Maciejewski, Jaroslaw P.

Abstract Abstract 400FN2 Patients with primary and secondary myelofibrosis (MF) have a worse prognosis than those with essential thrombocytosis (ET) or polycythemia vera (PV). MF and chronic myelomonocytic leukemia (CMML) share chromosomal and genetic lesions such as ASXL1 and JAK2 mutations, but effective treatments are lacking. The aim of the study was to identify perturbed pathways in MPN and CMML that were amenable to targeted molecular therapies. In a large genomic analysis of MPN cases, we identified recurrent deletions of multiple DNA repair genes, including BRCA2 and Fanconi anemia (FANC) proteins, which have been associated with poly (ADP-ribose) polymerase (PARP) inhibitor sensitivity. Neoplastic cells from these patients are hypersensitive to PARP inhibitors in vitro and may provide a therapeutic strategy to improve treatment response for patients with advanced MPNs. Genomic screens utilizing SNP-A karyotyping were performed on primary cells from 144 patients with either ET, PV, or MF (90 were previously reported, McDevitt et al., ASH 2009). We focused on the potential functional relevance of recurrent genomic deletions, including BRCA2, by performing a GO analysis using the EASE software application (Hosack et al. 2003). This revealed statistically significant (p≤0.05) enrichment of 13 biological pathways. Notably, genes involved in cell cycle regulation and DNA repair (DR) were enriched in MF loss regions (p=0.007) as compared to regions lost in ET and PV. Several genes directly involved in DR including BRCA2, XRCC2, and several members of the FANC pathway, also critical for DNA crosslink repair, were deleted or present in copy neutral LOH regions. DNA methyltransferase inhibitors are being tested clinically in MF patients, and both cell cycle and DNA repair genes have been identified as epigenetically silenced in hematological malignancies. We therefore screened for BRCA1, BRCA2, FANC-C, L, and N promoter CpG island methylation in a series of 48 MPN samples. No methylation was identified in BRCA2 and FANC members, suggesting a potential haploinsufficiency mechanism. Methylation of BRCA1 was identified in a small number of cases and is under further study in a larger cohort to investigate the effects on BRCA1 expression, DR and sensitivity to PARP inhibitors. Based on these genetic and epigenetic findings, we then focused on a functional analysis of the homologous recombination (HR) pathway. Leukocytes from normal controls and MPN patients were exposed to ionizing radiation (IR) and stained for Rad51 foci, a marker of HR activity. Six of 15 MPN/CMML samples (40%), but none of the controls failed to form IR-induced Rad51 foci, suggesting impaired HR. Of the samples that demonstrated defects in HR [MPN-U, MF, CMML (2), MDS/MPN-U, and CML], there was no significant correlation between the MPN subtype, the JAK2 mutation status, or the specific metaphase karyotype, but the most sensitive case in our series exhibited a deletion of Ch13q that spanned the BRCA2 gene. We then examined sensitivity of MPN vs. normal myeloid progenitors to the PARP inhibitors veliparib and/or olaparib in methylcellulose (MC)-based colony forming assays. Failure to form Rad51 foci with irradiation was statistically correlated with PARP inhibitor sensitivity (p = 0.021). When an expanded series of cases were then analyzed for PARP inhibitor sensitivity using the MC colony assay, lower IC50s for both veliparib and olaparib were observed in MPN cases (N= 25, IC50S=2.69uM vs. 11.2uM, N=15 IC50S=.64uM vs. 1.27uM, respectively) relative to normal controls (p =.0003, p =.05, via Wilconon rank-sum test respectively). Two cases in this series were treated on a clinical trial combining the ABT-888 PARP inhibitor with