Additional Cytogenetic Aberrations Research Articles

Impact of additional cytogenetic aberrations at diagnosis on prognosis of adults patients with Philadelphia chromosome positive acute lymphoblastic leukemia undergoing allogeneic hematopoietic cell transplantation: a retrospective analysis.

Additional chromosomal abnormalities(ACAs) at diagnosis are associated with inferior prognosis in chronic myeloid leukemia. However, the prognostic significance of ACAs in adult patients with Philadelphia Chromosome Positive acute lymphoblastic leukemia (Ph + ALL) receiving TKI-targeted drugs and allogeneic hematopoietic stem cell transplantation(HSCT) is unknown. One hundred thirty-six adult patients with Ph + ALL were included in the study and retrospectively analysed, evaluating the effect of ACAs on outcomes of transplantation. ACAs are observed in 60 cases (44%). ACAs detected in more than 5% of cases were defined as major-route and encompass: +der(22), +der(9), + 8, -7 and complex karyotype. The median follow-up was 26.4 months. In the subgroup analyses of major route ACAs, three-year cumulative incidence of relapse (CIR) and progression-free survival(PFS) are statistically significant in + 8[66.7% vs.23.7%, P = 0.024; 77.8% vs. 23.7%, P = 0.0087], -7[53.8% vs. 23.7%, P = 0.035%; 61.5% vs. 32.9%, P = 0.033], and complex karyotypes[42.9% vs. 23.7%, P = 0.027; 47.6% vs. 23.7%] compared with t(9;22) sole. Additionally, the 3-year CIR for Ph + ALL with + der(22) is 44% vs. 23.7% for t(9;22) sole(P = 0.045). The 3-year overall survival (OS) in the - 7 group is 46.5%, which is statistically significant compared with the other groups(P = 0.001). In multivariate analyses, three years CIR and PFS are statistically significant in + der(22), + 8, -7 and complex karyotype compared with t(9;22) sole(P < 0.05). More importantly, Ph + ALL with - 7 was negatively associated with the rate of 3-year OS(P = 0.012). Thus, ACAs at diagnosis appear to have a significant prognostic impact on transplantation outcomes in patients with Ph + ALL.

Optimized cytogenetic risk-group stratification of KMT2A-rearranged pediatric acute myeloid leukemia

AbstractA comprehensive international consensus on the cytogenetic risk-group stratification of KMT2A-rearranged (KMT2A-r) pediatric acute myeloid leukemia (AML) is lacking. This retrospective (2005-2016) International Berlin-Frankfurt-Münster Study Group study on 1256 children with KMT2A-r AML aims to validate the prognostic value of established recurring KMT2A fusions and additional cytogenetic aberrations (ACAs) and to define additional, recurring KMT2A fusions and ACAs, evaluating their prognostic relevance. Compared with our previous study, 3 additional, recurring KMT2A-r groups were defined: Xq24/KMT2A::SEPT6, 1p32/KMT2A::EPS15, and 17q12/t(11;17)(q23;q12). Across 13 KMT2A-r groups, 5-year event-free survival probabilities varied significantly (21.8%-76.2%; P < .01). ACAs occurred in 46.8% of 1200 patients with complete karyotypes, correlating with inferior overall survival (56.8% vs 67.9%; P < .01). Multivariable analyses confirmed independent associations of 4q21/KMT2A::AFF1, 6q27/KMT2A::AFDN, 10p12/KMT2A::MLLT10, 10p11.2/KMT2A::ABI1, and 19p13.3/KMT2A::MLLT1 with adverse outcomes, but not those of 1q21/KMT2A::MLLT11 and trisomy 19 with favorable and adverse outcomes, respectively. Newly identified ACAs with independent adverse prognoses were monosomy 10, trisomies 1, 6, 16, and X, add(12p), and del(9q). Among patients with 9p22/KMT2A::MLLT3, the independent association of French-American-British–type M5 with favorable outcomes was confirmed, and those of trisomy 6 and measurable residual disease at end of induction with adverse outcomes were identified. We provide evidence to incorporate 5 adverse-risk KMT2A fusions into the cytogenetic risk-group stratification of KMT2A-r pediatric AML, to revise the favorable-risk classification of 1q21/KMT2A::MLLT11 to intermediate risk, and to refine the risk-stratification of 9p22/KMT2A::MLLT3 AML. Future studies should validate the associations between the newly identified ACAs and outcomes and unravel the underlying biological pathogenesis of KMT2A fusions and ACAs.

Complex karyotype determined using conventional cytogenetic analysis is a poor prognostic factor in patients with multiple myeloma.

High-risk cytogenetic abnormalities (HRCAs) influence the prognosis of multiple myeloma (MM). However, additional cytogenetic aberrations can lead to poor outcomes. This study aimed to clarify whether HRCAs and additional chromosomal abnormalities affect MM prognosis. Patients with newly diagnosed MM who were treated with novel agents were retrospectively evaluated. The primary objective was to assess the difference in progression-free survival (PFS) and overall survival (OS) between patients with/without HRCAs and between patients with/without complex karyotype (CK). The secondary objectives were to identify factors affecting PFS/OS and factors related to CK. HRCAs were defined as del(17p), t(4;14), t(14;16), and gain/amplification(1q) assessed using fluorescence in situ hybridization. CK was defined as ≥3 chromosomal abnormalities on G-banding. Among 110 patients, 40 had HRCAs and 15 had CK. In this study, survival durations between patients with/without HRCAs were similar, while the CK group had significantly poorer PFS/OS than the no-CK group (median PFS: 9 vs. 24 months and median OS: 29 vs. 97 months, respectively), and a poor prognostic impact of CK was maintained in patients with HRCAs. In multivariate analysis, CK was correlated with poor PFS/OS (hazard ratio [HR]: 2.39, 95% confidence interval [95% CI]: 1.22-4.66 and HR: 2.66, 95% CI: 1.10-6.45, respectively). Bone marrow plasma cell (BMPC) ≥60% (odds ratio [OR] = 6.40, 95% CI: 1.50-27.2) and Revised International Staging System III (OR = 7.53, 95% CI: 2.09-27.1) were associated with CK. Our study suggests that CK may contribute to the poor prognosis of MM. Aggressive disease status including high BMPC proliferation could be relevant to CK.

The study of the impact of additional chromosomal aberrations and c-MYC and BCR::ABL1 genes amplification on CML patient’s characteristics: relation to haematological parameters and patient outcome

BackgroundChronic myeloid leukaemia is characterised by genetic instability which results in additional cytogenetic aberrations that have been linked to progression to advanced phase. Genomic study linked amplified genes in the form of c-MYC and/or the rare BCR::ABL1 genes amplification to chronic myeloid leukaemia. The effect of these genes’ amplification on patients’ characteristics and disease progression still needs further study.This cross-sectional study aimed to investigate the frequency of additional chromosomal aberrations in addition to c-MYC and BCR::ABL1 genes amplification in chronic myeloid leukaemia patients and their impact on patient’s characteristics, disease progression, and level of remission. The study included cytogenetic analysis of 49 Philadelphia positive chronic myeloid leukaemia patients and investigation of c-MYC and BCR::ABL1 genes amplification by fluorescence in situ hybridization.ResultsPatients with additional chromosomal aberrations represented 36.7% and had significantly lower platelet count (P = 0.003) and higher blast count (P = 0.008). The acquisition of additional chromosomal aberrations was significantly higher in chronic myeloid leukaemia patients with advanced stages (P = 0.014). Follow-up of the patients for 6 months revealed significant higher frequency of additional chromosomal aberrations in patients with failure of remission (P < 0.0001). A highly significant association between cases with failure of molecular remission (P = 0.001) and co-existing additional chromosomal aberrations.Amplification of the c-MYC gene was detected in 6 cases. The cases with c-MYC amplification showed significantly higher peripheral blood and bone marrow blasts (P = 0.029 and P = 0.008, respectively) and significantly lower platelet count (P = 0.044). Amplification of c-MYC was significantly associated with additional chromosomal aberrations (P = 0.011). Molecular remission was not achieved in any of the instances with c-MYC amplification. A highly significant association between c-MYC amplification and poor patient outcome was detected (P = 0.002). BCR::ABL1 amplification was detected in three cases, and ABL amplification was detected in four cases. Patients with BCR::ABL1 amplification showed significantly higher blast count. BCR::ABL1 amplification was significantly associated with disease progression and failure of molecular remission (P = 0.002).ConclusionAdditional chromosomal aberrations, c-MYC amplification, and BCR:ABL1 amplification in chronic myeloid leukaemia stratify patients with disease progression, which may lead to better interventions and improved outcome in the future chronic myeloid leukaemia patients.

