ALBERT

Description: Introduction: Aberrant DNA methylation is frequently found in hematologic malignancies where it is associated with altered gene expression. DNA hypomethylating agents (DNMTi), e.g. 5-aza-2'-deoxycytidine (DAC), are used for both global and gene-specific in vivo demethylation and offer a therapeutic option in myelodysplastic syndromes (MDS) and AML. DNMTi have already been utilized to upregulate suppressed fetal hemoglobin (HbF) in adult patients (pts) suffering from hemoglobinopathies. Here we systematically investigated the potential of DAC for in vitro induction of erythroid differentiation as well as HbF expression in the bipotent myeloid leukemia cell line K562 and in vivo in a clinical treatment situation in MDS pts. Methods and Results: We treated K562 cells with non-toxic concentrations of DAC (100 nM, three 24 hour pulses), hemin (50 nM) and phorbol myristate acetate (PMA, 5 nM). DAC treatment led to morphological changes indicating erythroid but not megakaryocytic differentiation. This was confirmed by benzidine staining where DAC (13% positive cells) and hemin (58%) but not PMA treated cells (0%) became positive for hemoglobin synthesis. Lack of CD41 detection by FACS analysis for DAC and hemin indicated absence of megakaryocytic differentiation. Transcriptome profiling by mRNA expression arrays (Affymetrix GeneChip® HG U133 Plus 2.0) revealed highest similarity between hemin and DAC treatment by unsupervised hierarchical clustering, followed by vehicle control and untreated cells. The transcriptome of PMA treated cells clustered most distantly to all other treatments. Both, DAC and hemin induced moderately balanced up- and downregulation of transcripts to an almost identical extent. 1414 transcripts were 〉2 fold upregulated and 1505 were 〉2 fold downregulated upon DAC treatment, whereas 1548 were up- and 2404 were downregulated in hemin treated cells, respectively. The extent of transcriptome dynamics was considerably stronger upon PMA treatment, where 4196 and 3780 transcripts were up- and downregulated, respectively. When intersecting transcriptome changes between the 3 drug treatments (Fig. 1), 368 out of 1548 (23.7%) upregulated transcripts in hemin treated cells were concordantly upregulated upon DAC treatment. The overlap of upregulated transcript was lower compared to PMA treated cells (14.9%). GO analyses of upregulated transcripts identified terms related to erythropoesis and iron metabolism among the top regulated groups of transcripts in DAC treated cells whereas terms related to megakaryocytic differentiation did not show significance. Particularly strong differences of transcripts were observed for a1-, a2-, Ag-, e- and z-globin expression upon DAC and hemin treatment, whereas b- and d-globin were expressed at low levels. These changes were not observed for PMA treated cells. Induction of a- and Ag-globin on mRNA level resulted in enrichment of a- and Ag-globin protein to 15.8% of total cellular protein amount, and consequently in HbF formation in K562 cells as assessed by reversed phase and anion exchange chromatography. HbF levels in peripheral blood were measured from 16 MDS pts, median age 74 years (range 66-78) also treated with a 3-day DAC schedule. Median HbF fraction at baseline was 0.4% (0.1-3.9%) of total hemoglobin with 6 pts (37.5%) exhibiting increased HbF levels (〉1%) already before treatment. In 13/16 (81%) pts, increase of HbF with a median increment of 1.2% (range 0.3-3.7%) was observed. In 3 pts, HbF decreased over the treatment course. Median number of courses until maximum increment was 3 (2-6). HbF levels in 2 pts with AML and 1 with pancreatic cancer treated with nucleoside analogues without demethylating activity (cytosine arabinoside and gemcitabine, respectively) according to standard chemotherapy protocols served as control group and did not show comparable increments. Conclusions: We describe an erythroid differentiation program, from transcriptome level to HbF protein formation, induced by the hypomethylating agent DAC in the bipotent cell line K562. This DAC-mediated differentiation process is specific for erythropoesis but not megakaryopoesis. This is substantiated by in vivo upregulation of HbF upon DAC adminstration in MDS pts. Therefore, we propose to utilize HbF expression as potential biomarker during DAC treatment. Figure 1. Intersection of 〉2 fold upregulated transcripts in K562 cells upon drug treatment. Figure 1. Intersection of 〉2 fold upregulated transcripts in K562 cells upon drug treatment. Disclosures No relevant conflicts of interest to declare.

Description: Key Points AML induction with liposomal daunorubicin (80 mg/m2 per day for 3 days) shows antileukemic activity comparable to idarubicin (12 mg/m2 per day for 3 days). Liposomal daunorubicin promises to be more active in the t(8;21) subgroup and causes less treatment-related toxicity.

