Ketterling, Rhett

Introduction: Angiocentric gliomas (ACG) are low grade, epileptogenic tumors with a good prognosis. Only one case of ACG with anaplastic features has been described. We report two examples. Methods: Routinely processed tissue used for histology, immunochemistry and FISH analysis. Results: Case1: 38‐man Two years chronic, worsening seizures. Resection frontal lobe primary (1995) and recurrence (2007). Case 2: 79 woman. Memory deficit and expressive dysphasia. Enhancing temporal lobe mass. Conclusions: The spectrum of ACG includes ependymal and astrocytic features. High grade transformation is uncommon and evidenced by histology, MIB‐1 elevation, strong p53 reactivity and a complex karyotype. The behavior of anaplstic ACG remains to be determined.

Abstract H-MM affects about 40–50% of patients, and a similar proportion of MGUS/SMM. The genetic evolution of the disease and the clinical implications of the co-existence of 13q- or t(14q32) are unknown. We conducted a global survey of genetic abnormalities in H-MM in order to describe genetic evolution pathways. H-MM cases from the Mitelman cancer genetic database were combined with cases from the Mayo Clinic MM genetic database. All abnormalities (regional/whole chromosome gains/losses, breakpoints and translocations) were plotted against a 344-chromosome band profile created in a matrix format, and the number of genetic abnormalities per tumor (NAPT) logged. The abnormalities present in more than 5% of tumors were considered recurrent and each karyotype was scored for the presence or absence of each of the recurrent abnormalities. To investigate the temporal pattern of acquisition of genetic abnormalities, all tumors with a given abnormality were selected and the distributions of NAPT plotted. The modes of these distributions were used as a value of ‘lateness’, referred to as time of occurrence (TO). The impact of co-existence of 13q- and t(14q32) on progression free survival (PFS) and overall survival (OS) in H-MM was determined for MM patients entered into an Eastern Cooperative Oncology Group chemotherapy trial. Four hundred and sixty-nine H-MM patients were included in the karyotypic analysis. The median chromosome number was 53 (range 48–74) and the median NAPT was 10 (range 1–25). The distribution of NAPT revealed a normal distribution, suggesting an obligatory acquisition of a given number of genetic abnormalities. The most common abnormalities were trisomies of chromosomes 3,5,7,9,11,15,19 and 21 affecting a third or more of the patients. Deletions and abnormalities of even-numbered chromosomes occur in 20% or less of patients. None of the more than 300 specific translocations detected were recurrent. However, 5 translocation breakpoints were recurrent including 14q32, 8q24 and 11q13. TO analysis suggest that for H-MM, the trisomies are early genetic events, translocations occur midway and deletions tend to be later events. Amongst the trisomies, correlation analysis does not suggest a particular order of acquisition. Clustering analysis using principal component analysis suggests that in H-MM, IgH translocations are secondary events associated with disease evolution rather than defining unique biological entities. Consistent with this, survival of H-MM patients is not affected by 13q- status but is negatively impacted by the presence of t(14q32) especially those with unknown partners (p<0.05). The data presented suggest that H-MM fit a proposed aneuploid model of cancer due to auto-catalytic chromosome reassortment (Duesberg et al Cell Cycle2003:2:202–210). The presence of tumor specific trisomies and the apparent similar phenotype induced by various combinations of trisomies are consistent with this model.

