Daniela Hoehn

Myeloid neoplasms with isolated isochromosome 17q represent a clinicopathologic entity associated with myelodysplastic/myeloproliferative features, a high risk of leukemic transformation, and wild-type TP53.

Isolated isochromosome (17q) is a rare cytogenetic abnormality in Philadelphia chromosome‐negative myeloid neoplasms, usually myelodysplastic and/or myeloproliferative neoplasms (MDS/MPN). De novo acute myeloid leukemia (AML) with isochromosome 17q has rarely been reported. The frequency of genetic mutations is unknown.

CD117 expression is a sensitive but nonspecific predictor of FLT3 mutation in T acute lymphoblastic leukemia and T/myeloid acute leukemia

Others have suggested that CD117, or an immunophenotypic profile including CD117, can serve as surrogate for FLT3 mutation in T acute lymphoblastic leukemia (ALL), thereby guiding targeted therapy. We report the results of flow cytometry immunophenotypic analysis in 42 cases of T-ALL and T/myeloid acute leukemia also assessed for FLT3 mutation. CD117 was expressed in 21 (50%), and FLT3 was mutated in 8 cases (19%; 1 T-ALL and 7 T/myeloid). FLT3-mutated cases were terminal deoxynucleotidyl transferase (TdT)+/CD2+ (7/8), cytoplasmic CD3+/CD5+ (5/8), CD7+/CD13+/CD15+ (4/6), CD33+ (4/8), CD34+, and CD117+ (bright). Cytochemistry showed myeloperoxidase-positive cells in all T/myeloid acute leukemias (3%-50%). We conclude that FLT3 mutation is rare in T-ALL, and its presence supports T/myeloid lineage. CD117 expression alone is sensitive but not specific for FLT3 mutation. The immunophenotypic profile of TdT, CD7, CD13, CD34, and CD117 (bright) is helpful for predicting FLT3 mutation, with a sensitivity of 100% and specificity of 94%.

Dual Targeting of Protein Degradation Pathways with the Selective HDAC6 Inhibitor ACY-1215 and Bortezomib Is Synergistic in Lymphoma

Purpose: Pan-class histone deacetylase (HDAC) inhibitors are effective treatments for select lymphomas. Isoform-selective HDAC inhibitors are emerging as potentially more targeted agents. HDAC6 is a class IIb deacetylase that facilitates misfolded protein transport to the aggresome for degradation. We investigated the mechanism and therapeutic impact of the selective HDAC6 inhibitor ACY-1215 alone and in combination with bortezomib in preclinical models of lymphoma. Experimental Design: Concentration–effect relationships were defined for ACY-1215 across 16 lymphoma cell lines and for synergy with bortezomib. Mechanism was interrogated by immunoblot and flow cytometry. An in vivo xenograft model of DLBCL was used to confirm in vitro findings. A collection of primary lymphoma samples were surveyed for markers of the unfolded protein response (UPR). Results: Concentration–effect relationships defined maximal cytotoxicity at 48 hours with IC50 values ranging from 0.9 to 4.7 μmol/L. Strong synergy was observed in combination with bortezomib. Treatment with ACY-1215 led to inhibition of the aggresome evidenced by acetylated α-tubulin and accumulated polyubiquitinated proteins and upregulation of the UPR. All pharmacodynamic effects were enhanced with the addition of bortezomib. Findings were validated in vivo where mice treated with the combination demonstrated significant tumor growth delay and prolonged overall survival. Evaluation of a collection of primary lymphoma samples for markers of the UPR revealed increased HDAC6, GRP78, and XBP-1 expression as compared with reactive lymphoid tissue. Conclusions: These data are the first results to demonstrate that dual targeting of protein degradation pathways represents an innovative and rational approach for the treatment of lymphoma. Clin Cancer Res; 21(20); 4663–75. ©2015 AACR.

Genome-wide analysis of pediatric-type follicular lymphoma reveals low genetic complexity and recurrent alterations of TNFRSF14 gene

Pediatric-type follicular lymphoma (PTFL) is a variant of follicular lymphoma (FL) with distinctive clinicopathological features. Patients are predominantly young males presenting with localized lymphadenopathy; the tumor shows high-grade cytology and lacks both BCL2 expression and t(14;18) translocation. The genetic alterations involved in the pathogenesis of PTFL are unknown. Therefore, 42 PTFL (40 males and 2 females; mean age, 16 years; range, 5-31) were genetically characterized. For comparison, 11 cases of conventional t(14:18)(-) FL in adults were investigated. Morphologically, PTFL cases had follicular growth pattern without diffuse areas and characteristic immunophenotype. All cases showed monoclonal immunoglobulin (IG) rearrangement. PTFL displays low genomic complexity when compared with t(14;18)(-) FL (mean, 0.77 vs 9 copy number alterations per case; P <001). Both groups presented 1p36 alterations including TNFRSF14, but copy-number neutral loss of heterozygosity (CNN-LOH) of this locus was more frequently observed in PTFL (40% vs 9%; P =075). TNFRSF14 was the most frequently affected gene in PTFL (21 mutations and 2 deletions), identified in 54% of cases, followed by KMT2D mutations in 16%. Other histone-modifying genes were rarely affected. In contrast, t(14;18)(-) FL displayed a mutational profile similar to t(14;18)(+) FL. In 8 PTFL cases (19%), no genetic alterations were identified beyond IG monoclonal rearrangement. The genetic landscape of PTFL suggests that TNFRSF14 mutations accompanied by CNN-LOH of the 1p36 locus in over 70% of mutated cases, as additional selection mechanism, might play a key role in the pathogenesis of this disease. The genetic profiles of PTFL and t(14;18)(-) FL in adults indicate that these are two different disorders.

