Hirsch, Betsy

Introduction. Myeloid leukemia in children with Down syndrome (ML-DS) is a unique subtype of acute myeloid leukemia, distinguished by an earlier age of onset (under 4 years of age); somatic mutations of GATA1; hypersensitivity of leukemic blasts to cytarabine and other chemotherapeutic agents; lack of CNS involvement; and superior event-free survival (EFS, 85-90% at 5 years). Due to these excellent outcomes, successive protocols by the Children's Oncology Group (COG) have aimed for a reduction of treatment intensity but continue to include a course containing high-dose cytarabine (HD-AraC) for all patients, which is associated with the bulk of infectious toxicity. COG AAML1531 is the first study to evaluate differential treatment for ML-DS patients based on risk-stratification. We report the outcomes for patients with Standard Risk (SR) ML-DS enrolled on AAML1531, who were treated without inclusion of HD-AraC (https://clinicaltrials.gov/ct2/show/NCT02521493?term=AAML1531&rank=1). Methods. Patients older than 90 days and younger than 4 years of age with ML-DS were eligible, including those presenting with myelodysplastic syndrome (< 20% blasts in the bone marrow) and trisomy 21 mosaicism. Pathological and cytogenetic data were reviewed centrally. All patients received the same first course of induction therapy (cytarabine 200 mg/m2/24h IV as continuous infusion, day 1-4; daunorubicin 20 mg/m2IV, day 1-4; thioguanine 50 mg/m2/dose PO twice daily, day 1-4; and a single dose of age-based intrathecal cytarabine on day 1). After this first course, measureable residual disease (MRD) in the bone marrow by multi-dimensional flow cytometry in a reference laboratory was used for risk stratification. Patients with negative MRD (<0.05%) were assigned to Standard Risk (SR) therapy, which was modeled after the AAML0431 predecessor study, but with further reduction of treatment by omission of the course containing HD-AraC/E. coli asparaginase (Induction II of AAML0431). Courses #2 and #3 of SR therapy were identical to the first course except that no further intrathecal chemotherapy was administered. Courses #4 and #5 (cytarabine 100 mg/m2/24h IV as continuous infusion day 1-7; etoposide 125 mg/m2 IV, day 1-3) were identical to the corresponding courses of AAML0431. For patients younger than 36 months, chemotherapy doses were calculated based on weight. Use of dexrazoxane during anthracycline-containing courses was at the discretion of the treating center but was captured by the data collection of the study. Patients with positive MRD (>0.05%) after the first course were assigned to the High Risk (HR) Arm and received intensified therapy (equivalent to that used for non-DS AML). Accrual to the HR arm is ongoing. Results. Interim analysis of SR therapy was performed after 50% of expected EFS events had occurred as of June 30, 2018. The observed EFS was 89.3 +/- 6.1% at 2 years from study entry and significantly lower than expected for comparable MRD-negative patients whose treatment in predecessor study AAML0431 included a course of HD-AraC/E. coliasparaginase (p=0.0002). OS at 2 years was 88.7 +/- 6.8%. Among a total of 114 SR ML-DS patients, 11 developed a relapse, all within the first year from study entry (range 136-327 days). OS at 1 year from relapse was 9.1 +/- 17.3%. Based on the results of interim analysis, the SR arm of AAML1531 was closed to accrual due to lack of efficacy. Cytogenetic analysis showed that complex karyotypes (defined as >3 independent abnormalities including >1 structural one) were significantly more frequent in SR patients who relapsed (40%, n=10) compared to SR patients who did not (9%; n=100; p=0.017). The most common abnormalities were trisomies (61% of cases) of chromosomes 3 and 8, and a gain of a fourth copy of chromosome 21. Monosomy 7 was present in 20% of relapsed vs. 5% of patients without a relapse (p=0.122). Conclusions. MRD measured by multi-dimensional flow cytometry is insufficient to identify a subset of ML-DS patients for whom HD-AraC/E.coliasparaginase can be eliminated from treatment. Cytogenetic profiling may aid in further refining risk-based subsets of ML-DS patients. Additional approaches to risk stratification of ML-DS should be pursued, which take into account the emerging genetic events that co-operate with mutant GATA1 in the development of ML-DS. At this time, HD-AraC/E.coli asparaginase should be included in the treatment of ML-DS, regardless of MRD. Disclosures Druley: Washington University: Employment; ArcherDX Inc.: Employment, Equity Ownership. Loken:Hematologics, Inc: Employment, Equity Ownership. Eidenschink Brodersen:Hematologics, Inc: Employment.

