Acute myeloid leukemia (AML) is a complex hematological malignancy with multiple disease sub-groups defined by somatic mutations and heterogeneous outcomes. Although genome-wide association studies (GWAS) have identified a small number of common genetic variants influencing AML risk, the heritable component of this disease outside of familial susceptibility remains largely undefined. Here we perform a meta-analysis of four published GWAS plus two new GWAS, totalling 4710 AML cases and 12938 controls. We identify a new genome-wide significant risk locus for pan-AML at 2p23.3 (rs4665765; P=1.35x10-8; EFR3B, POMC, DNMT3A, DNAJC27) which also significantly associates with patient survival (P=6.09x10-3). Our analysis also identifies three new genome-wide significant risk loci for disease sub-groups, including AML with deletions of chromosome 5 and/or 7 at 1q23.3 (rs12078864; P=7.0x10-10; DUSP23) and cytogenetically complex AML at 2q33.3 (rs12988876; P=3.28x10-8; PARD3B) and 2p21 (rs79918355; P=1.60x10-9; EPCAM). We also investigated loci previously associated with risk of clonal hematopoiesis (CH) or clonal hematopoiesis of indeterminate potential (CHIP) and identified several variants associated with risk of AML. Our results further inform on AML etiology and demonstrate the existence of disease sub-group specific risk loci.

Precision medicine can significantly improve outcomes for patients with cancer, but implementation requires comprehensive characterization of tumor cells to identify therapeutically exploitable vulnerabilities. Here, we describe somatic biallelic TET2 mutations in an elderly patient with acute myeloid leukemia (AML) that was chemoresistant to anthracycline and cytarabine but acutely sensitive to 5 '-azacitidine (5 '-Aza) hypomethylating monotherapy, resulting in long-term morphological remission. Given the role of TET2 as a regulator of genomic methylation, we hypothesized that mutant TET2 allele dosage affects response to 5 '-Aza. Using an isogenic cell model system and an orthotopic mouse xenograft, we demonstrate that biallelic TET2 mutations confer sensitivity to 5 '-Aza compared with cells with monoallelic mutations. Our data argue in favor of using hypomethylating agents for chemoresistant disease or as first-line therapy in patients with biallelic TET2-mutated AML and demonstrate the importance of considering mutant allele dosage in the implementation of precision medicine for patients with cancer.

The fusion gene MLL/AF4 defines a high-risk subtype of pro-B acute lymphoblastic leukemia. Relapse can be associated with a lineage switch from acute lymphoblastic to acute myeloid leukemia, resulting in poor clinical outcomes caused by resistance to chemotherapies and immunotherapies. In this study, the myeloid relapses shared oncogene fusion breakpoints with their matched lymphoid presentations and originated from various differentiation stages from immature progenitors through to committed B-cell precursors. Lineage switching is linked to substantial changes in chromatin accessibility and rewiring of transcriptional programs, including alternative splicing. These findings indicate that the execution and maintenance of lymphoid lineage differentiation is impaired. The relapsed myeloid phenotype is recurrently associated with the altered expression, splicing, or mutation of chromatin modifiers, including CHD4 coding for the ATPase/helicase of the nucleosome remodelling and deacetylation complex. Perturbation of CHD4 alone or in combination with other mutated epigenetic modifiers induces myeloid gene expression in MLL/AF4+ cell models, indicating that lineage switching in MLL/AF4 leukemia is driven and maintained by disrupted epigenetic regulation.

Prognostication in patients with chronic lymphocytic leukemia (CLL) is challenging due to heterogeneity in clinical course. We hypothesize that constitutional genetic variation affects disease progression and could aid prognostication. Pooling data from seven studies incorporating 842 cases identifies two genomic locations associated with time from diagnosis to treatment, including 10q26.13 (rs736456, hazard ratio (HR) = 1.78, 95% confidence interval (CI) = 1.47–2.15; P = 2.71 × 10 −9 ) and 6p (rs3778076, HR = 1.99, 95% CI = 1.55–2.55; P = 5.08 × 10 −8 ), which are particularly powerful prognostic markers in patients with early stage CLL otherwise characterized by low-risk features. Expression quantitative trait loci analysis identifies putative functional genes implicated in modulating B-cell receptor or innate immune responses, key pathways in CLL pathogenesis. In this work we identify rs736456 and rs3778076 as prognostic in CLL, demonstrating that disease progression is determined by constitutional genetic variation as well as known somatic drivers.

