Immunohistochemical loss of enhancer of Zeste Homolog 2 (EZH2) protein expression correlates with EZH2 alterations and portends a worse outcome in myelodysplastic syndromes.

EZH2 coding mutation (EZH2MUT), resulting in loss-of-function, is an independent predictor of overall survival in MDS. EZH2 function can be altered by other mechanisms including copy number changes, and mutations in other genes and non-coding regions of EZH2. Assessment of EZH2 protein can identify alterations of EZH2 function missed by mutation assessment alone. Precise evaluation of EZH2 function and gene-protein correlation in clinical MDS cohorts is important in the context of upcoming targeted therapies aimed to restore EZH2 function. In this study, we evaluated the clinicopathologic characteristics of newly diagnosed MDS patients with EZH2MUT and correlated the findings with protein expression using immunohistochemistry. There were 40 (~6%) EZH2MUT MDS [33 men, seven women; median age 74 years (range, 55-90)]. EZH2 mutations spanned the entire coding region. Majority had dominant EZH2 clone [median VAF, 30% (1-92)], frequently co-occurring with co-dominant TET2 (38%) and sub-clonal ASXL1 (55%) and RUNX1 (43%) mutations. EZH2MUT MDS showed frequent loss-of-expression compared to EZH2WT (69% vs. 27%, p = 0.001). Interestingly, NINE (23%) EZH2WT MDS also showed loss-of-expression. EZH2MUT and loss-of-expression significantly associated with male predominance and chr(7) loss. Further, only EZH2 loss-of-expression patients showed significantly lower platelet counts, a trend for higher BM blast% and R-IPSS scores. Over a 14-month median follow-up, both EZH2MUT (p = 0.027) and loss-of-expression (p = 0.0063) correlated with poor survival, independent of R-IPSS, age and gender. When analyzed together, loss-of-expression showed a stronger correlation than mutation (p = 0.061 vs. p = 0.43). In conclusion, immunohistochemical assessment of EZH2 protein, alongside mutation, is important for prognostic workup of MDS.

Improved outcomes among newly diagnosed patients with FMS-like tyrosine kinase 3 internal tandem duplication mutated acute myeloid leukemia treated with contemporary therapy: Revisiting the European LeukemiaNet adverse risk classification.

Mutations in fms-like tyrosine kinase 3 (FLT3) gene are common genomic alterations in acute myeloid leukemia (AML). FLT3 internal tandem duplication mutations (FLT3-ITD) have consistently been shown to be adversely prognostic, particularly those with high allelic ratio (AR). Current AML treatment strategies, including high dose cytarabine, purine analogs, FLT3 inhibitors (FLT3i), and with or without allogeneic stem cell transplant (SCT) have been shown to improve the outcomes in patients with FLT3 mutations. We analyzed a consecutive cohort of newly diagnosed patients with AML treated at a large academic medical center from January 2012 to January 2020. A total of 1576 patients with a new diagnosis of AML were reviewed. Among these, 1438 (91%) had molecular testing for FLT3 mutations and 21% (304/1438) had an FLT3 mutation, including 17% with an FLT3-ITD mutation. We show that FLT3-ITD high AR with NPM1 wild-type have significantly improved survival compared with other European LeukemiaNet (ELN) adverse risk disease. In multivariable cox proportional hazards model of patients receiving intensive or low-intensity induction regimens, FLT3 mutations did not have prognostic significance. The use of allogeneic SCT in CR1 for patients with FLT3 mutations appears to improve survival, particularly in those with ELN adverse risk disease. Overall, this data highlights the changing prognostic impact of FLT3 mutations in a contemporary era with appropriate use of induction therapy combined with targeted agents and allogenic SCT.

The survival impact of CKS1B gains or amplification is dependent on the background karyotype and TP53 deletion status in patients with myeloma.

