WHO and ICC 2022 classifications. We provide consensus recommendations for reporting bone marrow biopsies. Additionally, we address the logistical challenges encountered implementing these changes into routine laboratory practice in alignment with the National Pathology Accreditation Advisory Council reporting requirements for Australia and New Zealand.

Analytical Validation of a 37-Gene Next-Generation Sequencing Panel for Myeloid Malignancies and Review of Initial Findings Incorporating Updated 2022 Diagnostic and Prognostic Guidelines.

Myeloid neoplasms are clonal disorders that arise via acquisition of genetic mutations leading to excessive proliferation and defective differentiation. Mutational profiling is vital as it has implications for diagnosis, prognosis, and therapeutic decision-making. Next-generation sequencing (NGS) has become a mainstay in the evaluation of myeloid malignancies, as it enables efficient characterization of multiple genetic changes. Herein, the analytical validation of the 37-gene Archer VariantPlex Core Myeloid panel is reported, using 58 DNA specimens with 87 single-nucleotide variants and 23 insertions/deletions. The panel achieved good depth of coverage, 100% analytical sensitivity and specificity for single-nucleotide variants and insertions/deletions ≤21 bp, and 100% reproducibility, with a reportable limit of detection determined as 5%. The Archer NGS panel can accurately and reproducibly detect variants of clinical significance in myeloid neoplasms. A retrospective analysis of 535 clinical specimens tested with the Archer NGS panel showed a frequency and pattern of mutations across myeloid malignancies that were similar to other published studies. A review of the diagnostic classification of patients with acute myeloid leukemia and myelodysplastic syndrome using the World Health Organization 2017/2022 and International Consensus Classification 2022 guidelines, in addition to European LeukemiaNet 2017/2022 risk stratification of patients with acute myeloid leukemia, was also performed to assess the utility of the molecular information provided by the Archer NGS panel.

Paediatric B lymphoblastic leukaemia with hyperdiploidy and a false-positive KMT2A fluorescence in situ hybridization result.

The dramatic improvement in the event-free survival of paediatric B-lymphoblastic leukaemia (B-ALL) has led to risk-stratified treatment. Through a combination of clinical features, cytogenetic abnormalities and assessment of treatment response, patients are stratified to receive different intensities of therapy. The presence of high hyperdiploidy (>50 chromosomes) is considered a favourable genetic feature. Conversely, KMT2A fusion genes in B-ALL are associated with a poor prognosis, resulting in intensification of treatment. We present a seven-year-old female with B-ALL, a high hyperdiploid karyotype (56 chromosomes) and KMT2A rearrangement detected on FISH, but with no productive fusion identified. Single nucleotide polymorphism (SNP) array suggested the KMT2A rearrangement was due to chromosome 11 chromothripsis. Subsequent targeted RNA fusion panel and whole transcriptomic sequencing (mRNA-seq) did not detect an expressed KMT2A fusion. Differential expression analyses of the mRNA-seq data led to clustering of this case with other hyperdiploid cases, consistent with the hyperdiploid cytogenetic results. Given the additional intensity and potential toxicity of high-risk treatment, unusual findings by chromosome analysis, FISH and/or chromosomal microarray should prompt consideration of testing for a KMT2A fusion by another method to avoid misclassification.

Real world molecular characterisation and clonal evolution of acute myeloid leukaemia reveals therapeutic opportunities and challenges.

Acute myeloid leukaemia (AML) is an aggressive haematological malignancy with poor prognosis. Increasing understanding of the molecular mechanisms driving clonal proliferation has resulted in advancements in classification and available therapeutic targets. Fms-related tyrosine kinase 3 (FLT3) mutations are prognostically important and offer options for targeted inhibition, however they are not stable and can emerge or disappear at relapse. Our aim was to review diagnostic testing of consecutive cases of newly diagnosed and relapsed AML reported across Queensland in comparison to available literature. We conducted a retrospective review of 1531 samples from 1231 patients to identify patterns of molecular testing and AML subtypes in our cohort. Outcomes included World Health Organization (WHO) classification, European LeukaemiaNet (ELN) risk category and rates of missed FLT3 mutation testing. Patients aged <60 years had significantly more favourable risk AML (48% vs 25%, p<0.01), with favourable risk chromosomal translocations [t(8;21) and inv(16)] being more common. Thirteen patients (1%) did not have FLT3 mutation testing at diagnosis, with 103 relapse samples (39%) not being tested. Eighteen patients (10%) had FLT3 mutations lost at relapse, with five patients (3%) developing new FLT3 mutations at relapse. This study identifies the subtypes and risk stratification of a large cohort of AML patients over an extended period. The relatively high rate of absent FLT3 mutation testing at relapse as well as FLT3 loss or gain highlights the potential missed opportunities for salvage treatment strategies.

Serum CD163 and TARC as disease response biomarkers in classical Hodgkin lymphoma.

PURPOSE: Candidate circulating disease response biomarkers for classical Hodgkin lymphoma (cHL) might arise from Hodgkin-Reed-Sternberg (HRS) cells or nonmalignant tumor-infiltrating cells. HRS cells are sparse within the diseased node, whereas benign CD163(+) M2 tissue-associated macrophages (TAM) are prominent. CD163(+) cells within the malignant node may be prognostic, but there is no data on serum CD163 (sCD163). The HRS-specific serum protein sTARC shows promise as a disease response biomarker. Tumor-specific and tumor-infiltrating circulating biomarkers have not been compared previously. EXPERIMENTAL DESIGN: We prospectively measured sCD163 and sTARC in 221 samples from 47 patients with Hodgkin lymphoma and 21 healthy participants. Blood was taken at five fixed time-points prior, during, and after first-line therapy. Results were compared with radiological assessment and plasma Epstein-Barr virus DNA (EBV-DNA). Potential sources of circulating CD163 were investigated, along with immunosuppressive properties of CD163. RESULTS: Pretherapy, both sCD163 and sTARC were markedly elevated compared with healthy and complete remission samples. sCD163 better reflected tumor burden during therapy, whereas sTARC had greater value upon completion of therapy. sCD163 correlated with plasma EBV-DNA, and associated with B symptoms, stage, and lymphopenia. Circulating CD163(+) monocytes were elevated in patients, indicating that sCD163 are likely derived from circulating and intratumoral cells. Depletion of cHL CD163(+) monocytes markedly enhanced T-cell proliferation, implicating monocytes and/or TAMs as potential novel targets for immunotherapeutic manipulation. CONCLUSION: The combination of circulating tumor-infiltrate (sCD163) and tumor-specific (sTARC) proteins is more informative than either marker alone as disease response biomarkers in early and advanced disease during first-line therapy for cHL.