Precision medicine can significantly improve outcomes for cancer patients, but implementation requires comprehensive characterization of tumor cells to identify therapeutically exploitable vulnerabilities. Here we describe somatic biallelic TET2 mutation (focal deletion and nonsense mutation) in an elderly patient with acute myeloid leukemia (AML) that was chemoresistant to anthracycline and cytarabine, but acutely sensitive to 5-azacitidine (5-Aza) hypomethylating monotherapy, resulting in long-term morphological remission (overall survival (OS) 850 days). Given the role of TET2 as a regulator of genomic methylation, we hypothesized that mutant TET2 allele dosage affects response to 5-Aza. Using an isogenic cell model system and an orthotopic mouse xenograft, we demonstrate that biallelic TET2 mutations confer sensitivity to 5-Aza compared to cells with monoallelic mutation. We subsequently identified 29 additional patients from the Study Alliance Leukemia biobank with chromosome 4 abnormalities and identified two further patients with complex biallelic TET2 mutations, including one with trisomy 4, homozygosity across the long arm and an inactivating point mutation. We also screened patients recruited to the PETHEMA FLUGAZA phase 3 clinical trial and identified three patients with biallelic TET2 mutations, two of whom had responded very well to single agent 5-Aza (OS 767 and 579 days) despite having adverse risk AML and poor performance status. Our data argue in favor of using hypomethylating agents for chemoresistant disease or as first line therapy in patients with biallelic TET2-mutated AML and demonstrate the importance of considering mutant allele dosage in the implementation of precision medicine for cancer patients.

Acute myeloid leukemia (AML) is a hematological malignancy with an undefined heritable risk. Here we perform a meta-analysis of three genome-wide association studies, with replication in a fourth study, incorporating a total of 4018 AML cases and 10488 controls. We identify a genome-wide significant risk locus for AML at 11q13.2 (rs4930561; P = 2.15 × 10 −8 ; KMT5B ). We also identify a genome-wide significant risk locus for the cytogenetically normal AML sub-group (N = 1287) at 6p21.32 (rs3916765; P = 1.51 × 10 −10 ; HLA ). Our results inform on AML etiology and identify putative functional genes operating in histone methylation ( KMT5B ) and immune function ( HLA ).