salvage chemotherapy consisting of carboplatin and topotecan (Karp et al., ASH 2010). Both patients, one with sAML evolving out of PPV-MF, and a second with accelerating MPN-U, had failed four prior therapies but achieved complete clearance of bone marrow blasts at day 14. Interestingly, cells from this MPN-U patient (13q-) were the most sensitive to PARP inhibition in vitro. Additional accrual and correlative evaluations are underway and will be updated at the meeting. Collectively, these results demonstrate that a subset of MPN and CMML patients have intrinsic genetic and epigenetic defects affecting the FANC and HR pathways, providing pre-clinical rationale for the use of PARP inhibitors in the treatment of aggressive MPN and CMML. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction Population level data about the survival outcomes of patients with hematologic malignancies occurring as second cancers is limited. We undertook one of the largest analyses of second hematologic malignancies (SHM) using the Surveillance, Epidemiology & End Results (SEER) registry to identify factors associated with survival. Methods SEER 9 &13 registries were queried to identify adult patients (pts>18 years) diagnosed with SHM that comprised of Acute Myeloid Leukemia (AML), Acute Lymphoid Leukemia (ALL), Myelodysplastic Syndromes (MDS), Chronic Myeloid Leukemia (CML) & Other Acute Leukemias (OAL, biphenotypic leukemias, myeloid sarcomas & leukemias NOS) > 1 year (yr) after diagnosis of a primary unrelated cancer, using ICD-O-3 codes over a 40 yr period (1973-2012). Data on demographics, follow up, primary tumor & survival were abstracted. Univariate & multivariate analyses were performed to identify factors influencing survival of SHM & compared with hematologic malignancies occurring as first cancers. Hazard ratios (HR) with 95% confidence intervals (CIs) are reported & significance was set at p< 0.01. Results SHM cases included 4665 AML, 3569 MDS, 1140 OAL, 1076 CML & 536 ALL pts. Median age at diagnosis of SHM was 73 yrs (range, 18-100) for AML, 79 yrs (18-100) for MDS, 74 yrs(20-99) for OAL, 74 yrs(18-98) for CML & 70 yrs(19-97) for ALL. Pts>60 yrs comprised 79.2% of AML, 92% of MDS, 88.7% of OAL, 82.9% of CML & 75.2% of ALL cases. Gender distribution was similar across all categories, with females comprising 48.5% of AML, 42.2% of MDS, 45.3% of OAL, 42.8% of CML & 50.2% of ALL cases. More than 85% of pts in each group were Caucasians. While the majority of pts had one primary unrelated cancer (82-89%), 14% of AML pts, 17.8% of MDS pts, 13.8% of OAL, 15.3% of CML pts& 10.6% of ALL pts had >1 primary unrelated cancer. Most common primary sites were prostate (19.1-29.6%), breast (16.1-21.9%) & colorectal (9.3-14.5%). Median survival (range) was as follows: AML 0.2 yrs (0-28.2); MDS 1.5 yrs (0-14); OAL 0.2 yrs (0-29.1); CML 2.5 yrs (0-27.1); & ALL 0.7 yrs (0-28.8). Median latency periods (range) for secondary cancers were as follows: AML 5.2 yrs (1.0-24.2); MDS 7.6 yrs (1.0-35.5); OAL 5.7 yrs (1.0-=34.3); CML 5.2 yrs (1.0-31.6); & ALL 6.2 yrs (1.0-35.5). In univariable analyses, age <60 yrs predicted for better survival (p<0.0001) for all SHM, as did diagnosis in recent yrs (2001-2012) (p< 0.0001 for AML, OAL, CML & ALL). Effect of time period on survival for MDS was not done, as it became formally reportable in 2001. Having >2 primaries was associated with an unfavorable outcome for subsequent AML (HR=1.15; 1.08-1.23; p < 0.0001), MDS (HR=1.13; 1.05-1.22: p=0.001) & CML (HR=1.30; 1.13-1.48: p=0.0002). In multivariable analyses, advancing age was an independent adverse prognostic factor for all secondary leukemias & MDS, both as a continuous variable & when categorized as <60 yrs vs. >60 yrs (p<0.001). Race & gender did not