Citations

Aneuploidy is a hallmark of cancer often associated with inferior prognosis. Copy number gains of chromosome 8 (chr8) are recurrent in multiple cancers, including breast, prostate, colorectal cancers, and sarcomas such as malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are aggressive, hard-to-treat sarcomas frequently linked to the Neurofibromatosis type 1 (NF1) cancer predisposition syndrome. To investigate the role of chr8 gain in MPNST pathogenesis, we performed a CRISPR knockout screen and identified 58 essential genes on chr8, including PTK2, which encodes focal adhesion kinase (FAK). We evaluated FAK as a therapeutic target and tested small-molecule FAK inhibitors (FAKi) alone or combined with RAF/MEK inhibitors (RAF/MEKi), a class of agents relevant to NF1-deficient tumors with ERK pathway hyperactivation. Both pharmacological and genetic inhibition of FAK reduced MPNST cell proliferation in vitro and tumor growth in vivo. Combined FAKi and RAF/MEKi treatment further suppressed phosphorylation of FAK, STAT3, and AKT while increasing cleaved caspase-3 and PARP-1, indicating enhanced apoptosis. In MPNST patient-derived xenograft (PDX) models, combination therapy significantly reduced tumor growth, showing superior efficacy, particularly in chr8 gain MPNST-PDX. These results support FAK/RAF/MEK co-targeting as a promising therapeutic strategy for chr8 gain MPNST and related tumors.

Intravoxel incoherent motion MRI parameters derived from two software packages demonstrated diagnostic value for breast cancer, with multivariable combinations of histogram metrics achieving high diagnostic accuracy.

Abstract On intergroup phase III trial, MRC UKALLXII/ECOG2993, 25% of 613 ECOG patients were positive for Ph or its molecular equivalent, BCR/ABL; all were B-lineage ALLs (B-ALL). When compared to Ph(−) B-ALL, Ph(+) ALL had more blasts expressing CD25 (α-chain of interleukin-2 [IL-2] receptor) (p=3E-31), CD34 (p=4E-10), CD13 (p=3.9E-16) and CD33 (p=3.5E-09), and blasts with higher density of CD10 (p=9.6E-12). There was no difference in antigen expression profiles between pts with e1a2 (N=107) and b2a2/b3a2 (N=48) BCR/ABL transcripts. Complete remission (CR) rate was lower (p= 7.4E-6) and overall survival (OS) was shorter in Ph(+) compared with Ph(−) B-ALL (p=6.5E-5). There was no difference in outcome between e1a2 and b2a2/b3a2 pts (p=0.65). CD25 was the most powerful prognostic indicator in Ph(+) cases, both for CR (p=0.004) and OS (p=1.3E-05). Strikingly, CD25 negatively affected OS in a continuous fashion; 1% increase in CD25 was related to a 1% increase in the hazard of death. On the other hand, CD25 expression was not associated with OS in Ph(−) pts (p=0.66). Among 152 Ph(+) pts, 30 lacked CD25 expression, 24 with e1a2 and 6 with b2a2/b3a2 transcripts. When analyzed separately, CD25(−)Ph(+) pts had outcome indistinguishable from that of Ph(−) pts (p=0.89). Compared to CD25(+)Ph(+) pts, CD25(−) Ph(+) pts had lower WBC counts at presentation (p=4.1E-05). Both CD25(+) and CD25(−) Ph(+) blasts expressed the γ-chain but not the β-chain of the IL-2 receptor, arguing against the presence of a functional IL-2 receptor. There was no association between CD25 expression or outcome and the presence of additional cytogenetic abnormalities seen in 52% of Ph(+) pts. To further examine the prognostic impact of CD25, BCR/ABL levels were quantitated by real-time PCR in 136 Ph(+) pts at presentation. There was no correlation between presenting BCR/ABL levels and blast count (p=0.98), achievement of CR (p=0.73), or OS (p=0.67). However, higher blast counts at diagnosis were associated with shorter survival (p=0.003). BCR/ABL levels were measured in 43 pts 1 month after induction therapy. Changes in BCR/ABL after therapy were classified as undetectable, >90% reduction, >50% reduction, or no change. While CR status did not correlate with BCR/ABL reduction (p=0.97), the chance of survival ranked in the order of undetectable (p=0.01), >90% reduction (p=0.05), >50% reduction (p=0.37), or no change (p=0.87). CD25 expression at presentation correlated with that order (p=0.002). CD25(−)Ph(+) pts fell into the group with undetectable BCR/ABL levels after treatment, whereas pts with highest initial CD25 expression fell into the group with no change. In conclusion, CD25(−)Ph(+) blasts are more sensitive to non-TKI therapy than CD25(+) Ph(+) blasts. Outcome in Ph(+) ALL is thus determined by CD25 expression rather than the presence of Ph per se. RESPONSE CD25(+)Ph(+) CD25(−)Ph(+) Ph(−) B-Lin ALL n 122 30 308 % CR Rate 57% 71% 81% MedianOS (months) 12.2 30.2 27.7

