•The most frequent epigenetic alterations in DLBCL are described.•We review potential targets for epigenetic therapies in DLBCL.•The current clinical development of epigenetic drugs and future ...direction for combination therapies are outlined.
After decades of intense research on genetic alterations in cancer and successful implementation of genetically-based targeted therapies, the field of cancer epigenetics is only beginning to be fully recognized. The discovery of frequent mutations in genes modifying the epigenome in diffuse large B-cell lymphoma (DLBCL) has highlighted the outstanding role of epigenetic deregulation in this disease. Identification of epigenetically-driven DLBCL subgroups and development of novel epigenetic drugs have rapidly advanced. However, further insights are needed into the biological consequences of epigenetic alterations and the possibility of restoring the aberrant epigenome with specific therapies to bring this treatment concept further into clinical practice. This review will summarize the main epigenetic changes found in DLBCL and their potential for precision medicine approaches.
Overexpression of BAALC is an adverse prognostic factor in adults with cytogenetically normal acute myeloid leukemia and T-cell acute lymphoblastic leukemia (ALL). Here, we analyzed the prognostic ...significance of BAALC in B-precursor ALL. BAALC MRNA expression was determined in 368 primary adult B-precursor ALL patients enrolled on the 06/99 and 07/03 GMALL trials. Patients were grouped into tertiles according to BAALC expression (T1-T3). Higher BAALC expression (T3 vs T2 vs T1) was associated with higher age (P < .001), a higher white blood cell count (P = .008), CD34 (P = .001), BCR-ABL (P < .001), and MLL-AF4 (P < .001). Higher BAALC expression predicted primary therapy resistance in the overall cohort (P = .002) and in the BCR-ABL− and MLL-AF4− subgroup (P = .01). In BCR-ABL− and MLL-AF4− patients, higher BAALC expression was associated with a shorter overall survival (OS; 5-year OS: T3, 38%; T2, 52%; T1, 70%; P = .004) and independently predicted OS in multivariate models (P = .03). Gene-expression profiling revealed an up-regulation of stem cell markers and genes involved in chemoresistance (TSPAN7 and LYN) in the high BAALC group. Thus, high BAALC expression is associated with an immature, chemoresistant leukemic phenotype and identifies patients with inferior OS. Determination of BAALC might contribute to risk assessment of molecularly undefined adult B-precursor ALL.
An increasing number of cytogenetic and molecular genetic aberrations have been identified in acute myeloid leukaemia (AML), highlighting the biological heterogeneity of the disease. Moreover, the ...characterisation of specific molecular abnormalities provides the basis for targeted therapies, such as all
trans
retinoic acid (ATRA) and arsenic trioxide treatment in acute promyelocytic leukaemia or tyrosine kinase inhibitors in AML with
FLT3
mutations. Several cytogenetic and molecular genetic changes have been shown to be prognostically relevant and have been acknowledged in the latest WHO classification of AML as separate entities. A detailed marker assessment at diagnosis is crucial for risk-stratification of AML patients, allowing the identification of those at high risk of relapse, who may benefit from early allogeneic stem cell transplantation. Finally, molecular markers are important for the detection of minimal residual disease after initial therapy and during long-term follow-up, which enables a more tailored treatment approach for individual AML patients.
Abstract 1581▪▪This icon denotes an abstract that is clinically relevant.
Poster Board I-607
High expression of the Brain And Acute Leukemia, Cytoplasmic (BAALC) gene is associated with primary ...chemotherapy resistance and inferior outcome in adult patients with cytogenetically normal (CN) acute myeloid leukemia (AML) and T-cell acute lymphoblastic leukemia (ALL). Due to the prognostic significance of BAALC in different leukemic lineages, we investigated its expression pattern and prognostic impact in adult B-precursor ALL, with a focus on patients lacking the molecular high-risk factors BCR-ABL and MLL-AF4.
BAALC expression was determined by quantitative real-time RT-PCR in pretreatment bone marrow samples of 368 adult patients with newly diagnosed B-precursor ALL treated on the 06/99 and 07/03 GMALL trials. Patients were grouped into tertiles (T1-T3) according to BAALC expression levels. The median follow-up was 44 months. Patients who received stem cell transplantation (SCT) in first remission (CR1) were censored at the time of SCT for survival analyses. In an additional set of 51 adult B-precursor ALL specimens, gene-expression profiling (GEP) was performed using HG-U133 Plus 2.0 (Affymetrix) to obtain insights into the biological function of BAALC and its potential role in drug resistance. Samples were divided into tertiles (t1-t3) by the median expression of the two probe sets representing BAALC (218899_s_at, 222780_s_at).