Gains or amplification (amp) of chromosome 1q21/CKS1B are reported to be a high-risk factor in myeloma. In this retrospective study, we analyzed the impact of CKS1B gain/amp on overall survival in the context of other genetic aberrations, such as TP53 deletion, FGFR3-IGH, IGH-MAF, MYEOV/CCND1-IGH, and RB1, as well as karyotype. The cohort included 132 myeloma patients with CKS1B gain/amp detected by fluorescence in-situ hybridization. There were 72 men and 60 women with a median age of 65 years (range 39-88 years). A normal, simple, or complex karyotype was observed in 39.5%, 5.4%, and 55% of patients, respectively. "Double hit," defined as CKS1B gain/amp coexisting with TP53 deletion, or "triple hit," defined as double hit plus t(4;14)FGFR3-IGH or t(14;16)IGH-MAF, were identified in 25 patients (18.9%) and five patients (3.8%), respectively. Double and triple hit were highly associated with a complex karyotype (p = 0.02). Ninety-nine patients (99/128, 77.3%) received stem cell transplantation. The median follow-up time was 48.2 months (range 2-104 months); 68 patients (51.5%) died, with a median overall survival of 58.8 months. Multivariate analysis (Cox model) showed that double hit with TP53 deletion (p = 0.0031), triple hit (p = 0.01), and complex karyotype (p = 0.0009) were each independently associated with poorer overall survival. Stem cell transplantation was associated with better overall survival, mainly in patients with a double or triple hit and complex karyotype (p = 0.003). These findings indicate that the inferior outcome of myeloma patients with CKS1B gain/amp is attributable to the high number of high-risk patients in this group. The prognostic impact of CKS1B gain/amp depends on the background karyotype and TP53 status.

B-cell lymphomas associated with breast implants: Report of three cases and review of the literature.

Since the first reported case in 1997, over 600 women with breast implant-associated anaplastic large cell lymphoma (BI ALCL) have been reported. BI ALCL is a CD30-positive T-cell lymphoma that carries clonal T-cell receptor gene rearrangements, and a subset of cases harbors mutations in the JAK-STAT signaling pathway. Rarely, other histologic types of lymphoma have been reported in association with breast implants, including fewer than 10 cases of B-cell origin. Here, we describe three additional patients with B-cell lymphoma occurring around breast implants. Two of these patients developed extranodal marginal zone lymphoma in the peri-implant capsule, one of which had a concurrent ALCL within the superficial lining of the capsule. The third patient presented with diffuse large B-cell lymphoma inside the breast parenchyma surrounding her implant. Determining the etiology and risk factors for the development of B-cell lymphomas associated with breast implants remains challenging, given the wide spectrum of histologic features and the rarity of these neoplasms. Ultimately, we document three new cases of B-cell lymphoma arising around breast implants and highlight their clinical and pathologic features in order to expand our understanding of this rare disease presentation.

CD123 expression patterns and selective targeting with a CD123-targeted antibody-drug conjugate (IMGN632) in acute lymphoblastic leukemia.

The potential of CD123-targeted therapies in acute lymphoblastic leukemia/lymphoma remains largely unexplored. We examined CD123 expression levels in a large cohort of patients with acute lymphoblastic leukemia/lymphoma and assessed the in vitro impact of IMGN632, a conjugate of CD123-binding antibody with a novel DNA-alkylating payload. CD123 expression on leukemic blasts was surveyed using multicolor/multiparameter flow cytometry. The in vitro effect of IMGN632 was evaluated on B acute lymphoblastic leukemia/lymphoma cell lines and primary B acute lymphoblastic leukemia/lymphoma blasts. The study cohort (n=213) included 183 patients with B acute lymphoblastic leukemia/lymphoma and 30 with T acute lymphoblastic leukemia/lymphoma. CD123 expression was more prevalent in B acute lymphoblastic leukemia/lymphoma than in T acute lymphoblastic leukemia/lymphoma (164/183, 89.6% versus 13/30, 43.3%; P<0.0001), and within B acute lymphoblastic leukemia/lymphoma CD123 expression was more prevalent in Philadelphia chromosome-positive patients than in Philadelphia chromosome-negative patients (96.6% versus 86.3%; P=0.033). In T acute lymphoblastic leukemia/lymphoma, 12/13 (92.3%) patients with CD123-positive blasts had either early T precursor (ETP) or early non-ETP immunophenotype. IMGN632 was highly cytotoxic to B acute lymphoblastic leukemia/lymphoma cell lines, with half maximal inhibitory concentrations (IC50) between 0.6 and 20 pM. In five of eight patients' samples, low picomolar concentrations of IMGN632 eliminated more than 90% of the B acute lymphoblastic leukemia/lymphoma blast population, sparing normal lymphocytes. In conclusion, CD123 expression is prevalent across acute lymphoblastic leukemia/lymphoma subtypes, and the CD123-targeted antibody-drug conjugate IMGN632 demonstrates promising selective activity in preclinical models of B acute lymphoblastic leukemia/lymphoma.