Background With the exception of therapy related MDS due to treatment with alkylating agents and/or radiation or with a topoisomerase II inhibitor, little is known about the etiology of myelodysplastic syndromes (MDS). A few studies have evaluated pre-existing medical conditions as risk factors for MDS, with evidence suggesting that autoimmune disease is associated with an increased risk of MDS. Here, we evaluated associations between history of autoimmune disease, overall and by individual disease subtype, and risk of MDS in a population-based case control study. Methods MDS cases were identified by rapid case ascertainment through the population-based Minnesota Cancer Surveillance System (MCSS). Participants were recruited if they were diagnosed with MDS between April 1, 2010 and October 31, 2014. Eligibility criteria included residence in Minnesota, age at diagnosis between 20 and 85 years, and ability to understand English or Spanish. Centralized pathology and cytogenetics review were conducted to confirm diagnosis and classify by subtypes. Controls were identified through the Minnesota State driver's license/identification card list. History of autoimmune disease was reported using a self-administered questionnaire; proxy interviews were not conducted. Unconditional logistic regression with adjustment for age, sex and confounders (education, NSAID use, benzene exposure, BMI) was used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (CI) for autoimmune disease and MDS. Results A total of 399 cases with a confirmed diagnosis of MDS and 1399 controls were included. Cases were significantly more likely to report a diagnosis of any autoimmune disease when compared with controls (OR=1.49, 95% CI 1.13-1.97). As illustrated in Figure 1, specific associations were observed for hypothyroidism (OR=2.07, 95% CI 1.39-3.08), ulcerative colitis (OR=2.26, 95% CI 1.09-4.69), Crohn's disease (OR=3.88, 95% CI 1.23-12.2), and systemic lupus erythematosus (SLE; OR=7.52, 95% CI 1.98-28.6). Autoimmune conditions were more commonly reported in both female cases and female controls when compared with males; however, associations for hypothyroidism and ulcerative colitis were significantly associated with MDS in males in an analysis stratified by sex. Associations between autoimmune disease and MDS remained statistically significant after exclusion of therapy-related MDS cases. Discussion Our results validate previous findings of an association between autoimmune disease and MDS risk from population-based registry studies and case-control studies. In addition, our results provide additional evidence to suggest that this association is largely driven by hypothyroidism, inflammatory bowel disease, and SLE. This increased MDS risk following a diagnosis for an autoimmune condition is hypothesized to be due to shared genetic or environmental risk factors, treatment for autoimmune diseases, altered immune surveillance or damage to the bone marrow caused by the autoimmune condition. Further studies are required to confirm which of these is the most plausible explanation. Disclosures No relevant conflicts of interest to declare.