Higher BAALC expression (T3 vs T2 vs T1) was associated with a higher age (P<0.001), a higher white blood cell (WBC) count (P=0.008), CD34 positivity (P=0.001), presence of BCR-ABL (P<0.001), and of MLL-AF4 (P<0.001) in the overall cohort. In multivariate analysis including clinical and molecular variables, higher BAALC expression was the only predictive factor for primary therapy resistance in the overall cohort OR 2.4 (95% CI 1.4-4.3); P=0.002. In the BCR-ABL- and MLL-AF4-negative subgroup, higher BAALC expression independently predicted primary resistant disease OR 4.2 (95% CI 1.4-12.3); P=0.01, as did the immunophenotype. BCR-ABL- and MLL-AF4-negative patients with higher BAALC expression had a significantly shorter overall survival OS; 5-year OS: BAALC T3: 38% (95% CI 22-54), BAALC T2: 52% (95% CI 36-67), BAALC T1: 70% (95% CI 59-81); P=0.004. Upon multivariate analysis, BAALC was of independent prognostic significance for OS in BCR-ABL- and MLL-AF4-negative patients HR 1.4 (95% CI 1.0-2.0); P=0.03, as well as the factors WBC and age. Furthermore, we identified high BAALC expression as an independent predictive factor for inferior OS in the GMALL standard risk (SR) group BCR-ABL- and MLL-AF4-negative patients with early therapy response and WBC '30/nl at initial diagnosis; HR 1.5 (95% CI 1.0-2.3); P=0.04. The other variable in the final model predicting OS for SR patients was age. Interestingly, BCR-ABL- and MLL-AF4-negative patients allocated to allogeneic SCT in CR1 with high BAALC expression showed a particular survival benefit with a 5-year OS of 62%. In GEP analysis, high BAALC expression (t3 vs t1) was associated with the up-regulation of hematopoietic stem cell markers (CD34, CD99, FZD6) and genes implicated in chemoresistance (TSPAN7, LYN). Moreover, GEP revealed down-regulation of genes in the high BAALC group that had been related to a favourable outcome in adult ALL and AML (CDKN1C/p57Kip2, RGS2).
In addition to T-ALL and CN-AML, we have shown that BAALC predicts an unfavourable response to induction chemotherapy and inferior OS in adult B-precursor ALL patients. These clinical observations are further supported by the GEP signature associated with high BAALC expression. The lineage-independent association of BAALC with an immature, highly proliferative, and resistant leukemic phenotype underscores a possible involvement of BAALC in leukemogenesis and its putative role in chemoresistance.
Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership.
Abstract 2629▪▪This icon denotes an abstract that is clinically relevant.
Poster Board II-605
The human gene BAALC (Brain And Acute Leukemia, Cytoplasmic) is a molecular marker of immature ...hematopoietic cells. In normal hematopoiesis, BAALC is highly expressed in CD34 positive progenitors and down-regulated with cell differentiation. Moreover, high mRNA expression levels of BAALC have shown to be an adverse risk factor and were associated with chemotherapy resistance in adult patients with cytogenetically normal acute myeloid leukemia (CN-AML) and acute T-lymphoblastic leukemia (T-ALL). While the prognostic value of BAALC expression has been validated, the function of BAALC in leukemia remains unknown. The aim of this study was to identify genes correlated with BAALC to gain further insights into the underlying pathways of the BAALC-associated chemotherapy resistant leukemic phenotype. Therefore, we generated gene expression profiles (GEP) using pre-treatment T-ALL samples (n=86) that differentiated high versus low BAALC expressers (HG-U133 Plus 2.0, Affymetrix). Samples were divided into quartiles (Q1-Q4) according to BAALC expression and QB1-3 was defined as low BAALC and QB4 as high BAALC. Differentially expressed genes between QB1–3 and QB4 were defined by a minimum expression change of three-fold (P'0.05). In order to identify BAALC-associated genes common to T-ALL, CN-AML and normal hematopoiesis we compared these BAALC-derived GEP in T-ALL with BAALC-associated profiles of CN-AML (Langer C et al, Blood 2008) and of normal CD34 positive progenitors (Komor et al, Stem Cells 2005). Only four genes (CD34, CD133, NPR3, IGFBP7) were common to the BAALC-associated GEP of all three entities (T-ALL, CN-AML, and CD34 positive progenitors). Of these genes, the human gene Insulin-like Growth Factor Binding Protein 7 (IGFBP7) was further investigated as the Insulin-like growth factor signaling plays an important role in various human cancers. Next we determined IGFBP7 expression levels by real-time RT-PCR in an independent cohort of 219 adults with