Description: Annamycin (Ann) is an anti-tumoral anthracycline whose anti-leukemia activity is relatively unaffected by P-glycoprotein-related multidrug resistance. Unlike for the related doxorubicin (DOX), Ann accumulates in multidrug resistant cell lines, which is accompanied by DNA damage and apoptosis. In preclinical toxicology studies, in contrast to DOX, free Ann displayed a greatly reduced cardiotoxicity, while L-Ann appeared to be non-cardiotoxic. A liposomal formulation of Ann, termed L-Annamycin (L-Ann), is currently evaluated in patients with acute myeloid leukemia (AML). Anti-leukemia activity of Ann was demonstrated in several leukemia models as judged by circulating blast cytoreduction and extension of overall survival. However, the efficacy of L-Ann in the microenvironment of the bone marrow and other organ tissues remains unclear. In the current study, we assessed the anti-AML efficacy of Ann in a novel AML model that allows visualizing the dynamics of individual AML cells in vivo by two-photon microscopy. In this model, mouse AML cells bearing the MLL/ENL-FLT3/ITD[p53-/-] mutations co-express high levels of the cyan fluorescent protein mTurquoise2. Upon intravenous infusion of several tens of thousands cells into syngeneic immunocompetent C57BL6 mice, lethal AML disease reliably develops within 2 weeks. Using host mice expressing appropriate fluorescence reporter genes, the bright cyan fluorescence enables sensitive intravital imaging of individual AML cells in the context of organ architecture. Using this model in Thy1-RFP reporter mice expressing red fluorescence in all organ tissues with the blood flow marked by BSA-AF647 fluorescence, we evaluated AML cellularity reduction in the bone marrow and other organs after a single dose of L-Ann as well as in response to chronic treatment. In addition, we assessed the localization of the surviving AML cells at a high spatial resolution. We evaluated the in vivo organ biodistribution of intravenously infused L-Ann in C57BL6 mice by flow cytometry and two-photon microscopy based on the intrinsic fluorescence of the drug. In addition, we visualized the intracellular compartmentalization of L-Ann using confocal microscopy. Consistent with in vitro findings, we observed a rapid and deep reduction of AML blasts in the peripheral blood after a single dose of L-Ann in a dose-dependent manner (1-4 mg/kg). This reduction was strongly correlated with prolongation of animal survival from 14 days (vehicle) to 37 days (L-Ann 4 mg/kg once weekly started on day 10). In vitro and intravital microscopy revealed a distinct pattern of L-Ann distribution in organ tissues, which correlated in part with the local index of AML cellularity reduction and residual disease localization. Interestingly, in addition to the expected uptake of Ann in the cell's nucleus, Ann was also accumulated in the cytosol of the cells. This bi-compartmental intracellular distribution pattern contrasted with the nuclear-only localization of DOX. Administration of L-Ann early in the course of AML resulted in occasional complete responses some of which associated with resistance to AML re-challenge, suggesting capacity for anti-AML immune memory induction. This study confirms the efficacy of the drug in the model setting of syngeneic, immune-competent AML. Besides reinforcing the rationale for further development of Annamycin in AML, this study demonstrates a highly advantageous AML mouse model that is highly informative in studies of AML pharmacology, minimum residual disease (MRD), microenvironment and immunology. Disclosures Fokt: Moleculin Biotech, Inc.: Equity Ownership, Research Funding. Andreeff:Oncoceutics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy; Amgen: Consultancy; AstaZeneca: Consultancy; 6 Dimensions Capital: Consultancy; Reata: Equity Ownership; Aptose: Equity Ownership; Eutropics: Equity Ownership; Leukemia Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; NCI-RDCRN (Rare Disease Cliln Network): Membership on an entity's Board of Directors or advisory committees; CLL Foundation: Membership on an entity's Board of Directors or advisory committees; BiolineRx: Membership on an entity's Board of Directors or advisory committees; German Research Council: Membership on an entity's Board of Directors or advisory committees; NCI-CTEP: Membership on an entity's Board of Directors or advisory committees; Cancer UK: Membership on an entity's Board of Directors or advisory committees; Oncolyze: Equity Ownership; Breast Cancer Research Foundation: Research Funding; CPRIT: Research Funding; NIH/NCI: Research Funding; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees. Priebe:Moleculin Biotech, Inc.: Consultancy, Equity Ownership, Research Funding. Zal:VueBio.com: Equity Ownership; BioLineRx: Research Funding; Daiichi-Sankyo: Research Funding; Moleculin Biotech, Inc.: Research Funding; NIH-CTEP: Research Funding; CPRIT: Research Funding; NIH/NCI: Research Funding.