Secondary Philadelphia chromosome acquired during therapy of acute leukemia and myelodysplastic syndrome.

The Philadelphia chromosome resulting from t(9;22)(q34;q11.2) or its variants is a defining event in chronic myeloid leukemia. It is also observed in several types of de novo acute leukemia, commonly in B lymphoblastic leukemia, and rarely in acute myeloid leukemia, acute leukemia of ambiguous lineage, and T lymphoblastic leukemia. Acquisition of the Philadelphia chromosome during therapy of acute leukemia and myelodysplastic syndrome is rare. We reported 19 patients, including 11 men and 8 women with a median age of 53 years at initial diagnosis. The diagnoses at initial presentation were acute myeloid leukemia (n = 11), myelodysplastic syndrome (n = 5), B lymphoblastic leukemia (n = 2), and T lymphoblastic leukemia (n = 1); no cases carried the Philadelphia chromosome. The Philadelphia chromosome was detected subsequently at relapse, or at refractory stage of acute leukemia or myelodysplastic syndrome. Of 14 patients evaluated for the BCR-ABL1 transcript subtype, 12 had the e1a2 transcript. In 11 of 14 patients, the diseases before and after emergence of the Philadelphia chromosome were clonally related by karyotype or shared gene mutations. Of 15 patients with treatment information available, 7 received chemotherapy alone, 5 received chemotherapy plus tyrosine kinase inhibitors, 2 received tyrosine kinase inhibitors only, and 1 patient was not treated. Twelve patients had follow-up after acquisition of the Philadelphia chromosome; all had persistent/refractory acute leukemia. Thirteen of 15 patients died a median of 3 months after the emergence of the Philadelphia chromosome. In summary, secondary Philadelphia chromosome acquired during therapy is rare, and is associated with the e1a2 transcript subtype, terminal disease stage, and poor outcome.

P53 protein overexpression in de novo acute myeloid leukemia patients with normal diploid karyotype correlates with FLT3 internal tandem duplication and worse relapse-free survival.

Although ~50% of acute myeloid leukemia (AML) patients have a normal diploid karyotype by conventional cytogenetics at diagnosis, this patient subset has a variable disease course and outcome. Aberrant overexpression of the p53 protein is usually associated with TP53 alterations and a complex karyotype, but the prevalence and impact of p53 overexpression in AML with diploid cytogenetics is unknown. We examined 100 newly diagnosed AML patients to evaluate the impact of p53 expression status quantified in bone marrow core biopsy samples using immunohistochemistry and computer-assisted image analysis. A total of 24 patients had p53 overexpression defined as 3+ staining intensity in ≥5% of cells; this finding correlated with lower platelet counts (P = .002), absence of CD34 expression in blasts (P = .009), higher bone marrow blast counts (P = .04), and a higher frequency of FLT3 internal tandem duplication (P = .007). Overexpression of p53 independently predicted for shorter leukemia-free survival in patients who underwent allogeneic stem cell transplantation by univariate (P = .021) and multivariate analyses (P = .004). There was no correlation between MDM2 and p53 protein expression in this cohort. We conclude that p53 expression evaluated by immunohistochemistry in bone marrow biopsy specimens at the time of AML diagnosis may indicate distinct clinical characteristics in patients with normal diploid cytogenetics and is a potentially valuable tool that can enhance risk-stratification.

