Greipp, Patricia T.

Abstract Introduction: IgM light chain amyloidosis (AL) is a rare complication of IgM associated disorders, with very limited data on biology and outcomes. Our study compares the clinical characteristics, laboratory findings and outcomes in a large cohort of patients with IgM vs. non-IgM AL to delineate the underlying disease biology of this entity. Methods: Patients with newly diagnosed AL (2006-15) were identified from a prospectively maintained institutional database and grouped by IgM heavy chain. Bone marrow (BM) morphology was reviewed by an expert hematopathologist (RLK). FISH testing included probes for t(11;14) and trisomies of odd numbered chromosomes. MYD88L265P testing was carried out by allele specific PCR and CXCR4WHIM mutation testing was performed by bridged nucleic acid (BNA)-enhanced Sanger sequencing. Results: Patients with IgM AL comprised 6.6% (75/1128) of the study cohort. Baseline characteristics are listed in Table 1. IgM AL patients were older and had a higher proportion of males. They had less frequent cardiac involvement (60 vs. 75%) and less frequent involvement of > 1 organ. Light chain burden was lower in this group (dFLC 12.5 vs. 22.7 mg/dL), while there was no difference in BM clonal cell percentage (10% each). Morphology: BM morphology in 71 patients with IgM AL revealed a pure plasma cell disorder (PPCD type) in 25% (n=18); low-grade B-cell lymphoma (LGBCL) with plasmacytic features (LPL type) in 62% (n=44) [well defined LPL: 38% (n=27), LGBCL with plasmacytic features: 24% (n=17)]; LGBCL, other: 6% (n=4). In the remaining 7%, three patients had other diagnoses and no BM disease in two patients. Median clonal cell % in LPL vs. PPCD type IgM AL was 20% vs. 5%, p<0.001. Genetics: In patients with IgM AL vs. non-IgM AL, t(11;14) was present in 27% vs. 49%, p=0.009 and trisomies in 9% vs. 24% of patients, p=0.06, respectively. In the IgM AL cohort, MYD88 mutation was seen in 56% (23/41) & CXCR4 mutation in 15% (5/34; S388 type: 3, other: 2) of patients. Importantly, MYD88 and CXCR4 mutations were found only in patients with LPL morphology, while t(11;14) was found only in the PPCD morphology group. There were no patients with both t(11;14) and MYD88 abnormalities (N=26 for both tested). Mutations seen in the LPL vs. PPCD type IgM AL were: MYD88, 88% (22/25) vs. 0% (0/14), p<0.001 and CXCR4, 26% (5/19) vs. 0% (0/13), p=0.02. Conversely, t(11;14) was seen in 0% (0/18) in LPL type vs. 60% (9/15) in PPCD type IgM AL, p <0.001. Treatment details were known in 63 patients with IgM AL; rituximab-based: 21 (33%), bortezomib/alkylator: 16 (25%), transplant 17 (27%), steroids: one and no treatment: 8 (13%). Treatment in IgM AL LPL type (n=36) was: rituximab based: 16 (44%),bortezomib/alkylator: 5 (14%), transplant: 10 (28%) and none: 5 (14%). In PPCD type [n=17), treatment was rituximab based: 2 (12%), bortezomib/alkylator: 8 (47%), transplant: 7 (41%). At 6 months, very good partial response or better was observed in 26% (10/39) vs. 41% (270/660) of patients with IgM vs. non-IgM AL, p=0.05. There was no difference in overall survival (OS) when all patients with IgM AL were compared to non-IgM AL (Fig 1a). However, when stratified by early (Stage 1/2) or advanced (stage 3/4) 2012 Mayo stage, patients with IgM AL fared worse (Fig 1b-c). On multivariate analysis, IgM AL was an independent predictor for inferior OS [HR with 95% CI: 1.6 (1.1-2.4), p=0.02] after adjusting for age, Mayo 2012 stage and type of therapy (transplant vs. not). However, when OS was adjusted for 6 month VGPR, there was no difference in OS for IgM AL vs. non IgM AL, p=0.2. In the IgM AL cohort, patients with LPL type IgM AL had inferior OS compared with PPCD type IgM AL, 21 vs. 82 months, p=0.01 (Fig 1d). Conclusions: Patients with IgM AL have distinct clinical and genetic features, with lower rates of cardiac involvement and a lower frequency of t(11;14) or trisomies compared with non-IgM AL. Even though IgM AL is a rare entity, we were able to delineate two distinct sub-types of IgM AL: LPL type and PPCD type, with implications for therapy and outcomes. Along with unique morphologic findings, presence of MYD88 and CXCR mutations was only seen in LPL type IgM AL and t(11;14) in PPCD type IgM AL. Despite lower cardiac involvement, IgM AL was associated with inferior OS outcomes, likely due to lower response rates, particularly in LPL IgM AL group, which had the lowest OS. Therapeutic approaches targeted towards disease biology to achieve deep responses are needed in this disorder. Disclosures Sidana: Janssen: Honoraria. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Kapoor:Takeda: Research Funding; Celgene: Research Funding. Lacy:Celgene: Research Funding. Kumar:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Roche: Research Funding; Novartis: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Gertz:Abbvie: Consultancy; Ionis: Honoraria; spectrum: Consultancy, Honoraria; Apellis: Consultancy; Amgen: Consultancy; Prothena: Honoraria; Teva: Consultancy; Alnylam: Honoraria; celgene: Consultancy; Medscape: Consultancy; janssen: Consultancy; Research to Practice: Consultancy; Physicians Education Resource: Consultancy; annexon: Consultancy.