Abstract MRC UKALLXII/ECOG2993 accrued 739 ECOG pts over 13 years. ECOG’s reference laboratories centrally characterized 613 (91%) and 505 were B-Lin ALLs. Expression of 32 antigens (Ags), including 9 myeloid-associated Ags, was determined by multiparameter flow cytometry on gated blasts, both as percentage of Ag expressing blasts and intensity of antibody staining (equivalent of Ag density). To test for the potential therapeutic efficacy of monoclonal antibodies, such as rituximab, epratuzumab, alemtuzumab, or gemtuzumab in future trials, expression of Ags for these antibodies (CD20, CD22, CD52, or CD33, respectively) was determined. In E2993, 14% of pts typed as Pro-B (CD10 negative), 71% as Early Pre-B (CD10 positive), 13% as Pre-B (intracytoplasmic mu positive), and 2% as Mature B-ALL (surface mu chains positive). CD20 expression correlated with the stage of B-lymphoid maturation (p=5.4E-13) (see table). Median CD20 intensity of fluorescence was lowest in Pro-B and highest in Mature B-ALL. Membrane expression of CD22 was lower in Pro-B compared with the other three groups, Early Pre-B, Pre-B and Mature B (p=1.0E-5) but indistinguishable among the latter three (p=0.21). While levels of CD20 and CD22 had no effect on complete remission (CR) and overall survival (OS) univariatly, higher CD22 expression was significantly correlated with better OS (p=0.02) in a bivariate Cox model of CD20 and CD22. With respect to myeloid Ags, CD33/CD13 expression was associated with Early Pre-B (p=0.02), and CD65(s)/CD15(s) with Pro-B ALL (p<0.0001). While CD65(s) and CD15(s) did not affect outcome, the combined expression of CD33/ CD13 conferred an inferior prognosis; this effect was due to the association of CD33/ CD13 with BCR/ABL positivity (p<0.0001). BCR/ABL negative B-Lin ALL (N=350) expressed CD33 on a median of only 4% of blasts, compared with a median of 54% in BCR/ABL positive ALL (N=152) (p=3.5E-09). However, intensity of CD33 staining was significantly lower in both BCR/ABL negative and positive blasts (median 3.1) compared with leukemic myeloblasts (median 56) (p=<0.001). Median CD52 expression was higher in BCR/ABL positive versus negative B-Lin ALL (p=3.5E-06); in neither group was CD52 associated with outcome. We conclude that antibodies to CD52 are better suited for BCR/ ABL positive than negative B-Lin ALL. Since expression of CD33 in ALL is weak, CD33- independent effects of gemtuzumab must be investigated. Low CD20 combined with high CD22 expression confers superior OS. The expression of these Ags in most B-Lin ALL pts justifies the incorporation of antibodies into frontline chemotherapy regimens. B-Lin ALL Stage CD20 Percentage Median Intensity CD22 Percentage Median Intensity ≥20% ≥50% ≥75% ≥20% ≥50% ≥75% Pro-B 21 10 3 2 88 72 55 12 Early PreB 66 48 37 21 96 90 84 28 Pre-B 61 46 37 21 100 90 81 37 Mature B 87 80 64 106 92 84 80 9

Abstract Both genome wide association studies (GWAS) of common variation and exome wide association studies (EXWAS) of rare variation have successfully identified disease susceptibility variants for a variety of diseases. One GWAS of inherited susceptibility to Acute Myeloid Leukemia (AML) has been conducted, but no EXWAS have been performed to measure risk of AML attributable to low-frequency constitutional genetic variation. We performed the first EXWAS of risk of AML as a nested case-control study in the DISCOVeRY-BMT (Determining the Influence of Susceptibility Conveying Variants Related to one-Year mortality after BMT) cohorts. The DISCOVeRY-BMT parent study