Clinical impact of c-KIT and CEBPA mutations in 33 patients with corebinding factor (Non-M3) acute myeloid leukemia.

Corebinding factor acute myeloid leukemia (CBF-AML) is the most common cytogenetic subtype of pediatric AML. CBF-AML is associated with a relatively favorable outcome, although the relapse rate of approximately 40% indicates a high degree of clinical heterogeneity. The clinical impact of additional cytogenetic aberrations, including c-KIT and CEBPA mutations, in pediatric CBF-AML has not been well characterized, especially in the multi-ethnic region of Yunnan Province in China. In this study, we retrospectively analyzed the clinical features, gene mutations, and prognoses of 72 pediatric patients newly diagnosed with non-M3 AML in Kunming Children's Hospital, China, from January 1, 2015 to May 31, 2020. Of the 72 pediatric patients with AML, 46% (33/72) had CBF-AML. Thirteen patients with CBF-AML (39%) had c-KIT mutations, five (15%) had CEBPA mutations, and eleven (33.3%) had no other cytogenetic aberrations. The c-KIT mutations, resulting from single nucleotide substitutions and small insertions or deletions, occurred in exons 8 and 17. All of the CBF-AML-associated CEBPA mutations were single mutations and occurred in patients with RUNX1-RUNX1T1 fusion. We found no significant differences in the clinical data between CBF-AML patients with c-KIT or CEBPA mutations and CBF-AML patients without other aberrations, and no prognostic significance was established for these mutations. Our study is the first to report the clinical impact of c-KIT and CEBPA mutations in pediatric patients with non-M3 CBF-AML from the multi-ethnic Yunnan Province, China. c-KIT and CEBPA mutations occurred at a higher frequency in CBF-AML cases and were associated with unique clinical characteristics; however, no potential molecular prognostic markers were identified.

The presence of additional cytogenetic aberrations in chronic myeloid leukemia cells at the time of diagnosis or their appearance on tyrosine kinase inhibitor therapy predicts the imatinib treatment failure

Currently used treatment of CML dramatically improved the prognosis of disease. However, additional chromosome aberrations (ACA/Ph+) are still one of the adverse prognostic factors. Objectivesevaluation of the impact of ACA/Ph+ appearance during disease outcome on the response to treatment. The study groupconsisted of 203 patients. The median time of follow-up was 72 months. ACA/Ph+ was found in 53 patients. Resultspatients were divided into four groups: standard risk, intermediate, high and very high risk. When ACA/Ph+ presence was documented at diagnosis time the optimal response was observed in 41.2%, 25%, and 0% of pts with intermediate, high and very high risk, respectively. If ACA/Ph+ were detected during imatinib treatment the optimal response was in 4.8% of patients. The risk of blastic transformation for patients with standard risk, intermediate, high and very high risk was 2.7%, 18.4%, 20% and 50%, respectively. Conclusionsthe presence of ACA/Ph+ at diagnosis time or their appearance on therapy seems to be clinically relevant not only in terms of the risk of blastic transformation but also in terms of the treatment failure. Gathering patients with various karyotypes and their responses to treatment would allow to set better guidelines and predictions.

Comparison and validation of the 2022 European LeukemiaNet guidelines in acute myeloid leukemia.

Risk stratification in acute myeloid leukemia (AML) remains principle in survival prognostication and treatment selection. The 2022 European LeukemiaNet (ELN) recommendations were recently published, with notable updates to risk group assignment. The complexity of risk stratification and comparative outcomes between the 2022 and 2017 ELN guidelines remains unknown. This comparative analysis evaluated outcomes between the 2017 and 2022 ELN criteria in patients enrolled within the multicenter Beat AML cohort. Five hundred thirteen patients were included. Most patients had 1 or 2 ELN risk-defining abnormalities. In patients with ≥2 ELN risk-defining mutations, 44% (n= 132) had mutations spanning multiple ELN risk categories. Compared with ELN 2017 criteria, the updated ELN 2022 guidelines changed the assigned risk group in 15% of patients, including 10%, 26%, and 6% of patients categorized as being at ELN 2017 favorable-, intermediate-, and adverse-risk, respectively. The median overall survival across ELN 2022 favorable-, intermediate-, and adverse-risk groups was not reached, 16.8, and 9.7 months, respectively. The ELN 2022 guidelines more accurately stratified survival between patients with intermediate- or adverse-risk AML treated with induction chemotherapy compared with ELN 2017 guidelines. The updated ELN 2022 guidelines better stratify survival between patients with intermediate- or adverse-risk AML treated with induction chemotherapy. The increased complexity of risk stratification with inclusion of additional cytogenetic and molecular aberrations necessitates clinical workflows simplifying risk stratification.

Risk Stratification, Measurable Residual Disease, and Outcomes of AML Patients with a Trisomy 8 Undergoing Allogeneic Hematopoietic Stem Cell Transplantation.

Simple SummaryTrisomy 8 is the most common numerical chromosome aberration in acute myeloid leukemia (AML). Although this AML type is often consolidated applying allogeneic hematopoietic stem cell transplantations (HSCT), detailed analyses of outcomes after HSCT are lacking. The purpose of this manuscript is to analyze biological and clinical features of patients with this cytogenetic aberration in the context of significant risk factors, including the ELN2017 risk stratification and measurable residual disease markers at HSCT. Our data provides evidence on the clinical disease courses and may aid in informed decisions on treatment and outcome prediction of trisomy 8 AML patients undergoing allogeneic HSCT.Background: For most patients with acute myeloid leukemia (AML) harboring a trisomy 8 an allogeneic hematopoietic stem cell transplantation (HSCT) is a suitable and recommended consolidation therapy. However, comparative outcome analyses between patients with and without trisomy 8 undergoing allogeneic HSCT have not been performed so far. Methods: We retrospectively analyzed clinical features, outcomes, and measurable residual disease (MRD) of 659 AML (12%, n = 81, with a trisomy 8) patients subjected to allogeneic HSCT as a consolidation therapy. Results: The presence of a trisomy 8 associated with a trend for higher age at diagnosis, AML of secondary origin, lower white blood cell counts at diagnosis, worse ELN2017 genetic risk, wild-type NPM1, and mutated IDH1/2 and JAK2. Outcomes after allogeneic HSCT in the entire cohort did not differ between patients with a sole trisomy 8, trisomy 8 with additional cytogenetic aberrations or without a trisomy 8. A trisomy 8 did not affect outcomes within the three ELN2017 risk groups. In accordance with findings in unselected patient cohorts, persistent MRD at allogeneic HSCT in patients with a trisomy 8 identified individuals with a higher risk of relapse following allogeneic HSCT. Conclusions: Outcomes of trisomy 8 patients after allogeneic HSCT did not compare unfavorably to that of other AML patients following allogeneic HSCT. Rather than the presence or absence of a trisomy 8, additional genetic aberrations and MRD at HSCT define outcome differences and aid in informed treatment decisions.