impact survival. Using breast cancer as a referent primary, AML pts had worse outcomes following colorectal (HR=1.31; 1.14-1.5; p=0.0002) or lung (HR=1.46; 1.22-1.74; p< 0.0001) primaries, while MDS pts fared worse with prior lung (HR=1.61; 1.22-2.12; p=0.0007) or Non-Hodgkin lymphoma (HR=1.58; 1.3-1.92: p< 0.0001). Of all 2ndCML cases, those after colorectal cancer had worst survival (HR=1.54; 1.12-2.13; p=0.008). Among SHM pts, MDS pts had better survival than those with AML (HR=0.42; 0.4-0.44: p< 0.0001), as did pts with CML (HR=0.37; 0.35-0.41: p< 0.0001) & ALL (HR=0.64; 0.58-0.70; p< 0.0001). Out OAL had similar outcomes compared to AML (HR=0.99; 0.92-1.05; p=0.66). Pts with CML fared better than MDS (HR=0.47; 0.41-0.54; p< 0.0001) & OAL (HR=0.37; 0.34-0.41: p< 0.0001). Pts with ALL had worse survival than CML (HR=1.8; 1.6-2.03: p< 0.0001) & MDS (HR=1.28; 1.11-1.48: p=0.0005), but better than OAL (HR=0.65; 0.58-0.73: p< 0.0001). (Figure 1) Patients with all SHM, except CML, had worse outcomes compared to those with primary hematologic cancers (Figure 2). Conclusion The prolonged latencies for SHM in this study suggest that they are likely therapy-related. Our findings show that type & number of primary cancers influence survival of subsequent leukemias & MDS. SHM have worse survival compared to those with primary hematologic malignancies except CML where non-separation of survival curves suggest that CML as SHM does not behave like a therapy-related neoplasm. Disclosures Sekeres: TetraLogic: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees.

Abstract Background: The incidence of thyroid cancers has been rising in the United States primarily due to the increased detection of well differentiated thyroid cancers (WDTC). Radioactive iodine (RAI), which is frequently used to treat WDTC, can be considered a circulating radiation emitter with the potential for mutagenic effects on hematopoietic stem cells. With a growing number of WDTC patients (pts) surviving long term following RAI therapy, establishing the risk of developing a myelodysplastic syndrome (MDS) in this cohort has important clinical implications. Methods: A novel R program, SEERaBomb (Radiat Environ Biophys. 2014;53(1):55-63) was used to query all 18 Surveillance Epidemiology and End Results (SEER) registries to identify WDTC cases treated with RAI and MDS as second cancers. SEERaBomb allows merging of all 18 SEER registries - a function not permitted by the SEER*Stat MP-SIR that limits researchers to use to one of two datasets (SEER 9 or SEER 13), thereby significantly increasing the capture of MDS cases (Figure 1). WDTC includes papillary and follicular thyroid histologies. WDTC survivor person-years at risk for developing MDS was based on age at diagnosis of WDTC, survival time, and age at diagnosis of MDS. Relative risks (RR) for developing MDS were then based on observed/expected cases between the cohorts receiving surgery alone (control), surgery combined with RAI as well as those receiving external beam radiation therapy (EBRT) and surgery with or without (+/-) RAI. Mean radiation exposure to bone marrow was compared between RAI and prostate cancer (as example) treated with other radiation modalities - brachytherapy (seeds), EBRT (3D, IMRT and VMRT). Results: In total 132,157 WDTC patients were identified from 1973-2011, of whom 69,975 (53%) received surgery alone, 59,015 (45%) underwent surgery + RAI and 3167 (2%) underwent EBRT [combined with surgery+/- adjuvant RAI]. Mean age at the time of WDTC diagnosis was: 49.4 years (yrs, range, 2-105) in the surgery group; 46.7 yrs (2-99) in the surgery + RAI group and 55.1 yrs (10-101) in the EBRT group. Median person years of follow up after WDTC diagnosis was: 6.1 yrs (2.5-11.6) in pts undergoing