examined transplant-related mortality in leukemia patients undergoing unrelated donor allogeneic BMT. To identify low frequency variants and genes contributing to increased susceptibility to AML we used genotype data from the Illumina HumanExome BeadChip typed in the DISCOVeRY-BMT cohorts; the HumanExome BeadChip contains 242,901 variants, which are mainly protein-coding variants. The optimal sequence kernel association test (SKAT-O) was used to analyze gene-level associations with risk of AML. These gene-based tests evaluate the cumulative effects of multiple single gene variants on risk of AML. Analyses were performed in all European American AML cases and two subtypes: 1) de novo AML, 2) de novo AML with normal cytogenetics. Models were adjusted for age at transplant and principal components to control for population stratification. For gene-based tests at least 2 variants with minor allele frequency (MAF) ≤ 5%, were required to be present in the gene. This yielded a total of 13,687 genes tested, and a Bonferroni corrected significance level of P<3.65 x 10-6. Association tests were performed in 1,189 AML cases reported to CIBMTR 2000-08 (Cohort 1) and 327 AML cases reported to CIBMTR from 2009-11 (Cohort 2). Controls in Cohorts 1 (n=1,986) and 2 (n= 515) were 10/10 HLA-matched unrelated donors who passed a comprehensive medical exam and deemed healthy. We used metaSKAT to combine Cohorts 1 and 2 and obtain p-values of association with AML. We present the results of gene-level tests significant in both cohorts. The likely pathogenicity of these variants was determined in silico using SIFT, PolyPhen and MutationTaster. Patient characteristics are in Table 1. DNMT3A, on chromosome 2, was associated in the gene-based test with risk of AML (Pmeta=1.70x10-9, Table 2). Three missense variants at MAF <1% comprise both overall AML and de novo AML gene-based association: exm177559 (Asn->Ser), exm177507 (Arg->His), and exm177543 (Arg->Trp). Normal cytogenetics de novo AML gene-based assocations consisted of only 2 of these variants: exm177559 and exm177507 (Table 2). While prevalence of exm177507 is <1% for all AML cases, in de novo AML with normal cytogenetics the MAF was higher at 3%. The other 2 variants had a MAF<1% irrespective of subtype. Somatically, DNMT3A is most frequently mutated in hematologic malignancies, with >30% of de novo AML cases with a normal karyotype and >10% of MDS patients having DNMT3A mutations. Although these are germline gene associations all three of the variants found have been reported somatically in hematologic malignancies. In 200 AML cases from The Cancer Genome Atlas (TCGA) p.R882H (represented as exm177507 on the exome chip) was a frequent somatic mutation (25%). Exm177543 (p.R635W) and exm177559 (p.N501S) are reported in the Catalogue of Somatic Mutations in Cancer (COSMIC) as somatic mutations involved in hematopoietic and lymphoid tissue in both cell lines and humans. Exm177507 and exm177543 show evidence of pathogenicity in all three in silico tools, while exm177559 was reported as deleterious and disease causing by Sift and MutationTaster, respectively. Our results show that multiple potentially pathogenic missense germline variants in DNMT3A comprise the gene-based association with AML, specifically de novo AML with normal cytogenetics. Given the functional nature of these variants it is possible germline risk stratification could be informative in determining AML risk, and subsequently development of AML harboring DNMT3A mutations. Confirmation of these findings in additional cohorts could have implications for individualized risk screening, prediction and prognosis. Additional cytogenetic subgroup analyses, including treatment-related AML, are underway. Disclosures Hahn: Novartis: Equity Ownership; NIH: Research Funding. McCarthy:Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; The Binding Site: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gamida Cell: Honoraria, Membership on an entity's Board of Directors or advisory committees. Sucheston-Campbell:NIH/NCI: Research Funding.