Impact of Allogeneic Hematopoietic Stem Cell Transplantation in First Complete Remission and Additional Cytogenetic Aberrations at Diagnosis on Prognosis in 1256 Pediatric Patients with KMT2A-Rearranged Acute Myeloid Leukemia: A Retrospective Study By the I-BFM-SG

IntroductionKMT2A-rearranged (KMT2A-r) acute myeloid leukemia (AML) is a heterogeneous genetic subgroup with a frequency of about 25% in children with AML. At the 62 nd ASH annual meeting last year, we reported on the differences in outcome of various KMT2A subgroups based on translocation partner and the significance of minimal residual disease (MRD) status during and after induction as a follow-up study of Balgobind et al., Blood 2009. The impact of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR1) and the presence of additional cytogenetic aberrations (ACAs) on prognosis have not yet been described for our cohort.MethodsData on allo-HSCT in CR1 and the presence of ACAs of 1256 KMT2A-r de novo pediatric AML patients from 15 AML study groups affiliated with the I-BFM Study Group, diagnosed between 2005 and 2016, were retrospectively collected and studied. Karyotypes were reviewed and classified by two of the authors (RW&CH). Based on translocation partners, patients were classified to the KMT2A high-risk subgroup (6q27, 10p11.2, 10p12, 4q21, and 19p13.3) or non-high-risk subgroup (9p22, 19p13, 19p13.1, 1q21, Xq24, 17q21, 1p32, and 17q12). These two categories have been used to estimate a Cox model. Patients with unknown translocation partners were excluded from these analyses (n=126). Flow cytometry MRD levels at the end of induction course 1 (EOI1) and 2 (EOI2) <0.1% were considered negative, and levels ≥0.1% positive. Kaplan-Meier's methodology was used to estimate disease-free survival (DFS) and overall survival (OS). DFS was calculated from EOI1 for patients in CR to date of relapse or death/last follow-up. OS was calculated from the time of diagnosis to date of death/last follow-up. Two-sided P-values of ≤ .01 were considered statistically significant. Covariates with P-values ≤ .05 in univariate analyses were included in multivariate analyses; allo-HSCT in CR1 was included as a time-dependent covariate in the Cox model. MRD status at EOI2 was excluded from multivariate analyses as therapy could have been adjusted to the MRD status and the number of MRD positive patients was small.ResultsOf 1256 pediatric patients with KMT2A-r AML, data on HSCT in CR1 and ACAs were available for 1186 (94.4%) and 1204 patients (95.9%), respectively; 211 (17.8%) patients received HSCT in CR1 and ACAs were present in 601 (49.9%) patients. Compared with the KMT2A non-high-risk subgroup, patients in the KMT2A high-risk subgroup underwent HSCT in CR1 more often (23.8% vs 15.0%; P < .001). ACAs were borderline significantly more common in the KMT2A high-risk subgroup (54.1% vs 46.4%; P = .015).Univariate analysis of the probability of DFS (Table 1) showed that the KMT2A high-risk subgroup (HR 2.1; 95% CI, 1.7-2.5), age ≥10 years (HR 1.4; 95% CI, 1.2-1.7), and MRD ≥0.1 at EOI1 (HR 1.5; 95% CI, 1.1-1.9) were associated with DFS. HSCT in CR1 was a borderline significant prognostic factor (HR 0.7; 95% CI, 0.6-0.9).In a multivariate analysis for DFS (n=515) (Table 1), the KMT2A high-risk subgroup (HR 2.0; 95% CI, 1.6-2.6), MRD ≥0.1 at EOI1 (HR 1.7; 95% CI, 1.2-2.3), and HSCT in CR1 (HR 0.6; 95% CI, 0.4-0.9) were associated with DFS.Univariate analysis of the probability of OS (Table 1) showed that the KMT2A high-risk subgroup (HR 1.8; 95% CI, 1.5-2.2), age ≥10 years (HR 1.6; 95% CI 1.3-2.0), WBC ≥100 x10 9/L (HR 1.4; 95% CI, 1.1-1.7), the presence of ACAs (HR 1.4; 95% CI, 1.2-1.7), and MRD ≥0.1 at EOI1 (HR 2.1; 95% CI, 1.6-2.7) were associated with OS. HSCT in CR1 was not associated with OS. The effect of HSCT in CR1 was not significantly different between the KMT2A high-risk and non-high-risk subgroups.In a multivariate analysis for OS (n=557) (Table 1), the KMT2A high-risk subgroup (HR 1.9; 95% CI, 1.4-2.5), age ≥10 years (HR 1.5; 95% CI, 1.1-1.9), the presence of ACAs (HR 1.6; 95% CI, 1.2-2.1), and MRD positivity at EOI1 (HR 1.9; 95% CI, 1.4-2.5) were associated with OS.ConclusionsIn this cohort of KMT2A-r pediatric AML patients, the presence of ACAs at diagnosis was independently associated with inferior OS, but not with DFS. This may be due to the exclusion of refractory patients in DFS analysis, who were significantly more common in the group of patients with ACAs. Analysis has yet to be performed to distinguish karyotype complexity. In addition, allo-HSCT in CR1 was an independent predictor of improved DFS, but was not a prognostic factor for OS. [Display omitted] DisclosuresAbrahamsson: wedish Children´s Cancer Foundation. Research grants and 50% senior research position for clinical research on pediatric leukemia: Research Funding. Locatelli: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharamceutical: Speakers Bureau; Takeda: Speakers Bureau.

Fish evaluation of additional cytogenetic aberrations and hyperdiploidy in childhood Burkitt lymphoma

Beyond MYC rearrangement, Burkitt lymphoma (BL) often presents with additional aberrations. Biopsy touch imprints from 72 children with BL were tested with interphase fluorescence in-situ hybridization (i-FISH) for MYC, BCL2, BCL6, IGH, IGK and IGL rearrangements and copy-number aberrations involving 1q21/1p32, 7cen/7q31, 9cen/9p21, 13q14/13q34 and 17cen/17p13. Diploid status deviations were investigated with chromosome enumeration probes. MYC rearrangement was demonstrated in all cases. Additional aberrations included +1q (21/72:29.2%), +7q (14/72:19.4%), 13q- (14/72:19.4%), 9p-(6/72:8.3%) and hyperdiploidy (6/72:8.3%). Advanced clinical stage IV, +7q and 9p- were associated with shorter overall survival, with stage IV and +7q retaining prognostic significance on multivariate analysis. No relapse or death was reported among the hyperdiploid cases. This i-FISH investigation provides information on the genetic profile of BL and may prove valuable for patients with no karyotype analysis. Demonstration of hyperdiploidy could evolve research on clonal evolution pathways and probably identify a subgroup of children with favorable prognosis.