Description: Abstract 536 Introduction: Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) are B-cell malignancies of different postulated origin, genetics, clinical presentation and prognosis. Several studies have reported that both MCL and CLL individually exhibit aberrant methylation in comparison to normal B-cells. However, a comprehensive comparison of the methylation profiles of these two B-cell disorders has not been performed yet. This strategy has the potential to identify cellular pathways and genes that are specifically targeted in each disease. Methods: We applied the genome-wide Illumina Infinium HumanMethylation27 BeadChip array (Illumina, San Diego, USA) which measures methylation levels at 27,578 CpG dinucleotides covering 14,495 genes, to compare the methylation profiles in: (i) 20 MCL cases; and, (ii) 30 CLL cases, 15 each with unmutated stereotyped subset #1 (IGHV1-5-7/IGKV1(D)-39) B cell receptors (BCRs) or mutated stereotyped subset #4 (IGHV4-34/IGKV2-30) BCRs, where these two subsets represent prototypes of unmutated and mutated CLL. The methylation status for each detected CpG site ranged between 0.1 (completely unmethylated) to 1 (completely methylated). Results: As expected, major differences in methylation patterns between MCL and CLL were observed. When the methylation profiles of the two entities were compared, 51 genes were identified as differentially methylated in all comparisons (MCL versus both CLL subsets combined and each subset separately). Among the 19 genes highly methylated in MCL were six (32%) homeobox or homeodomain-containing transcription factors (e.g. POU4F1, PITX3), whereas genes enhancing cell proliferation and tumor progression such as MERTK and CAMP were hypomethylated in MCL. Of the 32 genes hypermethylated in CLL were six pro-apoptotic genes, including DYRK2 and CYFIP2, the tumor suppressor PRDM2 and the cell cycle regulator CCND1. Conclusions: We report for the first time disease-biased methylation profiles for different functional classes of genes in MCL or CLL. Homeobox genes were highly methylated in MCL, whereas CLL was characterized by methylation of apoptosis-related genes. The identified differences in global methylation profiles between MCL and CLL may assist in unfolding distinct epigenetic silencing mechanisms involved in the pathogenesis of these B-cell malignancies. Disclosures: No relevant conflicts of interest to declare.

Description: Lymphomatoid papulosis (LyP) represents an intriguing cutaneous T-cell lymphoproliferative disorder with a histologic appearance resembling malignant lymphoma. This finding strongly contrasts with the benign clinical course of the disease. However, in 10% to 20% of cases, LyP can precede, coexist with, or follow malignant lymphoma. In these cases, the same T-cell population has been shown to be present in the LyP as well as in the associated lymphoma. In most LyP cases, there is—despite the sometimes extremely long course of the disease—no evolution of a secondary lymphoma. The investigation of these uncomplicated LyP cases for the presence of clonal T-cell receptor rearrangements has produced heterogeneous results. This might be explained by biologic or technical reasons arising from analyzing whole tissue DNA extracts. To definitively clarify whether the large atypical CD30+ cells in LyP without associated lymphoma all belong to the same clone or represent individually rearranged T cells, we analyzed the T-cell receptor–γ rearrangements of single CD30+ as well as of single CD30− cells isolated from 14 LyP lesions of 11 patients. By using this approach we could demonstrate that the CD30+ cells represent members of a single T-cell clone in all LyP cases. Moreover, in 3 patients the same CD30+ cell clone was found in anatomically and temporally separate lesions. In contrast, with only a few exceptions, the CD30− cells were polyclonal in all instances and unrelated to the CD30+ cell clone. Our results demonstrate that LyP unequivocally represents a monoclonal T-cell disorder of CD30+ cells in all instances.

Description: Patients with core binding factor acute myeloid leukemia (CBF-AML) benefit from more intensive chemotherapy, but whether both the t(8;21) and inv(16)/t (16;16) subtypes requires intensification remained to be determined. In the 2 successive studies (AML-BFM-1998 and AML-BFM-2004), 220 CBF-AML patients were treated using the same chemotherapy backbone, whereby reinduction with high-dose cytarabine and mitoxantrone (HAM) was scheduled for these cohorts only in study AML-BFM-1998 but not in AML-BFM-2004 against the background to minimize overtreatment. Five-year overall survival (OS) and event-free survival (EFS) were significantly higher and the cumulative incidence of relapse (CIR) lower in t(8;21) patients treated with HAM (n = 78) compared with without HAM (n = 53): OS 92% ± 3% versus 80% ± 6%, plogrank0.047, EFS 84% ± 4% versus 59% ± 7%, plogrank0.001, and CIR 14% ± 4% versus 34% ± 7%, p(gray)0.006. These differences were not seen for inv(16) (n = 43 and 46, respectively): OS 93% ± 4% versus 94% ± 4%, EFS 75% ± 7% versus 71% ± 9% and CIR 15% ± 6% versus 23% ± 8% (not significant). The subtype t(8;21), but not inv(16), was an independent predictor of worse outcome without HAM reinduction. Based on our data, a 5-year OS of 〉 90% can be expected for CBF-AML, when stratifying t(8;21), but not inv(16), patients to high-risk chemotherapy, including HAM reinduction.

