Reichard, Kaaren K.

Abstract Background: The World Health Organization (WHO) system lists five morphological categories of systemic mastocytosis (SM): indolent (ISM), smouldering (SSM), SM with an associated hematological neoplasm (SM-AHN), aggressive (ASM) and mast cell leukemia (MCL) (Blood. 2016;127:2391). Recent studies have highlighted the prognostic importance of mutations in SM, including ASXL1, RUNX1 and SRSF2 (AJH 2016;91:888;Leukemia 2016;30:2342). In the current study, we reviewed the cytogenetic findings in 348 cases of SM, in order to clarify incidence and prognostic impact of cytogenetic abnormalities, stratified by WHO morphologic subcategories. Methods : Study patients were selected, based on availability of cytogenetic information. Diagnoses of SM and its morphological subcategories were confirmed by both clinical and bone marrow examinations, in line with WHO criteria (Blood. 2016;127:2391). Next-generation sequencing was performed in a subset of the study population. Abnormal karyotype was further distinguished into favorable and unfavorable class based on previously published criteria for myelodysplastic syndromes (MDS) (Blood 2012;120:2454) and myeloproliferative neoplasms (MPN) (Leukemia 208;32:1189). Statistical analyses considered clinical and laboratory data collected at the time of initial diagnosis at the Mayo Clinic, which coincided with collection of bone marrow for cytogenetic studies. Conventional statistics was used for calculation of overall survival and determination of risk factors. JMP® Pro 13.0.0 software from SAS Institute, Cary, NC, USA, was used for all calculations. Results: 348 SM patients were included in the current study (median age 59 years; range 18-88 years; 53% males); 142 (41%) constituted ISM and 206 (59%) advanced SM; the latter included 155 (45%) SM-AHN, 49 (14%) ASM and 2 MCL cases. The SM-AHN cases included 39 (11%) SM-MPN, 36 (10%) SM-CMML, 22 (6%) SM-MDS, 22 (6%) SM-myeloid unclassified, 14 (4%) SM-MDS/MPN, 12 (3%) SM-lymphoid malignancy and 10 (3%) SM-acute leukemia. Adverse mutations, including ASXL1 (19% mutated), RUNX1 (3% mutated) and NRAS (3% mutated) were detected in 30 (23%) of 129 cases screened. After a median follow-up of 21 months, 139 (40%) deaths and 6 (5%) leukemic transformations were documented. Karyotype was abnormal in 53 (15%) cases and included unfavorable (n=29; 8%) and favorable (n=24; 7%) abnormalities. Abnormal karyotype incidences were 6% for ISM and 22% for advanced SM (p<0.001). Among advanced SM cases, abnormal karyotype incidences were 26% for SM-AHN and 8% for ASM (p<0.001); one of 2 MCL cases displayed abnormal karyotype. Among SM-AHN cases, abnormal karyotype incidences were 0% for SM-AHN-lymphoid, 28% for SM-AHN-myeloid (p<0.001); the latter included 19% for SM-CMML, 21% for SM-MDS/MPN, 23% for SM-MPN, 36% for SM-MDS and 41% of SM-myeloid-unclassified (p<0.001). Clinical correlative studies disclosed significant associations between abnormal karyotype and male sex (p=0.002), age >60 years (p=0.04), thrombocytopenia (p<0.001; 27% vs 10%) and anemia (p<0.001; 25% vs 6%), but not with the presence of adverse mutations (p=0.19). In univariate analysis, abnormal karyotype was associated with inferior survival (HR 3.0, 95% CI 2.0-4.3) and significance was sustained when analysis was adjusted for two-tiered (advanced vs indolent SM; p<0.01) or multi-tiered (ISM vs ASM vs SM-AHN; p<0.01) WHO subcategories. WHO category-specific analysis clarified prognostic relevance of abnormal karyotype in ASM (HR 4.4, 95% CI 1.0-14.4; p=0.05; figure 1a) and SM-AHN-myeloid (HR 1.9, 95% CI 1.2-2.9; p=0.005; figure 1b); however, the near-significance in ASM was fully accounted for by thrombocytopenia (p value corrected to 0.35) and for SM-AHN-myeloid by thrombocytopenia and anemia (p value corrected to 0.06); further stratification of abnormal karyotype into favorable vs unfavorable categories did not affect the results in ASM but revealed an independent prognostic effect for unfavorable karyotype in SM=AHN-myeloid (p=0.009). Conclusions: Abnormal karyotype in SM clusters with SM-AHN-myeloid. We found no correlation between abnormal karyotype and adverse mutations. Anemia and thrombocytopenia were significantly associated with abnormal karyotype and accounted for the apparent prognostic relevance of the latter in ASM. Unfavorable karyotype carries independent prognostic effect in SM-AHN-myeloid. Disclosures No relevant conflicts of interest to declare.