Abstract Background: Limited data exist regarding histological transformation in patients with Waldenström macroglobulinemia (WM). In this study, we present the disease characteristics, outcomes and risk factors for histological transformation in WM. Methods: Patients with WM seen at Mayo Clinic, Rochester, MN between January 1996 and December 2017 were included. Patients with aggressive non-Hodgkin lymphoma in the setting of WM were considered to have transformation. Univariate analysis for comparing baseline characteristics of transformed versus non-transformed WM was performed using Wilcoxon, Fisher's exact and Chi square tests, as appropriate. Multivariate analysis was performed using logistic regression analysis. Cox proportional hazard method was used to assess the impact on time-to-transformation. All time-to-event analyses were calculated by the Kaplan-Meier method. Results: Of 1014 patients with WM, 42 patients (4.1%) developed histological transformation. The median follow-up for the entire cohort was 9.5 years (95% CI: 8.8-10.5 years). The cumulative probability of transformation was 2.3% at 5 years, 5.3% at 10 years and 8.5% at 15 years from diagnosis of WM, respectively. There was no difference in the 5-year cumulative probability of transformation in patients with WM diagnosed between 1996-2000 (2.1%), 2001-2005 (2.9%), 2006-2010 (2.7%) and 2011-2015 (3.8%), p=0.61.The disease characteristics, laboratory parameters and histology at transformation are outlined in Table 1. In patients with DLBCL histology (n=39), Revised-International Prognostic Index was calculable in 28 patients, with 50% (n=14), 46% (n=13) and 4% (n=1) of DLBCL belonging to poor, good and very good risk groups, respectively. For DLBCL histology, 18 patients were classifiable using Hans algorithm into germinal center B-cell (GCB) type (n=3, 17%) and non-GCB type histology (n=15, 83%). The median lines of therapy received prior to transformation for the entire cohort was 2 (range 0-9), with 5 (11%) patients not having received any therapy for WM before transformation. Number of lines of alkylator-based therapy used prior to transformation [median 1 line (range 0-4)] was comparable to that used in patients in whom WM did not occur [median 1, (range 0-6); p=0.78]. The median time-to-transformation from diagnosis of WM was 4.8 years (95% CI: 2.6- 6.8 years). Overall survival (OS) from transformed disease was 3.2 years (95% CI 1.1-3.9 years). The 10-year OS of patients with WM who transformed was lower (46%) compared to patients without transformation (60%) with a trend towards statistical significance (p=0.08), Figure 1. The MYD88L265P mutation status was available in 333 patients in the entire cohort (22/42 pts in the transformed cohort and 311/972 in the non-transformed cohort. Of the 22 patients in the transformed WM cohort, 13 (59%) exhibited MYD88WT genotype and 9 (41%) exhibited MYD88L265P genotype. The risk of transformation was higher in patients with MYD88WT status [Odds ratio 6.3 (95% CI: 2.6-15.5); p<0.0001]. Additionally, serum lactate dehydrogenase (LDH) was higher at diagnosis of WM in patients who transformed, Table 2. On multivariate analysis, MYD88WT status remained an independent predictor of disease transformation [p=0.003; odds ratio 10 (95% CI: 2.1-48)]. On univariate Cox proportional hazard analysis for identifying predictors of time-to-transformation, only MYD88WT mutational status was associated with shorter time-to-transformation with a 5-year transformation rate of 15.5 % for MYD88WT versus 2.6 % with MYDL265P mutated patients [risk ratio 6.2 (95% CI: 2.5-16.4); p<0.0001]. Treatment-related details in the transformed cases were available for 37 (90%) patients; R-CHOP was the most common (41%) frontline therapy for transformation; 33% patients underwent autologous stem cell transplantation for transformed disease during their disease course. Conclusion: Histological transformation is an uncommon event in WM but confers poorer survival. MYD88WT genotype is independently associated with histological transformation a shorter time-to- transformation in patients with WM. Disclosures Ansell: Trillium: Research Funding; Pfizer: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding; Takeda: Research Funding; Celldex: Research Funding; Regeneron: Research Funding; Merck & Co: Research Funding; Bristol-Myers Squibb: Research Funding. Gertz:Apellis: Consultancy; Alnylam: Honoraria; spectrum: Consultancy, Honoraria; janssen: Consultancy; annexon: Consultancy; Prothena: Honoraria; Abbvie: Consultancy; Amgen: Consultancy; celgene: Consultancy; Teva: Consultancy; Medscape: Consultancy; Ionis: Honoraria; Research to Practice: Consultancy; Physicians Education Resource: Consultancy. Dingli:Millennium Takeda: Research Funding; Millennium Takeda: Research Funding; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Lacy:Celgene: Research Funding. Kumar:Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding. Kapoor:Takeda: Research Funding; Celgene: Research Funding.