MYC Protein Expression in Primary Diffuse Large B-Cell Lymphoma of the Central Nervous System

Primary diffuse large B-cell lymphoma of the central nervous system (CNS DLBCL) is a rare, aggressive subtype of DLBCL, the biology of which is poorly understood. Recent studies have suggested a prognostic role of MYC protein expression in systemic DLBCL, but little is known about the frequency and significance of MYC protein expression in CNS DLBCL. Hence, we investigated MYC protein expression profiles of CNS DLBCL and assessed the relationship between MYC expression and a variety of histopathologic, immunophenotypic, genetic, and clinical features. Fifty-nine CNS DLBCL diagnosed at our institution over the past 13 years were evaluated. The majority of cases (80%) showed centroblastic morphology, and 12 (20%) displayed a perivascular pattern of infiltration. According to the Hans criteria, 41 (69%) cases had a non-germinal center B-cell and 18 (31%) had a germinal center B-cell cell-of-origin (COO) phenotype. Mean MYC protein expression was 50% (median: 50%, range: 10-80%). Forty-three cases (73%) showed MYC overexpression (≥40%), and 35 (60%) showed MYC/BCL2 coexpression. MYC overexpression was seen in the single case harboring MYC translocation and in the cases showing increased copies of MYC (27%); however, no significant difference in mean MYC expression was seen between groups harboring or lacking MYC aberrations. In our series, age was associated with a significantly increased risk of death, and the perivascular pattern of infiltration was associated with a significantly increased risk of disease progression. Neither MYC expression (with or without BCL2 coexpression) nor other variables, including COO subtype were predictive of clinical outcome. Our findings indicate that the proportion of CNS DLBCL overexpressing MYC is higher compared to systemic DLBCL, and MYC overexpression appears to be independent of genetic MYC abnormalities. Thus, MYC expression and other immunophenotypic markers used for prognostication of systemic DLBCL might not apply to CNS DLBCL due to differences in disease biology.

Classical Hodgkin lymphoma arising in the setting of iatrogenic immunodeficiency: a clinicopathologic study of 10 cases.

Iatrogenic immunodeficiency-associated lymphoproliferative disorders are rare. A small subset of these lesions resembles classical Hodgkin lymphoma (CHL), but there are few data in the literature about these lesions. We describe 10 patients with autoimmune diseases treated with immunomodulator therapeutic agents who developed CHL. The autoimmune diseases included rheumatoid arthritis (n=5), systemic lupus erythematosus (n=2), dermatomyositis (n=1), autoimmune hepatitis (n=1), and Crohn disease (n=1), and the immunomodulatory therapies were methotrexate, azathioprine, tumor necrosis factor-&agr; inhibitors, and thalidomide alone or in various combinations. The study group included 9 women and 1 man with a median age of 50 years (range, 25 to 77 y). The histologic features supported CHL in all cases with Reed-Sternberg (RS) and Hodgkin (H) cells in an inflammatory cell background, although the neoplasm could only be subclassified in 3 patients: 2 nodular sclerosis and 1 mixed cellularity. Immunohistochemical analysis supported the diagnosis of CHL. In all cases the RS-H cells were CD30+. Nine of 10 cases were CD15+, whereas CD20 was expressed variably in 4/10 cases. CD45/LCA was negative in 8 cases assessed. In situ hybridization for Epstein-Barr virus–encoded RNA was positive in the RS-H cells in 8/10 cases. The microenvironment of these lesions depicted a predominance of T-regulatory cells and M2 histiocytes. Clinical follow-up data were available for 7 patients, with a median posttreatment period of 27 months (range, 12 mo to 7 y). In all 7 patients immunomodulatory drug therapy was discontinued, and chemotherapy for CHL was administered; 2 patients also received local radiation. All 7 patients achieved complete remission and are alive. We conclude that iatrogenic immunodeficiency-associated CHL is highly associated with Epstein-Barr virus infection, and patients usually have a good outcome after discontinuation of immunomodulatory agents and chemotherapy for CHL.