thyroidectomy; 5.4 yrs (2.4-9.7) in the surgery + RAI group and 5.9 yrs (1.7-11) in the EBRT group. A total of 55 patients developed MDS; 24 had surgery alone, 27 received surgery + RAI and 4 had EBRT. Median time to development of MDS after WDTM diagnosis (25-75 interquartile range) was: 6.4 yrs (4-15) in pts receiving surgery alone; 4 yrs (1.7-6.7) in the surgery + RAI group and 3.6 yrs (2.4-7.9) in the EBRT group. MDS cases were classified as RA (n=11), RARS (n=2), RCMD (n=3), RAEB (n=9), MDS with 5q deletion syndrome (n=1), and MDS-U (n=29). Compared to patients definitively treated with surgery, those who additionally received RAI (+/- EBRT) had a statistically significantly increased risk of developing MDS within the first two years of exposure (RR=1.9; 95% CI, 0.43-5.61 vs. RR=5.8; 95% CI, 2.84-12.22). Beyond 2 years, the risk for MDS drops to baseline rates, and a trend observed beyond 12 years, which did not reach statistical significance (Figure 2). Conclusion: WDTC pts undergoing RAI treatment appear to have an increased risk of developing MDS within the first two years of exposure to RAI. It is difficult to determine whether this early excess risk is true risk or an effect of ascertainment bias (RAI pts followed more closely), as the kinetics of RAI indicate a lower magnitude of bone marrow exposure compared to other radiation modalities (Figure 3). Considering the long latency of MDS seen in atomic bomb cohorts, relative young age of WDTC pts, current trend towards overdiagnosis and overtreatment of WDTCÕs, MDS rates are likely to continue to rise. Disclosures Sekeres: Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; TetraLogic: Membership on an entity's Board of Directors or advisory committees.

Abstract Introduction: Surveillance, Epidemiology, and End Results (SEER) registry captures data on acute leukemias (AL) that morphologically do not conform to well characterized acute leukemic entities in the established French-American-British (FAB) nomenclature. Not much is known about population level outcomes of these rare AL. We performed a comprehensive survival analysis of these rare AL over a forty-year period using the SEER registry. Methods: SEER 18 dataset was queried to identify adult patients (pts > 18 years) diagnosed with Acute Myeloid Leukemia (AML), Acute Lymphoblastic Leukemia (ALL) and rare AL from 1973-2012. Rare AL cases were identified using ICD-O-3 morphology codes and included Leukemias, Not Otherwise Specified (NOS) (9800-01, 9860) and myeloid sarcoma (9930). Data on demographics,follow up and survival was abstracted. Univariate and multivariate analysis was performed to identify factors influencing survival of rare AL and survival patterns were compared to AML and ALL. Hazard ratios (HR) with 95% confidence intervals (CIs) are reported. Results: We identified 61,550 AML pts, 13,457 ALL pts, 525 myeloid sarcoma pts and 13,446 pts with leukemia NOS. Median age at diagnosis was 68 years (yrs, range 18-100) for AML, 54 yrs (18-100) for ALL, 65 yrs (18-95) for myeloid sarcoma and 76 yrs (18-100) for leukemia NOS. Gender distribution was similar with females comprising 45.9% of AML, 43% of ALL, 42.3% of myeloid sarcoma and 47.2% of leukemia NOS cases. Over 80% pts in all categories were Caucasian. Median survival was as follows: 0.4 (0-40) yrs for AML; 1.4 (0-39.8) yrs for ALL; 0.7 (0-32.9) yrs for Myeloid Sarcoma; and 0.3 (0-38.9) yrs for leukemia NOS. In univariable analysis, younger age predicted for better survival for both myeloid sarcoma and leukemia NOS (p<0.0001). Improvement in survival over time period was observed for pts with leukemia NOS (p < 0.0001). In multivariable analysis, advancing age was an independent prognostic factor for rare AL, both as a continuous variable