Clinical implications of cytogenetic heterogeneity in multiple myeloma patients with TP53 deletion.

TP53 deletion (ΔTP53) in myeloma is known to be a high-risk finding associated with poorer prognosis. The prognostic impact of underlying cytogenetic heterogeneity in patients with myeloma associated with ΔTP53 is unknown. We studied 90 patients with myeloma associated with ΔTP53 identified by interphase fluorescence in situ hybridization and assessed the impact of karyotype and coexisting alterations of IGH, RB1, and CKS1B. There were 54 men and 36 women with a median age of 59 years (range 38-84); 14 patients had a normal karyotype (NK/ΔTP53), 73 had a complex karyotype (CK/ΔTP53), and 3 had a non-complex abnormal karyotype. Patients with CK/ΔTP53 showed a significantly poorer overall survival compared with patients with NK/ΔTP53 (P=0.0243). Furthermore, in the CK/ΔTP53 group, patients with IGH rearrangement other than t(11;14)(q13;q32)/CCND1-IGH, designated as adverse-IGH, had an even worse outcome (P=0.0045). In contrast, RB1 deletion, CKS1B gain, ploidy, additional chromosome 17 abnormalities, or ΔTP53 clone size did not impact prognosis. Stem cell transplant did not improve overall survival in either the NK/ΔTP53 or CK/ΔTP53 (P=0.8810 and P=0.1006) groups, but tandem stem cell transplant did improve the overall survival of patients with CK/ΔTP53 (P=0.0067). Multivariate analysis confirmed in this cohort that complex karyotype (hazard ratio 1.976, 95% CI 1.022-3.821, P=0.043), adverse-IGH (hazard ratio 3.126, 95% CI 1.192-8.196, P=0.020), and tandem stem cell transplant independently correlate with overall survival (hazard ratio 0.281, 95% CI 0.091-0.866, P=0.027). We conclude that comprehensive genetic assessment adds to TP53 status in the risk stratification of myeloma patients.

Malignancy-associated hemophagocytic lymphohistiocytosis in adults: Relation to hemophagocytosis, characteristics, and outcomes.

BACKGROUND: Malignancy-associated hemophagocytic lymphohistiocytosis (HLH) in adults is a highly lethal disorder. Knowledge gaps have resulted in under diagnosis or delayed diagnosis. METHODS: The University of Texas MD Anderson Cancer Center pathology database (1991-2014) was retrospectively interrogated for the keywords "hemophagocytosis" and/or "lymphohistiocytosis." Seventy-seven adult patients were identified. All had an underlying malignancy. Sixteen patients who had insufficient documentation were excluded. RESULTS: The majority of patients who had pathologic evidence of hemophagocytosis/lymphohistiocytosis had an incomplete workup to confirm or refute HLH using the 2004 HLH criteria (HLH-2004; n = 8 variables), which is a common problem in adult HLH. Only 13 of 61 patients (21%) met the HLH-2004 diagnostic criteria based on available retrospective data. To identify potentially missed cases of HLH, the published literature was reviewed, and selected additional variables known to be associated with adult HLH were selected, resulting in extended diagnostic criteria of 18 variables. Thirty-five patients met the extended criteria, and 33 had follow-up data available. The median overall survival of the 13 patients who met both the extended criteria and the HLH-2004 criteria was similar to that of the 20 patients who met the extended criteria but NOT the HLH-2004 criteria (1.43 vs 1.76 months, respectively; P = .34) indicating a similar underlying, aggressive, systemic process. Twenty-six patients did not meet either criteria, and 17 had follow-up data available. The median overall survival of the 17 patients who had pathologic hemophagocytosis or lymphohistiocytosis but met neither criteria was significantly superior to the survival of those who met both the extended criteria and the HLH-2004 criteria and those who met the extended criteria but not the HLH-2004 criteria (17.27 vs 1.43 vs 1.76, respectively; P = .002). CONCLUSIONS: The addition of diagnostic laboratory variables that are more easily and rapidly available in smaller institutions and primary care settings than the HLH-2004 variables may be a good surrogate to raise early suspicion of malignancy-associated HLH. Prospective validation is warranted. Cancer 2016. © 2016 American Cancer Society. Cancer 2016;122:2857-2866. © 2016 American Cancer Society.