Abstract Background: Primary systemic amyloidosis is an uncommon plasma cell dyscrasia characterized by organ deposition of immunoglobulin light or heavy chain fragments. It is related to the other plasma cell dyscrasias such as multiple myeloma and monoclonal gammopathy of undetermined significance. cIg-FISH on bone marrow plasma cells has become well established in the initial evaluation of myeloma as the t(4;14), t(14;16),13q-, and the 17p- abnormality are of major prognostic value. The corresponding data does not exist in amyloidosis, as there are only three small studies published to date. Methods: Using a prospectively held dysproteinemia database, we reviewed all cases of amyloidosis seen at our institution who had cIg-FISH or cytogenetics performed as part of their routine clinical testing. Three hundred thirty nine patients were identified with amyloidosis and cytogenetic testing. Of these 69 had cIg-FISH testing results. cIg-FISH was performed with fluorescent-tagged antibodies to kappa/lambda immunoglobulin and FISH probes corresponding to the following anomalies: trisomies 3, 7, 9 and 15; del17p/-17; -13/del13q; 14q32 split; and t(11;14). CCND1/IGH. If an IGH rearrangement was detected that did not involve CCNDI, we also evaluated t(4;14) or IGH/FGFR3 and t(14;16) or IGH/c-MAF. These probes constitute the standard screening panel used in MM at our institution. Results: The study population had a median age of 61 years with a male to female ratio of 1.6:1. Median follow up time was 13.5 months. By conventional cytogenetics, 88% of patients had no detectable abnormality. In contrast, only 33% were normal by cIg-FISH. The abnormalities demonstrated were 28% 13-/del13q, 42% IgH translocation, 33% t(11;14), and 3% t(14;16). No patients had a -17/del 17p- or t(4;14). Nine patients had del13q/-13 with an IgH translocation, with 7 of these having t(11;14). Both t(14;16) patients had del 13q. A trend towards increased mortality was seen in patient with any abnormality (p=0.11), but this could not be demonstrated for any single abnormality, likely due to lack of statistical power. There was no correlation between renal involvement or cardiac involvement and cIg-FISH results. Conclusion: The majority of chromosomal abnormalities in amyloidosis are undetected by conventional cytogenetics. With further study, chromosomal abnormalities may carry the same prognostic value in amyloidosis that they currently enjoy in myeloma. This effect may be independent of currently recognized risk factors. Chromosomal abnormalities in Amyloidosis as detected by cIg-FISH Abnormality Amyloidosis % (n=69) Normal 33(23) −13/del13q 28(19) IgH Abnormality 42(29) t(4;14) 0(0) t(11;14) 33(23) t(14;16) 3(2) del 17 0(0) Other 3(2)

6614 Background: CDKN2A locus on chromosome 9p21 is implicated in altered molecular pathways leading to leukemogenesis as a tumor suppressor by inhibiting the proliferative kinases CDK4/CDK6 and blocking the cell-cycle division during G1/S phase. Deletion of CDKN2A locus is frequently seen in ALL, although prognostic significance remains unclear. Methods: Retrospective chart review at Mayo Clinic between 8/2005-11/2011 was performed on adult B-ALL patients (pts) who underwent fluorescent in situ hybridization (FISH) studies at diagnosis. Survival estimate was calculated using Kaplan-Meier statistics. Event-free survival (EFS) was defined as time between diagnosis and induction failure, relapse, or death, while overall survival (OS) as time between diagnosis and death Results: Out of 27 pts who had FISH studies for CDKN2A, 15 (56%) pts had CDKN2A deletions (8 homozygous/7 hemizygous), while 12 (44%) pts had diploid cytogenetics (none had abnormalities of MLL, bcr/abl fusion or CDKN2A deletion on FISH). There was no significant difference in median age, gender, WBC, hemoglobin, platelet count, LDH or complete remission (CR) rate (p=0.924) between the two groups. CDKN2A-deleted pts had higher circulating blasts (34% vs 16%, p=0.017). Of 13 CDKN2A-deleted pts, chromosome 9p was intact in 9 (69%) pts using routine cytogenetics. In the CDKN2A-deleted group, allogeneic stem cell transplant (ASCT) was performed in 7 (47%) pts at first CR and 1 at second CR. Four of 15 (27%) CDKN2A-deleted pts also had bcr/abl fusion. Five-year EFS was poorer in CDKN2A-deleted pts compared to normal FISH group (22% vs 60%, p=0.042), while 5-year OS was 72% vs 60% (p=0.308), respectively. Excluding the 4 bcr/abl fusion pts, 5-year EFS was still statistically significant (p=0.008). In the CDKN2A deleted group, both 5-yr EFS (80% vs 0%, p=0.006) and OS (100% vs 42%, p=0.016) were significantly superior in pts who received ASCT. Conclusions: CDKN2A deletions predict earlier relapse in pts with B-ALL. Majority of 9p abnormalities were only found by FISH testing and missed by conventional cytogenetics. In CDKN2A deleted pts, ASCT gave overall survival advantage. Further investigation through larger cohorts of pts is needed to validate these findings.