Abstract Myelodysplastic syndromes (MDS) are a heterogeneous collection of clonal disorders of hematopoietic stem cells characterized by ineffective hematopoiesis, dysplasia, and risk of progression to secondary acute myeloid leukemia (AML). Despite the development of numerous prognostic scoring systems (MDS Comorbidity Index (MDS-CI),International Prognostic Scoring System (IPSS) and IPSS-R, updated WHO classifications, and WHO prognostic scoring system (WPSS)), little prospective data regarding the influence of these and other factors on patient outcomes is available. To better elucidate the features of early mortality in MDS we compare characteristics of patients dying within one year of MDS diagnosis with those surviving longer in our Adults in Minnesota with MDS (AIMMS) population based case-control study. The AIMMS study is a statewide prospective population-based case-control study (R01 CA142714) conducted by the University of Minnesota (UMN), Mayo Clinic, and the Minnesota Department of Health. Adults (age 20-85 years) with a new diagnosis of MDS between April 2010 and October 2014 were recruited through the Minnesota Cancer Surveillance System. Patients completed a comprehensive questionnaire to capture retrospective epidemiologic data. All cases went through central medical review including pathology review by two independent hematopathologists, cytogenetic analyses, and oncologist medical record review with assignment of IPSS, IPSS-R, WPSS 1.2 noting past medical history, exposures, and treatment history and response. Annual clinical review of all patient cases for four years after initial enrollment is ongoing in a batched, non-real time manner. Three hundred and ninety-nine patients with a confirmed diagnosis of MDS based on central review and one year of clinical follow-up review were included in the analysis. For the entire group, we observed early mortality in those with abnormal cytogenetics, three or greater cytogenetic abnormalities, treatment at a community medical center only (versus academic), and with 2-3 concurrent medical comorbidities (Table 1). Treatment with hypomethylating agents also correlated with early mortality but when adjusted for WPSS and IPSS-R, this association was no longer significant. To investigate varied impact of disease and patient characteristics within different groups of MDS patients, we did multivariable regression analysis within the following categories: High/Very High Risk IPSS-R; Very low/Low/Intermediate Risk IPSS-R; Treated Patients; Supportive Care Only Patients. In patients with high or very high risk IPSS-R, the presence of 3 or more cytogenetic abnormalities was the only significant predictor early mortality in a multivariable adjusted model (OR: 3.66, 95% CI: 1.57-8.53). Similarly, in those with very low, low, or intermediate IPSS-R, abnormal cytogenetics was the only significant predictor of early mortality in an adjusted model (OR: 3.71, 95% CI 1.49-9.26). In patients receiving supportive care only, early mortality was seen in those who had diabetes (OR: 3.06, 95% CI 1.11-8.42), had complex cytogenetics (OR for ≥ 3 abnormalities: 4.94, 95% CI 1.25-19.46), and had very high or high IPSS-R (OR: 4.20, 95% CI 1.43-12.34). Likewise, complex cytogenetics remained the sole significant predictor of early mortality in treated patients (OR: 4.84, 95% CI 1.43-16.37). Complex cytogenetics and prognostic risk category (either by WPSS or IPSS-R) have previously been associated with higher risk disease and early mortality without intervention. Our data confirm this association in a large prospectively followed MDS cohort and highlight the significance of cytogenetic abnormalities and complexity regardless of IPSS-R risk categorization or treatment. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction Expanding treatment options for MDS have changed therapeutic decision-making for clinicians. To better characterize therapeutic choices in newly diagnosed MDS, we report the practice patterns captured during the first year of MDS diagnosis for patients enrolled in our statewide population-based study. We highlight a comparison of treatment in community and academic centers. Methods Adults in Minnesota with MDS (AIMMS) is a statewide prospective population-based study conducted by the University of Minnesota (UMN), Mayo Clinic, and Minnesota Department of Health. Starting in April 2010, all newly diagnosed adult cases (ages 20+) of MDS were invited to participate. After patient enrollment, central review was performed consisting of independent hematopathology and cytogenetic review coupled with oncologist chart review assigning prognostic risk scores [International Prognostic Scoring System (IPSS) and IPSS-R (Revised)] and abstracting treatment exposures. All enrolled patients with one year follow-up were included in this analysis. Treatment was divided into supportive, active, transplant, or other. Supportive care included observation, growth factors, and transfusions. Active care included azacitidine, decitabine, lenalidomide, or 7+3 chemotherapy. Academic centers were defined as the