MYC/BCL6 double-hit lymphoma (DHL): a tumour associated with an aggressive clinical course and poor prognosis.

AIMS: Large B cell lymphomas with MYC and BCL6/3q27 rearrangements, designated MYC/BCL6 DHL, are uncommon. Our aim was to better characterize this group of tumours. METHODS AND RESULTS: We studied the clinicopathological features and outcome of 13 patients with MYC/BCL6 DHL and compared this group to a group of 83 MYC/BCL2 DHL patients. There were eight men and five women, with a median age of 63 years. Eleven tumours were classified as diffuse large B cell lymphomas (DLBCL) and two were B cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma (BCLU). Immunohistochemical analysis showed that these tumours were positive for BCL6 (100%), BCL2 (eight of 10; 80%) and CD10 (eight of 10; 80%). Nine of 12 (75%) cases had a germinal centre B cell (GCB) immunophenotype; in one case data were incomplete. All patients were treated with chemotherapy. The clinicopathological features of MYC/BCL6 DHL were similar to MYC/BCL2 DHL, except that MYC/BCL6 DHL had a GCB immunophenotype less often. Patients with MYC/BCL6 DHL had a poor overall survival, similar to patients with MYC/BCL2 DHL (P = 0.32). CONCLUSIONS: MYC/BCL6 DHL is an aggressive B cell lymphoma and patients often have an aggressive clinical course and poor prognosis, similar to patients with MYC/BCL2 DHL.

Enhancing anti-AML activity of venetoclax by isoflavone ME-344 through suppression of OXPHOS and/or purine biosynthesis in vitro.

Venetoclax (VEN), in combination with low dose cytarabine (AraC) or a hypomethylating agent, is FDA approved to treat acute myeloid leukemia (AML) in patients who are over the age of 75 or cannot tolerate standard chemotherapy. Despite high response rates to these therapies, most patients succumb to the disease due to relapse and/or drug resistance, providing an unmet clinical need for novel therapies to improve AML patient survival. ME-344 is a potent isoflavone with demonstrated inhibitory activity toward oxidative phosphorylation (OXPHOS) and clinical activity in solid tumors. Given that OXPHOS inhibition enhances VEN antileukemic activity against AML, we hypothesized that ME-344 could enhance the anti-AML activity of VEN. Here we report that ME-344 enhanced VEN to target AML cell lines and primary patient samples while sparing normal hematopoietic cells. Cooperative suppression of OXPHOS was detected in a subset of AML cell lines and primary patient samples. Metabolomics analysis revealed a significant reduction of purine biosynthesis metabolites by ME-344. Further, lometrexol, a purine biosynthesis inhibitor, synergistically enhanced VEN-induced apoptosis in AML cell lines. Interestingly, AML cells with acquired AraC resistance showed significantly increased purine biosynthesis metabolites and sensitivities to ME-344. Furthermore, synergy between ME-344 and VEN was preserved in these AraC-resistant AML cells. In vivo studies revealed significantly prolonged survival upon combination therapy of ME-344 and VEN in NSGS mice bearing parental or AraC-resistant MV4-11 leukemia compared to the vehicle control. This study demonstrates that ME-344 enhances VEN antileukemic activity against preclinical models of AML by suppressing OXPHOS and/or purine biosynthesis.

Phenotypic evolution in a case of peripheral T-cell lymphoma suggests the presence of tumor heterogeneity.

