Kooperativer Bibliotheksverbund

In: Blood, American Society of Hematology, Vol. 134, No. Supplement_1 ( 2019-11-13), p. 531-531

Abstract: Chromosomal translocations found in acute myeloid leukemia (AML) can generate oncogenic fusions with aberrant epigenetic and transcriptional functions. However, direct therapeutic targeting of leukemia fusion proteins has not been accomplished so far. Although high remission rates can be induced in patients diagnosed with AML1-ETO/t(8;21)-positive AML only half of them achieve long-term disease-free survival (Papaemmanuiel et al., NEJM, 2016). In the other half of these patients, the disease maintaining leukemia stem cell (LSC) clone is not eliminated by chemotherapy. A functional characteristic of LSCs is unlimited self-renewal capacity and several signaling pathways have been identified that maintain stem cell self-renewal. Targeting the oncogene induced self-renewal capacity of LSCs has great potential to eliminate the malignant clone and prevent relapse. To identify oncogenic cellular functions with relevance for LSC self-renewal, we performed global proteome profiling in murine AML1-ETO9a (AE) compared to MLL-AF9 (MA9) driven LSCs. Gene set enrichment analyses revealed a significant enrichment of calcium-dependent cellular functions and Phospholipase C (PLC)-signaling in AE LSCs. These data could be confirmed in sorted CD34+ blasts from AE-positive AML when compared to non-AE-AML. All PLC family members are regulators of Ca2+ homeostasis. However, when analyzing published AML gene expression datasets we found exclusively PLCG1 to be highly expressed in t(8;21) AML. Conditional activation of AE in embryonic stem cells resulted in induction of PLCG1 expression and PLCG1 was identified as a direct target of the AE fusion by ChIP-sequencing in AE-positive Kasumi-1 cells.Here, PLCG1 depletion resulted in reduced Ca2+ release, impaired proliferation and reduced colony formation in vitro. In a xenograft model, inactivation of PLCG1 resulted not only in delayed disease development (median survival shNT vs. shPLCG1: 135 days vs. not reached, p=0.02) but also in reduction of disease penetrance by 87%. Consistent with these results, transcriptome analysis revealed strong induction of gene sets related to myeloid differentiation and down-regulation of gene sets linked to proliferation, stemness and c-Myc targets. To confirm the functional role of PLCG1-signaling in AE-driven LSCs, we generated a new conditional knockout mouse model for Plcg1 and induced leukemia using the oncogenes AE and KRAS-G12D (AE/K). Genetic inactivation of Plcg1in vivo after engraftment of leukemic cells resulted in significant reduction of LSC numbers (p=0.04) and a reduction of disease penetrance by 67% in primary recipients. Isolated LSCs revealed induction of differentiation, loss of cell cycle activity and failed to re-establish disease in secondary recipients (Plcg1+/+ vs. Plcg1-/-: median survival 12 days vs. not reached; p=0.0001). In contrast, genetic deletion of Plcg1 appeared to be dispensable for normal murine HSC function during primary and secondary transplantation. Primary human t(8;21) AML cells (derived from 4 different donors) showed impaired colony forming capacity following PLCG1 inactivation in vitro irrespective of co-occurring mutations while colony formation of human CD34+ BM cells was not affected to a major extent. As Ca2+ signaling appeared deregulated in t(8;21) AML, we aimed to investigate the effects of pharmacologic Ca2+ inhibition as a tractable target downstream of PLCG1. To assess specifically for LSC function, we treated primary recipient mice with established AE/K-driven leukemia with the clinically approved calcineurin inhibitor ciclosporin (CsA), a compound that blocks intracellular Ca2+ release. CsA-treated animals showed reduction in total leukemic burden (spleen weight diluent vs. CsA, p=0.01) and LSC numbers (p=0.02). This resulted in increased survival of secondary recipient hosts (diluent vs. CsA: median 15 vs. 29 days, p=0.0002). These effects could not be observed for other oncogenes (e.g. MA9), confirming its specificity for AE-induced disease. Consistently, CsA treated primary human t(8;21)-positive AML blasts failed to form colonies in methylcellulose. In summary, our findings identified PLCG1-dependent Ca2+ signaling as a critical pathway for t(8;21) LSC maintenance and self-renewal. Most importantly, as PLCG1 is dispensable for maintenance of normal HSPCs, PLCG1 could serve as a novel therapeutic target in t(8;21) AML. Disclosures Döhner: Daiichi: Honoraria; Jazz: Honoraria; Novartis: Honoraria; Celgene: Honoraria; Janssen: Honoraria; CTI Biopharma: Consultancy, Honoraria. Bullinger:Novartis: Honoraria; Menarini: Honoraria; Jazz Pharmaceuticals: Honoraria; Abbvie: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Seattle Genetics: Honoraria; Sanofi: Honoraria; Janssen: Honoraria; Hexal: Honoraria; Gilead: Honoraria; Daiichi Sankyo: Honoraria; Celgene: Honoraria; Bristol-Myers Squibb: Honoraria; Bayer: Other: Financing of scientific research; Pfizer: Honoraria.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood-2019-121996