Personalised medicine is predicted to significantly improve outcomes for cancer patients, but implementation requires comprehensive genetic characterisation of malignant cells to identify therapeutically exploitable vulnerabilities. Using an isogenic cell model system with CRISPR-inactivated TET2 in HEL acute myeloid leukemia (AML) cells and an orthotopic mouse xenograft model we demonstrate that mutant TET2 allele dosage significantly affects sensitivity to 5-azacitidine hypomethylating therapy in AML, with biallelic mutation conferring hypersensitivity relative to monoallelic mutation. In the presence of 5-azacitidine, cell clones with biallelic TET2 mutation had significantly lower cloning efficiency (P = 3 x 10-3) and proliferation in liquid culture (P < 1 x 10-4) compared to isogenic clones with monoallelic TET2 mutation. Mixed populations of monoallelic and biallelicTET2 mutated HEL AML cells were transplanted via intrafemoral injection into Rag2−/−Il2rg−/−129×Balb/c mice, and treatment with 5-azacitidine resulted in significant negative in vivo selection against TET2 null cells relative to cells with monoallelic TET2 mutation (P = 4 x 10-4). Methylation analysis revealed the acquisition of an overall hypermethylation phenotype in TET2 null cells and RNA sequencing identified significant down-regulation of ABCB1 transcript, resulting in concomitant pronounced down-regulation of the MDR1 drug efflux transporter at the protein level. RNA sequencing pathway analysis also identified a global effect on ribosome pathway (KEGG pathway ko03010) transcript levels (Padjusted = 0.002), evidenced by down-regulation of numerous RNA polymerase II components in cells with bi-allelic TET2 mutation compared to cells with monoallelic TET2 mutation. Consistent with our isogenic model data, we characterise biallelic somatic TET2 mutation in a patient with AML that was chemoresistant to anthracycline/cytarabine-based chemotherapy but acutely sensitive to 5-azacitidine, resulting in durable cytomorphological remission. Integration of next generation sequencing, interphase FISH and SNP array analysis of bone marrow at AML presentation, relapse and during remission was used to infer tumour phylogeny which indicated that disease pathogenesis was initiated by a TET2 nonsense mutation (c.2815C>T, Q939*) with subsequent deletion of the second TET2 allele and a NPM1 mutation (c.863_864ins, TCTG) that arose after the acquisition of bi-allelic TET2 mutation. Furthermore, our data demonstrate that 5-azacitidine treatment almost completely eliminated the TET2/NPM1-mutated clone. 5-azacitidine also induced a modest reduction in ancestral pre-leukemic cells carrying bi-allelic TET2 mutation but negative for the NPM1 mutation, although the majority retained viability and re-acquired the ability to differentiate and recapitulate normal haematopoiesis rendering a cytomorphological remission. These observations suggest that bi-allelic TET2 mutation confers sensitivity to the cytotoxic effects of 5-azacitidine, but that the major effect of 5-azacitidine is the induction of phenotypic re-programming. The frequency of TET2 mutation in primary AML is estimated at 10-20%, with the majority of these being monoallelic. We determined the frequency of TET2 alterations in AML patients presenting with a chromosome 4 abnormality discernible cytogenetically. TET2 copy number and mutational status were determined using high density SNP arrays and gene sequencing, respectively. In a panel of 30 AML cases with a chromosome 4 abnormality, four patients were heterozygous for TET2 mutation (all deletions resulting in reduced copy number) and three patients were homozygous for TET2 mutation (deletion plus base substitution in two cases and homozygous base substitution resulting from uniparental disomy in one case). Furthermore, all seven cases with TET2 mutation were characterised by cytogenetics that included loss or gain of material on chromosome 4. In contrast, only 1 case with a TET2 mutation had a translocation affecting chromosome 4. In summary, our data argue in favour of using 5-azacitidine in patients with biallelic TET2-mutated AML and demonstrate the importance of considering mutant allele dosage in the implementation of personalised medicine for cancer patients. Disclosures Stoelzel: JAZZ Pharmaceuticals: Consultancy; Neovii: Other: Travel funding; Shire: Consultancy, Other: Travel funding. Jackson:Celgene, Amgen, Roche, Janssen, Sanofi: Honoraria. Meggendorfer:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

The ataxia telangiectasia and Rad3-related (ATR) protein kinase promotes cancer cell survival by signaling stalled replication forks generated by replication stress, a common feature of many cancers including acute myeloid leukemia (AML). Here we show that the antileukemic activity of the chemotherapeutic nucleoside analogs hydroxyurea and gemcitabine was significantly potentiated by ATR inhibition via a mechanism involving ribonucleotide reductase (RNR) abrogation and inhibition of replication fork progression. When administered in combination with gemcitabine, an inhibitor of the M1 RNR subunit, the ATR inhibitor VX-970, eradicated disseminated leukemia in an orthotopic mouse model, eliciting long-term survival and effective cure. These data identify a synergistic interaction between ATR inhibition and RNR loss that will inform the deployment of small molecule inhibitors for the treatment of AML and other hematologic malignancies.