P-128: Accompanying with additional complex karyotype is a poor prognostic factor in patients with multiple myeloma with high-risk cytogenetics in the era of novel agents

<h3>Background</h3> High-risk cytogenetic abnormality (CA) influences the prognosis of multiple myeloma (MM) even in the era of novel agents. However, prognostic heterogeneity could exist in MM patients with high-risk CA and additional cytogenetic aberrations are possibly correlated with worse outcomes. We conducted a retrospective study in patients with MM with high-risk CA to evaluate whether the outcomes are different in each high-risk group and whether the existence of additional chromosomal abnormalities would lead to poor outcomes. <h3>Method</h3> Patients with newly diagnosed MM (NDMM) in our institute between February 2006 and December 2020 were enrolled in this retrospective cohort. We analyzed only patients who were treated with novel agents including proteasome inhibitor and/or immunomodulatory drugs. All of cytogenetic abnormalities were analyzed from bone marrow samples. In this cohort, we defined high-risk CA as del(17p), t(4;14), t(14;16), and/or 1q21 gain, all of which were identified using FISH analysis. We surveyed additional chromosomal aberrations using G-banding testing. Complex chromosomal abnormality was defined as three or more chromosomal aberrations accompanying with at least one structural aberration. The survival was calculated by the Kaplan Meier method, and statistical analysis was performed by the Log-rank test. Factors affecting OS and PFS were evaluated using Cox proportional hazard model. <h3>Results</h3> We analyzed 36 MM patients who had high-risk CA at initial diagnosis. Twelve patients had del(17p), 16 had t(4;14), four had 1q21 gain, and four had more than one high-risk CA; two patients with t(4;14) and 1q21 gain, one with del(17p) and 1q21 gain and one with del(17p), t(4;14), and 1q21 gain. G-banding testing showed that patterns of complex chromosomal abnormality were found in nine patients. No significant differences in progression-free survival (PFS) and overall survival (OS) were seen between each high-risk CA group. The tendency of shorter PFS and OS was observed in patients with concurrent complex chromosomal karyotype than patients with no additional chromosomal aberrations. Furthermore, we found that the existence of complex cytogenetic abnormality by G-banding was correlated with poor PFS by multivariate analysis (hazard ratio 4.01, 95% confidence interval 1.35–11.9, p=0.012). In addition, seven of nine MM patients with complex chromosomal karyotype had concurrent plasmacytoma. <h3>Conclusion</h3> Although the limitation of retrospective study design and the small sample size exists, our findings indicate that the coexistence of complex chromosomal abnormality, probably which reflects aggressive disease status like extraosseous or extramedullary disease, could be associated with poor prognoses of MM patients with high-risk CA.

Characteristics and Outcomes of Pediatric Patients with t(16;16)-AML: Results of a Case Series By the International BFM Study Group

IntroductionCore binding factor (CBF) acute myeloid leukemia (AML) inv(16)(p13.1q22)/t(16;16)(p13.1;q22)/CBFβ-MYH11 [inv(16)/t(16;16)] is associated with a favorable outcome in children. Aberrations inv(16) and t(16;16) result in the same fusion of the CBFβ subunit at 16q22 and the myosin-11 heavy chain gene at 16p13, and are thought to share common biological features and outcomes. However, CBFβ-MYH11 fusion transcripts are heterogeneous and may vary in terms of biological activity. Therefore, in this cohort study by the International Berlin-Frankfurt-Munster (I-BFM) study group, we evaluated clinical characteristics, prognostic features and outcomes in pediatric patients with t(16;16)-AML.MethodsPatients (age 0‒19 years) with cytogenetically or molecularly confirmed t(16;16)-AML, diagnosed by members of the I-BFM study group between 1990 and 2015, were included in the study. Patients with previous malignancies, chemotherapy, or radiotherapy were excluded. Data on baseline characteristics, including cytogenetic and molecular information, fusion type, treatment details and follow up were collected using standardized case report forms. If data on the CBFβ fusion type were missing, real-time quantitative PCR for fusion types A, D, and E was performed on available biobank material. The molecular characterization part of the study is ongoing. Herein, we present descriptive statistics and estimated outcomes related to achieving complete remission (CR) and probabilities of event-free survival (pEFS) and overall survival (pOS).ResultsThe study included 46 patients with t(16;16)-AML. Median age was 9.8 [interquartile range (IQR) 1.7‒11.8] years, median white blood cell (WBC) count at diagnosis was 74 [IQR 35‒80] ×109/L and the predominant FAB-type was M4Eo (49%). Eleven patients (24%) had central nervous system involvement at diagnosis. Information on common additional molecular aberrations (e.g. cKIT and RAS mutations) was unavailable for more than 50% of patients and therefore not considered. Information on fusion types was available for 13 patients (28%). Biobank material was used to determine CBFβ fusion type in 2 patients for whom it had previously been unknown. Another 9 samples from international groups are available and pending analysis. Most patients for whom information was available on CBFβ fusion type had type A (n=7, 54%), followed by type D (n=3, 23%) and type E (n=3, 23%). No other fusion types were identified. Patients with type non-A (n=6, 46%) were predominantly male (67%) and had FAB-type M4Eo (83%). They were older than patients with type A (11.9 vs 8.8 years, respectively) and had a higher WBC count (69 vs 48 ×109/L, respectively), but these differences were not significant. Additional cytogenetic aberrations occurred in 38% of patients. Gain of chromosome 8, 21 or 22 were the most common additional chromosomal aberrations. Distribution of additional cytogenetic aberrations was comparable between patient with fusion type A and other types.Patient outcome was excellent with a 100% CR rate and a 5-year pEFS and pOS of 80% [standard error (SE), 6.4%] and 87% [SE, 5.6%], respectively (Figure 1). Five patients suffered a relapse. Of them, 4 had WBCs >50 ×109/L at diagnosis. None of the 5 patients had additional cytogenetic aberrations. Two patients had fusion type A and type was unknown for the other 3 patients. Of 46 patients, 2 died after relapse and 3 died from toxic complications in first CR. These complications included failure to recover bone marrow hypocellularity and subsequent multi-organ failure (n=1), and sepsis after stem cell transplantation in CR (n=2).ConclusionThis is the first report of a relatively large cohort of pediatric t(16;16)-AML patients. Patient outcomes were very good, especially compared with those reported for patients with non-CBF leukemias. However, these patients were at risk of toxic death in CR. Clinical characteristics and outcomes were comparable with those reported previously for patients with inv(16). Although this case series was large, patient numbers remained too small to identify significant prognostic factors associated with outcome. Prospective trials are needed to determine other biological features that may explain differences in outcomes among patients with either t(16;16) or inv(16)-AML. [Display omitted] DisclosuresKaspers:Janssen-Cilag: Research Funding.

Comparison of the Outcome between Newly Diagnosed Patients in the Accelerated Phase and Chronic Phase with Chronic Myeloid Leukemia Treated with Frontline Tyrosine Kinase Inhibitors