7077 Background: MDS includes a heterogenous group of hematopoietic stem cell malignancies characterized by ineffective hematopoiesis and recurring clonal cytogenetic abnormalities with poorly understood functional consequences. Interstitial deletion of chromosome 5 including band q31 is of special interest currently because of the striking effectiveness of lenalidomide therapy in patients with this lesion. Methods: We reviewed the clinical and pathological features of 175 consecutive patients with 5q31 deletions whose final diagnosis was MDS from 1996 to 2006. Patients not meeting the definition of a clonal chromosomal anomaly (i.e., only 1 abnormal metaphase) and those with >20% marrow blasts (now defined as AML) were excluded. Results: The median age at diagnosis was 73 years old (range 8–91). The 5 most common MDS subtypes (WHO classification) were RAEB2 (38 cases), 5q- syndrome (33 cases), MDS NOS (26 cases), RCMD (22 cases), and RAEB1 (20 cases). Chromosomal breakpoints encountered most frequently were q13q33 (86 cases), q15q33 (38 cases), and q22q33 (14 cases). The 5q deletion was present as a sole cytogenetic anomaly in 31%, was present along with one other anomaly in 10%, and was part of complex karyotype in 59%. Median time to death from confirmation of diagnosis at our institution was only 7.2 months (range 1 month –1.8 years). Survival was greatest in those diagnosed with 5q- syndrome, but the median survival time of 1.8 years (p=0.001) was lower than reported in other series. Survival was also superior in women (7.9 months, versus 6.6 months for men, p=0.05) and those with non-complex cytogenetics (1.44 versus 0.41 years, p<0.001). Poorer survival was noted in those with prior chemotherapy (median 6.6 months versus 7.6 months, p=0.01). Differences in breakpoint (p=0.55) and number of metaphases involved with the 5q abnormality (p=0.08) did not have a statistically significant impact on survival. Conclusion: Classic 5q- syndrome as defined by the WHO represents only a minority of MDS patients with interstitial 5q deletions. Although the short survival in our series compared with previous reports may be due in part to referral bias, it is also possible that deletions of chromosome 5q are less benign than previously suspected. No significant financial relationships to disclose.

Abstract Background : Current prognostication in primary myelofibrosis (PMF) utilizes international prognostic scoring systems that rely on clinical parameters that are sensitive to day-to-day variations and subjective interpretation. Recent studies in PMF have disclosed important prognostic information attached to additional cytogenetic details (Blood. 2011;118:4595) and somatic mutations, including CALR and ASXL1 (NEJM. 2013;369:2379; Leukemia. 2013;27:1861). Methods : PMF diagnosis and definition of blast transformation (BT) were according to World Health Organization criteria (Blood. 2009;114:937). Cytogenetic analysis and reporting was done according to the International System for Human Cytogenetic Nomenclature (Cytogenetic and genome research. 2013. Prepublished on 2013/07/03 as DOI 10.1159/000353118). Previously published methods were used for analyses of CALR, JAK2, MPL and other prognostically-relevant mutations, including ASXL1, SRSF2, EZH2 and IDH(Leukemia. 2014;28:1472). Results : The training set included 964 Mayo Clinic patients (median age 65 years; 62% males) in whom informative karyotype or mutation information was available; cytogenetic information was available in 903 (94%) cases, JAK2/CALR/MPL mutational status in 532 (55%), ASXL1 in 425 (44%), SRSF2 in 434 (45%), IDH1/2 in 376 (39%) and EZH2 in 268 (28%). DIPSS-plus (JCO. 2011;29:392) risk distribution was high in 37% of patients, intermediate-2 in 37%, intermediate-1 in 15% and low in 11%. We used a revised risk stratification for cytogenetics (see accompanying ASH 2014 abstract) to distinguish four distinct cytogenetic risk categories: very high (monosomal karyotype, inv(3), i(17q), -7/7q-, 11q or 12p abnormalities; n=67), high (complex non-monosomal, two abnormalities not included in very high risk category, 5q-, +8, other autosomal trisomies except +9, and other sole abnormalities not included in other risk categories; n=164), intermediate (sole abnormalities of 20q-, 1q+ or any other sole translocation, and -Y or other sex chromosome abnormality; n=133) and low (normal or sole abnormalities of 13q- or +9; n=539). Mutational frequencies were 58% for JAK2, 25% CALR, 7% MPL, 36% ASXL1, 11% SRSF2, 5% IDH1/2 and 6% EZH2. The 131 cases with CALR mutations were further subclassified into two prognostically