Wang, Wei

Abstract The dismal outcome of acute leukemia undergoing immunophenotype-switch, compounded by the increased incidence in the era of immunotherapy, highlights the need for in-depth systemic studies. We investigated the clinicopathological, cytogenetic, and molecular features of 33 patients experiencing switch between acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). The median duration from the primary diagnosis to lineage switch was 7.8 months, with the subsequent median survival being < 3 months. The majority experienced a transition from B-ALL to AML. The AML cases demonstrated a spectrum of differentiation, ranging from minimal to erythroid, with monocytic being the most common. Cytogenetic analysis revealed 11q23/KMT2A fusions as the most recurrent abnormalities (n = 18); also observed were complex karyotype, 7/7q-, 9p-/CDKN2A deletion, t(5;14)/TCLX3::BCL11b, t(8;9)/PCM1::JAK2, t(9;22)/BCR::ABL1, and t(12;19)/TCF3::ZNF384. Remarkably, in 60% of patients lacking KMT2A fusions, a chronic myeloid neoplasm was observed preceding the first leukemia. In contrast, no prior hematological malignancies were observed in KMT2A cases. Deep mutational profiling reinforced the inherent clonal relationship between the initial and subsequent leukemias, evident from the overlapping mutational signatures. The presence of distinct additional mutations across the two phases supports the long-standing theory of lineage switch emerging via divergent evolution of a multipotential progenitor.

AbstractObjectivesT-cell prolymphocytic leukemia (T-PLL) is a rare mature T-cell leukemia usually characterized by inv(14)(q11.2q32)/t(14;14)(q11.2;q32). In this study, we aimed to investigate the clinicopathologic features and molecular profile of T-PLL associated with t(X;14)(q28;q11.2).MethodsThe study group included 10 women and 5 men with a median age of 64 years. All 15 patients had a diagnosis of T-PLL with t(X;14)(q28;q11.2).ResultsAll 15 patients had lymphocytosis at initial diagnosis. Morphologically, the leukemic cells had features of prolymphocytes in 11 patients, small cell variant in 3, and cerebriform variant in 1. All 15 patients had hypercellular bone marrow with an interstitial infiltrate in 12 (80%) cases. By flow cytometry, the leukemic cells were surface CD3+/CD5+/CD7+/CD26+/CD52+/TCR α/β+ in 15 (100%) cases, CD2+ in 14 (93%) cases, CD4+/CD8+ in 8 (53%) cases, CD4+/CD8– in 6 (40%) cases, and CD4–/CD8 + in 1 (7%) case. At the cytogenetic level, complex karyotypes with t(X;14)(q28;q11.2) were seen in all 15 patients assessed. Mutational analysis showed mutations of JAK3 in 5 of 6 and STAT5B p.N642H in 2 of 6 patients. Patients received variable treatments, including 12 with alemtuzumab. After a median follow-up of 17.2 months, 8 of 15 (53%) patients died.ConclusionsT-PLL with t(X;14)(q28;q11.2) frequently shows a complex karyotype and mutations involving JAK/STAT pathway, and it is an aggressive disease with a poor outcome.

AimsIt is unknown whether Epstein–Barr virus (EBV) infection can occur in high‐grade B cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, also known as double‐ or triple‐hit lymphoma (DHL/THL).Methods and resultsHere we report 16 cases of EBV+ DHL/THL from screening 846 cases of DHL/THL and obtaining additional EBV+ cases through multi‐institutional collaboration: eight MYC and BCL2 DHL, six MYC and BCL6 DHL and two THL. There were eight men and eight women, with a median age of 65 years (range = 32–86). Two patients had a history of follicular lymphoma and one had AIDS. Nine of 14 patients had an International Prognostic Index of ≥3. Half of the cases showed high‐grade/Burkitt‐like morphology and the other half diffuse large B cell lymphoma morphology. Using immunohistochemistry, the lymphoma cells were positive for MYC (n = 14 of 16), BCL2 (n = 12 of 16), BCL6 (n = 14 of 16), CD10 (n = 13 of 16) and MUM1 (n = six of 14). Using Hans’ algorithm, 13 cases were classified as germinal centre B cell (GCB) and three as non‐GCB. The lymphomas frequently showed an EBV latency Type I with a median EBV‐encoded small RNAs of 80% positive cells (range = 20–100%). After a median follow‐up of 36.3 months (range = 2.0–41.6), seven patients died, with a median survival of 15.4 months (range = 3.4–47.3) after diagnosis of EBV+ DHL/THL. Five of six patients with MYC and BCL6 DHL were alive, including four in complete remission. In contrast, only four of 10 patients with MYC and BCL2 DHL or THL were alive, including two in complete remission. The median survival in patients with MYC and BCL6 DHL was unreached and was 21.6 months in patients with MYC and BCL2 DHL or THL.ConclusionsEBV infection in DHL/THL is rare (~1.5%). Cases of EBV+ DHL/THL are largely similar to their EBV– counterparts clinicopathologically. Our findings expand the spectrum of EBV+ B cell lymphomas currently recognised in the World Health Organisation classification and suggest differences between EBV+ MYC and BCL2 DHL versus EBV+MYC and BCL6 DHL that may have therapeutic implications.