and when categorized as older vs. younger pts using age cutoff of 60 yrs. Compared to younger pts, HR for pts > 60 yrs with rare AL was as follows: 2.68 (2.13-3.37; p <0.0001) for myeloid sarcoma; and 2.18 (2.07-2.31; p<0.0001) for leukemia NOS. No difference in survival over time was seen for myeloid sarcoma. Pts with leukemia, NOS diagnosed in yrs 2006-2012 (HR=0.87; 0.82-0.92; p < 0.0001) had better survival compared to the referent years 1973-80. Race and gender did not impact survival. In multivariable analysis, pts with leukemia NOS did worse overall compared to AML (HR=1.13; 1.11-1.53; p<0.0001) and ALL (HR=1.86; 1.81-1.91; p<0.0001). Interestingly, younger pts had a poorer outcome than AML (HR=1.10; 1.04-1.16; p=0.0003), but pts > 60 yrs had a better outcome (HR=0.93; 0.91-0.95; p<0.0001). Both younger (HR=1.33; 1.26-1.41; p<0.0001) and older pts (HR=1.45, 1.40-1.50: p<0.0001) compared unfavorably to ALL (Figure 1). Pts with myeloid sarcoma had a better survival compared to AML pts (HR=0.77; 0.7-0.85; p<0.0001) (Figure 2). This was uniform for pts <60 yrs (HR=0.77; 0.64-0.93; p=0.006) and > 60 yrs (HR= 0.77; 0.69-0.87; p<0.0001). Conclusion: Pts with leukemias NOS have poor outcomes compared to AML and ALL but prognosis has improved in recent years. The most probable explanation is identification of prognostic molecular mutations that has allowed accurate risk-stratification of pts using the WHO classification and in turn better selection of treatment strategies. Several reasons have limited our understanding of these rare AL - small numbers, exclusion from clinical trials and wide variability in treatment options used. Efforts at better molecular characterization of these AL holds the most promise for improving outcomes. Disclosures Sekeres: Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; TetraLogic: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees.

Purpose To investigate the risk and outcomes of second hematologic malignancies (SHMs) in a population-based cohort of patients with well-differentiated thyroid cancer (WDTC) treated or not with radioactive iodine (RAI). Methods Patients with WDTC were identified from SEER registries. Competing risk regression analysis was performed to calculate the risks of SHMs that occurred after WDTC treatment and outcomes after SHM development were assessed. Results Of 148,215 patients with WDTC, 53% received surgery alone and 47% received RAI. In total, 783 patients developed an SHM after a median interval of 6.5 years (interquartile range, 3.3 to 11.2 years) from WDTC diagnosis. In multivariable analysis, compared with those undergoing thyroidectomy alone, RAI treatment was associated with an increased early risk of developing acute myeloid leukemia (AML; hazard ratio, 1.79; 95% CI, 1.13 to 2.82; P = .01) and chronic myeloid leukemia (CML; hazard ratio, 3.44; 95% CI, 1.87 to 6.36; P < .001). This increased risk of AML and CML after RAI treatment was seen even in low-risk and intermediate-risk WDTC tumors. Occurrence of AML but not CML in patients with WDTC was associated with shorter median overall survival compared with matched controls (8.0 years v 31.0 years; P = .001). In addition, AML developing after RAI trended toward inferior survival compared with matched controls with de novo AML (median overall survival, 1.2 years v 2.9 years; P = .06). Conclusion Patients with WDTC treated with RAI had an increased early risk of developing AML and CML but no other hematologic malignancies. AML that arises after RAI treatment has a poor prognosis. RAI use in patients with WDTC should be limited to patients with high-risk disease features, and patients with WDTC treated with adjuvant RAI should be monitored for myeloid malignancies as part of cancer surveillance.