Background: Cell lines provide a powerful model to study cancer and here we describe a new spontaneously immortalised epithelial ovarian cancer cell line (NUOC-1) derived from the ascites collected at a time of primary debulking surgery for a mixed endometrioid / clear cell / High Grade Serous (HGS) histology.Results: This spontaneously immortalised cell line was found to maintain morphology and epithelial markers throughout long-term culture. NUOC-1 cells grow as an adherent monolayer with a doubling time of 58 hours. The cells are TP53 wildtype, positive for PTEN, HER2 and HER3 expression but negative for oestrogen, progesterone and androgen receptor expression. NUOC-1 cells are competent in homologous recombination and non-homologous end joining, but base excision repair defective. Karyotype analysis demonstrated a complex tetraploid karyotype. SNP array analysis of parent and derived subpopulations (NUOC-1-A1 and NUOC-1-A2) cells demonstrated heterogeneous cell populations with numerous copy number alterations and a pro-amplification phenotype. The characteristics of this new cell line lends it to be an excellent model for investigation of a number of the identified targets.Materials and Methods: The cell line has been characterised for growth, drug sensitivity, expression of common ovarian markers and mutations, clonogenic potential and ability to form xenografts in SCID mice. Copy number changes and clonal evolution were assessed by SNP arrays.

The ataxia telangiectasia and RAD3-related (ATR) protein kinase is a component of the cellular DNA damage response pathway and promotes cell survival by signalling repair of collapsed replication forks generated by replication stress. We hypothesised that inhibition of ATR potentiates the anti-leukaemic activity of chain terminating nucleoside analogues used in the treatment of acute myeloid leukaemia (AML). We used VE-821 and its derivative VX-970 (Vertex Pharmaceuticals, Abingdon, UK) as potent and specific inhibitors of ATR kinase activity to examine the effects of ATR inhibition in AML cell lines, primary AML cells and AML xenografts.

t(8;21) is a frequent chromosomal translocation in acute myeloid leukemia (AML) and is also reported in lymphoid and biphenotypic acute leukemia.1, 2 t(8;21) fuses the RUNX1 gene (AML1) on chromosome 21 to the ETO gene (RUNX1T1) on chromosome 8, encoding the RUNX1/ETO chimeric transcription factor that represses expression of RUNX1 target genes, promoting self-renewal and blocking myeloid differentiation.3, 4, 5, 6 t(8;21) is insufficient for leukemogenesis and additional co-operating mutations are required for transformation,7 including point mutations that activate and/or over express c-KIT.8 The mechanisms driving the acquisition of co-operating mutations remain unclear, although there is evidence that initiating lesions such as RUNX1/ETO may promote mutagenesis.9, 10 For example, ectopic expression of RUNX1/ETO downregulates several DNA-repair proteins (BRCA2, OGG1 and ATM) and increases the level of phosphorylated TP53 and γH2AX, indicating elevated DNA damage and a possible pro-mutagenic phenotype.10, 11

ATRis an attractive target in cancer therapy because it signals replication stress and DNA lesions for repair and to S/G2 checkpoints. Cancer-specific defects in the DNA damage response (DDR) may render cancer cells vulnerable to ATR inhibition alone. We determined the cytotoxicity of the ATR inhibitor VE-821 in isogenically matched cells with DDR imbalance. Cell cycle arrest, DNA damage accumulation and repair were determined following VE-821 exposure. Defectsin homologous recombination repair (HRR: ATM, BRCA2 and XRCC3) and baseexcision repair (BER: XRCC1) conferred sensitivity to VE-821. Surprisingly, the loss of different components of the trimeric non-homologous end-joining (NHEJ) protein DNA-PK had opposing effects. Loss of the DNA-binding component, Ku80, caused hypersensitivity to VE-821, but loss of its partner catalytic subunit, DNA-PKcs, did not. Unexpectedly, VE-821 was particularly cytotoxic to human and hamster cells expressing high levels of DNA-PKcs. High DNA-PKcs was associated with replicative stress and activation of the DDR. VE-821 suppressed HRR, determined by RAD51 focus formation, to a greater extent in cells with high DNA-PKcs. Defects in HRR and BER and high DNA-PKcs expression, that are common in cancer, confer sensitivity to ATR inhibitor monotherapy and may be developed as predictive biomarkers for personalised medicine.