different groups: type 1/type 1-like (n=110) and type 2/type 2-like (n=21) (see accompanying ASH 2014 abstract). At a median follow-up time of 4.2 years for patients who are alive, 664 (69%) deaths and 70 BT (7%) were recorded. Age-adjusted multivariable analysis that included cytogenetic and mutational risk groups disclosed the following as independent predictors of shortened survival: very high risk karyotype (HR 4.2; 3 points), high risk karyotype (HR 1.9; 1 point), triple-negative (HR 2.8; 2 points), JAK2 (HR 3.1; 2 points), MPL (HR 3.1; 2 points), type 2/type 2-like CALR (HR 3.6; 2 points), ASXL1 (HR 1.9; 1 points) and SRSF2 (HR 1.9; 1 point); EZH2 (p=0.24) and IDH1/2 (p=0.68) and intermediate risk karyotype (p=0.87) were not significant. The above-mentioned significant variables and age demarcated at 60 years (2 points), were subsequently used to develop an HR-derived, genetics-based prognostic scoring system (GPSS) for 369 patients who were fully informative for both karyotype and all significant mutations: low risk (0 points; n=31), intermediate-1 (1 or 2 points; n=90), intermediate-2 (3 or 4 points; n=133) and high (5 or more points; n=115); the corresponding median survivals were >17, 9 (HR 4.7, 95% CI 1.7-13.0), 5 (HR 10.7, 95% CI 3.9-29.3) and 2.2 (HR 29.2, 95% CI 10.6-80.0) years (Figure 1). High risk GPSS was also associated with higher BT rate (HR 7.4, 95% CI 2.1-26.3). The prognostic distinction between high/intermediate-2 and low/intermediate-1 risk GPSS, in terms of both overall (median 5 vs 26.4 years; HR 7.1, 95% CI 3.3-14.9) and leukemia-free survival (median 11.6 years vs not reached; HR 9.4, 95% CI 2.2-41.0) was validated in an independent cohort of 183 patients from the University of Florence (Figure 2). Conclusions : The current study demonstrates the feasibility of genetics-based prognostic models in PMF that rely on objective parameters that are amenable to further refinement as new genetic information becomes available. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Abstract Background: The prognostic significance of cytogenetic abnormalities in chronic myelomonocytic leukemia (CMML) was recently revisited (AJH, 89; 813-818, 2014 and Blood April, 2013). Using a large Mayo Clinic-French Consortium database, we analyzed the molecular and prognostic correlates of cytogenetic abnormalities in CMML. Methods: CMML diagnosis was according to World Health Organization criteria. Cytogenetic analysis and reporting was done according to the International System for Human Cytogenetic Nomenclature. Statistical analyses considered clinical and laboratory parameters obtained at time of cytogenetic studies. Results: Spectrum and frequency of cytogenetic abnormalities: A total of 409 patients participated in this study including, 268 (66%) from the Mayo Clinic and 141 (34%) from the French CMML consortium. Of these, 396 (97%) had ≥20 metaphases and 13 (3%) had ten to 19, analyzed. One hundred and fifteen (30%) patients displayed an abnormal karyotype, including 82 (71%) sole, 20 (17%) two and 13 (11%) complex abnormalities. The most common abnormalities were; +8 (23%), -Y (20%), -7/7q- (14%), 20q- (8%), +21 (8%) and der (3q) (8%). Other cytogenetic abnormalities included 5q-, 12p-, 13q- and i(17q), present at a much lower frequency (0.9-4%). Phenotypic correlates: Abnormal vs normal karyotype was associated with older age (p=0.03), hemoglobin<10 g/dL (p=0.0009), white blood cell count (WBC) >15 x 109/L (p=0.02), absolute neutrophil count (ANC) >10 x 109/L (p=0.03), absolute lymphocyte count (ALC) >2.5 x109/L ( p=0.04), peripheral blood (PB) blast ≥1% (p<0.0001), bone marrow (BM) blast ≥10% (p<0.0001) and circulating immature myeloid cells (IMC) (p=0.0003). +8 (p=0.01), +21 (p=0.03) and der (3q) (p=0.03) were associated with hemoglobin <10 g/dL. -Y was associated with older age (p=0.04), lower PB (p=0.04) and BM (p=0.02) blasts. -7/7q was associated with leukocytosis (p=0.005), neutrophilia (p=0.04), and higher PB blasts (p=0.004). 