Abstract Introduction: The revised international prognostic scoring system (IPSS-R) for myelodysplastic syndrome (MDS) is widely accepted and has been validated in multiple studies. Patients with adverse cytogenetics do poorly and that is reflected in this scoring system by having the highest score for cytogenetics; 2 for intermediate, 3 for poor and 4 for very poor. Little is known about the effect of marrow blasts in adverse cytogenetic in the high-grade MDS defined by IPSS-R intermediate (>3), high (>4.5) and very high (>5). The goal is to examine the effect of marrow blast percentage on outcome in patients with adverse cytogenetics that is present in the high-grade MDS. Methods: We performed data collection from the Mayo clinic records for patients with confirmed MDS after obtaining appropriate IRB approval. Patients were divided based on their total IPSS-R score and we extracted high-grade MDS cases with intermediate, high and very-high IPSS-R only. Cytogenetics and baseline CBC were available for analysis. We calculated the survival difference in patients with blasts <5% and patient with blasts of 5% to 19% for every group. Survival estimates were calculated by Kaplan-Meier method and compared by log-rank testing using JMP v.13. Results: Our database had 1300 patients with confirmed MDS, 41% (N=536) are high-grade MDS. From those, the median age was 70 and 70% were males. Median bone marrow blast was 6% (0-19). Baseline hemoglobin is 9.2 g/dL, WBC 2.7, ANC 1.05, and platelets 69. Their cytogenetics were 1% very good, 31% good, 23% intermediate, 16% poor and 29% very poor. The total IPSS-R groups were 39%,31%, and 30% for the intermediate, high, and very-high groups respectively. The overall survival (OS) for the high-grade MDS with marrow blast <5% was 12.3 months and for patients with marrow blasts ≥5% 11.4 months (P=.4). At each high-grade MDS; intermediate, high and very high, there were no statistically significant differences for patients with marrow blasts below or above 5%. In term of risk of progression to AML, patients with blasts ≥5% were at higher risk of progression compared with <5% (25% vs 10% , P<.001), with no statistically significant difference in term of time-to-AML progression. Conclusion: The percentages of bone marrow blasts had no impact on overall survival among patients with high grade MDS. However, patients with ≥5% marrow blasts are at a higher risk for progression to AML. Disclosures Al-Kali: Novartis: Research Funding.