Background: Accelerated phase (AP) chronic myeloid leukemia (CML) has an aggressive clinical course. Some patients with CML present as AP at the time of diagnosis. Although many studies have confirmed that tyrosine kinase inhibitors (TKIs) significantly improved survival in patients with CML in the chronic phase (CP), there is limited data on the outcome of newly diagnosed CML-AP patients in the era of TKIs.Aims: To compare progression-free survival and overall survival in CML-AP patients with those in CML-CP patients treated with frontline TKIs and identify factors associated with the outcome.Methods: According to the definition of European LeukemiaNet 2013, data of newly diagnosed CML-AP and CML-CP patients receiving TKIs at least 3 months from 2002 to 2016 were retrospectively analyzed. Kaplan-Meier curves were used to compare the probabilities of PFS and OS. Uni- and multivariate Cox regression models were built to identify independent variables (demographics; co-morbidity; disease phase and risk, CBC, and additional cytogenetic aberrations in Ph-positive cells at diagnosis; interval from diagnosis to start TKI-therapy; initial TKI used and early treatment-response) associated with the outcome.Results: In total, 101 CML-AP patients [with excess blasts (blasts ≥15%), n=13; with excess basophils (basophils ≥20%), n=88] and 656 CML-CP patients (Sokal low-risk, n=291; intermediate-risk, n=194; high-risk, n=111; unknown, n=60) were included. 463 (61%) were male. Median age was 39 (14-87) years. Patients received initial therapy with imatinib (n=660), nilotinib (n=85), or dasatinib (n=11) within 6 months from diagnosis. At 3 months, CML-AP patients with excess blasts (62%, 15% and 23%) and excess basophils (65%, 27% and 8%) achieved similar response (optimal, warning and failure) rates to CML-CP patients in Sokal intermediate-risk (66%, 20% and 14%) and high-risk (58%, 26% and 16%) (p=0.338), but significantly lower than those in Sokal low-risk (83%, 13% and 4%) and unknown (77%, 17% and 7%) (p<0.001). With a median follow-up of 39 months (range, 3-184 months), probabilities of PFS (p=0.014) and OS (p=0.152) at 5 years were the lowest in the CML-AP patients with excess blasts (78% and 92%), followed by CML-CP patients in Sokal high-risk (87% and 91%), intermediate-risk (92% and 95%), low-risk (95% and 97%), CML-AP patients with excess basophils (95% and 97%), and those with unknown-risk (96% and 98%). In multivariate analyses, while analyzing baseline and initial therapy variables, interval from diagnosis to starting TKI-therapy >2 months [HR 2.4 (1.1-4.9), p=0.020 and HR 2.6 (1.1-6.5), p=0.037) was associated with inferior PFS and OS; in addition, CML-CP patients in Sokal high-risk [HR 3.6 (1.1-6.5), p=0.038] was associated with inferior PFS, >60 years [HR 3.9 (1.2-13.3), p=0.027], inferior OS. While involving early therapy response, interval from diagnosis to starting TKI-therapy >2 months [HR 3.1 (1.4-6.6), p=0.009 and HR 3.2 (1.2-8.4), p=0.016] and achieving a response of “failure” at 3 months [HR 7.6 (3.7-15.6), p<0.001 and HR 8.1 (3.1-21.3), p<0.001] were variables associated with inferior PFS and OS; in addition, >60 years [HR 4.8 (1.4-16.1), p=0.010], inferior OS. There was no impact of initial TKI used (imatinib or 2nd generation TKI) on the outcome.Conclusions: Newly diagnosed CML-AP patients have comparable outcome to CML-CP patients treated with frontline TKIs, especially CML-AP patients with excess basophils. However, delayed therapy and poor early response to TKIs are significantly associated with unfavorable prognosis in either AP or CP patients with CML. Our data indicates timely and proper TKI-therapy and close monitoring will be a reasonable option for the treatment strategy in CML-AP patients in the era of TKIs. DisclosuresNo relevant conflicts of interest to declare.

Comprehensive Molecular Characterization of Myeloid Malignancies with 9q Deletion

Background and aims: Deletions in the long arm of chromosome 9, del(9q), are recurrent cytogenetic aberrations in myeloid neoplasms. While relatively common in patients with acute myeloid leukemia (AML), del(9q) occurs less frequently in other myeloid malignancies such as myelodysplastic syndromes (MDS) or myeloproliferative neoplasms (MPN). To present, cases with del(9q) in MDS and MPN are poorly characterized on a molecular level. We set out to define the size and minimally deleted region (MDR) of del(9q) as well as the spectrum of accompanying gene mutations in patients with MDS or MPN. Furthermore, the prognostic impact of del(9q) in MDS is still under debate. According to the revised international prognostic scoring system (IPSS-R), MDS patients with isolated del(9q) fall into the cytogenetic intermediate risk group (median overall survival, OS, of 32 months) based on the presence of a single aberration (Greenberg et al, Blood 2012). We therefore aim to evaluate if this risk stratification is appropriate for our patient cohort.Patients and methods: A total of 55 (26 female and 29 male) patients with MDS (n=40), MPN (n=8) and MDS/MPN overlap (n=7) were included in this study. The median age was 75 years (range: 23-94 years). Conventional cytogenetic analysis was performed for all patients. Cases (n=38) with sufficient clone size were investigated by array CGH (SurePrint G3 ISCA CGH+SNP Microarray, Agilent, Waldbronn, Germany). Mutation status was examined using an amplicon-based NGS panel targeting 40 genes commonly affected in myeloid neoplasia.Results: In 36/55 (65%) of patients, del(9q) was the sole cytogenetic aberration. Additional recurrent cytogenetic abnormalities included unbalanced rearrangements, n=8; del(5q), n=5; del(11q), del(20q), +8, +21 (n=2, each). Clinical follow-up data was available for 16 MDS patients with isolated del(9q), median OS was 35 months (range, 1- 91 months). In cases with array CGH data, size of the 9q deletion varied between 2.2 and 70.5 Mb (median, 33.9 Mb). We identified a MDR of 3.6 Mb ranging from genomic position 85,716,785 to 89,340,559 (UCSC hg19). A total of 21 genes are located in the MDR, including FRMD3, UBQLN1, KIF27, HNRNPK, SLC28A3 and NTRK2, which have previously been described in the MDR of del(9q) AML patients. Driver gene mutations were identified in 43/55 (78%) of patients. The number of mutated genes ranged from 1-5 (median: n=2). We did not observe significant differences in the number of mutated genes between younger or older patients (cut-off: 70 years), and patients with isolated del(9q) or additional cytogenetic aberrations. However, patients without evidence for a gene mutation (n=12) were significantly younger than patients with respective mutations (median age 70 vs. 76 years, p=0.014). Recurrently mutated genes included TET2 (39%), ASXL1 (31%), JAK2 (25%), U2AF1 (17%), RUNX1 (11%), EZH2 (8%), NRAS (7%), BCOR, KRAS, TP53 (6% each) and SRSF2 (5%). ASXL1 and TET2 were frequently co-mutated, as 12/20 (60%) of TET2 mutated cases also harbored ASXL1 mutations (p< 0.001). Overall, we identified a high prevalence of TET2 mutations in patients with del(9q). This association was even more pronounced when we limited our analyses to patients with isolated del(9q), where we observed a TET2 mutation frequency of 45%. In 7/31 (23%) of patients without TET2 mutation, other genes associated with epigenetic regulation, namely DNMT3A, ASXL1, EZH2, WT1, IDH1 and IDH2, were affected, underlining a high mutation rate (49% of total cohort) in this functional class. Mutations linked to the spliceosome machinery, SF3B1, SRSF2 and U2AF1, were mutated in 13/55 (24%) of patients in the total cohort and in 9/40 (23%) patients with MDS.Conclusions: Deletions in 9q are rare aberrations in MDS and MPN. Our analyses provide novel insights into the molecular profile of this cytogenetic subgroup. 1) Our patient cohort with MDS or MPN and del(9q) demonstrated a minimal deleted region in concordance with previous reports on the MDR of del(9q) AML patients, indicating a general pathogenic mechanism. 2) We identified gene mutations in 78% of our patient cohort, TET2 and other epigenetic regulators were mutated in 49% of patients with del(9q), suggesting cooperative pathogenic potential. 3) We observed a median OS of 35 months in patients with MDS and isolated del(9q), confirming the current stratification according to IPSS-R. [Display omitted] DisclosuresHartmann:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Meggendorfer:MLL Munich Leukemia Laboratory: Employment. Fasan:MLL Munich Leukemia Laboratory: Employment. Stengel:MLL Munich Leukemia Laboratory: Employment. Zenger:MLL Munich Leukemia Laboratory: Employment. Zieschang:MLL Munich Leukemia Laboratory: Employment. Kern:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