Abstract Background: CD123 is the α-subunit of the high-affinity receptor for interleukin-3; its expression in normal bone marrow (BM) is highly restricted, however CD123 is highly expressed in certain hematolymphoid malignancies. In a pilot study of 11 systemic mastocytosis (SM) patients (Lasho et al., Leukemia, 2015), we made the following novel observations (i) CD123 was aberrantly expressed on neoplastic mast cells (MC); and (ii) there was focal proliferation of plasmacytoid dendritic cells (PDC) around MC aggregates, suggesting a tumor promoting role for PDC. Objectives: To study MC CD123 expression by IHC in a larger cohort of SM patients to ascertain: (i) whether there is a significant difference in CD123 expression between SM subtypes; (ii) whether focal PDC proliferation around MC aggregates is correlated with CD123 expression; and (iii) whether CD123 expression has prognostic value for overall survival (OS). Methods: The current study was approved by the Mayo Clinic institutional review board. SM was classified as per standard criteria. Archived BM slides were stained for tryptase and CD123 as previously described (Lasho et al., Leukemia, 2015). Slides were reviewed independently by 2 hematopathologists who were blinded with regards to SM subgroups and scored on the following pre-defined parameters: (i) CD123 expression yes/no; (ii) CD123 expression strong/weak; (iii) focal PDC proliferation yes/no; and (iv) BM MC%. Results: We studied 58 SM patients and 3 controls. Of the former, 23 had indolent SM (ISM), 10 aggressive SM (ASM), 23 SM with associated hematological disease (SM-AHD), and 2 had mast cell leukemia (MCL). Of the SM-AHD patients, 10 (43%) had CMML, 5 (22%) myeloproliferative neoplasm-unclassified (MPN-u), 3 (13%) PV, 2 (9%) acute myeloid leukemia, and 1 each had lymphoma, myeloma and myelodysplastic syndrome. The median follow up from diagnosis was 32 months (range 0.1 to 162). Over this period, 3 patients (5%) had leukemic transformation and 30 patients (52%) died. Concordance rates between hematopathologists for CD123 positive/negative, CD123 strong/weak, focal PDC proliferation yes/no and MC% were 97%, 94%, 98% and 100%, respectively. MC CD123 expression was absent in control cases but demonstrable in 37 (64%) SM patients; expression rates were 100%, 61%, 57%, and 0% in ASM, ISM, SM-AHD and MCL, respectively (p=0.02). Similar to MCL, both cases with SM-AML showed absent MC CD123 expression. Strong MC CD123 expression (comparable to background interstitial PDC) was observed in 23 patients (62%), including 85% with SM-AHD, 60% with ASM, and 43% with ISM (p=0.08). Focal PDC proliferation around MC aggregates, regardless of CD123 expression status, was noted in 44 patients (76%), including 90% with ASM, 87% with ISM, 65% with SM-AHD and 0% with MCL (p=0.02). Focal PDC proliferation was significantly higher in CD123-positive versus -negative patients (87% versus 50%, p=0.005). OS was predicted by SM subtype; the median OS for ISM, ASM, SM-AHD and MCL patients was not reached, 30 months, 25 months and 3 months, respectively (p=0.005). CD123 expression status did not have prognostic value for OS overall, however, in SM-AHD patients, CD123 expression was associated with significantly inferior survival (p=0.04), independent of the associated disease (ie, CMML vs AML vs MPN vs other). Survival outcome of SM-CMML patients expressing MC CD123 (n=3, median OS=11 months) was significantly inferior as compared to patients who did not (n=7, median OS=44 months), independent of age and absolute monocyte count (p=0.01). CD123 staining intensity had borderline significance for OS in the overall cohort (p=0.08). When restricted to non-indolent SM cases, strong CD123 expression was associated with significantly worse overall survival (15 versus 88 months, p=0.04). Conclusions: In this cohort, aberrant MC CD123 expression was observed in the majority of SM patients with highest prevalence in ASM patients and uniformly absent expression in leukemic phase SM (MCL or SM-AML). Focal PDC proliferation around MC aggregates was significantly higher in CD123-positive cases, indicating a potential functional interaction. CD123 expression identified SM-AHD patients with inferior OS, especially those with SM-CMML. Strong CD123 staining intensity may be associated with inferior OS in non-indolent SM patients. CD123 expression on MC and PDC constitutes a novel therapeutic target in non-leukemic SM. Disclosures Pardanani: Stemline: Research Funding. Brooks:Stemline Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties.