Peripheral T-cell lymphoma (PTCL), not otherwise specified (NOS), represents a heterogeneous group of nodal and extranodal lymphomas that express a variety of T-cell antigens indicative of mature T-cell lineage. Most cases of PTCL express CD4 and lack CD8 expression and have a T-helper immunophenotype. Although the immunophenotype of PTCL is usually stable over time, immunophenotypic switch or evolution from T-helper to T-suppressor or vice versa has been rarely reported. Herein, we report a patient who presented with nasal PTCL, NOS, that was CD8+ and negative for Epstein-Barr virus, with concurrent skin lesions that had a CD8+/TIA-1+ T-cell immunophenotype. Patient received multi-agent chemotherapy and matched unrelated donor stem cell transplant, and subsequently suffered a cutaneous relapse with a CD4+/TIA-1(-) immunophenotype. Molecular analysis of the neoplasm biopsied at presentation showed one monoclonal T-cell receptor gamma gene rearrangement, and a second oligoclonal peak. At the time of CD4-positive recurrence, the oligoclonal peak was rather prominent, suggesting that the emergence of this peak is related with the phenotypic evolution from CD8+ to CD4+ predominant. These results highlight the utility of sequential immunophenotypic and molecular analysis of PTCL cases at the time of relapse to better understand the mechanisms of disease.

Enhancing anti-AML activity of venetoclax by isoflavone ME-344 through suppression of OXPHOS and/or purine biosynthesis.

Venetoclax (VEN), in combination with low dose cytarabine (AraC) or a hypomethylating agent, is FDA approved to treat acute myeloid leukemia (AML) in patients who are over the age of 75 or cannot tolerate standard chemotherapy. Despite high response rates to these combination therapies, most patients succumb to the disease due to relapse and/or drug resistance, providing an unmet clinical need for novel therapies to improve AML patient survival. ME-344 is a potent isoflavone with demonstrated inhibitory activity toward oxidative phosphorylation (OXPHOS) and clinical activity in solid tumors. Given that OXPHOS inhibition enhances VEN antileukemic activity against AML, we hypothesized that ME-344 could enhance the anti-AML activity of VEN. Here we report that ME-344 synergized with VEN to target AML cell lines and primary patient samples while sparing normal hematopoietic cells. Cooperative suppression of OXPHOS was detected in a subset of AML cell lines and primary patient samples. Metabolomics analysis revealed a significant reduction of purine biosynthesis metabolites by ME-344. Further, lometrexol, an inhibitor of purine biosynthesis, synergistically enhanced VEN-induced apoptosis in AML cell lines. Interestingly, AML cells with acquired resistance to AraC showed significantly increased purine biosynthesis metabolites and sensitivities to ME-344. Furthermore, synergy between ME-344 and VEN was preserved in these AraC-resistant AML cells. These results translated into significantly prolonged survival upon combination of ME-344 and VEN in NSGS mice bearing parental or AraC-resistant MV4-11 leukemia. This study demonstrates that ME-344 enhances VEN antileukemic activity against preclinical models of AML by suppressing OXPHOS and/or purine biosynthesis.

Acute promyelocytic leukemia: Immunophenotype and differential diagnosis by flow cytometry.