Abstract Background: Folate receptor (FR) is a recently recognized tumor marker that is being investigated for targeted delivery of drugs, imaging of cancer cells, and tumor immunotherapy. The small size of the molecule, simple conjugation chemistry and lack of immunogenicity make folate an ideal candidate for targeted delivery to tumors bearing the FR (Lu Y, Low PS. Folate-mediated delivery of macromolecular anticancer therapeutic agents. Adv Drug Deliv Rev. 2002 Sep 13;54(5):675–93). FR is overexpressed in 90% of ovarian cancers and in other human tumors including endometrial, colorectal, breast, and neuroendocrine carcinomas, it is negatively or only weakly expressed in most normal tissues including some myeloid cells. In view of the above we wished to learn if overexpression of FR by marrow plasma cells (PC) might differentiate MM from MGUS and SMM. Methods: We obtained marrow biopsy sections from 20 patients each with MM, MGUS, or SMM, and 11 normals and stained them by immunohistochemistry using a FR-beta antibody. Expression was graded 0 (negative), 1 (equivocal), 2 (positive) or 3 (strong positive) based on immunohistochemical staining of marrow PC. We recorded the percent PC, percent positive PC, and the staining of other cell types including myeloid, erythroid, lymphocytes, macrophages, megakaryocytes and control tissues. Results: PC of patients with MM positively expressed FR compared to MGUS, SMM and normal PC (p<0.0001) (Figure 1 and 2). Of interest, 6 of 20 SMM patients showed positive expression. Maturing myeloid cells were also positive, acting as internal positive controls. Macrophages were often positive; some endothelial cells were positive; early erythroid precursors were rarely positive; megakaryocytes, maturing erythroid precursors and lymphocytes did not express FR. The chromosomal location of the FOLR gene cluster is 11q13. Gene expression arrays of purified PC failed to show evidence of overexpression of FOLR1, FOLR2, or FOLR3. We are currently performing Western blots to examine levels of protein product of purified PC. Conclusion: Immunohistochemistal studies show differential expression of FR in MM PC compared to absent or equivocal expression in MGUS and normal PC and variable expression in SMM. The data suggest that FR may be used as a diagnostic tumor marker and has implications for development of folate-based tumor imaging, drug delivery, and immunotherapy. Figure Figure Figure Figure

Abstract Abstract 4238 Background Duplication of the long arm of chromosome 1 (1q) is a recurrent finding in hematologic neoplasms. It is most commonly observed as an unbalanced whole arm translocation with chromosome 7, resulting in concurrent deletion of 7q (ISCN as der(1;7)(q10q10)). It is less frequently observed as an unbalanced translocation with a chromosome other than chromosome 7 or as a duplication of only a segment of 1q. The der(1;7) has been described in myelodysplastic syndrome (MDS), and acute myeloid leukemia (AML), and is reportedly less commonly associated with myeloproliferative neoplasms (MPN). The effect of this rearrangement on prognosis is unclear, although it is classified by the International Scoring System (IPSS) as a karyotypic variant of del(7q)/-7 and is thus assigned poor risk. We have initiated a thorough review of all cases of duplication of the long arm of chromosome 1 seen at our institution. Methods After approval from the Institutional Review Board, all cases seen at Mayo Clinic over a 20 year period (1989-2009) were searched for a duplication of the long arm of chromosome 1. The sole exclusion criterion was a complex karyotype (3 or more independent chromosome abnormalities in the clone). Cytogenetic and hematopathology review was done and relevant clinical data were abstracted from the Mayo Clinic record. Survival of MDS patients and MPN patients was determined from time of cytogenetic diagnosis of der(1;7) until death or last contact with the patient, using the Kaplan-Meier method. Results Among 23,375 unique patients at Mayo Clinic with a cytogenetic study for hematologic neoplasm, 229 (0.98%) patients carried a duplication of 1q. Within this group, 99 (0.42%) had duplication of part of 1q, 123 (0.53%) carried a whole arm duplication of 1q, and 7 patients carried an isochromosome 1q (resulting in 4 copies of 1q). The most common karyotype among those with a whole arm duplication of 1q was der(1;7) (n=84), followed by similar whole arm translocations involving chromosomes 9 and 19 (n=7 each) or chromosomes 12, 13, 14, 15, 16, 17, 18, 20, 21, or 22 (n=1 to 6 each). We focused on 65 der(1;7) patients who had adequate hematopathological material that could be reviewed and sub-classified according to WHO criteria. MDS was identified in 30 patients and MPN in 20. MDS (therapy related, RARS, RAEB-1 or 2) was seen in 9 patients (14%), MDS/ refractory cytopenia with multilineage dysplasia (RCMD) in 19 (29%). MDS/Myeloproliferative neoplasm (MPN) in 2 (3%), MPN not otherwise classified in 5 (8%), and MPN / primary myelofibrosis (including 1 post-polycythemic and one post-thromobocythemic) (PMF) in 15 (23%). The bone marrow was apparently normal in 5 patients (8%), CLL was noted in 3 (5%), and 1 each exhibited features of systemic mast cell