Abstract #the authors contributed equally to this work While survival outcomes after HLA-matched unrelated donor (URD) blood and marrow transplant (BMT) have significantly improved over the last two decades, about 40% of patients die before 1-year post URD BMT. Previously we performed a genome-wide association study (GWAS) named DISCOVeRY-BMT (Determining the Influence of Susceptibility COnveying Variants Related to one-Year mortality after BMT) to investigate the contributions of common genetic variants on survival outcomes. To address the specific contributions of low frequency (≤ 1%) exonic variants on survival outcomes, we used the DISCOVeRY-BMT cohorts typed with the Illumina HumanExome BeadChip containing 242,901 variants, which are mainly protein-coding variants. We used a gene-based test (the optimal sequence kernel association test (SKAT-O)) to evaluate the cumulative effects of multiple genetic variants within a gene on overall survival (OS), transplant-related mortality (TRM), and disease-related mortality (DRM) 1 year after URD BMT. SKAT-O measures the overall significance of the gene and allows the variants to have different directions and magnitude of effects. We used a 2-stage study design: SKAT-O analysis was carried out in Cohort 1 consisting of 1,972 AML, ALL or MDS patients reported to the Center for International Blood and Marrow Transplant Research from 2000 to 2008 and their 2,006 10/10 HLA-matched URD. Genes with a suggestive association with each outcome (P < 1×10-3) entered the final meta-analysis including Cohort 1 and an independent cohort (Cohort 2), consisting of 503 recipients and 520 10/10 HLA-matched URD from 2009 to 2011. The analysis included recipients and URD of European descent due to the low frequency of other populations. All association models included age at BMT, diagnosis (AML, ALL, MDS), disease status at BMT, cell source (peripheral blood, marrow), year of BMT, and principal components from EIGENSTRAT to control for population stratification. Only coding variants (missense and nonsense) with minor allele frequency ≤ 1% were included in our analysis, which resulted in > 12,000 genes tested in our gene-based analysis in recipients and donors. Exome-wide significance was set at Pmeta< 4.10×10-6 after Bonferroni correction for the total number of genes tested. The likely pathogenicity of these variants was determined in silico using SIFT and PolyPhen. In recipients, we identified OR51D1, a member of the olfactory receptor gene family, as significantly associated with both OS and TRM. The OS association with ORD51D1 is driven by TRM as the same six missense variants contribute to both TRM and OS, but not to DRM. In donors, four (ALPP, EMID1, SLC44A5, LRP1), one (HHAT), and two (LYZL4, NT5E) genes were significantly associated with OS, TRM, and DRM, respectively (Table). ALPP encodes an alkaline phosphatase. SLC44A5 is a member of the solute carrier gene family. LRP1 (low density lipoprotein receptor-related protein 1) encodes an endocytic receptor involved in several cellular processes, including intracellular signaling, lipid homeostasis, and clearance of apoptotic cells. HHAT encodes an enzyme that acts within the hedgehog secretory pathway, which is involved in hematologic malignancy. LYZL4 is a member of a family of lysozyme-like genes, which have a protective role in host defense. The encoded protein of NT5E, CD270, is used as a determinant of lymphocyte differentiation. The likely pathogenicity of several of the functional variants in all significant genes identified was predicted to be both (possibly or probably) damaging and deleterious (Table), thus indicating that the amino acid substitution of the variant may not be well tolerated. One damaging variant in LRP1 has been identified as a somatic mutation in hematopoietic and lymphoid tissue. Our study is the first analysis of the low-frequency coding variant contribution to URD BMT survival outcomes. We found that the missense variants contributing to many of these significant gene associations shows evidence of pathogenicity and thus it is biologically plausible these variants are contributing to survival outcomes. Further confirmation of these findings, and studies of the functional consequences of protein-coding changes in these genes, may provide more individualized risk prediction and prognosis as well as alternative donor selection strategies. Table. Table. Disclosures McCarthy: Gamida Cell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; The Binding Site: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hahn:Novartis: Equity Ownership; NIH: Research Funding. Sucheston-Campbell:NIH/NCI: Research Funding.