Cytarabine (1-β-D-arabinofuranosylcytosine; Ara-C) is an effective remission induction treatment for acute myeloid leukemia (AML).1,2 However, the majority of patients relapse within 3 years, often with aggressive AML2 characterised by the gain of novel base substitution mutations in genes including IDH2 and TET2.3,4 Chemotherapy used to treat AML is predicted to induce mutations detectable in relapsed disease, although direct evidence for this is lacking. The cytotoxicity of Ara-C is mediated in part by incorporation into replicating DNA leading to inhibition of chain extension. However, even at concentrations that induce significant cell death, arabinofuranosylcytosine triphosphate, the reactive metabolite of Ara-C, is primarily incorporated into DNA at internucleotide positions,5,6 suggesting that this nucleoside analogue is likely mutagenic and could contribute to the aetiology of novel somatic mutations acquired during AML relapse.

Abstract Cytarabine (1-β-D-arabinofuranosylcytosine; Ara-C) forms the backbone of chemotherapeutic regimes for acute myeloid leukemia (AML) and has a high success rate in inducing complete remission. However, the majority of AML patients will relapse within 2 years, often with an aggressive, chemoresistant form of the disease. Mechanisms associated with the development of relapsed disease remain to be fully elucidated, although recent whole-genome deep sequencing data derived from matched primary AML-relapse pairs demonstrated that relapse is associated with gain of novel mutations not seen at initial diagnosis [1] . Furthermore, the nature of relapse-specific mutations suggests these to be shaped, at least in part, by the chemotherapy used to induce and maintain remission. In order to investigate this further we have assessed the mutagenicity of Ara-C. We show here that the frequency of induction of mutations at thymidine kinase (TK) and hypoxanthine phosphoribosyltransferase (HPRT) loci in vitro is increased following exposure to Ara-C, confirming this agent to be mutagenic in human cells. In addition, molecular characterization of Ara-C-induced mutations at the HPRT locus revealed that this commonly used nucleoside analogue induces a mutational fingerprint in vitro that can also be identified in vivo. Specifically, our data demonstrate that Ara-C is able to induce both deletion and base substitution mutations and has a strong propensity to induce mutations at 5′TGA3′/5′TCA3′ sequences in the genome, and particularly at the central G:C position consistent with its function as a cytosine analogue (p<0.001). Subsequent analysis of 4039 somatic AML mutations (3587 at disease presentation and 452 at relapse) derived from genome-wide deep sequencing data revealed that the frequency of putative Ara-C-associated G:C mutations in 5′TGA3′/5′TCA3′ sequences was significantly higher in AML relapse following Ara-C therapy compared to chemotherapy-naïve leukemia at initial presentation (OR 2.2, 95% CI 1.4-3.6; p=0.003). Given that most cancer patients die from progressive disease, understanding the etiology of somatic mutations responsible for driving the evolution of relapse is a substantial challenge in the management of malignant disease. Although long suspected to exist, our study is the first to identify a chemotherapy-induced mutational fingerprint in a relapsing cancer and demonstrates that chemotherapy plays a role in driving evolution of the somatic cancer genome. The approaches we present could be used to discern the contribution of other treatments to evolution of relapsed disease, informing both personalized medicine and drug development strategies. [1] Ding L et al. Nature 2012; 481(7382):506-10 Citation Format: Sarah E. Fordham, Michael Cole, Julie A. Irving, James M. Allan. Cytarabine leaves a mutational fingerprint in relapsing leukemia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5457. doi:10.1158/1538-7445.AM2014-5457

Ionising radiation is a potent human carcinogen. Epidemiological studies have shown that adolescent and young women are at increased risk of developing breast cancer following exposure to ionising radiation compared with older women, and that risk is dose-dependent. Although it is well understood which individuals are at risk of radiation-induced breast carcinogenesis, the molecular genetic mechanisms that underlie cell transformation are less clear. To identify genetic alterations potentially responsible for driving radiogenic breast transformation, we exposed the human breast epithelial cell line MCF-10A to fractionated doses of X-rays and examined the copy number and cytogenetic alterations. We identified numerous alterations of c-MYC that included high-level focal amplification associated with increased protein expression. c-MYC amplification was also observed in primary human mammary epithelial cells following exposure to radiation. We also demonstrate that the frequency and magnitude of c-MYC amplification and c-MYC protein expression is significantly higher in breast cancer with antecedent radiation exposure compared with breast cancer without a radiation aetiology. Our data also demonstrate extensive intratumor heterogeneity with respect to c-MYC copy number in radiogenic breast cancer, suggesting continuous evolution at this locus during disease development and progression. Taken together, these data identify c-MYC as a radiosensitive locus, implicating this oncogenic transcription factor in the aetiology of radiogenic breast cancer.