disease or myeloma. Acute myeloid leukemia (AML) was identified 5 patients (8%). The M:F ratio of the der(1;7) patients was 2.8:1. The median age at occurrence of the der(1;7) was 63 years (range: 13-87 years). All 5 AML patients have died (median survival 9 months). Of the MDS and MPN patients, the median survival was 2.2 and 2.8 years, respectively, from the time of cytogenetic diagnosis. Overall survival was not significantly different between the MDS and MPN group, and they exhibited 30% survival after 5 years (see Figure). Conclusions Duplication of 1q was observed in nearly 1% of the Mayo Clinic patients who had a bone marrow cytogenetic study for a hematologic neoplasm. Among those with a der(1;7), AML was uncommon but MDS and MPN were similar in frequency. Median survival of 2.2 to 2.8 years for the MDS and MPN group justifies assignment to a more favorable group than the current IPSS assignment. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 3538 Background: Cytogenetics detection of common recurring genetic defects by FISH is an important clinical prognostication tool in CLL and is frequently used by clinicians for counseling and risk stratification. Thus, any improvement in FISH technology is a welcome advance in our care for CLL patients. Mayo Clinic CLL FISH analyses are prepared directly from buffy coat samples rather than mononuclear cells or lymphocytes. FISH probes (deletion 6q, 11q, 13q, 17p, +12 & IGH/CCND1) are scored among consecutive nuclei without selection for nuclear morphology (so called clinical scoring). CLL B-cells are observed, microscopically, primarily as round lymphocytes with round nuclei, and we found (ASH 2010, #3606) that the % abnormal nuclei in the CLL round cell population is significantly higher than that of the non-round nuclei population. In 79 of 87 (91%) patients, the % abnormal nuclei was greater in round vs unselected nuclei (mean difference 24%; range 1.5 – 57%). Round nuclei (p = 0.004) correlated better with % B-cells by flow cytometry than either consecutive unselected nuclei (p = 0.046) or the lobed (non-round) nuclei (p = 0.40). Utilizing this “Poor Man's” sorting technique, we proposed that scoring consecutive round nuclei would improve sensitivity of detection of CLL FISH defects in patients, especially those with low B-cell counts. In a retrospective study of Mayo Clinic patients with normal baseline FISH who had a FISH defect in follow-up, we showed that by re-scoring 28 baseline cases for round nuclei exclusively, 12 originally normal samples remained normal but 16 (57%) were abnormal using the “Poor Man's” scoring technique. In the present study, we prospectively compared FISH scoring on unsorted samples using the “Poor Man's” technique vs the clinical technique. Methods: After IRB approval, we collected 63 consecutive unsorted Mayo Clinic patient blood samples referred for CLL FISH testing with an absolute lymphocyte count (ALC)< 30K × 109/L, and scored each sample using both the “Poor Man's” round nuclei method and the standard clinical method. The kappa statistic was used to adjust for chance agreement. Bland Altman plots of difference (“Poor Man's” result minus clinical result) vs the average of the two methods were generated. Results: Median age of the 40 males (64%) and 23 females (36%) was 66 years (range 36–87), and median ALC was 6.803 (range 0.980–29.750). The most common FISH defects were 11q-, trisomy 12 & 13q- by clinical technique (14%, 22% & 46% respectively) as well as by “Poor Man's” method (16%, 24% & 49% respectively). A high degree of agreement was observed between the two methods when positive/negative comparisons were made (p<0.0001). Additional FISH defects were observed in 12 of 63 (19%) patients (one 11q-, one +12; six 13q-, and four 17p-) when we utilized the “Poor Man's” method that were not observed by the clinical method. Discussion: The “Poor Man's” sorting method compares well with the clinical method for the presence and absence of FISH defects. The abnormal CLL FISH patterns are truly confined to round nuclei. The “Poor Man's” method is more sensitive than the clinical method, resulting in higher reported abnormal cells and detection of more defects. Importantly, additional FISH defects were identified in 12 patients via “Poor Man's” method that were not observed by clinical technique and 6 of these involved a change in the patients' hierarchical (Döhner) classification due to detection of the more unfavorable prognostic markers of trisomy 12 or deletion 11q or 17p. Thus, selectively scoring FISH in the round nuclei increases the sensitivity for detection of a genetic defect in CLL and provides a practical framework for prognostication in CLL patients with low lymphocyte counts and, we would speculate, including those in clinical remission or with minimal residual disease. Disclosures: Kay: Biothera: Research Funding; Clegene: Research Funding; Cephalon: Research Funding; Genentech: Research Funding; Glaxo Smith Kline: Research Funding; Hospira: Research Funding; Novartis: Research Funding; Supergen: Research Funding; Calistoga: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Emergent Biosolutions (Formerly Trubion): Membership on an entity's Board of Directors or advisory committees.