Composite mantle cell lymphoma and chronic lymphocytic leukemia/small lymphocytic lymphoma: A clinicopathologic and molecular study

Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) share many features and both arise from CD5+ B-cells; their distinction is critical as MCL is a more aggressive neoplasm. Rarely, cases of composite MCL and CLL/SLL have been reported. Little is known about the nature of these cases and, in particular, the clonal relationship of the 2 lymphomas. Eleven composite MCL and CLL/SLL cases were identified. The clinical, morphologic and immunophenotypic features of the MCL and CLL/SLL were characterized. IGH (immunoglobulin heavy chain) gene analysis was performed on microdissected MCL and CLL/SLL components to assess their clonal relationship. Ten patients had lymphadenopathy, and 7 patients had bone marrow involvement. The MCL component had the following growth patterns: in situ (n = 1), mantle zone (n = 3), nodular and diffuse (n = 3), diffuse (n = 3), and interstitial in the bone marrow (the only patient without lymphadenopathy) (n = 1); 6 MCLs had blastoid or pleomorphic and 5 small lymphocytic features. The CLL/SLL component was nodular (n = 9) or diffuse (n = 2). All MCL were CD5(+) and cyclin D1(+) with t(11;14) translocation. All CLL/SLL were CD5(+), CD23(+) and negative for cyclin D1 or t(11;14). IGH gene analysis showed that the MCL and CLL/SLL components displayed different sized fragments, indicating that the MCL and CLL/SLL are likely derived from different neoplastic B-cell clones. The lack of a clonal relationship between the MCL and CLL/SLL components suggests that MCL and CLL/SLL components represent distinct disease processes and do not share a common progenitor B-cell.

Splenic B-cell lymphomas with more than 55% prolymphocytes in blood: evidence for prolymphocytoid transformation

We describe 4 patients aged 62 to 79 years with splenomegaly and bone marrow involvement by splenic B-cell lymphoma who developed more than 55% prolymphocytes in blood. The diagnosis of B-cell prolymphocytic leukemia was considered clinically based on a markedly elevated leukocyte (up to 131.5×10(9)/L) or prolymphocyte (up to 86%) count. Splenectomy was performed in all patients, and spleen weight ranged from 1500 to 2380 g. In 3 patients, the neoplasms were classified as splenic marginal zone lymphoma, and in 1 patient, the neoplasm was classified as splenic diffuse red pulp small B-cell lymphoma. In 2 patients, splenectomy preceded a B-cell prolymphocytic leukemia-like picture, and the spleen showed splenic marginal zone lymphoma or splenic diffuse red pulp small B-cell lymphoma with increased (10%-20%) nucleolated cells consistent with prolymphocytes. In the other 2 patients, a B-cell prolymphocytic leukemia-like picture prompted splenectomy. Initial examination of bone marrow in these patients suggested splenic marginal zone lymphoma. The spleen specimens showed extensive involvement by splenic marginal zone lymphoma with numerous prolymphocytes. Flow cytometry immunophenotyping in all cases showed lymphocytes positive for monotypic surface immunoglobulin (bright), pan-B-cell antigens, CD11c, CD22, and FMC7. Immunohistochemical analysis in all patients showed moderate to bright p53 expression in the spleen (n=3) or bone marrow (n=2). Annexin A1 and cyclin D1 were negative in all cases. Conventional cytogenetic analysis showed del(7q) in 3 patients. We conclude that splenic B-cell lymphoma of various types can undergo prolymphocytoid transformation with more than 55% prolymphocytes in the blood mimicking B-cell prolymphocytic leukemia.

C-myc protein expression in B-cell acute lymphoblastic leukemia, prognostic significance?

C-myc protein expression has been studied in mature B-cell lymphomas and overexpression has been associated with poor prognosis. We sought to determine the prognostic significance of c-myc protein expression in B-ALL. We found ≥ 20% c-myc expression to predict risk of persistent disease in all age groups (odds ratio 7.487, p=0.013). There was no statistically significant association between c-myc expression and risk of relapse or death in our study. Routine c-myc immunostaining may help identify higher risk patients and guide management of B-ALL. Additional studies are needed to further determine the molecular mechanisms and role of c-myc expression in B-ALL.

Digital image analysis as a tool to assess the effects of imatinib on trabecular bone in patients with chronic myelogenous leukemia

Skeletal integrity is sustained by osteoblast-osteoclast interactions, controlled by several signaling pathways that include tyrosine kinases. Imatinib is a tyrosine kinase inhibitor with an extended therapeutic range based on its ability to differentially bind to receptor and nonreceptor tyrosine kinases. In this study, we used digital image analysis to assess changes in trabecular bone surface area within bone marrow biopsy specimens of 34 patients with chronic phase chronic myelogenous leukemia treated with single-agent imatinib. These patients were 25 men and 9 women with a median age of 59 years. We selected representative areas of paired bone marrow biopsy specimens obtained at baseline and within the subsequent 48 months. Computer-assisted analysis was performed to calculate trabecular bone area (TBA) within the sample by using the equation TBA% = sum of trabecular area/total biopsy specimen area. Percentage changes were defined as ΔTBA% and were arbitrarily subdivided into marked (>50%), moderate (10%-50%), and mild (<10%). During the study interval, TBA% increased in 24 patients (71%) and decreased in 10 patients (29%). Overall, there was a significant increase in TBA% (P = .02). No correlation was found between changes in trabecular bone area and either clinical or cytogenetic response (P = .25). The results show that imatinib therapy can alter trabecular bone in bone marrow biopsy specimens of chronic myelogenous leukemia patients, most often resulting in an increase in TBA%.