AbstractBackgroundBlood involvement by mycosis fungoides (MF)/Sézary syndrome (SS) influences prognosis and therapeutic decisions. MF/SS blood stage is currently determined by absolute CD4 + CD26− or CD4 + CD7‐cell counts, which quantification method may overestimate MF/SS by including CD26− or CD7− normal CD4+ T‐cells, or underestimate disease burden when MF/SS cells show incomplete loss of CD26 and/or CD7. Recently, through the standardization effort led by the International Clinical Cytometry Society (ICCS), recommendation was made to quantify MF/SS by enumerating immunophenotypically aberrant CD4+ T‐cells, rather than CD26− or CD7− in isolation.MethodsWe compared these two quantitation methods in 309 MF/SS patients who had blood samples analyzed by flow cytometry immunophenotyping (FCI) over a 1‐year period.ResultsUsing the European Organization of Research and Treatment of Cancer (EORTC)/International Society for Cutaneous Lymphomas (ISCL) criteria, 221 (71.5%) patients had a blood stage corresponding to B0, 57 (18.4%) to B1, and 31 (10%) to B2. By FCI analysis, a total of 62 patients (20.0%) were found positive for MF/SS. Among EORTC B0 patients, 11/221 (5%) were positive by FCI (false negatives), and among EORTC Stage B1 patients, 35/57 (61%) were negative by FCI (false positives). Regarding patients positive for MF/SS cells by FCI, there was an overall excellent correlation (r = .999, p < .001) between the EORTC/ISCL method and FCI method; however, four (6.5%) patients would have an altered B stage between B0 and B1.ConclusionThe MF/SS cell quantification method using immunophenotypic aberrancies, as recommended by the ICCS, allows to distinguish MF/SS cells from background benign T‐cells and enables for more accurate staging, especially among patients currently being considered to have B0 and B1 stage diseases.

AimsRearrangement of the platelet‐derived growth factor receptor B (PDGFRB) gene defines a unique group of myeloid/lymphoid neoplasms with frequent eosinophilia and high sensitivity to tyrosine kinase inhibitors. This genetic abnormality is also rarely reported in Philadelphia‐like B‐cell acute lymphoblastic leukaemia/lymphoma (B‐ALL). PDGFRB rearrangement was initially thought to only occur in cases with 5q31–33 rearrangement as determined with conventional cytogenetics; however, there are reported cases with cryptic rearrangements. We aim to develop a broader strategy for screening of PDGFRB rearrangements of patients with myeloid/lymphoid neoplasms.Methods and resultsWe performed fluorescence in‐situ hybridisation (FISH) for PDGFRB rearrangement in 197 patients, including 70 with B‐ALL, 10 with myeloid neoplasms with 5q31–33 rearrangements, and 117 with eosinophilia (≥0.5 × 109/l in peripheral blood or ≥5% in bone marrow), and identified PDGFRB rearrangement in four of 197 (2.0%) cases. In an attempt to identify clinicopathological and genetic features that may have a stronger association with PDGFRB rearrangement, we analysed 13 patients with confirmed PDGFRB rearrangements, including 10 with myeloid neoplasms and three with B‐ALL. Among the 10 patients with myeloid neoplasms, eosinophilia was present in eight, monocytosis in two, 5q31–33 rearrangement in seven, and abnormal bone marrow morphology in all. All patients with myeloid neoplasms showed an excellent response to imatinib, including a patient in blast crisis. The three B‐ALL patients presented de novo, showed no eosinophilia, had a complex karyotype including 5q31–33 rearrangement, and had clinically aggressive courses with ultimate patient demise.ConclusionsThese findings suggest that a higher yield for the identification of PDGFRB rearrangement may result from an index of suspicion in patients with eosinophilia, monocytosis, bone marrow features of a myeloid neoplasm, and 5q31–33 rearrangement, and patients with Philadelphia‐like B‐ALL.

AbstractNF-κB and Notch signaling can be simultaneously activated in a variety of B-cell lymphomas. Patients with B-cell lymphoma occasionally develop clonally related myeloid tumors with poor prognosis. Whether concurrent activation of both pathways is sufficient to induce B-cell transformation and whether the signaling initiates B-myeloid conversion in a pathological context are largely unknown. Here, we provide genetic evidence that concurrent activation of NF-κB and Notch signaling in committed B cells is sufficient to induce B-cell lymphomatous transformation and primes common progenitor cells to convert to myeloid lineage through dedifferentiation, not transdifferentiation. Intriguingly, the converted myeloid cells can further transform, albeit at low frequency, into myeloid leukemia. Mechanistically, coactivation of NF-κB and Notch signaling endows committed B cells with the ability to self renew. Downregulation of BACH2, a lymphoma and myeloid gene suppressor, but not upregulation of CEBPα and/or downregulation of B-cell transcription factors, is an early event in both B-cell transformation and myeloid conversion. Interestingly, a DNA hypomethylating drug not only effectively eliminated the converted myeloid leukemia cells, but also restored the expression of green fluorescent protein, which had been lost in converted myeloid leukemia cells. Collectively, our results suggest that targeting NF-κB and Notch signaling will not only improve lymphoma treatment, but also prevent the lymphoma-to-myeloid tumor conversion. Importantly, DNA hypomethylating drugs might efficiently treat these converted myeloid neoplasms.