Abstract Rearrangements involving TCF3 (E2A) at 19p13.3 are a common cytogenetic abnormality in B-lymphoblastic leukemia/lymphoma (B-LL) across all age groups accounting for at least 5% of B-LL. The most common translocation partner, PBX1 at 1q23, is associated with an unbalanced der(19) or a balanced t(1;19) in 80% vs. 20% patients, respectively, and results in a PBX1/TCF3 fusion transcriptional activator. Several other rearrangement partners have been described, and as such TCF3 is approaching the dubious status of a "promiscuous" gene partner. Clinically, our laboratory uses a dual-color, dual fusion PBX1/TCF3 FISH probe to characterize the most common gene fusion; however, this FISH strategy also allows for the identification of atypical disruptions of the TCF3 gene region, and may suggest a gene partner based on abnormal metaphases/metaphase-FISH. Interrogation of our pediatric leukemia database (ages 0-30) identified 219 patients with abnormal TCF3 FISH results. We selected 23 samples for mate-pair evaluation to test the methodology, characterize novel rearrangements and identify new TCF3 fusion partners. In total, 19 patient samples were successfully sequenced by Mate-Pair, including 13 samples with variants of the 1;19 translocation. Of the samples with TCF3/PBX1 fusion, 3 patients demonstrated novel insertional translocation events characterized by mate-pair. A total of 6 samples with undefined/unknown TCF3 partner genes were evaluated. The mate-pair results identified 5 samples with a t(12;19)(p13.31;p13.3), resulting in TCF3/ZNF384 fusion. Interestingly, two of the ZNF384 rearrangements were observed in the unbalanced form, suggesting a similar mechanism related to the der(19)t(1;19) regularly observed in the common PBX1-TCF3 rearrangement. From a karyotype perspective, since these rearrangements result in only a small portion of chromosome 12p translocated onto distal 19p, this rearrangement would "cryptic" by conventional karyotyping. One patient sample demonstrated a new TCF3 gene fusion partner (TEF), associated with a t(19;22)(p13.3;q13.2). Overall, our results demonstrate the utility of mate-pair evaluation as an adjunct methodology in the identification of novel TCF3 rearrangements in B-LL. We have successfully expanded the application of mate-pair to characterize other novel/cryptic abnormalities in various hematologic and oncologic neoplasms encountered in our laboratory. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 2486 In patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL), deletion of 17p13 (17p-) resulting in loss of one allele of TP53 and 11q22 (11q-) resulting in loss of one allele of ATM predicts a significantly poorer prognosis. These lesions are nearly always monoallelic in patients with CLL and their consequences are considerably influenced by the integrity of the remaining allele. A dysfunctional mutation in the remaining allele, resulting in more aggressive disease, ultimately occurs in most patients with 17p- (> 80%) but fewer patients with 11q- (30%). Because ATM and TP53 are integral components of the p53 pathway, we hypothesize that patients with clonal 17p- and 11q- in the same CLL cell would have a worse prognosis than patients with only one of these deletions. To test this hypothesis, we compared the clinical outcomes (overall survival (OS) and time to treatment (TTT)) of patients with 17p- and 11q- in the same cell to patients with either 17p- or 11q- or neither defect. Methods: We used the Mayo Clinic CLL Database and the Cytogenetics laboratory database to identify all CLL patients seen in the Division of Hematology from 1/1/1995-3/29/2012 who had FISH analysis. Data was extracted on demographics, date of first (sentinel) occurrence of 11q- and 17p-, treatment, and vital status. FISH studies were performed on uncultured blood or bone marrow by standard methods using the Mayo Clinic CLL FISH panel of centromere specific control probes and probes for 6q (MYB), 11q (ATM), 13q14, and 17p (TP53) deletions, trisomy 12 and IGH. Patients with both 11q- and 17p- were further tested with the Abbott Molecular (Des Plaines, IL) ATM/TP53 combination probe set, to determine if the 11q and 17p deletions were present in the same cells. Patients were grouped into 4 cohorts: 1) clonal 17p- and 11q-; 2) 17p- only; 3) 11q- only; and 4) neither 17p- nor 11q-. OS and TTT were calculated and Kaplan-Meier curves were drawn from sentinel FISH date until their last known alive date or death date for OS and until treatment or last known untreated date for TTT. We censored all data on 3/29/2012 and analyzed using log-rank tests from date of sentinel FISH. Sanger sequencing of exons 4–9 of TP53 was done in samples from 15 patients with clonal 17p- and 11q- with an available sample collected within 1 year of the sentinel FISH test and without treatment in that interval. All mutations were confirmed by a repeat assay and analyzed for their predicted