Abstract Myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN) are hematologically diverse stem cell malignancies sharing phenotypic features of both myelodysplastic syndromes and myeloproliferative neoplasms. There are currently no standard treatment recommendations for most adult patients with MDS/MPN. To optimize efforts to improve the management and disease outcomes, it is essential to identify meaningful clinical and biologic end points and standardized response criteria for clinical trials. The dual dysplastic and proliferative features in these stem cell malignancies define their uniqueness and challenges. We propose response assessment guidelines to harmonize future clinical trials with the principal objective of establishing suitable treatment algorithms. An international panel comprising laboratory and clinical experts in MDS/MPN was established involving 3 independent academic MDS/MPN workshops (March 2013, December 2013, and June 2014). These recommendations are the result of this collaborative project sponsored by the MDS Foundation.

Abstract Even though mutations in epigenetic regulators frequently occur in myeloproliferative neoplasms, their effects on the epigenome have not been well studied. Furthermore, even though primary myelofibrosis (PMF) has a markedly worse prognosis than essential thrombocytosis or polycythemia vera, the molecular distinctions between these subgroups are not well elucidated. We conducted the HELP (HpaII tiny fragment enriched by LM-PCR) assay to study genome-wide methylation in polycythemia vera, essential thrombocytosis, and PMF samples compared with healthy controls. We determined that polycythemia vera and essential thrombocytosis are characterized by aberrant promoter hypermethylation, whereas PMF is an epigenetically distinct subgroup characterized by both aberrant hyper- and hypomethylation. Aberrant hypomethylation in PMF was seen to occur in non-CpG island loci, showing further qualitative differences between the disease subgroups. The differentially methylated genes in polycythemia vera and essential thrombocytosis were involved predominantly in cell signaling pathways and were enriched for binding sites of GATA1 and other transcription factors. In contrast, aberrantly methylated genes in PMF were involved in inflammatory pathways and were enriched for NF1, LEF1, and other transcription factors. Within the PMF subgroup, cases with ASXL1 disruptions formed an epigenetically distinct subgroup with relatively increased methylation. Cases of myeloproliferative neoplasms (MPN) with TET2 mutations showed decreased levels of hydroxymethylation and distinct set of hypermethylated genes. In contrast, the JAK2V617F mutation did not drive epigenetic clustering within MPNs. Finally, the significance of aberrant methylation was shown by sensitivity of MPN-derived cell lines to decitabine. These results show epigenetic differences between PMF and polycythemia vera/essential thrombocytosis and reveal methylomic signatures of ASXL1 and TET2 mutations. Cancer Res; 73(3); 1076–85. ©2012 AACR.

Lenalidomide is the first karyotype-selective therapeutic approved for the treatment of myelodysplastic syndromes (MDS) owing to high rates of erythroid and cytogenetic response in patients with chromosome 5q deletion [del(5q)]. Although haploinsufficiency for the RPS14 gene and others encoded within the common deleted region (CDR) have been implicated in the pathogenesis of the del(5q) phenotype, the molecular basis of the karyotype specificity of lenalidomide remains unexplained. We focused our analysis on possible haplodeficient enzymatic targets encoded within the CDR that play key roles in cell-cycle regulation. We show that the dual specificity phosphatases, Cdc25C and PP2Acα, which are coregulators of the G 2 -M checkpoint, are inhibited by lenalidomide. Gene expression was lower in MDS and acute myeloid leukemia (AML) specimens with del(5q) compared with those with alternate karyotypes. Lenalidomide inhibited phosphatase activity either directly (Cdc25C) or indirectly (PP2A) with corresponding retention of inhibitory phospho-tyrosine residues. Treatment of del(5q) AML cells with lenalidomide induced G 2 arrest and apoptosis, whereas there was no effect in nondel(5q) AML cells. Small interfering RNA (shRNA) suppression of Cdc25C and PP2Ac α gene expression recapitulated del(5q) susceptibility to lenalidomide with induction of G 2 arrest and apoptosis in both U937 and primary nondel(5q) MDS cells. These data establish a role for allelic haplodeficiency of the lenalidomide inhibitable Cdc25C and PP2Acα phosphatases in the selective drug sensitivity of del(5q) MDS.