The combination of NPM1, DNMT3A, and IDH1/2 mutations leads to inferior overall survival in AML.

Acute myeloid leukemia (AML) is a genetically heterogeneous disease with a clinical course predicted by recurrent cytogenetic abnormalities and/or gene mutations. The NPM1 insertion mutations define the largest distinct genetic subset, ∼30% of AML, and is considered a favorable risk marker if there is no (or low allelic ratio) FLT3 internal tandem duplication (FLT3 ITD) mutation. However, ∼40% of patients with mutated NPM1 without FLT3 ITD still relapse, and the factors that drive relapse are still not fully understood. We used a next-generation sequencing panel to examine mutations at diagnosis; clearance of mutations after therapy, and gain/loss of mutations at relapse to prioritize mutations that contribute to relapse. Triple mutation of NPM1, DNMT3A and IDH1/2 showed a trend towards inferior overall survival in our discovery dataset, and was significantly associated with reduced OS in a large independent validation cohort. Analysis of relative variant allele frequencies suggests that early mutation and expansion of DNMT3A and IDH1/2 prior to acquisition of NPM1 mutation leads to increased risk of relapse. This subset of patients may benefit from allogeneic stem cell transplant or clinical trials with IDH inhibitors.

Outcomes of DA-EPOCH-R induction plus autologous transplant consolidation for double hit lymphoma.

High-grade B cell lymphoma with MYC and BCL2 rearrangements (double hit) has a poor prognosis with standard R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). We report here a treatment algorithm of DA-EPOCH-R (dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, rituximab) followed by BEAM (carmustine, etoposide, cytarabine, melphalan) autologous transplant in 36 cases of previously untreated double hit lymphoma (DHL) from 2010 to 2015. A high risk International Prognostic Index (IPI) was present in 42% of cases. At median follow-up of 38 months, the 2-year progression free survival (PFS) and overall survival (OS) were 69% (95% CI 54-84%) and 71% (95% CI 56-86%). Eight cases were refractory to induction with 1-year OS 20%, and no factors were predictive for primary refractory disease. Of 28 responders, 17 proceeded to transplant while 11 were observed, primarily due to age and co-morbidities. By 24-week landmark analysis after diagnosis, the 2-year PFS and OS were both 94% (95% CI 83-100%) vs 79% (95% CI 52-100%) for transplant vs observation (p = .59 for both PFS and OS). There was no significant benefit to consolidative transplant in our series, and primary refractory DHL needs novel approaches.

TdT-positive Infiltrate in Inflamed Pediatric Kidney: A Potential Diagnostic Pitfall.

We encountered a patient with infantile nephrotic syndrome associated with a dense interstitial inflammatory infiltrate and prominent extramedullary hematopoiesis. Immunohistochemical analysis revealed numerous terminal deoxynucleotidyl transferase (TdT)-positive cells, which may raise concern for lymphoblastic lymphoma. Thus, we further characterized a group of pediatric kidneys with inflammation. TdT-positive nuclei were quantitated, and dual immunostains for TdT/CD79a, TdT/CD3, and TdT/CD43 were performed in a subset of cases; flow cytometry was performed in 1 case. TdT-positive nuclei were present in inflamed pediatric kidneys in 40 of 42 patients. TdT counts (average of 3 maximal high-power fields) ranged from 1 to >200, with a mean of 47. The presence and number of TdT-positive nuclei showed a strong association with younger patient age. Extramedullary hematopoiesis was identified in 11/42 patients, all under the age of 1. The presence of extramedullary hematopoiesis did not correlate with TdT count (P=0.158). Dual immunostaining and flow cytometric analysis in 1 case showed weak expression of B-cell markers and favored normal precursor B cells. Although TdT is a common marker of lymphoblastic lymphoma, we have demonstrated that TdT-positive cells may be part of the inflammatory milieu in infant kidneys. Together with cytologic, architectural, and clinical features, these data can help to avoid misinterpretation of involvement by lymphoblastic lymphoma/leukemia.

Mutant calreticulin-expressing cells induce monocyte hyperreactivity through a paracrine mechanism.

Mutations in the calreticulin gene (CALR) were recently identified in approximately 70-80% of patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis. All frameshift mutations generate a recurring novel C-terminus. Here we provide evidence that mutant calreticulin does not accumulate efficiently in cells and is abnormally enriched in the nucleus and extracellular space compared to wildtype calreticulin. The main determinant of these findings is the loss of the calcium-binding and KDEL domains. Expression of type I mutant CALR in Ba/F3 cells confers minimal IL-3-independent growth. Interestingly, expression of type I and type II mutant CALR in a nonhematopoietic cell line does not directly activate JAK/STAT signaling compared to wildtype CALR and JAK2-V617F expression. These results led us to investigate paracrine mechanisms of JAK/STAT activation. Here we show that conditioned media from cells expressing type I mutant CALR exaggerate cytokine production from normal monocytes with or without treatment with a toll-like receptor agonist. These effects are not dependent on the novel C-terminus. These studies offer novel insights into the mechanism of JAK/STAT activation in patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis.

Aberrations of MYC are a common event in B-cell prolymphocytic leukemia.

OBJECTIVES: B-cell prolymphocytic leukemia (B-PLL) remains a controversial entity, and its molecular pathogenesis is largely unknown. Patients are older, typically having marked lymphocytosis and splenomegaly in the absence of lymphadenopathy. It is defined as a mature B-cell leukemia with more than 55% circulating prolymphocytes. Leukemic mantle cell lymphoma and chronic lymphocytic leukemia in prolymphocytic transformation must be excluded. METHODS: Case archives were retrospectively reviewed for B-PLL in patients without a previous diagnosis of chronic lymphocytic leukemia or other B-cell neoplasm. RESULTS: We identified six cases of B-PLL with available cytogenetic data, five of which showed evidence of aberrations in MYC. Three cases showed additional signals for the MYC gene by fluorescence in situ hybridization (FISH), and two cases demonstrated t(8;14)MYC/IGH by karyotyping or FISH. High levels of MYC protein expression were detected in all cases tested with MYC aberrations. CONCLUSIONS: These results suggest that deregulation of MYC plays an important role in the pathogenesis of B-PLL and expands the spectrum of B-cell neoplasms associated with aberrations of MYC.

Cytogenetic analysis of a primary bone angiosarcoma.

Primary bone angiosarcomas are rare and aggressive vascular malignancies with a high mortality rate. To our knowledge, there are no reported cytogenetic abnormalities in primary bone angiosarcomas, although several have been reported in soft tissue angiosarcomas. We report a case of primary bone angiosarcoma, arising in the tibia of a 79-year-old woman, with a unique clonal chromosomal rearrangement: t(1;14)(p21;q24), that has not been reported in either soft tissue or primary bone angiosarcoma. The biologic significance of this translocation is not clear; however, the 1p21 locus is in the region of colony stimulating factor (CSF-1), which may play a role in tumorigenesis, as has been described in pigmented villonodular synovitis and tenosynovial giant cell tumor.