Abstract Isolated trisomy 2 in hematopoietic malignancies is rare, having only been reported in eight cases in the literature. Of these cases, the majority are older male patients (7/8) ranging in age from 64 to 84 years. The underlying hematologic malignancies include: myelodysplastic syndrome (MDS), refractory anemia (RA) subtype; MDS, RA with excess blasts (RAEB-II) subtype; MDS, RAEB in transformation (RAEB-t); chronic myelomonocytic leukemia (CMML-t) in transformation; MDS transformed into AML; acute monoblastic and monocytic leukemia (AMoL; FAB M5); and AML in relapse. The molecular pathogenesis and prognostic significance of isolated trisomy 2 remains unknown due to the small number of reported cases. Herein, we report 11 cases of isolated trisomy 2 in hematologic disorders seen in the Mayo Clinic Cytogenetics laboratory from 1996-2012. The majority of patients were older males (7/11) ranging in age from 63 to 93 years. The underlying bone marrow pathologic diagnoses include: hypercellular bone marrow without diagnostic features of malignancy (cases 1 and 2); MDS, refractory cytopenia with multilineage dysplasia (RCMD) subtype (cases 3 and 4); RAEB-1 (cases 5 and 6); long-standing history of primary myelofibrosis now with 7% bone marrow blasts (case 7); acute myeloid leukemia (AML), not otherwise specified (cases 8 and 9); AML with myelodysplasia-related changes (cases 10 and 11). Trisomy 2 has been suggested to represent an age-related phenomenon as it is seen predominantly in older individuals demonstrating this abnormality. Our data suggests that this could be a possible explanation since all of the eleven cases were ages 63 and over. Based on the limited clinical information in our study, it appears that isolated trisomy 2 harbors little prognostic significance and that, rather, the prognostic significance is driven by the underlying pathologic diagnosis. For example, 3 of the 4 AML cases and the case of PMF with increasing bone marrow blasts survived only 7, 8, 6 weeks and 21 weeks post bone marrow biopsy/cytogenetic evaluation, respectively. Although our study only has two cases that lack diagnostic features of malignancy, one of these cases survived 10 years following the identification of the cytogenetic abnormality. Therefore, trisomy 2 as a sole abnormality should not be considered as definitive evidence for MDS in the absence of diagnostic morphological criteria (similar to trisomy 8 and 20q deletion). Disclosures: No relevant conflicts of interest to declare.

AbstractObjectivesMyeloid sarcoma with CBFB-MYH11 fusion may be enriched in abdominal sites. The clinicopathologic features of 11 cases are reported.MethodsWe collected clinical features, morphology, immunophenotype, and bone marrow (BM) involvement of myeloid sarcoma cases with CBFB-MYH11 fusion.ResultsEleven of 29 total myeloid sarcoma cases were CBFB-MYH11 positive and all 11 involved abdominal sites. The blastic infiltrate was associated with eosinophils in four of 11 cases and plasmacytoid dendritic cell (pDC) nodules in four of six cases. CD34, CD117, and myeloperoxidase were expressed in eight of nine, 10 of 10, and 10 of 10 cases, respectively. Ten of 10 cases showed no BM involvement.ConclusionsOur current series, combined with a literature review, identifies a compelling series of 31 (94%) of 33 cases of myeloid sarcoma with CBFB-MYH11 fusion showing a marked predilection for abdominal sites. In addition, the lack of obvious associated eosinophils, presence of pDC nodules, and lack of concurrent BM involvement suggest that “myeloid sarcoma with CBFB-MYH11 fusion” may represent a unique phenomenon.

The prevalence, clinicopathologic correlates, and outcomes of previously untreated chronic lymphocytic leukemia (CLL) patients with IGH‐BCL2 and IGH‐BCL3 translocations are not well known. Using the Mayo Clinic CLL database, we identified patients seen between March 1, 2002 and September 30, 2016 who had FISH testing performed within 3 years of CLL diagnosis. The prognostic profile, time to first therapy (TTT), and overall survival (OS) of patients with IGH‐BCL2 and IGH‐BCL3 translocation were compared to patients without these abnormalities (non‐IGH group). Of 1684 patients who met the inclusion criteria, 38 (2.2%) had IGH‐BCL2, and 16 (0.9%) had IGH‐BCL3 translocation at diagnosis. Patients with IGH‐BCL3 translocation were more likely to have high and very‐high CLL‐International Prognostic Index, compared to patients with IGH‐BCL2 translocation and the non‐IGH group. The 5‐year probability of requiring therapy was significantly higher for IGH‐BCL3 compared to IGH‐BCL2 and non‐IGH groups (84% vs 33% vs 29%, respectively, P < 0.0001). The 5‐year OS was significantly shorter for IGH‐BCL3 compared to IGH‐BCL2 and non‐IGH groups (45% vs 89% vs 86%, respectively, P < 0.0001). On multivariable analyses, IGH‐BCL3 translocation was associated with a shorter TTT (hazard ratio [HR] = 2.7; P = 0.005) and shorter OS (HR = 5.5; P < 0.0001); IGH‐BCL2 translocation did not impact TTT and OS. In conclusion, approximately 3% of all newly diagnosed CLL patients have either an IGH‐BCL2 or IGH‐BCL3 translocation. Patients with IGH‐BCL3 translocations have a distinct prognostic profile and outcome. These results support the inclusion of an IGH probe during the routine evaluation of FISH abnormalities in newly diagnosed CLL.