Description: Deregulated c-MYC is found in a variety of cancers where it promotes proliferation as well as apoptosis. In many hematologic malignancies, enhanced NF-κB exerts prosurvival functions. Here we investigated the role of NF-κB in mouse and human c-MYC–transformed lymphomas. The NF-κB pathway is extinguished in murine lymphoma cells, and extrinsic stimuli typically inducing NF-κB activity fail to activate this pathway. Genetic activation of the NF-κB pathway induces apoptosis in these cells, whereas inhibition of NF-κB by an IκBα superrepressor provides a selective advantage in vivo. Furthermore, in human Burkitt lymphoma cells we find that NF-κB activation induces apoptosis. NF-κB up-regulates Fas and predisposes to Fas-induced cell death, which is caspase-8 mediated and can be prevented by CFLAR overexpression. We conclude that c-MYC overexpression sensitizes cells to NF-κB–induced apoptosis, and persistent inactivity of NF-κB signaling is a prerequisite for MYC-mediated tumorigenesis. We could also show that low immunogenicity and Fas insensitivity of MYC-driven lymphoma cells are reversed by activation of NF-κB. Our observations provide a molecular explanation for the described absence of the NF-κB signaling in Burkitt lymphoma and question the applicability of NF-κB inhibitors as candidates for treatment of this cancer.

Description: Loss of neurofibromin or interferon consensus sequence binding protein (Icsbp) leads to a myeloproliferative disorder. Transcription of NF1 is directly controlled by ICSBP. It has been postulated that loss of NF1 expression resulting from loss of transcriptional activation by ICSBP contributes to human hematologic malignancies. To investigate the functional cooperation of these 2 proteins, we have established Icsbp-deficient mice with Nf1 haploinsufficiency. We here demonstrate that loss of Icsbp and Nf1 haploinsufficiency synergize to induce a forced myeloproliferation in Icsbp-deficient mice because of an expansion of a mature myeloid progenitor cell. Furthermore, Nf1 haploinsufficiency and loss of Icsbp contribute synergistically to progression of the myeloproliferative disorder toward transplantable leukemias. Leukemias are characterized by distinct phenotypes, which correlate with progressive genetic abnormalities. Loss of Nf1 heterozygosity is not mandatory for disease progression, but its occurrence with other genetic abnormalities indicates progressive genetic alterations in a defined subset of leukemias. These data show that loss of the 2 tumor suppressor genes Nf1 and Icsbp synergize in the induction of leukemias.

Description: According to WHO’s current criteria, follicular lymphoma is morphologically divided into grades 1, 2, and 3, and grade 3 is further subdivided into 3a and 3b, depending on the presence of centrocytes and solid sheets of centroblasts. The clinical relevance of this grading system is unclear. Although there is consensus that grades 1 and 2 share clinical characteristics of indolent lymphoma, it is debated whether grade 3 should be treated intensively with anthracycline-containing regimens. Furthermore, the 3a/3b subdivision is not universally implemented. We wanted to investigate the clinical relevance of the grading system with respect to clinical characteristics, treatment and survival. Totally, 186 cases were diagnosed between January 1994 and January 2004 in South Stockholm County with de novo follicular lymphoma and without concomitant transformation. The biopsies were re-graded according to the current WHO criteria by two experienced hematopathologists. 129 cases were grade 1 or 2, 44 grade 3a, and 13 grade 3b. Clinical characteristics in the patients with follicular lymphoma grade 1–2 and 3a are shown in Table 1. The local policy has been to treat all patients with grade 3 disease aggressively. In grade 3a disease, front-line anthracyclines did not seem to improve overall survival (Figure 1). Grades 1–2 and 3a show similar overall survival curves of indolent and incurable lymphoma, while the 13 patients with grade 3b disease (of whom 12 received aggressive front-line therapy) seem to reach a plateau after four years (Figure 2). We conclude that follicular lymphoma grade 3a is not clinically different from grade 1 and 2 disease, and that patients with grade 3a do not seem to benefit from front-line anthracyclines. Although our findings are limited by the few cases of grade 3b, it seems that grade 3b is another disease entity and, when treated aggressively, it is maybe curable with chemotherapy. The histopathological distinction between grade 3a and 3b is clinically of great importance. Table 1 Grade 1–2 Grade 3a P Clinical characteristics in patients with follicular lymphoma grade 1-2 and 3a. Age 〉60 years 50% 61% NS Elevated LDH 32% 49% 0.046 Stage III or IV 68% 80% NS Front-line anthracyclines 41% 73% 0.0004 Subsequent transformation 21% 19% NS Figure Figure Figure Figure