Language: English

Publisher: American Society of Hematology

Publication Date: 2019

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 134, No. Supplement_1 ( 2019-11-13), p. 529-529

Abstract: Several cellular pathways control the fine balance between self-renewal and differentiation to maintain leukemia-initiating cell (LIC) function. To identify cellular dependencies with relevance for oncogenic fusion proteins, we performed global proteome profiling. Acute myeloid leukemia (AML) was induced by retroviral expression of either MLL-AF9 (MA9) or AML1-ETO9a (AE) in murine hematopoietic stem and progenitor cells (HSPCs) (Lineage-Sca1+Kit+, LSK) which were subsequently transplanted into irradiated syngeneic recipients. After onset of leukemia, LIC-enriched (GFP+ Kithigh) cells isolated from 4 different primary recipients (per oncogene) were analyzed by in-depth quantitative proteomic analysis using high-resolution mass spectrometry (MS). More than 3,000 proteins were quantified with 868 proteins being differentially expressed between MA9 and AE LIC-enriched populations. In MLL-rearranged (MLLr) cells, gene set enrichment analysis (GSEA) revealed significant enrichment of cellular functions related to protein degradation and proteasome function. As this enrichment is present in MLLr-leukemia but not AE-driven LICs, may indicate an oncogene specific vulnerability. Expression of proteasome subunits is highly heterogeneous between different cell types and therefore may also be influenced by the underlying differentiation stage or oncogenic fusion. In published AML gene-expression datasets, immunoproteasome (IP) subunits PSMB8/LMP7 (p=0.0003***), PSMB9/LMP2 (p=0.0007***) and PSMB10/MECL1 (p & lt;0.0001****) showed significantly higher expression in MLLr compared to non-MLLr-AML. IP is a proteasomal variant constitutively expressed in cells of hematopoietic origin, induced under stimulation with pro-inflammatory cytokines and relevant for mediating stress-responses during inflammation and infection. To assess for functional dependency of MLLr cells on IP subunits we performed an in vitro CRISPR/Cas9 dropout screen in MLLr MOLM-13 cells. Genetic inactivation of PSMB8/LMP7 resulted in outcompetition with 3/5 sgRNAs, while there was less dependency detectable for the other subunits. Specificity of this finding was confirmed in 5 different cell lines (4 MLLr; 1 non-MLLr) by RNAi using 2 shRNAs against PSMB8/LMP7 versus non-targeting control. To confirm these findings in primary cells, we used a previously published conventional LMP7 knockout mouse model (Fehling et al., Science, 1994). LSK cells sorted from the bone marrow (BM) of LMP7 knockout and wildtype mice were retrovirally transformed with either MA9, MLL-ENL (ME) or NUP98-HOXA9 (as non-MLLr control) to assess for disease development by serial plating in methylcellulose. Only in MA9 or ME transformed cells LMP7-deficiency limited re-plating capacity to 2-4 rounds. When we injected 2,5x 104 MA9-infected LSK cells into sublethally irradiated recipient mice, recipients of MA9-LMP7-/- cells (n=12) and MA9-LMP7+/+ (n=12) showed development of AML. However, recipients of MA9-LMP7-/- cells had a significant delay in AML development (median survival 63.0 days for LMP7+/+ versus 92.5 days for LMP7 -/- animals, p=0.0387*). Besides the significant delay in AML development, disease penetrance was reduced by 50%, indicating that deficiency for LMP7 impairs development of MA9 driven AML. In contrast, immunophenotypic abundance of HSPCs in LMP7-/- versus LMP7+/+ animals revealed comparable numbers in all relevant subpopulations. Competitive transplantation of LMP7-/- BM into recipient hosts showed no competitive disadvantage or lack of self-renewal capacity compared to LMP7+/+ controls. Pharmacologic inhibition of IP function using the specific LMP7-inhibitor PR-957 (ONX-0914) resulted in significant delay of disease development in secondary recipient hosts. To assess its effect on LIC frequency we performed limiting dilution assays of MA9 leukemic cells in sublethally irradiated recipient mice. PR-957 treatment reduced LIC frequency compared to DMSO control (1/57410 vs. 1/4450). Pharmacologic inhibition of PSMB8/LMP7 in human MLLr leukemia cell lines induced cellular differentiation. Likewise, cell cycle and metabolism appeared affected, functions which could be confirmed by global transcriptome analysis. Taken together, our studies uncover a selective dependency of MLLr-leukemia on IP function and identify PSMB8/LMP7 as a tractable target. Disclosures Heidel: Celgene: Consultancy; Novartis: Consultancy, Research Funding; CTI: Consultancy.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood-2019-122100