20q- was associated with thrombocytopenia (p=0.04). Molecular correlates: ASXL1 mutations were associated with abnormal karyotype (p=0.04) and SRSF2 with normal karyotype (p=0.02). In comparison to other abnormal karyotypes, the incidence of ASXL1 mutations was lower in –Y (P=0.04) and der(3q) (p=0.03). U2AF1 mutations were associated with monosomal karyotype (p=0.03) and SF3B1 with der (3q) (p<0.0001). Prognostic relevance : Median follow-up was 1.8 years with 244 (60%) deaths and 79 leukemic transformations (19%). A step-wise survival analysis resulted in three distinct cytogenetic risk categories (Figure 1): high (complex and monosomal karyotype), intermediate (all abnormalities not in high or low risk) and low (normal, sole -Y and sole der (3q)); the corresponding median survivals were 0.2 (HR 8.1, 95% CI 4.6-14.2), 1.7 (HR 1.7, 95% CI 1.2-2.3). In multivariable analysis, the particular cytogenetic risk stratification remained significant in the context of Mayo molecular model (p<0.0001), MDAPS (p<0.0001), and the GFM risk model (P<0.0001). The Mayo-French cytogenetic risk model was also effective in predicting leukemic transformation with HR of 10.9 (95% CI 4.2-27.8) for high and 2.2 (95% CI 1.3-3.7) for intermediate risk groups. Conclusion: Cytogenetic abnormalities are seen in approximately 30% of patients with CMML and display significant associations with certain molecular and phenotypic characteristics. We describe a novel cytogenetic prognostic model for both over-all and leukemia free survival in CMML. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 4013 Background: In recent years, azacytidine (AZA) has become the standard of treatment for high risk myelodysplasia (MDS). The approved schedule of AZA uses a 75mg/m2/d s.c. regimen for 7 days based on the CALGB-9221 (Silverman, JCO 2002) and the AZA-001 studies (Fenaux, Lancet Oncol 2009). The clinical response rates after AZA have been extensively presented but there is only limited data on the rates of cytogenetic response (CyR). Based on the review of the literature, there are no specific cytogenetic data published on prospective trials. Methods: We based our analysis on a randomized phase 2 study from the US Leukemia Intergroup (E1905 study, NCT00313586) testing 10 days of AZA (50mg/m2/d s.c.) vs 10 days of AZA+ the histone deacetylase inhibitor entinostat (4 mg/m2/d PO days 3 and day 10). MDS, CMML, and AML with myelodysplasia-related changes were included. This analysis includes all patients with cytogenetic abnormalities (at baseline or acquired following treatment) with available cytogenetic follow-up (cycle 6). Of 150 patients, 70 demonstrated baseline cytogenetic abnormalities. To date, forty patients (27 MDS and 13 AML) were evaluable for both time points. Karyotypes were performed at local laboratories, and reviewed centrally (RPK and GH). Cytogenetic response was assessed using IWG 2000 (Cheson et al, Blood 2000) criteria. Results: The clinical response rate (CR+PR+ trilineage HI) according to IPSS cytogenetic risk stratification were of 20%, 33%, and 35% for favorable, intermediate and poor cytogenetic risk groups respectively (p=NS). Patients with Chr 7 abnormalities (i.e. -7 or -7q, n=18) had a response rate of 28% including 17% CR. Of patients with complete cytogenetic data, the rate of overall CyR was 52% (n=21): 22% (n=9) complete CyR, 30% (n=12) partial CyR. This represents a complete CyR of 13% and a partial CyR of 23% as a proportion of all treated patients with initial cytogenetic abnormalities (including those who did not receive six cycles of therapy). To date, confirmatory FISH analyses were available for 4 patients with CyR (2 CCyR and 2 PCyR). All four had complete clearance of their cytogenetic clone. Among the cytogenetic responders, 15 had MDS and 6 had AML (p=NS). CyR did not differ between the two treatment arms. CyR and clinical response were highly correlated (p<0.001): all patients with complete CyR and 7/10 partial CyR had a clinical CR. Only 3 patients (1 CCyR and 2 PCyR) had a CyR without associated clinical response. Among 8 patients with cytogenetic progression, 3 pts showed increased frequency of a known aberration and 5 showed new or additional aberration including 2 cases involving Chr7. 65 AZA-treated patients from AZA001 had comparable cytogenetic results available. Only 3 patients experienced complete CyR 4.6% with 33.8% partial CyR (n=22). In contrast, the reported rate of clinical response was similar in the two studies. Complete CyR were more frequent in the E1905 10 days AZA schedule compared to the 7 days AZA schedule (p=0.007). There was no difference in overall CyR between the two studies. Conclusions: Both the standard AZA schedule and the 10 day schedule administered on E1905 lead to high rates of cytogenetic response. The novel schedule explored in E1905 demonstrated a particularly high rate of complete CyR (22%) with complete clearance of abnormal clone by FISH in 4 tested patients. Further prospective comparison of different AZA schedules will be needed to confirm this higher rate of complete CyR and determine its clinical significance. Disclosures: Beach: Celgene: Employment. Gore:Celgene: Consultancy, Research Funding, stock options; Syndax: Consultancy.