UMN and Mayo Clinic; all other centers were designated as community based practices. Results The median patient age was 73 years, with 68% males. IPSS and IPSS-R risk scores were calculated for 100% and 97% of patients, respectively. Treatment choices stratified by IPSS risk group showed 89% low risk, 53% INT-1, 31% INT-2, and 13% high risk with supportive care; active and transplant strategies were utilized for 9% low risk, 44% INT-1, 64% INT-2, and 88% high risk. INT-1 in the community received 70% supportive treatment, in academic 35%. Active treatment for INT-1 was 30% in community and 45% in academic. Community INT-2 received supportive care in 45% of cases, in academic 23%. Transplants were limited to academic centers, with the highest rate in INT-2 at 34%. Among community diagnoses, 100% of high risk, 52% INT-2, 26% INT-1, and 13% low risk were referred to an academic center. Comparison of age <65 and 65+ years showed 83% of transplants occurred in those <65. INT-2/high risk group patients <65 received 95% active therapy or transplant, compared to 51% of those 65+. Discussion This prospective, population based study provides a well-defined patient cohort based on central review of pathologic and clinical data. Evaluation of practice patterns during the first year after diagnosis showed higher utilization of active and transplant treatment strategies as IPSS risk score increased. Further, compared to community, higher utilization occurred for patients at academic centers, suggesting more aggressive treatment in these settings. Age was also a predictor of treatment choice. In addition, referral patterns followed IPSS score. Whether these treatment differences are driven by patient preference and/or translate into improved disease control and decreased mortality requires continued prospective analysis and will be detailed in future reports. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1733 Introduction: Much remains to be elucidated regarding the etiology of myelodysplastic syndrome (MDS) and why some cases progress to acute myeloid leukemia. Further, there are few data on how accurate case classification is within state cancer registries and the impact of the 2008 WHO MDS classification modifications on clinical practice. We are conducting a large population-based prospective study of MDS to investigate risk factors for initial disease as well as disease progression. Our study includes comprehensive central review of all cases. Initial findings are reported here. Methods: We began evaluation and follow-up of all newly diagnosed MDS cases in Minnesota between the ages of 20 and 85 years from April 1, 2010 onward. Our process includes rapid case identification by the Minnesota Cancer Surveillance System (MCSS), contact of individual patients after primary physician approval, and, for interested patients, participation in an extensive questionnaire with medical history review and optional saliva sample for DNA. In concert, all cases pass through central medical review including: 1) independent pathology report +/− slide review by two hematopathologists to confirm diagnosis and subclassification; 2) independent cytogenetic review by a cytogeneticist; and 3) medical chart review by an oncologist to identify pertinent clinical history and prospectively calculate the International Prognostic Scoring System (IPSS) and WHO-based prognostic scoring system (WPSS) scores. Annual follow-up is planned to monitor for disease progression and outcome. In cases of unknown cytogenetics, IPSS calculations are not completed. In cases of unknown cytogenetics or diagnosis of MDS-U, not currently stratified in the WPSS, WPSS calculations are not completed. Results: We describe the first 67 patients enrolled on this study that have completed central review. The majority of patients were male (n=44) and the median age of the cohort at diagnosis was 71 (range 41–85). Table 1 Conclusion: Ours is the first large prospective population-based study of MDS that includes central pathology, cytogenetic, and clinical review of newly diagnosed patients with prospective calculation of IPSS and WPSS and plans for long term follow-up. This study is expected to enroll approximately 700 MDS cases over a five year period. While early in investigation, our initial review highlights the variability in distinct WHO diagnosis between initial cancer registry (i.e., MCSS) designation and designation after thorough central review of all appropriate diagnostic components. Our data suggest the robustness of the WHO RA, RARS, and RCMD classifications, the possible over-utilization of MDS-U classification, and highlight the under-representation of therapy-related MDS identification with registry designation. The impact of discordant diagnoses between MCSS and central review on therapeutic strategies is uncertain, but warrants continued evaluation and underscores the importance of complete central review in evaluation of MDS cases. Supported by NIH R01 CA142714. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Polymorphisms in mitochondrial DNA can be used to group individuals into haplogroups that reflect human global migration. These mitochondrial variants are associated with differences in mitochondrial function and have been associated with multiple diseases, including cancer. In this analysis, we evaluated the association between mtDNA haplogroup and risk of myelodysplastic syndromes (MDS). Methods Cases were identified by rapid case ascertainment through the population-based Minnesota Cancer Surveillance System (MCSS). Participants were recruited to the MDS study if they were diagnosed with MDS between April 1, 2010 and October 31, 2014. Eligibility criteria included residence in Minnesota, age at diagnosis between 20 and 85 years, and ability to understand English or Spanish. Centralized pathology and cytogenetics review were conducted to confirm diagnosis and classify by subtypes. Controls were identified through the Minnesota State driver's license/identification card list. Genomic DNA from cases and controls was collected using Oragene DNA collection kits (DNA Genotek, Ontario, Canada) and extracted via Autopure LS Instrument according to manufacturer's instructions (Qiagen). We genotyped 15 mtSNPs that capture common European mitochondrial haplogroup variation (Mitchell et al Hum Genet 2014; Raby et al J Allergy Clin Immunol 2007) on the Sequenom iPLEX Gold MassArray platform (Sequenom, Inc., San Diego, CA) in the University of Minnesota Genomics Core. Because haplogroup frequencies vary by race and ethnicity, we restricted analyses to non-Hispanic white cases and controls. All statistical analyses were conducted using SAS v.9.3 (SAS Institute, Cary, NC). Odds ratios (OR) and 95% confidence intervals (CI) were calculated. We also evaluated associations by MDS subtype and IPSS-R risk category. Results We were able to classify 215 cases with confirmed MDS and 522 controls into one of the 11 common European haplogroups. The distribution of haplogroups in our control sample was similar to the distribution reported in a previous sample of non-Hispanic white individuals from the United States (Mitchell et al Hum Genet 2014), with the highest number in the H haplogroup (42%). Due to small sample sizes in some subgroups, we combined mt haplogroups into larger bins based on the haplogroup evolutionary tree, including HV (H+V), JT (J+T), IWX (I+W+X), UK (U+K), and Z (van Oven & Kayser Hum Mut 2009) for comparisons of cases and controls. Using haplogroup HV as the reference group, we found a statistically significant association between haplogroup JT and MDS (OR=0.57, 95% CI 0.36, 0.90, p=0.02). No other significant associations were observed in a comparison of cases and controls (Figure). In the analysis stratified by MDS subtype, the association with haplogroup JT reached statistical significance only in MDS cases with the RCMD subtype (OR=0.42, 95% CI 0.18, 0.97), although the association was similar in magnitude for RARS and the p-value for heterogeneity was non-significant (0.76). Similarly, the associations between haplogroup JT and MDS were similar in the analysis stratified by IPSS-R risk category (p-value for heterogeneity = 0.71). Conclusions In this population-based study of MDS, we observed an association between mtDNA haplogroup JT and risk of MDS. Previous studies using cybrid cells have reported functional differences by mtDNA haplogroup and provide biological plausibility for the observed association, including higher capacity to cope with oxidative stress in haplogroup T (Meuller et al PLoS One 2012) and lower levels of ATP and reactive oxygen species production in haplogroup J (Kenney et al PLoS One 2013). Further studies of the relationship between mtDNA variation and MDS are warranted in larger sample sizes. Figure 1. Association between mtDNA haplogroup and MDS Figure 1. Association between mtDNA haplogroup and MDS Disclosures No relevant conflicts of interest to declare.

Abstract Background MDS is a clonal hematopoietic stem cell disorder characterized by dysplastic changes in the bone marrow, ineffective hematopoiesis and an increased risk for developing acute myeloid leukemia (AML). The majority of MDS cases are sporadic, but rare familial cases have been described and are often ascertained through clinic-based referrals. To our knowledge, no population based study of MDS has examined the frequency of family history of hematologic malignancies and disorders in patients, nor associations with disease characteristics and outcomes. Methods Newly diagnosed MDS cases are being identified by rapid case ascertainment by the Minnesota Cancer Surveillance System (MCSS), a population-based cancer registry in Minnesota. Eligibility criteria include all newly diagnosed cases of MDS during the period April 1, 2010-October 31, 2014, between 20-85 years, Minnesota resident, and ability to understand English or Spanish. Proxy interviews are not being conducted. Medical records and biologic samples are obtained and questionnaires are filled out by participants. Centralized pathology and cytogenetics review confirm diagnosis and classify by subtype and risk score including the Revised International