newly diagnosed T-ALL, registered within the German Multicenter Acute Lymphoblastic Leukemia Study 06/99 and 07/03 protocols. In T-ALL samples, IGFBP7 showed a heterogeneous expression pattern compared to normal bone marrow (expression range: 0–79.1 vs 0.6–2.3). For correlation of IGFBP7 expression with clinical and molecular features, samples were divided into quartile groups according to IGFBP7 expression and defined as low IGFBP7 with expression levels in QI1 to QI3 (n=158) and as high IGFBP7 with expression levels in QI4 (n=53). High expression levels of IGFBP7 were associated with an immature phenotype of early T-ALL (62% of patients in QI4 showed an early T-ALL immunophenotype as compared to only 15% in QI1–3; P<0.001), high cell surface expression of CD34 (mean: 36% vs 15%; P<0.001) and CD33 (mean: 24% vs 3%; P<0.001). Moreover, high IGFBP7 expression significantly predicted a higher frequency of refractory disease (11% vs 3%; P=0.03) and an inferior overall survival (OS; 4-year OS: IGFBP7 QI4: 42% vs IGFBP7 QI1–3: 55%; P=0.03). In vitro, studies revealed that treatment with rIGFBP7 significantly inhibited proliferation of KG1a leukemic cells (65% reduction of proliferation compared to untreated cells; P<0.001) determined by Cell Proliferation Reagent WST-1. Moreover, a 26% reduction (P<0.001) of the DNA synthesis phase was detected by BrdU incorporation after rIGFBP7 treatment of KG1a cells. Taken together, we identified IGFBP7 as a lineage-independent, BAALC co-expressed gene involved in leukemia. High IGFBP7 expression was associated with stem cell features and treatment failure in T-ALL. In contrast to BAALC which likely represents only a surrogate marker of treatment failure in acute leukemias, IGFBP7 might play functional role and contribute to the molecular basis of BAALC-associated drug resistance. As rIGFBP7 inhibits proliferation of leukemic cells, secreted IGFBP7 protein may therefore promote resistance to cell cycle dependent cytostatic drugs targeting highly proliferate blast cells.
Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership.
Outcome of patients with relapsed/refractory (r/r) diffuse large B-cell lymphoma (DLBCL) remains poor, highlighting the need for novel treatment approaches. The multicentre randomised phase II LEGEND ...trial evaluated lenalidomide in combination with rituximab, methylprednisolone and gemcitabine (R-GEM-L) vs. standard R-GEM-P as second-line treatment of DLBCL. The study closed early to recruitment after the planned interim analysis failed to demonstrate a complete response (CR) rate of ≥ 40% in either arm. Among 34 evaluable patients, 7/18 (38.9%) achieved CR with R-GEM-L and 3/16 (18.8%) with R-GEM-P. Median event-free and overall survival was 3.5/3.8 months and 10.8/8.3 months for R-GEM-L and R-GEM-P, respectively. The incidence of grade ≥ 3 toxicities was 52% in R-GEM-L and 83% in R-GEM-P. Efficacy and tolerability of R-GEM-L seem comparable with R-GEM-P and other standard salvage therapies, but a stringent design led to early trial closure. Combination of lenalidomide with gemcitabine-based regimens should be further evaluated in r/r DLBCL.
Aberrant activation of the Wnt pathway plays a pathogenetic role in various tumors and has been associated with adverse outcome in acute lymphoblastic leukemia (ALL). LEF1, a key mediator of Wnt ...signaling, has been linked to leukemic transformation, and recurrent mutations of LEF1 have been identified in pediatric T-ALL. Here we evaluated the prognostic significance of LEF1 expression in B-precursor ALL patients. LEF1 expression was determined by quantitative real-time RT-PCR in 282 adult B-precursor ALL patients treated on 06/99 and 07/03 GMALL trials. Patients were grouped into quartiles (Q1-Q4) according to LEF1 expression levels (LEF1 high, Q4; n = 71; LEF1 low, Q1-Q3; n = 211). Patients with high LEF1 expression had a significantly shorter relapse-free survival (RFS) compared with low LEF1 expressers (5-year RFS: LEF1 high, 27%; LEF1 low, 47%; P = .05). Importantly, high LEF1 expression was also associated with inferior RFS in standard-risk patients and was independently predictive for RFS (P = .02) in multivariate analyses for this subgroup. Thus, high LEF1 expression identifies B-precursor ALL patients with inferior RFS, supporting a pathogenetic role of Wnt signaling in ALL. Standard-risk patients with high LEF1 expression might benefit from early treatment modifications and new molecular therapies, including agents targeting the Wnt pathway.
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