BACKGROUND: Prompt diagnosis of acute promyelocytic leukemia (APL) is critical for patient care. In this study, we aimed to characterize the immunophenotype of APL and explore immunophenotypic difference between APL and its mimics using flow cytometric analysis. METHODS: Eighty-five cases were collected, including 47 APL, 26 NPM1-mutated acute myeloid leukemia (AML) and 12 KMT2A-rearranged AML with an APL-like immunophenotype. Immunophenotypes were analyzed using flow cytometric analysis. RESULTS: APL showed four distinct patterns (designated a-d) based on CD45/SSC plots. Blasts in patterns a-c showed high side scatter, whereas blasts in pattern d had low side scatter and were located in the traditional blast gate. Compared with patterns a-c, pattern d of APL (APL-D) was more often positive for CD2 (p = 0.0005) and CD34 (p = 0.0002) in blasts. All NPM1-mutated AML and KMT2A-rearranged AML cases with an APL-like immunophenotype had blasts in the traditional blast gate on CD45/SSC, mimicking APL-D. In comparison, uniform CD13 and positive CD64 were seen in 100% (n = 13) APL-D cases and in only 2 of 26 (8%) NPM1-mutated AML cases (p < 0.0001). In addition, APL-D cases were more likely to be positive for CD2 and/or CD34 than NPM1-mutated AML (p < 0.0001 and p = 0.0007, respectively). In comparison with APL-D, KMT2A-rearranged AML cases were less often positive for myeloperoxidase (MPO) (p = 0.001), with none being strongly positive. Similar to NPM1-mutated AML and different from APL-D, KMT2A-rearranged AML cases were rarely positive for CD34 and all negative for CD2. CONCLUSIONS: APL and its immunophenotypic mimics share some immunophenotypic similarities but can be distinguished by CD2, CD13, CD34, CD64, and MPO.

Activation of RAS/MAPK pathway confers MCL-1 mediated acquired resistance to BCL-2 inhibitor venetoclax in acute myeloid leukemia.

Despite high initial response rates, acute myeloid leukemia (AML) treated with the BCL-2-selective inhibitor venetoclax (VEN) alone or in combinations commonly acquires resistance. We performed gene/protein expression, metabolomic and methylation analyses of isogenic AML cell lines sensitive or resistant to VEN, and identified the activation of RAS/MAPK pathway, leading to increased stability and higher levels of MCL-1 protein, as a major acquired mechanism of VEN resistance. MCL-1 sustained survival and maintained mitochondrial respiration in VEN-RE cells, which had impaired electron transport chain (ETC) complex II activity, and MCL-1 silencing or pharmacologic inhibition restored VEN sensitivity. In support of the importance of RAS/MAPK activation, we found by single-cell DNA sequencing rapid clonal selection of RAS-mutated clones in AML patients treated with VEN-containing regimens. In summary, these findings establish RAS/MAPK/MCL-1 and mitochondrial fitness as key survival mechanisms of VEN-RE AML and provide the rationale for combinatorial strategies effectively targeting these pathways.

De novo acute myeloid leukemia with inv(3)(q21q26.2) or t(3;3)(q21;q26.2): a clinicopathologic and cytogenetic study of an entity recently added to the WHO classification.

Acute myeloid leukemia with inv(3)(q21q26.2) or t(3;3)(q21;q26.2) is a rare type of leukemia recently added to the World Health Organization (WHO) classification scheme. In this study, we analyzed the clinicopathologic and cytogenetic features of 30 cases of de novo acute myeloid leukemia with inv(3)/t(3;3). The median patient age was 53 years (range, 27-77 years). The platelet count was variable (range, 21-597 × 10(9)/l, median: 128 × 10(9)/l), and two (6.7%) patients presented with thrombocytosis (>450 × 10(9)/l). Morphologically, these neoplasms showed a spectrum of findings. Myelomonocytic differentiation was most common in 11 (37%) cases. Morphological evidence of dysplasia was observed in at least one lineage in 23 of 25 (92%) cases in which maturing elements could be assessed. In all, 5 (17%) patients had isolated inv(3) or t(3;3) and 25 (83%) patients had additional cytogenetic abnormalities, most often monosomy 7 (40%). Eleven (37%) patients had a complex karyotype (≥ 3 additional abnormalities). FLT3 gene mutation by internal tandem duplication was identified in 2 of 23 (9%) cases assessed. No clinical, pathological, or cytogenetic features independent of inv(3) or t(3;3) correlated with a worse outcome. However, patients treated with allogeneic stem cell transplantation (n=11) had a significantly better survival than did those treated with chemotherapy alone (n=17) (13.8 vs 8.0 months, P=0.041). We conclude that de novo acute myeloid leukemia associated with inv(3)/t(3;3) is an aggressive type of leukemia regardless of morphological or karyotypic findings, supporting the inclusion of this disease as a specific entity defined by inv(3)/t(3;3) in the WHO classification. Allogeneic stem cell transplantation seems to improve outcome in patients with this disease.