Abstract Over the past decade, there have been numerous published candidate gene association studies of non-HLA variants, genes and/or pathways in relation to BMT survival outcomes. Most of these studies investigated a small number of candidate single nucleotide polymorphisms (SNPs), chosen based on known gene function, in a limited number of cases without replication. Here we test the association of previously reported SNPs with survival outcomes (overall survival (OS), progression-free survival (PFS), death due to disease (DD) or transplant-related mortality (TRM)) after URD BMT using data from the DISCOVeRY-BMT (Determining the Influence of Susceptibility Conveying Variants Related to one-Year mortality after BMT) study which included 2,052 European descent recipient-unrelated donor pairs (Cohort 1) and 763 recipient-unrelated donor pairs (Cohort 1) reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) between 2000-2009 and 2009-2011, respectively. DISCOVeRY-BMT is a Genome Wide Association Study (GWAS) that includes over 9 million typed or imputed SNPs. This represents the largest study to date and is well powered to test both SNP and gene-based association hypotheses. We conducted an extensive literature review of PubMed using MESH terms related to transplant and hematologic disease which yielded 76 candidate gene association studies that investigated a total of 46 genes with any survival outcome. Of the 46 genes, 11 genes (CTLA4, CYP2B6, CYP2C19, GSTM1, GSTT1, IL23R, IL6, MTHFR, NOD2/CARD15, TNFSRF1B, and VDR) were studied in at least 2 publications. A total of 16 SNPs in 8 of these genes reported a significant (P< 0.05) association with at least one survival outcome (OS, PFS, DD or TRM). We tested these 16 SNPs for an association with the survival outcome originally reported in each article (Table 1). All association models included age at BMT, diagnosis (AML, ALL, MDS), disease status at BMT, cell source (blood, bone marrow) and year of BMT. P-values from Cohorts 1 and 2 were combined using a fixed-effects model in METAL software. Since the candidate gene studies have a gene-based hypothesis, we also performed gene-level testing using the VErsatile Gene-Based Association Study (VEGAS2) software to measure the aggregate effect of all available typed and imputed SNPs from our GWAS data in these 8 genes. The candidate gene association studies included heterogeneous patient populations of autologous and/or allogeneic (related or unrelated donors) BMT for a variety of hematologic diseases. Most candidate gene studies performed genotyping on both donors and recipients, and SNPs were tested either independently for donor or recipient genomes, or considering the total number of variant alleles the recipient-donor pair had at a given locus (0-4) (Table 1). The 16 SNPs from the previous candidate gene association studies were not significantly associated at a nominal P<0.05 to either the survival outcome reported in the original published paper, or to any survival outcome (Table 1). Likewise, the VEGAS2 gene-based analysis did not reveal any statistically significant associations for any of the 8 genes at P<0.05. Our study also corroborated prior reports of SNPs and genes that were not associated with survival outcomes. Candidate gene association studies use a priori biological knowledge to select genes that are likely associated with outcome and subsequently SNPs within the gene thought likely to affect function based on knowledge at the time of the investigation. Our findings suggest that neither the genetic variation tested in these candidate genes, nor other individual SNPs in the gene independently or collectively are not associated with survival outcomes in recipients of URD BMT. Our failure to replicate the prior candidate gene studies may be due to these SNPs being dependent on the underlying disease (ie. AML, ALL, etc), the donor relation (related, unrelated, autologous), or that there is no true association of these SNPs with the outcomes studied. #These authors contributed equally Table 1. Table 1. Disclosures McCarthy: Gamida Cell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; The Binding Site: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hahn:Novartis: Equity Ownership; NIH: Research Funding. Sucheston-Campbell:NIH/NCI: Research Funding.