Prognostic Scoring System (IPSS-R). Since 2010, information on family history has been obtained through questionnaire responses and/or medical record review on 353 MDS patients. Cases were considered to have a positive family history if they reported a first degree relative with MDS, leukemia, lymphoma or other hematologic condition (multiple myeloma [n=4], Waldenstrom’s macroglobulinemia [n=1] and idiopathic thrombocytopenic purpura [n=1]). Treatment related MDS cases were excluded leaving 330 MDS patients for analysis. Unconditional logistic regression was used to calculate crude odds ratios (ORs) and 95% confidence intervals (CI) overall and by sex. Results A total of 61/330 (18.5%) cases reported a family history of a hematologic condition. The mean age at diagnosis was 71.3 years in those with a family history compared to 72.2 years in those without a family history (p=0.53). There was no difference in the sex distribution between the two groups. Though not statistically significant, the odds of having abnormal cytogenetics or an IPSS-R of High/Very High was lower for those having a positive family history (OR 0.57 [CI 0.25-1.33, p=0.19 and 0.67 [CI 0.24-1.84, p=0.29], respectively). The odds of survival at one year after diagnosis was significantly higher in those with a family history (OR 2.79 [CI 1.04-7.51, p=0.04]) compared to those without (Table). Further stratification by sex revealed that this association was strongest for males (OR=4.23, [CI 0.94-19.0, p=0.06] compared to females (OR=1.84 [CI=0.47-7.19, p=0.38]). Discussion In this population based study of adults with MDS, the prevalence of MDS cases having a positive family history was higher than previous reports. Additionally, cases reporting a family history of hematologic malignancies and disorders appear to experience lower risk disease and have significantly improved overall survival, especially males. It is possible that patients with a family history of hematologic conditions are diagnosed earlier in the course of their disease secondary to increased awareness about blood disorders and/or more active screening within the family. Our analysis is limited by relatively small numbers, but enrollment is ongoing so subsequent analyses with larger numbers of subjects may be more revealing. Additionally, a prospective study to examine these families further, including detailed medical histories and collection of biospecimens (saliva, blood, skin) for genetic analyses is underway in order to identify potential mechanisms and mutations involved in the development of MDS and progression to AML. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction Much remains unknown regarding the etiology of MDS and why some cases progress to acute myeloid leukemia (AML). With MDS reportable as a distinct myeloid malignancy for the first time only in 2001, there are few data on state cancer registry case identification and classification accuracy. To grasp the true incidence and the scope of this heterogeneous clonal hematopoietic malignancy, the accuracy of such information is essential. In our third year of a large population-based prospective study of MDS to investigate risk factors for initial diagnosis and disease progression, we report our experience with MDS case identification and classification according to both our state cancer registry and our comprehensive central review process Methods We began our identification and follow-up of all newly diagnosed adult MDS cases in Minnesota in April 2010. Our process includes rapid case identification by the Minnesota Cancer Surveillance System (MCSS), contact of individual patients, and their participation in an extensive questionnaire and medical history review. In concert, all cases pass through central medical review including: 1) independent pathology review by two hematopathologists; 2) independent cytogenetic review by a cytogeneticist; 3) integrated central pathology-cytogenetic review; and 4) medical chart review by an oncologist to identify pertinent clinical history and treatments and prospectively calculate risk stratification scores (International Prognostic Scoring System (IPSS)). Annual follow-up monitors for disease progression and outcome. Results We describe the first 161 patients enrolled who have completed central review. Our data highlight the excellent concordance between MCSS and central review for the MDS subtypes RAEB (n=40/50, 80%), RARS (n=20/23, 87%), and RCMD (n=19/25, 76%). However, we noted poor concordance for the MDS subtypes RA (n=1/7 (14%) with 5 cases re-classified as RCMD) and MDS-U (n=3/24(13%) with 21 cases re-classified into other MDS subtypes). Notably, our integrated central review process identified and reclassified 12 additional cases of t-MDS when all data were considered. Our central review process noted an additional 30 cases classified as MDS by MCSS that we deemed ineligible after central review due to insufficient morphology (n=20) or reclassification to chronic myelomonocytic leukemia (CMML) (n=5), MDS/MPD (n=3), or AML (n=4). Conclusion Ours is the first large prospective