Mutation Screening at Diagnosis Reveals a High Frequency of ASXL1 Mutations in CML Patients Who Fail to Achieve Molecular Remission Criteria after One Year of TKI Treatment

Background: Tyrosine kinase inhibitors (TKI) revolutionized treatment of chronic myeloid leukemia (CML). While response rates are high, a subset of patients does not show the expected decrease or eradication of BCR-ABL1 . According to ELN guidelines (Baccarani et al. 2013) BCR-ABL1/ABL1 ratio>1% after one year of TKI is considered failure. Mechanisms of failure include the acquisition of additional genetic changes, e.g. cytogenetic aberrations and mutations in the ABL1 kinase domain but also in other genes. Here, we ask the question, if specific mutations are not only acquired but may already be present at initial diagnosis of patients with slow or no TKI response (primary failure according to ELN). Aim: To screen CML patients at diagnosis, who failed ELN remission criteria after one year, for mutations in genes, which are frequently mutated in myeloid malignancies. Patients and Methods: In a backtracking approach, we selected diagnostic samples of 48 CML patients (25 males, 23 females) with a median age of 64 (range: 23-84) years, who failed first year molecular remission criteria. Median BCR-ABL1/ABL1 ratio was 3.603 [1.158-58.318] after 12 (11-16) months of imatinib (n=42), second generation TKI (n=5) treatment or both (n=1). Patients had a p210 BCR-ABL1 fusion (e13a2 [n=24], e14a2 [n=18], both [n=6]) and no additional cytogenetic aberrations at diagnosis. We sequenced DNA of bone marrow (n=28) or peripheral blood (n=20) samples drawn at diagnosis on NextSeq or MiSeq sequencers after TruSeq library preparation (Illumina, San Diego, CA). We used SeqNext 4.3 for data analysis (JSI, Kippenheim, Germany). The panel covered 48 genes including the epigenetic regulators: ASXL1, ASXL2, BCOR, DNMT3A, EZH2, IDH1, IDH2 and TET2 . Results: We identified mutations in 13/48 samples at initial diagnosis (27%). Only one patient had two mutations (total, n=14 mutations). There was no correlation of mutations with types of transcript, age, gender, hemoglobin level, WBC count, percentage of Ph+ cells by FISH, BCR-ABL1/ABL1 ratio at diagnosis or with BCR-ABL1/ABL1 ratio after one year of TKI. Twelve of the 14 (86%) mutations were found in genes involved in chromatin modification or DNA methylation. We screened four splicing machinery genes (SF3B1, SRSF2, U2AF1, ZRSR2), which are frequently mutated in other myeloid malignancies, but no mutation was found. In 8/48 (17%) patients, we found an ASXL1 mutation (57% of all mutations). Other mutated genes were ASXL2, BCOR, CALR, NRAS (n=1 each) and DNMT3A (n=2). The comparison of ASXL1 mutation types in this CML cohort to other myeloid malignancies revealed a significant shift in mutation types: e.g. in myelodysplastic syndrome (Haferlach et al. 2014) and chronic myelomonocytic leukemia (Meggendorfer et al . 2012), c.1934dup and c.1900_1922del (ENS0375687) constitute the majority of mutations (64 [42%] and 23 [15%] of 152, respectively), whereas there was only one c.1900_1922del and no c.1934dup in our CML cohort (p=0.023). Further, we used follow-up samples after one year of TKI to evaluate if mutations are derived from the CML clones. In all patients with available data for ASXL1 (n=6), mutation burdens showed a quantitative course which paralleled BCR-ABL1 ratio indicating that ASXL1 mutations are part of the CML clone present at diagnosis. In the patient with a CALR mutation, the CALR burden remained unchanged despite BCR-ABL1 reduction, indicating a BCR-ABL1 gain in a preexisting CALR mutated myeloproliferative neoplasm. In comparison to ASXL1 mutation rates (4/74 [5%]) in a published cohort with optimal responders (Kim et. al. 2017), we found a significantly higher number of ASXL1 mutations (8/48 [17%]) at diagnosis of our CML patients, who failed first year molecular remission criteria (p=0.041). Conclusions: (1) At diagnosis of CML, mutations were detected (esp. in ASXL1) in 27% of patients with TKI failure according to ELN criteria after one year. Compared to other myeloid malignancies, patients showed a different pattern of ASXL1 mutations. (2) No mutations in spliceosome genes were found. (3) Stringent BCR-ABL1 monitoring allows early adjustment of therapy in case of suboptimal response, but analysis of additional mutation patterns could help understanding the biology of failure and would allow up-front adjusted therapy decisions or different monitoring strategies. (4) Mutations such as ASXL1 at diagnosis may contribute to suboptimal TKI response. Disclosures Baer: MLL Munich Leukemia Laboratory: Employment. Kern: MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach: MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach: MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

PPM1D Mutations in MDS Patients with Deletion of Chromosome 5q

Background: Patients with myelodysplastic syndrome with deletion of chromosome 5q (MDS del(5q)) have a favorable prognosis, but TP53 mutations occur in 13-18% of these patients and are known as unfavorable prognostic marker. Recently, Protein Phosphatase Magnesium-Dependent 1 (PPM1D) mutations have been described in clonal hematopoiesis and were found more commonly in patients with therapy-related MDS than in patients with primary MDS (15% vs. 3%) (Lindsley et al. 2017). PPM1D encodes a serine-threonine protein phosphatase that inhibits the p53 tumor suppressor pathway. It is therefore of great interest to evaluate the frequency and potential co-occurrence of PPM1D mutations in patients with MDS del(5q).Aim: To determine the frequency and potential clinical impact of PPM1D mutations in a large cohort of MDS del(5q) patients.Methods: 219 patients with MDS or AML following MDS (sAML) and deletion of chromosome 5q were included in the analysis. Patients were classified following the 2008 WHO classification. Patients with MDS (n=196) or sAML (n=23) were cytogenetically characterized by chromosome banding analysis and molecularly analyzed for mutations in all exons (1 to 6) of PPM1D by Sanger or next-generation sequencing (NGS). Patients were also analyzed for mutations in TP53 and CSNK1A1 .Results: A total of 11 PPM1D mutations were found in 10 (4.6%) MDS patients with del(5q). The mutation frequency was similar in patients with MDS with isolated del5q (8 of 167, 4.8%) compared to patients with more advanced MDS or secondary AML (2 of 52, 3.8%, P=.78). Four patients had nonsense mutations, 3 patients had frameshift mutations (one patient with 2 frameshift mutations), and 3 patients had missense mutations. Nine mutations were found in the previously described hotspot region of PPM1D between amino acids 427 and 542, which is located downstream of the phosphatase domain of PPM1D. Three of the 10 PPM1D mutated patients had additional cytogenetic aberrations besides del(5q) (trisomy 8; complex karyotype in two patients). TP53 was also mutated in the two patients with complex karyotype and in one additional patient with a nonsense mutation of PPM1D . None of the PPM1D mutated patients had a mutation in CSNK1A1 .Patients with mutated PPM1D were slightly older than PPM1D wildtype patients (median age 77.7 vs 71 years, not significant). Eight of 10 PPM1D mutated patients had a diagnosis of MDS del(5q) and 2 patients had MDS RAEB2 with del(5q) accompanied by a complex karyotype. There were no significant differences in the distribution of sex, WHO subtypes, cytogenetic risk according to the international prognostic scoring system (IPSS), WBC count, hemoglobin, platelet count and IPSS risk score between PPM1D wildtype and mutated patients. Two of the 10 patients were transfusion dependent and none of 7 patients with available information transformed to AML.Survival information was available for 156 patients with MDS del(5q) (excluding other WHO subtypes of MDS/sAML) including 8 patients with mutated PPM1D and 15 patients with mutated TP53 . Median follow-up from the time of sample harvest was 2.5 years. The probability of survival at 2 years was 100% for PPM1D mutated and TP53 mutated patients, respectively, and 84% for PPM1D/TP53 wildtype patients (P=.18, log-rank test, Figure 1A). None of 7 PPM1D mutated patients and 1 of 13 TP53 mutated patients with available information underwent allogeneic hematopoietic cell transplantation.Survival information was available for 45 patients with del(5q) and more advanced MDS or secondary AML. The 14 patients with TP53 mutation (including 2 patients with additional PPM1D mutation) had a significantly shorter OS than TP53 wildtype patients (P<.001, 2-year OS 0% vs 51%, Figure 1B). One PPM1D mutated patient responded well to lenalidomide treatment for the duration of 3.2 years.Conclusion:PPM1D mutations are recurrently mutated in MDS patients with del(5q) with a frequency of 4.6% and may co-occur with TP53 mutations. PPM1D mutated patients were not specifically associated with patient characteristics or outcome. Interestingly, in our cohort of patients with MDS with isolated del(5q), TP53 mutations were not associated with unfavorable outcome.VP and MM contributed equally as first authors. TH and MH contributed equally as last authors. [Display omitted] DisclosuresMeggendorfer:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Platzbecker:Novartis: Consultancy, Research Funding; Acceleron: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding. Thiede:Novartis: Consultancy, Speakers Bureau; Roche: Consultancy; Agendix: Employment; Bayer: Consultancy, Speakers Bureau. Germing:Novartis: Honoraria, Research Funding; Janssen: Honoraria; Celgene: Honoraria, Research Funding. Schroeder:Celgene: Consultancy, Honoraria, Other: travel support. Kobbe:Celgene: Other: Advisory Board, Research Funding. Haase:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Research Funding. Dohner:Novartis: Honoraria, Research Funding. Sperr:Novartis: Other: Register; Phadia: Research Funding; Meda: Research Funding; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Teva: Honoraria. Valent:Novartis: Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Incyte: Honoraria; Blueprint: Research Funding; BMS: Honoraria; Celgene: Honoraria, Research Funding; Pfizer: Honoraria; Deciphera: Honoraria, Research Funding; Teva: Honoraria. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