Abstract DNA methylation at cytosine position 5 (5mC) is a genetic modification that regulates gene expression and is critical for cancer initiation and development. The methylcytosine dioxygenase TET2 participates in active DNA demethylation by converting 5mC to 5-hydroxymethylcytosine (5hmC) and its subsequent intermediates thereby regulating gene expression. TET2 gene is frequently mutated in hematological disorders, including 15-25% of myelodysplastic syndrome (MDS) cases. Loss of TET2 function leads to DNA hypermethylation and subsequent dysregulated gene expression in hematopoietic stem cells, and has been considered as an initial step of myeloid malignant transformation including MDS and acute myeloid leukemia (AML). While enzymatic activity of TET2 is well studied, little is known about post-translational modifications (PTMs) that regulate its activity in hematopoietic cells. Lysine acetylation, one of the most crucial PTMs, occurs in a variety of proteins and modulates protein-protein or protein-nucleic acids interactions. Here, we first observed that ectopic expression of histone acetyltransferase EP300 or CREB binding protein (CBP) increased the endogenous TET2 acetylation in 293T cells. Mass spectrometry analysis of TET2 identified several conserved acetylated lysine residues located on the exterior surface of its catalytic domain (CD), which is predicted to be essential for the interaction of TET2 with DNA. Modeling of TET2/DNA interaction using x-ray crystal structure (PDB code: 4NM6) indicates acetylated TET2 interferes with DNA binding thereby impairing the catalytic activity of the enzyme. Like other acetylated proteins, TET2 modification is reversible, since ectopic expression of the protein deacetylase Sirtuin1 (SIRT1) significantly decreases acetylation of TET2. A domain mapping analysis revealed that SIRT1 preferentially interacts with TET2 CD, further supporting the regulatory role of SIRT1 on TET2. To explore the role of SIRT1 mediated deacetylaion of TET2 in more physiological condition, SIRT1 knockdown (KD) MDS-L cells as well as SIRT1 knockout (KO) murine hematopoietic c-kit+ cells were used. In MDS-L cells derived from a MDS patient, SIRT1 KD promoted hyperacetylation of endogenous TET2 which is associated with 50% decrease in 5hmC levels compared to control (p=0.03, n=3). Similarly, SIRT1 KO murine c-Kit+ cells showed TET2 hyperacetylation and 62% decrease in 5hmC compared to wildtype (WT) counterpart (p=0.009, n=5). Phenotypically, the transforming ability of SIRT1 shRNA transduced MDS-L cells was evaluated in vitro through serial replating assay. In contrast to first plating which showed no difference between two groups, the number of colonies derived from SIRT1 KD cells was 2.39 fold higher than that from the control shRNA transduced group after two rounds of replating (p=0.0002, n=3). Importantly, we tested the in-vivo effect of SIRT1 KD on MDS-L cells engrafted in immunodeficient NSGS mice. SIRT1 KD significantly enhanced MDS-L cell engraftment compared to control shRNA (50±5% of human CD45+ cells in SIRT1 KD group vs. 19±4% human CD45+ cells in control group, p=0.003, n=6). Interestingly, increased transformation capacity of SIRT1 KD MDS-L cells was associated with decreased expression of TET2 regulated tumor suppressor genes. For example, expression levels of Mtss1 and Dusp6 were significantly decreased in SIRT1 KD MDS-L cells compared to control shRNA counterpart (Mtss1, 49±5% decrease compared to control, p=0.005; Dusp6, 25±2% decrease compared to control, p=0.01). Similar results were observed in SIRT1 KO cells. The validation of physical binding of TET2 to its targets is ongoing. Moreover, the effect of an SIRT1 allosteric activator-SRT1720 in MDS-L cells is similar to that of Vitamin C, a known TET2 activator. Specifically, SRT1720 significantly increased Mtss1 expression in MDSL cells (p=0.0005, n=3), indicating that SIRT1 agonist may lead to activation of TET2 downstream tumor suppressor genes. In summary, our data demonstrate that TET2 activity can be functionally modified by acetylation and may be enhanced in MDS patients that do not harbor loss-of-function mutations through the SIRT1 mediated deacetylation. These results support further exploration of molecular mechanisms inducing TET2 acetylation, and evaluation of SIRT1 activation as a potential therapeutic approach in MDS. Disclosures No relevant conflicts of interest to declare.

Key PointsIKZF1 associations with high-risk B-ALL may differ by age and sex. A novel variant on chromosome 14, rs189434316, is associated with over a 3.5-fold risk of normal cytogenetic B-ALL.