Language: English

Publisher: American Society of Hematology

Publication Date: 2019

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 140, No. Supplement 1 ( 2022-11-15), p. 491-492

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood-2022-157574

Language: English

Publisher: American Society of Hematology

Publication Date: 2022

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 127, No. 23 ( 2016-06-09), p. 2890-2902

Abstract: CDK6 directly regulates transcription of FLT3 and PIM1 in a kinase-dependent manner. CDK6 kinase inhibition impairs not only FLT3-dependent cell growth in vitro but also FLT3-driven leukemogenesis in vivo.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood-2015-11-683581

Language: English

Publisher: American Society of Hematology

Publication Date: 2016

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 140, No. Supplement 1 ( 2022-11-15), p. 726-727

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood-2022-157245

Language: English

Publisher: American Society of Hematology

Publication Date: 2022

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 130, No. Suppl_1 ( 2017-12-07), p. 792-792

Abstract: The family of cold shock proteins (CSPs) is highly conserved and consists of 8 members, including Ybx1-3, Csde1 and Lin28. Ybx1 is a multifunctional DNA/RNA binding protein that modulates gene transcription and translation during inflammation and malignant transformation. Recently, our group identified Ybx1 as a mediator of Jak2 signaling in MPN that protects Jak2-mutated cells from Jak-inhibitor induced apoptosis. In a recently published genome wide CRISPR-Cas9 dropout screen in AML cell lines, depletion of Ybx1 resulted in the highest dropout indices compared to other CSP members, with strongest dependencies in cell lines harboring MLL-rearrangements. Protein expression of Ybx1 in healthy individuals (n=10), primary MDS (n=54) and AML (n=58) bone marrow (BM) biopsies, revealed high protein expression in the majority of AML and MDS cases. Consistently, gene expression data revealed high mRNA expression of Ybx1 in AML samples compared to normal controls. Genetic inactivation of Ybx1 in human AML cell lines by RNAi resulted in reduced proliferative capacity. Therefore, we sought to investigate the requirement for Ybx1 in malignant transformation. We used BM cells from a previously published conventional knockout (ko) mouse model (Lu et al., 2005) in which homozygous deletion is embryonically lethal due to brain malformation. We sorted Lineage-Sca1+Kit+ (LSK-) cells from the BM of heterozygous (Ybx1+/-) and wildtype (Ybx1+/+) mice. Cells were retrovirally infected with either MLL-AF9 (MA9) or HoxA9 and Meis1a (HA9M1) to assess for disease development by serial plating in methylcellulose. Haploinsufficiency for Ybx1 in MA9- or HA9M1 transformed cells limited re-plating capacity to 2-4 rounds. When we injected 2,5x 104 MA9-infected LSK cells into sublethally irradiated recipient mice, recipients of MA9-Ybx1+/- cells (n=8) and MA9-Ybx1+/+ (n=10) showed development of AML. However, recipients of