Wang, Endi

Abstract Objective Rare large B-cell lymphomas (LBCLs) present with concurrent or subsequent lymphomatous effusion (solid-effusion LBCL, SE-LBCL), which may have an inferior prognosis compared with their noneffusion counterpart. In addition, the relationship between SE-LBCL and human herpesvirus 8–negative effusion-based LBCL (EB-LBCL) remains unclear. Methods We collected 141 cases of SE-LBCL and a control cohort of 101 cases of stage IV solid-only LBCL. The clinicopathologic features were analyzed and compared between SE-LBCL and solid-only LBCL. Results Patients with SE-LBCL had a median age of 67 years with a male-to-female ratio of 1.3:1. Eighty-six patients had concurrent solid lymphoma and lymphomatous effusion, whereas 55 developed lymphomatous effusion subsequently. Most cases involved the pleural cavities (79%, 112/141), followed by the peritoneal (21%, 29/141) and pericardial (11%, 16/141) cavities. BCL6, CD10, and MUM1 were expressed in 77% (90/117), 46% (60/130), and 61% (58/95) of cases, respectively, and 58% (71/123) were subclassified into the germinal center B-cell (GCB) subtype. Rearrangements of BCL2, BCL6, and MYC were detected in 42% (31/73), 35% (22/63), and 40% (35/88), respectively, and 22% (19/87) had both MYC and BCL2 rearrangements. The patients with SE-LBCL had a dismal prognosis, with a median survival of 5.7 months, which was significantly worse than solid-only LBCL (147.5 months; P < .0001). Conclusions The pathologic features of SE-LBCL were similar to those of solid-only LBCL but distinct from those of EB-LBCL; in particular, lymphomatous effusion was an independently adverse prognostic factor in LBCL. Our study underscores the need for surveillance of lymphomatous effusion during LBCL staging and development of effective therapeutic regimens for SE-LBCL.

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.

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.