Abstract HCT entails substantial TRM justifying continued efforts to better risk stratify patients. Single institutional studies have suggested several clinically available biomarkers of CRP, ferritin and albumin influence TRM if not overall survival (OS). We sought to confirm the independent prognostic value of these biomarkers in a large multi-institutional cohort. The study population consisted of 784 adults with AML in remission (80%) or MDS (20%) undergoing unrelated donor HCT between 2008 and 2010 and available cryopreserved samples through the Center for International Blood and Marrow Transplant Research (CIBMTR) repository. CRP and ferritin were centrally quantified by ELISA from cryopreserved plasma whereas albumin levels obtained from center reported data. Correlation studies for biomarkers required log transformation of CRP and ferritin to produce a normal distribution. Multivariate models were fitted separately for each biomarker applying protocol specified thresholds generated from the literature of CRP > 10 mg/L, ferritin > 2500 ng/mL, albumin < 3.5 g/dL on TRM. Further analysis explored optimal cutpoints for this cohort for all significant clinical variables for TRM. HCT characteristics included a median age of 50 (range 18-78) years, HCT-CI (co-morbidity index) 3 or more in 35%, single allele/antigen mismatch (7/8) in 23%, PB as stem cell source in 83%, and myeloablative conditioning in 72%. Biomarker data were available in 783, 781 and 695 cases for CRP, ferritin and albumin respectively. The median values and ranges for each biomarker were as follows: 5.0 mg/L (0.3 - 316) for CRP, 1148 ng/mL (51 – 14,298) for ferritin and 3.6 g/dL (0.6-5.3) for albumin. Log transformed CRP and ferritin showed a modest correlation (r=0.35, P<0.001), and log CRP was marginally associated with albumin (r=-0.12, P=0.002). HCT-CI had no correlation to CRP and albumin. Higher ferritin was associated with HCT-CI (P=0.014) and disease (P<.001). In the entire population, TRM and overall survival (OS) at 2 years were 23% and 54%, respectively. The table shows the independent association of each biomarker with TRM and OS. Ferritin had no association with these outcomes but only 12% had levels above 2500 by ELISA. The optimal cutpoints for TRM were defined as follows: CRP > 3.67 (HR=1.75, P=0.001); albumin < 3.4 (HR 1.70, P <0.001); and ferritin as a continuous variable (HR 1.30, P = 0.008). A risk score was created modeling optimal biomarker thresholds to predict TRM based on the following formula: risk score = 0.44633*I(CRP>3.67)+0.18330*ln(Ferritin)+0.44730*I(albumin<3.4), where “I” is an indicator function and represent 1 or 0 depending on the presence of the abnormal biomarker level in parenthesis. The risk score included adjustment for HCT-CI. The biomarkers did not influence the incidence of relapse or graft-versus-host disease with any of these models. Elevated CRP and ferritin and decreased albumin prior to HCT were associated with impaired transplant survival, primarily through higher TRM. Integration of a biomarker panel in clinical practice once validated can enhance risk-stratification, improve adjustment for comparative studies and point towards the design of biomarker driven trials. Abstract 422. Table: Multivariate analysis of TRM and OS for biomarkers, and biomarker panel risk score* Abnormal, N (%) Transplant related mortality Overall Survival Biomarker HR 95% CI P HR 95% CI P Protocol defined CRP >10 mg/L 184 (24) 1.52 1.11 – 2.07 0.008 1.22 0.98 – 1.53 0.072 Ferritin >2500 ng/mL 93 (12) 1.26 0.84 – 1.88 0.27 1.15 0.86 – 1.54 0.35 Albumin < 3.5 g/dL 290 (42) 1.48 1.10 – 2.0 0.010 1.39 1.13 – 1.72 0.002 Optimal threshold, combined model ** CRP >3.67 mg/L 497 (64) 1.56 1.11 – 2.19 0.010 1.24 1.00 – 1.55 0.054 Log(Ferritin), linear n/a 1.20 0.99 – 1.46 0.07 1.20 1.04 – 1.38 0.010 <3.4 g/dL 203 (29.5) 1.58 1.16 – 2.15 0.004 1.37 1.10 – 1.72 0.005 Biomarker Score ** N Low (<1.5) 200 1.0 - - 1.0 Intermediate (1.5-2.0) 331 1.66 1.10-2.49 0.015 1.38 1.06-1.80 0.017 High (>2.0) 159 2.72 1.77-4.19 <0.001 2.01 1.51-2.70 <0.001 * biomarkers adjusted for significant covariates of BMI, disease, mismatch, and CMV serostatus and stratified on conditioning regimen ** combined model includes all biomarkers and HCT-CI Disclosures No relevant conflicts of interest to declare.