Impact of 9q Deletions on the Classification in AML

Background: In the 2016 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia the deletion of the long arm of chromosome 9 (del(9q)) was excluded as a defining cytogenetic abnormality for AML with myelodysplasia-related changes due to its frequent association with NPM1 and biallelic CEBPA mutations.Aim: Investigation of the frequency of del(9q) in AML and its accompanying molecular and cytogenetic abnormalities to assess whether or not del(9q) is associated with a myelodysplasia-related mutation profile.Patients and Methods: We evaluated 9762 AML patients (pts) diagnosed between 2005 and 2017 for del(9q) using chromosome banding analysis (CBA). Pts with del(9q) were further analyzed for mutations in NPM1 , CEBPA and RUNX1 with amplicon sequencing to categorize them according to the WHO classification. Pts without a class defining aberration or a complex aberrant karyotype were screened for AML- or MDS-related mutations (ASXL1, BCOR, EZH2, FLT3- ITD , FLT3- TKD , SF3B1, SRSF2, STAG2, TET2, TP53, U2AF1, WT1 and ZRSR2 ). Variants of unknown significance were excluded from statistical analysis. The size of the deleted region on chromosome 9 was evaluated by array CGH (Agilent Technologies, Santa Clara, CA) and NUP98 -rearrangements were investigated by FISH(MetaSystems, Altlussheim, Germany).Results: In 114/9762 pts (1 %) a del(9q) was detected by CBA. This cohort with del(9q) comprised 60 male and 54 female pts, median age was 63 years (range: 16 - 90 years). Del(9q) was accompanied by the following rearrangements: RUNX1-RUNX1T1 rearrangement in 20/114 pts (18 %), PML-RARA in 5/114 pts (4 %), KMT2A in 2/114 pts (2 %) and MECOM in 1/114 pts (1 %). In 20/114 pts (18 %) a NPM1 mutation and in 7/114 pts (6 %) a biallelic CEBPA mutation was observed. Furthermore, RUNX1 mutations were found in 3/114 pts (3 %). The remaining 56 pts (49 %) were divided into the following three groups: pts with del(9q) as a sole cytogenetic abnormality (del(9q) sole, 8/114 pts, 7 %), pts with one or two additional cytogenetic aberrations (del(9q) other, 19/114 pts, 17 %) and pts with complex aberrant karyotype (complex, 29/114 pts, 20 %) harboring 4 to 29 cytogenetic aberrations (median: 8). Cases with del(9q) sole and other (n = 27) were further characterized. NUP98 -FISH analysis revealed a NUP98 -rearrangement in 5/27 pts (19 %) in the del(9q) sole and other group. Moreover, two pts with del(9q) showed AML specific rearrangements (t(8;16)(p11;p13) and t(3;5)(q25;q35)). The most frequently mutated genes in del(9q) sole and other were: FLT3 -ITD (8/23 pts, 35 %), TET2 (7/27 pts, 26 %), FLT3 -TKD (4/21 pts, 19 %) and WT1 (3/26 pts, 11 %). A very high frequency of FLT3 -ITD and FLT3 -TKD were found in pts with del(9q) and balanced rearrangements (5/7 pts, 71 %).To identify whether pts with del(9q) sole and other rather resemble a molecular mutation profile typical for secondary AML arising from MDS (s-AML), the presence of gene mutations related to s-AML (according to Lindsley, et al., 2015, Blood) was evaluated. 9 pts (33 %) had a mutation in at least one of these genes, 14 pts (52 %) showed no such mutation and 4 pts (15 %) could not be fully analyzed.Array CGH showed that in pts with del(9q) sole the deletion size ranged from 14 - 42 Mb (median: 28 Mb), in pts with del(9q) other from 19 - 70 Mb (median: 32 Mb). A minimal deleted region for pts with del(9q) sole and other could not be determined for all pts due to the strong variation between the respective deleted regions.Follow up data was available for 75 pts with a median follow-up of 27 months. The median overall survival (OS) for pts with RUNX1-RUNX1T1 , NPM1 and bialleic CEBPA mutation was not reached. It was 73 month for pts with del(9q) sole and other and 16 month for pts with complex karyotype, RUNX1 mutations or MECOM rearrangements. The OS of first two groups did not differ significantly, but was significantly distinct from the last group (p = 0.03 and 0.03, respectively).Conclusion: In 1 % of AML pts a del(9q) was present. Del(9) frequently co-occured with RUNX1-RUNX1T1 , biallelic CEBPA and NPM1 mutations, NUP98 -rearrangements and other AML-typical translocations. A mutation signature typical for s-AML was infrequent. Thus, it seems reasonable that the del(9q) is no longer regarded as a defining cytogenetic abnormality for AML with myelodysplasia-related changes, in particular as prognosis in del(9q) cases with non-complex karyotype is favorable. DisclosuresBalk:MLL Munich Leukemia Laboratory: Employment. Stengel:MLL Munich Leukemia Laboratory: Employment. Meggendorfer:MLL Munich Leukemia Laboratory: Employment. Fasan:MLL Munich Leukemia Laboratory: Employment. Kern:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