HDM4 is overexpressed in mantle cell lymphoma and its inhibition induces p21 expression and apoptosis.

In mouse models and cell lines, murine double minute 2 (MDM2) and MDM4 have been shown to synergistically promote proteasome-mediated degradation of p21 and p53. MDM4 also inhibits p53-mediated transcriptional activation of p21. p53 expression results in increased p21 expression, a negative cell-cycle regulatory protein and an inhibitor of cyclin D1. As mantle cell lymphoma is characterized by cyclin D1 overexpression, we assessed for human homolog of MDM4 (HDM4) expression and its effect on p21 in mantle cell lymphoma. Using immunohistochemical methods, in reactive lymph nodes (n=19) germinal center cells strongly expressed HDM4 in the nucleus and the cytoplasm, but mantle zone B-cells were only dimly positive. In mantle cell lymphoma tumors, aberrant HDM4 nuclear expression was observed in 18 of 19 (95%) cases. In contrast, HDM4 in other B-cell non-Hodgkin lymphoma types retained its normal pattern of expression. To further characterize the differential upregulation of HDM4 in mantle cell lymphoma, HDM4 was assessed by quantitative real-time polymerase chain reaction in four mantle cell lymphoma cell lines (Granta 519, Z-138, SP-53, and Mino) and six mantle cell lymphoma tumors. Both the splicing variant HDM4-S, containing only the p53-binding domain, and full length HDM4 were increased compared with normal CD19+ B-cells (P<0.05). Using small interfering RNA to inhibit HDM4 in the SP53 and Mino cell lines showed increased p21 and active caspase-3, the latter indicating increased apoptosis. Our results show that HDM4 is overexpressed in mantle cell lymphoma and, at least in part, exerts its effect by suppressing p21 expression, thereby enhancing cell-cycle progression. Inhibition of HDM4 may serve as a potential approach in the design of therapy for patients with mantle cell lymphoma.

Acute myeloid leukemia harboring t(8;21)(q22;q22): a heterogeneous disease with poor outcome in a subset of patients unrelated to secondary cytogenetic aberrations.

Acute myeloid leukemia with t(8;21)(q22;q22) is a distinct type of leukemia considered to have a favorable prognosis. However, some patients rapidly succumb to disease despite chemotherapy. We studied 56 patients with acute myeloid leukemia associated with t(8;21) and correlated clinicopathologic, cytogenetic and molecular findings with outcome to identify markers of prognosis. In a subset of patients, we also assessed the status of the c-KIT, FLT3 and RAS genes. There were 31 men and 25 women, with a median age of 38 years (range 4-76). The follow-up period ranged from 17 to 104 months (median 52). At the last follow-up, 29 patients had died, 25 patients were in complete remission and two patients were alive with disease. The median survial was 38 months. The 5-year overall survival rate of newly diagnosed patients was 56%. Most patients (39/56, 70%) had chromosomal aberrations in addition to t(8;21), with loss of a sex chromosome (39%) being most common followed by del(9q)(q21-22) (11%) and trisomy 8 (7%). These aberrations, however, did not predict survival. C-KIT (D816V or D816Y), FLT3 (ITD or D835) and RAS mutations were detected in 26, 10 and 7%, respectively, of cases assessed. The 5-year overall survival rate of patients with mutated leukemia was 20%. No mutations were observed in three patients who died within 7 months of diagnosis. Leukocytosis or CD56 expression did not correlate with a poor survival nor did the levels of CD19 expression predict c-KIT mutation status. We conclude that acute myeloid leukemia associated with t(8;21) is a heterogeneous disease with poor survival in a subset of patients unrelated to common secondary cytogenetic aberrations.