population-based study of MDS that includes central pathology, cytogenetic, and clinical review of newly diagnosed patients with prospective risk stratification calculation and long term follow-up. Our review highlights the variability in the diagnosis and subclassification of MDS between our state cancer registry and after integrated central review, with as many as 80% of cases in certain MDS subtypes being re-classified, and an approximately 20% ineligibility rate. The high proportion of cases submitted in MCSS as MDS-U that were re-classifiable into specific MDS subtypes following central review suggests a possible misapplication of this MDS category in a way not intended by the 2008 WHO guidelines. The additional classification of t-MDS by our central review process suggests that this subtype is likely underestimated by cancer registries. Assessment of therapeutic implications will be important to determine if these variabilities are consequential. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 3841 Introduction: The International Prognostic Scoring System (IPSS) has recently been revised (IPSS-R) to capture more inclusive cytogenetic characterization, more stringent blast description, and more detailed cytopenia assignments. To validate the IPSS-R in a prospective cohort of patients, we compared IPSS and IPSS-R categorization within a group of newly diagnosed MDS patients in a prospective population-based epidemiologic study in Minnesota. Methods: We identified all newly diagnosed MDS cases in Minnesota between the ages of 20 and 85 years from April 1, 2010 to April 2012. Our process includes rapid case identification by the Minnesota Cancer Surveillance System (MCSS), patient contact and enrollment, central medical review including: 1) independent review by two hematopathologists to confirm diagnosis and WHO subclassification; 2) independent cytogeneticist's review for classification as defined by IPSS and IPSS-R; and 3) medical chart review with prospective calculation of IPSS, IPSS-R, and WPSS by a an oncologist. Results: Classification of the 128 patients by IPSS versus IPSS-R is shown (Table) Kendall's Tau = 0.77 In this comparative classification, IPSS-R scoring refined the MDS prognostic risk groups. Low IPSS remained low risk in the IPSS-R spanning the Very Low and Low groups, while all high risk IPSS remained in the Very High risk group in the IPSS-R. However, those in the INT-1 and INT-2 IPSS categories were inconsistently reclassified in the IPSS-R. INT-1 IPSS spanned from Very Low to High and INT-2 IPSS spanned from Intermediate to Very High in the IPSS-R. While reclassification of this prospective cohort resembles results in the IPSS-R reports, ongoing follow-up will be needed to determine if the survival and AML progression measures are reproducible. Conclusion: Until molecular data are available to refine future prognostic scoring systems, the IPSS-R enhances our prognostic risk stratification abilities and is applicable to the general MDS population. As treatment decisions are based on this initial prognostic risk assessment, the more diverse differentiation of risk within the IPSS-R will directly refine prognosis and impact decisions on therapy. Disclosures: Miller: Celgene: Membership on an entity's Board of Directors or advisory committees; Coronado Bioscience: Membership on an entity's Board of Directors or advisory committees.

Benzene exposure is one of the few well‐established risk factors for myeloid malignancy. Exposure to other chemicals has been inconsistently associated with hematologic malignancies. We evaluated occupational and residential chemical exposures as risk factors for acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) using population‐based data. AML and MDS cases were identified by the Minnesota Cancer Surveillance System. Controls were identified through the Minnesota driver's license/identification card list. Chemical exposures were measured by self‐report. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CI). We included 265 MDS cases, 420 AML cases and 1388 controls. We observed significant associations between both MDS and AML and benzene (OR = 1.77, 95% CI 1.19, 2.63 and OR = 2.10, 95% CI 1.35, 3.28, respectively) and vinyl chlorides (OR = 2.05, 95% CI 1.15, 3.63 and OR = 2.81, 95% CI 1.14, 6.92). Exposure to soot, creosote, inks, dyes and tanning solutions and coal dust were associated with AML (range ORs = 2.68–4.03), while no association was seen between these exposures and MDS (range ORs = 0.57–1.68). Pesticides and agricultural chemicals were not significantly associated with AML or MDS. Similar results were observed in analyses stratified by sex. In addition to providing risk estimates for benzene from a population‐based sample, we also identified a number of other occupational and residential chemicals that were significantly associated with AML; however, all exposures were reported by only a small percentage of cases (≤10%). While chemical exposures play a clear role in the etiology of myeloid malignancy, these exposures do not account for the majority of cases.