Hu, Shimin

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.

Composite classic Hodgkin lymphoma and follicular lymphoma (CHLFL) is a rare and poorly characterized entity. Herein, we report the clinicopathologic features of 22 cases of CHLFL from 3 institutions and we assess 27 additional cases reported in the literature. In our cohort (n=22), patients with CHLFL had a median age of 61 years and an equal male to female incidence. Most cases (95%) arose de novo with the remaining patients having a history of non-Hodgkin lymphoma. CHLFL always involved lymph nodes (100%) and most cases (95%) revealed 2 distinct areas separately diagnostic for CHL and FL. The CHL component represented a variable proportion of the overall neoplasm (5% to 90%) and was either mixed cellularity (82%) or nodular sclerosis (18%) type. The Hodgkin/Reed-Sternberg cells expressed CD30 (100%), PAX5 (100%), CD15 (62%), BCL6 (47%), BCL2 (29%), and EBER (25%), in a polymorphous inflammatory background typical of CHL. The FL component was low-grade in 55%, grade 3A in 36%, and grade 3B in 9% of cases. All 3 cases investigated by cytogenetic methods for a clonal relationship between the CHL and FL components were clonally related. These clinicopathologic features of our cohort are similar to those of cases reported in the literature. The 5-year overall survival in combined patients with CHLFL (n=49) was 48%, comparable to CHL but worse than FL in the elderly. In summary, CHLFL is a rare entity that most often occurs in older adults, involves lymph nodes, and most commonly presents de novo. In the small number of cases assessed, the CHL and FL components are usually clonally related suggesting that the CHL and FL components may share a common progenitor B-cell, likely a mutated germinal center B-cell.

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.

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.