Abstract Systemic mastocytosis (SM) is a clinically heterogeneous disease with prognosis chiefly assigned based on World Health Organization (WHO) morphologic subclassification. We assessed the feasibility of developing contemporary risk models for SM based on clinical and integrated clinical-genetics information. Diagnosis of SM was per WHO criteria, and karyotype and next-generation sequencing data were available in a subset of the total 580 patients (median age, 55 years; range, 18-88 years) seen at the Mayo Clinic between 1968 and 2015. Morphologic subcategories were indolent/smoldering in 291 (50%) and “advanced” in 289 (50%): SM with an associated hematological neoplasm in 199, aggressive SM in 85, and mast cell leukemia in 5. Multivariable analysis of clinical variables identified age &gt;60 years, advanced SM, thrombocytopenia &lt;150 × 109/L, anemia below sex-adjusted normal, and increased alkaline phosphatase (ALP) as independent risk factors for survival; respective hazard ratios (HRs) 95% confidence intervals (95% CIs) were 2.5 (1.9-3.4), 2.7 (1.8-4.0), 2.5 (1.9-3.4), 2.2 (1.6-3.1), and 2.1 (1.5-3.0). In addition, ASXL1 (HR, 4.5; 95% CI, 2.6-7.6), RUNX1 (HR, 4.3; 95% CI, 1.3-10.8), and NRAS (HR, 5.0, 95% CI, 1.5-13.2) mutations were independently associated with inferior survival. Combined clinical, cytogenetic, and molecular risk factor analysis confirmed the independent prognostic contribution of adverse mutations (2.6, 1.6-4.4), advanced SM (4.0, 1.8-10.0), thrombocytopenia (2.8, 1.7-4.5), increased ALP (2.1, 1.2-4.0), and age &gt;60 years (2.2, 1.3-3.6). These data were subsequently used to develop clinical and hybrid clinical-molecular risk models. The current study advances 2 complementary risk models for SM and highlights the independent prognostic contribution of mutations.

AbstractThe World Health Organization (WHO) system lists five morphological categories of systemic mastocytosis (SM): indolent (ISM), smoldering, SM with an associated hematological neoplasm (SM‐AHN), aggressive (ASM) and mast cell leukemia (MCL). Recent studies have highlighted the prognostic importance of mutations in SM, including ASXL1, RUNX1, and SRSF2. In contrast, information on incidence of cytogenetic abnormalities in SM and their prognostic relevance, especially in the context of mutations, is limited. In the current study, we retrospectively reviewed the cytogenetic findings in 348 consecutive cases of SM (median age 59 years; 53% males); 41% constituted ISM, 45% SM‐AHN, 14% ASM and two cases of MCL. Karyotype was abnormal in 53 (15%) cases with incidences of 6% for ISM, 26% for SM‐AHN and 8% for ASM (P < .001); among SM‐AHN cases, abnormal karyotype incidences were 0% for SM‐AHN‐lymphoid and 28% for SM‐AHN‐myeloid (P < .001). Clinical correlative studies disclosed significant associations between abnormal karyotype and male sex (P = .002), age > 60 years (P = .04), thrombocytopenia (P < .001) and anemia (P < .001), but not with the presence of adverse mutations (P = .19). In univariate analysis, abnormal karyotype was associated with inferior survival (HR 3.0, 95% CI 2.0‐4.3), specifically confirmed for ASM (HR 4.9, 95% CI 1.1‐16.1) and SM‐AHN (HR 1.8, 95% CI 1.2‐2.7). Sample size adequacy allowed additional multivariable analysis in SM‐AHN‐myeloid, which disclosed independent prognostic contribution from adverse mutations (P = .003), anemia (P = .003) and thrombocytopenia (P = .001), but not from abnormal karyotype (P = .31). Our observations suggest that mutations are prognostically more relevant than karyotype in SM.