Th erapy-related myelodysplastic syndrome (t-MDS) and therapy-related acute myeloid leukemia (t-AML), collectively defi ned as therapy-related myeloid neoplasms by the 2008 World Health Organization (WHO) “ classifi cation of tumours of haematopoietic and lymphoid tissues ” [1], are almost always associated with a poor prognosis relative to de novo disease. Intuitively, this is not unexpected, since therapyrelated disease is derived from aberrant myeloid cells which have survived and proliferated despite prior cytotoxic exposure. However, other than a broad designation of “ poor outcome, ” accurate prognostication in t-MDS/t-AML remains elusive, and the contribution of disease- and patient-specifi c characteristics would benefi t from further clarifi cation. In an attempt to address the problem of prognostication in therapy-related myeloid disease, in this issue of Leukaemia and Lymphoma Bacher and colleagues [2] report data from a series of 508 patients with t-MDS/ t-AML, including 277 with outcome data. Within the study, patients with t-MDS (defi ned as 20% blasts detected in the bone marrow at diagnosis) had signifi cantly better overall survival than patients with t-AML ( 20% blasts at diagnosis) (43.8 vs. 18.2 months). Singh and colleagues [3] also previously reported a signifi cantly better overall survival for patients with t-MDS, although the diff erence between patient groups was relatively modest by comparison (8.5 months vs. 6.5 months for t-MDS and t-AML, respectively). Taken together, these data suggest that stratifi cation by blast count, based on the 2008 WHO defi nitions of t-MDS and t-AML, provides prognostically relevant information, and that co-classifi cation of these neoplasms as a single entity, although perhaps relevant from an etiological perspective, may be too simplistic for the purposes of prognostication. Consistent with this notion, Bacher and colleagues [2] also report that blast count was signifi cantly prognostic when included as a continuous variable in survival analysis, suggesting prognostic value of this marker within, as well as between, the t-MDS and t-AML subgroups. If confi rmed, then morphological subclassifi cation, which is primarily based on blast count in the marrow and the extent of morphological dysplasia, could also have prognostic relevance in t-MDS, as it does in de novo MDS [4].

The regulation of hematopoietic lineage fate and commitment is fundamental to normal and malignant hematopoiesis. Switches between lymphoid and myeloid lineages in leukemia are rare and associated with poor clinical outcome, but potentially very informative regarding the regulation of hematopoietic lineage commitment. In contrast to therapy-related acute leukemia (AL) after a first primary leukemia, lineage-switch ALs arise from a common pre-leukemic or leukemic clone and share a founder mutation, most often rearrangement of MLL at 11q23. The majority of switches are from acute lymphoblastic leukemia (ALL) to acute myeloid leukemia (AML); however, conversions from myeloid to lymphoid and even oscillations between the two lineages have been observed, although the molecular mechanisms underlying lineage switch have not yet been identified. Here we describe a male patient who presented at 9 months of age with a t(4;11)-positive B-ALL and was subsequently treated according to the Interfant06 protocol. He achieved complete remission, but relapsed at the age of 4 years with a t(4;11)-positive AML. He underwent allogeneic BM transplantation and has remained in remission 13 months. Sanger sequencing revealed identical translocation breakpoints in the ALL and AML samples, demonstrating a lymphoid to myeloid lineage switch with a common pre-leukemic or leukaemic cell of origin for both ALs. Interestingly, whereas the AML shows no V(D)J rearrangements, we found incomplete rearrangements in the ALL cells indicating a ProB cell origin. In line with this observation, B-ALL cells expressed 6-fold and 120-fold higher levels of PAX5 and EBF1, respectively, compared to AML blast cells. Microsatellite instability measurements argued against a strong therapy-associated impairment of DNA mismatch repair in the AML. The translocation t(4;11) is the most frequently found chromosomal rearrangement in infant leukaemia and is almost exclusively associated with ALL at presentation, suggesting a strong instructive potential towards the lymphoid cell fate. However, the occurrence of lineage switch in t(4;11) AL demonstrates that this instruction can be overcome by as yet unknown mechanisms.