Abstract Background: Most patients with chronic myelomonocytic leukemia (CMML) are elderly and age >65 years is an adverse prognostic factor (JCO 2013;31:2428). Our objective in the current study was to examine risk factors for survival and treatment outcome in younger patients (age ≤65 years), with emphasis on molecular and cytogenetic markers. Methods: DNA analysis for SRSF2, SF3B1, U2AF1, ASXL1 and SETBP1 mutations was carried out on specimens obtained at time of diagnosis. We used both conventional and revised (see accompanying ASH 2014 abstract) cytogenetic risk models to query their application in the current study population. Treatment data included outcome of allogeneic stem cell transplant (HCT) and treatment with hypomethylating agents (HMA), including azacitidine (AZA) and decitabine (DAC). Results: Survival: 259 patients (median age 59 years, range 18-65; 75% males) with WHO-defined CMML and age≤ 65 years were included in the study: 108 from the French consortium, 81 Mayo Clinic, 47 Moffitt Cancer Center and 23 University of Milan; 217 (84%) patients had CMML-1 and the remainder CMML-2. At a median follow-up of 26 months, 124 (48%) deaths and 79 (31 %) leukemic transformations were documented. Mutational frequencies were 34% (61/178) for ASXL1, 45% (74/165) for SRSF2, and 4% (7/168) for SETBP1. Cytogenetic data was available in 248 of 259 study patients; 56 (23%) patients displayed abnormal karyotype and the revised cytogenetic risk designations included 196 (80%) low, 29 (12%) intermediate, and 23 (9%) high. In univariate analysis, lower hemoglobin (p<0.0001), higher WBC (p=0.005), higher monocyte count (AMC) (P=0.004), lower platelet count (p=0.004), presence of circulating immature myeloid cells (IMC) (p=0.004), presence of circulating blasts (p<0.0001), bone marrow (BM) blasts ≥10% (p=0.005), WHO morphological subtype (p=0.0003), Spanish cytogenetic risk stratification (p=0.0002), revised Mayo cytogenetic risk stratification (p<0.0001), SRSF2 (p=0.03) and ASXL1 (p=0.03) mutational status predicted shortened survival. In multivariable analysis, lower hemoglobin (p<0.0002), presence of circulating blasts (p<0.0001), SRSF2 (p=0.03) and ASXL1mutational status (p=0.04) retained their negative prognostic impact. A similar analysis identified circulating IMC (p<0.0001), presence of circulating blasts (p<0.0001), and BM blast % (p=0.0002) as predictors of blast transformation (BT). Response to hypomethylating agents: Seventy-two (28%) patients received HMA (AZA-46, DAC-26, both-6). In the AZA group, median number of cycles was 5 (range; 1-44), median duration of therapy 5 months (range;1-59) with 4 (6%) receiving DAC on progression and 26 (42%) proceeding with HCT. Over-all response rate (ORR) was 25% (6/24) and included complete response (CR) in 2 (8%) patients, partial response (PR) in 2 (8%) and hematological improvement in 2 (8%). In the DAC group, median number of cycles was 6 (2-25), median duration of therapy 5 months (range;1-49), with 2 (8%) receiving AZA on progression; ORR was 50% (7/14) and included CR in 4 (29%) patients, PR in 1 (7%) and HI in 2 (14%). ASXL1 (p=0.4), SRSF2 (p=0.7) mutational status or karyotype (p=0.5 for Spanish and 0.3 for revised Mayo) did not correlate with response to HMA. Allogeneic stem cell transplant: 50 patients underwent HCT. Conditioning regimen was reported in 41 patients and included myeloablative (MA) in 14 (34%) (median age 51 years, 27-62) and reduced intensity (RIC) in 27 (66%) (median age 48 years, 18-65). Donor source was documented in 40 patients and included matched related in 19 (48%), matched unrelated in 12 (30%), mismatched unrelated in 4, haploidentical in 2 and umbilical cord transplant in one. 27 (63%) patients had chronic GVHD (50% in MA group and 80% in the RIC group). Among 40 evaluable patients, 23 (57%) achieved CR, 8 (21%) relapsed and 8 (21%) died from transplant-related complications. ASXL1 (p=0.9), SRSF2 (p=0.5) mutational status or karyotype (p=0.2 for Spanish and 0.3 for revised Mayo) did not affect transplant outcome. Conclusions: Survival in young CMML patients is poor and even worse in the presence of SRSF2 or ASXL1 mutations, anemia or circulating blasts. Treatment outcome was more impressive with transplant than it was with HMA and neither was influenced by karyotype or ASXL1/SRSF2 mutational status. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1038 The relationships of inherent disease-related characteristics and of treatment to the nature of APL cell clones that emerge at disease relapse are poorly understood. We studied these relationships in 45 patients who relapsed after ATRA/chemotherapy treatment on the non-arsenic trixoxide arm of intergroup phase III trial C9710 (Powell, et al. Blood, Epub). Four variably-expressed APL cell clonal markers were assessed: PML-RARA ligand binding domain mutations (LBD-M), FLT3 internal tandem duplication mutations (ITD), FLT3 receptor tyrosine kinase mutations (D835; RTK-M) and additional chromosome abnormalities (ACA), i.e., in addition to the hallmark t(15;17). The methods for mutation analysis of PML-RARA and FLT3 have been reported and were RNA transcript-initiated supplemented by selected quantitative FLT3 mutation analyses initiated from DNA. Karyotype data were derived by standard cytogenetic methods. Four patients were excluded from analysis because the sample level of PML-RARA, as determined by quantitative RT-PCR, was insufficient to exclude possible false-negative mutation results. In 41 evaluable patients, the marker incidences were: LBD-M, 44%; ITD, 37%; RTK-M, 12%; ACA (22 tested), 59%. At presentation, the corresponding incidences were: LBD-M, 0% (by high-sensitivity testing a minor subclone of the relapse mutation was found in 2/7 patients tested); ITD, 43% (37 tested); RTK-M, 22% (37 tested); ACA, 24% (34 tested). The low frequency of RTK-M impeded further analysis. The other markers, using relapse determinations, were assessed for potential associations between the markers and with the following parameters: age, sex, presenting WBC count, PML-RARA type, time to relapse, relapse on or off ATRA treatment (on = taking or within 30 days of discontinuing) and post-relapse survival. The most essential positive findings are summarized below:Association of Marker with Parameter or Other MarkerCases with ParameterCases without Parameterp-valuePretreatment parameters: LBD-M with WBC count < 5,000/uL12/18 (67%)7/23 (30%)0.030 ITD with WBC count >10,000/uL10/15 (67%)5/26 (19%)0.006 ITD with S-form PML-RARA15/15 (100%)10/26 (38%)<0.0001Relapse parameters: ITD with lack of ACA1/7 (14%)12/15 (80%)0.007 LBD with relapse On-ATRA11/18 (61%)7/23 (30%)0.064 Off-ATRA only: LBD with lack of ITD0/7 (0%)9/16 (56%)0.019 The results confirm reports, which tested pretreatment samples, of a strong association between FLT3ITD mutations present at relapse and high WBC count and S-form PML-RARA. At relapse, there was, also, divergent selection of ITD-harboring vs ACA-harboring clones. LBD-M occurred more frequently in patients with low presenting WBC counts. They, also, occurred in patients who relapsed while on ATRA, consistent with an ATRA selective role for clones harboring LBD mutations. A significant segregation of patients with LBD-M or ITD was observed after relapse off ATRA treatment (p = 0.019), while no segregation was observed in overall relapse patients (p = 0.346) or after relapse on ATRA (p = 0.316). In 2 patients who relapsed on ATRA, quantitative analysis indicated that LBD-M and ITD mutations must be present in the same APL cell clone. There were no significant survival differences related to any clonal marker (post-relapse survival = 66%). Although the small number of cases is cautionary, the overall data suggest that LBD-M may have an overriding, dominant APL clone selection role in relapse that occurs on ATRA therapy. Other inherent clinicopathologic characteristics of APL may predispose to divergent molecular pathways of disease progression and relapse in patients alternatively harboring clones with LBD-M or ITD after the termination of ATRA selection pressure. Disclosures: No relevant conflicts of interest to declare.