effect using the UMD p53 database. Results: We studied 2234 CLL patients with a median follow-up of 4.8 years (range 0 – 29.6 years). Twenty (1%) patients had clonal 17p- and 11q-, 159 (7%) had 17p-, 251 (11%) had 11q-, and 1804 (81%) had neither 17p- nor 11q-. Median OS from sentinel FISH study (Figure 1) was significantly shorter in the clonal 17p- and 11q- group (1.9 years), 17p- group (3.2 y), and 11q- group (4.7 y) compared to the patients with neither 17p- nor 11q- (9.2 y) (p < 0.0001). OS was significantly shorter in the patients with clonal 17p- and 11q- cells vs those with 17p- (p=0.048). TTT was also significantly different among the 4 groups (p<0.0001) with median time to treatment of 0.07 y in the clonal 17p- and 11q-, 0.2 y in 17p-, 0.7 y in 11q-, and 5.6 y in the neither 17p- nor 11q- group. TP53 analysis performed in samples from 15 patients with clonal 17p- and 11q- showed that 10 patients had mutations in the remaining TP3 allele predicted to be deleterious to normal p53 protein function. Median OS was 2.1 years for those with TP53 mutations and 0.9 years for those without mutations (p = 0.03) and median TTT was 0.25 years for those with TP53 mutations and 0.05 years for those without mutations (p = 0.049). Conclusion: “Double hit” clonal deletions of 17p and 11q occurred in 1% of this large cohort of CLL patients and were associated with a significantly poorer prognosis. We recommend that testing for this “double hit” phenomenon, by use of an ATM/TP53 combination probe set, should thus be performed in all patients with 17p- and 11q- on FISH analysis because these patients have a poorer prognosis than those with either 17p- or 11q- and could be candidates for novel therapies. The finding that dysfunctional TP53 mutations in the remaining allele did not worsen prognosis in patients with clonal 17p- and 11q- suggests that monoallelic deletion of both ATM and TP53 in a clone of CLL cells is sufficient to disable p53 pathway function in these patients. Future study of clonal 17p- and 11q- CLL could thus be informative in this regard. Disclosures: Kay: Celgene: Research Funding. Shanafelt:Genentech: Research Funding; Glaxo-Smith-Kline: Research Funding; Cephalon: Research Funding; Hospira: Research Funding; Celgene: Research Funding; Polyphenon E International: Research Funding. Zent:Biothera: Research Funding; Genzyme: Research Funding; Genentech: Research Funding; Novartis: Research Funding; GlaxoSmithKline: Research Funding.

Abstract Abstract 3606 Background: Cytogenetic abnormalities are important prognostic indicators in CLL. At Mayo Clinic, CLL FISH analyses are derived from buffy coat samples not purified for lymphocytes. Scoring is therefore performed on consecutive qualifying nuclei regardless of cell size, shape or morphology. This scoring may not reflect the percent of abnormal nuclei of the affected cell type, but rather the entire population of cells present in the sample. We sought to determine whether the percent abnormal nuclei in only the affected cell type (e.g. lymphocytes) of patients with CLL differed from that of the general cell population. Scoring only B-lymphocytes could increase the sensitivity of the test in patients with low B-cell counts, either early in their disease or after treatment. Cell sorting techniques could be used to reach this goal but can be expensive, labor intensive and add to completion time. We propose a “Poor Man's Cell Sorting” technique based on cell morphology when stained with 4',6-diamidino-2-phenylindole (DAPI). In CLL samples, both round and so called “lobed” cells are seen by DAPI staining but we hypothesize that the CLL B-cells typically present as perfectly round in shape (Fig. 1). Thus our hypothesis: if only the round cells are scored for a genetic defect, would this more accurately represent the malignant leukemic B-cell population and allow for enhanced disease status by FISH? Methods: After IRB approval, we identified 87 CLL patients (75% male; 25% female, mean age 62.4 y, range 43–89 y) in the Mayo Clinic CLL Database, who were seen at Mayo Clinic between March, 2002 - July, 2010. We selected patients known to have low level FISH abnormalities and who therefore should have a significant population of both lymphocytes and neutrophils. Selection criteria included <20×106 B-cells per microliter (by flow cytometry) of peripheral blood and ≤40% of interphase nuclei expressing a specific FISH abnormality. Although most of the 87 patients exhibited more than one FISH abnormality, we focused on only one FISH defect per patient for this study. The original specimen (slide or fixed cell pellet) was rescored for % abnormal nuclei among 100 consecutive round and 100 consecutive lobed (or multilobular) nuclei, using DAPI to identify nuclear architecture. These scores were compared to each other and to the original clinical FISH analysis (scored for 200 consecutive nuclei and not selected for nuclear