Background: Primary culture and animal and cell-line models of prostate and bladder development have limitations in describing human biology, and novel strategies that describe the full spectrum of differentiation from foetal through to ageing tissue are required. Recent advances in biology demonstrate that direct reprogramming of somatic cells into pluripotent embryonic stem cell (ESC)-like cells is possible. These cells, termed induced pluripotent stem cells (iPSCs), could theoretically generate adult prostate and bladder tissue, providing an alternative strategy to study differentiation.Objective: To generate human iPSCs derived from normal, ageing, human prostate (Pro-iPSC), and urinary tract (UT-iPSC) tissue and to assess their capacity for lineage-directed differentiation.Design, setting, and participants: Prostate and urinary tract stroma were transduced with POU class 5 homeobox 1 (POU5F1; formerly OCT4), SRY (sex determining region Y)-box 2 (SOX2), Kruppel-like factor 4 (gut) (KLF4), and v-myc myelocytomatosis viral oncogene homolog (avian) (MYC, formerly C-MYC) genes to generate iPSCs.Outcome measurements and statistical analysis: The potential for differentiation into prostate and bladder lineages was compared with classical skin-derived iPSCs. The student t test was used.Results and limitations: Successful reprogramming of prostate tissue into Pro-iPSCs and bladder and ureter into UT-iPSCs was demonstrated by characteristic ESC morphology, marker expression, and functional pluripotency in generating all three germ-layer lineages. In contrast to conventional skin-derived iPSCs, Pro-iPSCs showed a vastly increased ability to generate prostate epithelial-specific differentiation, as characterised by androgen receptor and prostate-specific antigen induction. Similarly, UT-iPSCs were shown to be more efficient than skin-derived iPSCs in undergoing bladder differentiation as demonstrated by expression of urothelial-specific markers: uroplakins, claudins, and cytokeratin; and stromal smooth muscle markers: alpha-smooth-muscle actin, calponin, and desmin. These disparities are likely to represent epigenetic differences between individual iPSC lines and highlight the importance of organ-specific iPSCs for tissue-specific studies.Conclusions: IPSCs provide an exciting new model to characterise mechanisms regulating prostate and bladder differentiation and to develop novel approaches to disease modelling. Regeneration of bladder cells also provides an exceptional opportunity for translational tissue engineering. (C) 2013 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Up to 15% of acute promyelocytic leukemia (APL) patients fail to achieve or maintain remission. We investigated a common G > A polymorphism at position -1377 (rs2234767) in the core promoter of the CD95 cell death receptor gene in 708 subjects with acute myeloid leukemia, including 231 patients with APL. Compared with the GG genotype, carrier status for the -1377A variant was associated with a significantly worse prognosis in APL patients. Carriers were more likely to fail remission induction (odds ratio = 4.22; 95% confidence interval, 1.41-12.6, P = .01), were more likely to die during the first 8 weeks of remission induction therapy (hazard ratio = 7.26; 95% confidence interval, 2.39-22.9, P = .0005), and had a significantly worse 5-year overall survival (odds ratio = 2.14; 95% confidence interval, 1.10-4.15, P = .03). The -1377A variant destroys a binding site for the SP1 transcriptional regulator and is associated with lower transcriptional activity of the CD95 promoter. Identifying patients at high risk of life-threatening events, such as remission induction failure, is a high priority in APL, especially because such events represent a major cause of death despite the introduction of differentiation therapy.