High Grade B Cell Lymphoma with MYC and BCL2 and/or BCL6 Rearrangements Depict a High Complexity on the Cytogenetic, but Not on the Molecular Genetic Level and Show MYC Mutations As Prognostic Marker

Background: In the revised WHO classification of 2016, cases of large B cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements were categorized as “HGBL (high grade B cell lymphoma, with MYC and BCL2 and/or BCL6 rearrangements)”, except for cases that fulfill the criteria for a follicular or lymphoblastic lymphoma. A detailed molecular analysis of these cases and comparison of accompanying aberrations has not been available to date.Aims: Evaluation of associated genetic alterations and prognosis in HGBL cases with rearrangement of (i) MYC + BCL2 , (ii) MYC + BCL6 or (iii) MYC + BCL2+BCL6.Patient cohorts and methods: The total cohort comprised 70 cases with MYC and BCL2 and/or BCL6 rearrangements (39 male, 31 female). Cases were selected by detection of the rearrangements by FISH (fluorescence in situ hybridization), cases diagnosed as CLL, follicular or lymphoblastic lymphoma were excluded. Median age was 67 years (range: 44-87 years). All patients were investigated using chromosome banding analysis (CBA) and FISH using probes for MYC , IGH-BCL2 and BCL6 . Additionally, mutation analyses of ATM , BCL2, BIRC3, BRAF, BTK, CBL, CSF3R, CSNK1A1, CXCR4, EGR2, ETNK1, FBXW7, FLT3, ID3, IDH1, IDH2, KIT, KLF2, KRAS, MAP2K1, MYC, MYD88, NFKBIE, NOTCH2, PHF6, PLCG2, POT1, PTPN11, SAMHD1, SETBP1, SF3B1, SRSF2, STAT3, STAT5B, TET2, TP53, U2AF1, UBR5, WT1, XPO1 and ZRSR2 was performed. Variants of unknown significance were excluded from statistical analysis.Results: We identified 33/70 cases with rearrangement of MYC + BCL2 , 10/70 cases with MYC + BCL6 and 27/70 cases with MYC + BCL2 + BCL6 (47%, 14% and 39%, respectively). In the total cohort, CBA revealed a complex karyotype (>3 abnormalities) in 59/70 (84%) of patients, 10/70 (14%) harbored an aberrant but non-complex karyotype, whereas in 2/70 (3%) of cases, CBA analyses failed due to insufficient cell proliferation. Regarding the subgroups, a complex karyotype was observed in 82%, 80% and 89% of cases, respectively (for MYC + BCL2 , MYC + BCL6 and MYC + BCL2 + BCL6 rearrangement). If only aberrations additional to MYC / BCL2 / BCL6 rearrangements were calculated, >3 aberrations were detected in 64% of cases (67%, 70% and 60%, respectively). The most frequent additional aberrations included 13q deletions, +12, gain of 1q and 6q deletions. Median number of additional cytogenetic aberrations was n=8 (range: 0-36). Despite the high cytogenetic complexity, the frequency of TP53 deletions was relatively low (6% in the total cohort), three of them harboured a concomitant TP53 mutation in the other allele. Mutation analyses of 40 genes revealed a median number of n=1 mutations in the total cohort with no differences between the three subgroups. The range of the number of molecular mutations was 0-3 (0 mutations: 31%; 1 mutation: 44%; 2 mutations: 20%; 3 mutations: 5%). Interestingly, out of the 40 genes analysed, mutations were almost exclusively detected in BCL2 (40%), MYC (21%) and TP53 (21%) in the total cohort. Other recurrent mutations were observed for ID3 and PHF6 only (3%, respectively). Cases with MYC+BCL6 rearrangement showed a higher - although not statistically significant - frequency of MYC mutations compared to the other cases (40% vs. 18%), while BCL2 mutations were rarely detected in this subgroup (10% vs. 45%, p=0.033). Of note, mutations in TP53 were found to show a trend towards a lower frequency in cases with a “triple hit” (MYC+BCL2+BCL6 ) in comparison to the “double hit” cases (MYC+BCL2 and MYC+BCL6 ) (11% vs. 28%).Median overall survival (OS) in the total cohort was 61 months. Cases with MYC + BCL2 showed a shorter OS compared to cases with MYC+BCL2+BCL6 rearrangements, although this was not statistically significant (37 vs.61 months). Unfortunately, OS could not be determined for cases with MYC+BCL6 due to the low number of cases. Mutations in MYC, but not in BCL2 or TP53 , showed a negative impact on OS in the total cohort (16 vs. 61 months, p=0.046).Conclusion: 1) Cases with rearrangements in MYC , BCL2 and/or BCL6 depict a high complexity on the cytogenetic, but not on the molecular genetic level. 2) Molecular mutations are almost exclusively detected in BCL2 , MYC and TP53. 3) Cases with MYC+BCL6 rearrangements differ from the other subgroups by showing a higher frequency of MYC mutations and a lower frequency of mutations in BCL2 . 4) Mutations in MYC negatively impact on OS. 5) Thus, our data support the current WHO classification and complement it on a molecular level. DisclosuresStengel:MLL Munich Leukemia Laboratory: Employment. Kern:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Meggendorfer:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

Secondary cytogenetic abnormalities in core-binding factor AML harboring inv(16) vs t(8;21)

Patients with core-binding factor (CBF) acute myeloid leukemia (AML), caused by either t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)(p13;q22), have higher complete remission rates and longer survival than patients with other subtypes of AML. However, ∼40% of patients relapse, and the literature suggests that patients with inv(16) fare differently from those with t(8;21). We retrospectively analyzed 537 patients with CBF-AML, focusing on additional cytogenetic aberrations to examine their impact on clinical outcomes. Trisomies of chromosomes 8, 21, or 22 were significantly more common in patients with inv(16)/t(16;16): 16% vs 7%, 6% vs 0%, and 17% vs 0%, respectively. In contrast, del(9q) and loss of a sex chromosome were more frequent in patients with t(8;21): 15% vs 0.4% for del(9q), 37% vs 0% for loss of X in females, and 44% vs 5% for loss of Y in males. Hyperdiploidy was more frequent in patients with inv(16) (25% vs 9%, whereas hypodiploidy was more frequent in patients with t(8;21) (37% vs 3%. In multivariable analyses (adjusted for age, white blood counts at diagnosis, and KIT mutation status), trisomy 8 was associated with improved overall survival (OS) in inv(16), whereas the presence of other chromosomal abnormalities (not trisomy 8) was associated with decreased OS. In patients with t(8;21), hypodiploidy was associated with improved disease-free survival; hyperdiploidy and del(9q) were associated with improved OS. KIT mutation (either positive or not tested, compared with negative) conferred poor prognoses in univariate analysis only in patients with t(8;21).

Additional Cytogenetic Aberrations Indicative of Poor Prognosis in AML with RUNX1/RUNX1T1 Rearrangement: Karyotype a Chromosomal Blueprint

AML is a highly heterogeneous disease with t(8;21)(q22;q22) as a frequently occurring aberration. While most studies show these patients to demonstrate a good response to standard chemotherapy, a lot of Indian and Western studies suggest otherwise. Trisomy 4 is a rare but a specific chromosomal abnormality in certain subtypes of AML. Although the significance of t(8;21) with trisomy 4 in AML remains uncertain, patients with this abnormality are typically associated with poor prognosis. Similarly, KIT mutations are also common with t(8;21) AML suggesting poorer outcomes. We report a case of AML with duplicated derivative 21 due to t(8;21), trisomy 4 and KIT mutation at baseline and an additional t(2;12) and ASXL2 mutation at relapse.