morphology). Results: Among 87 cases, FISH signals were scored for 6q-(1), 11q-(9), +12(15), 13q-(58), 17p-(2) and 2 IGH rearrangements. In 86/87 cases, the abnormal lobed nuclei did not have FISH defects. One patient exhibited 35% +12 by clinical assay, 52% +12 in the round nuclei, and 11% by lobed nuclei. For all cases, the mean percentage of abnormal nuclei was greater in the round cells (46%) vs original scoring (23.6%). In 79/87 patients (91%), the % of abnormal nuclei was greater in the round cells vs original FISH (mean increase 24.3%; range 1.5–57%). One patient's score was the same in round cells vs original, and 7 patients exhibited fewer abnormal nuclei in the round cells vs original. For these 7 cases, the mean % abnormal nuclei was 5.6% for round nuclei vs 8.4% for original score (score differences ranged from 1 – 5.5%). Overall, by univariate regression analysis, round cells (p=0.0043) have a better correlation with % B-cells, ascertained by flow cytometry, than either the current clinical approach (p=0.0462) or the lobed-cell approach (p=0.4058). Discussion: In virtually all cases (99%), the abnormal FISH patterns were confined to the round nuclei, and the lobed nuclei were virtually always normal by FISH. For patients with <20×106 lymphocytes, selecting for round nuclei uniformly resulted in identification of a higher percentage of abnormal cells. Further studies, including comparison of our round nucleus approach to CLL FISH analysis to actual sorted B-lymphocyte cell selection and the association of this leukemic restricted estimation of abnormal FISH levels to clinical outcome are necessary. Given our findings, we believe that estimating FISH defects restricted to the leukemic B-cell population will become an important adjunct to cytogenetic analysis for patients with low lymphocyte counts, including those in clinical remission and those with minimal residual disease. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2785 Poster Board II-761 Background: Cytogenetic abnormalities are common in the myelodysplastic syndromes (MDS) and carry considerable prognostic weight. One of the most common cytogenetic abnormalities in MDS is isolated trisomy 8 (∼20%). However, the impact of this abnormality on prognosis in MDS is unclear. In the following, we report on all MDS cases with isolated trisomy 8 seen at our institution and describe the natural history of this abnormality. Methods: After approval from the Institutional Review Board, the cytogenetics laboratory database at Mayo Clinic was searched for all cases of isolated trisomy 8. All patients had given written informed consent to enable use of their medical record for research. The medical records were reviewed and relevant demographic, clinical, and laboratory characteristics were abstracted. Survival was determined from diagnosis until death or last contact with the patient and measured using the Kaplan-Meier method. Univariate and multivariate analysis for survival were performed using the Cox proportional hazard method. Results: Out of a total of 23, 375 unique patient specimens evaluated over a twenty year period (January 1988 – December 2008), we identified a cohort of 106 patients (0.45%) with trisomy 8 as the sole cytogenetic abnormality (males with –Y were included). Of these patients, 89 had a classical MDS and 66 patients were males. The median age at diagnosis of MDS was 70.0 years (range: 31 – 91) for the whole cohort (females: 67 yr, males: 71.5 yr, p=0.22). All patients presented with at least one cytopenia, median Hb: 9.8g/dl (3.9 – 15.4); WBC: 4.6×103/ml (1.0 – 102.6); PLT: 119×103/ml (3.0 – 740), bone marrow blasts: 5% (0 – 22.5), LDH: 221 (62 – 1342). Considering trisomy 8 as an intermediate risk abnormality (score = 0.5), the median IPSS for the cohort was 1.0 (0.5 – 2.5) (Intermediate-1). The distribution of cases included: MDS with <5% blasts (55%), RAEB-1 (16%), RAEB-2 (18%), and CMML (11%). 85% of patients required transfusion sometime after diagnosis and 40% were treated with some form of chemotherapy. Transformation to acute myeloid leukemia (AML) occurred in 25 patients (28.1%) and of these, 22 have died. The median time from diagnosis to transformation to AML was 33 months. The median overall survival from diagnosis was 36 months, similar to what is expected for Int-1 patients (Blood 89:2079, 1997). On univariate analysis, age at diagnosis (p=0.05), LDH (p=0.017) and time to transformation (p<0.0001) were prognostic. On multivariate analysis, LDH (p=0.007) and time to transformation (p=0.009) remained independent prognostic factors. Conclusions: Isolated trisomy 8 in MDS is associated with intermediate risk disease. The risk of transformation to acute leukemia is 28% and the median survival from diagnosis of MDS is approximately 3 years. A significant fraction of patients die due to causes unrelated to their hematopoietic disorder. Disclosures: No relevant conflicts of interest to declare.