MA9-Ybx1+/- cells had a significant delay in AML development (median survival 67.5 days for Ybx1+/+ versus 101.5 days for Ybx1+/- animals, p=0.0078**). This effect appeared even more pronounced when 1x 106 whole BM cells were transplanted into sublethally irradiated secondary recipients. Besides a significant delay in AML development (median survival 37.5 days for recipients of MA9-Ybx1+/+ versus 79 days for MA9-Ybx1+/- BM, p=0.0042**), disease penetrance was reduced by 40%, indicating that haploinsufficiency for Ybx1 impairs development of MA9 driven AML. In contrast, immunophenotypic abundance of stem- and progenitor cells in Ybx1+/+ versus Ybx1+/- animals revealed comparable numbers in all relevant subpopulations. Serial competitive transplantation of Ybx1+/+ and Ybx1+/- BM into primary and secondary recipient animals showed no competitive disadvantage or lack of self-renewal capacity of Ybx1+/- cells. To address the question whether Ybx1 may also be essential for maintenance of AML, we used RNAi to deplete Ybx1 in already established MA9 driven AML. LSK cells from BL/6 mice transformed with MA9 were injected into primary recipient mice. After AML onset, MA9-LSK cells were sorted and infected with either one of 3 shRNAs against Ybx1 or non-targeting (NT-) control. Lentiviral knockdown of 40% reduced colony formation by more than 50% but did not limit the re-plating capacity in vitro. When injected into sub-lethally irradiated recipient mice, lentiviral knockdown (kd) of Ybx1 resulted in a significant delay in AML development (median survival 39.5 days for NT-control versus 53 days for Ybx1 kd, p=0.0446*). To validate our findings, we used a newly generated conditional ko mouse model for Ybx1, in which exon 3 coding for the cold-shock domain is deleted by activation of an Mx1-Cre-recombinase following pIpC administration. Preliminary results provide first evidence that genetic deletion of Ybx1 after onset of MA9 driven leukemia resulted in improved survival of primary recipient (median survival 73 versus 83 days) and a reduced penetrance in secondary recipient mice. Taken together our results may provide first evidence for a functional role of Ybx1 in MLL-AF9 driven AML. As Ybx1 seems to be dispensable for normal hematopoietic cells, these findings may offer a potential therapeutic index. Experiments to assess for the requirement for Ybx1 in maintenance of murine and human AML as well as analysis on proteomic and transcriptional changes following Ybx1 deletion are currently under way. Disclosures No relevant conflicts of interest to declare.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood.V130.Suppl_1.792.792

Language: English

Publisher: American Society of Hematology

Publication Date: 2017

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 139, No. 7 ( 2022-02-17), p. 1080-1097

Abstract: In an effort to identify novel drugs targeting fusion-oncogene–induced acute myeloid leukemia (AML), we performed high-resolution proteomic analysis. In AML1-ETO (AE)-driven AML, we uncovered a deregulation of phospholipase C (PLC) signaling. We identified PLCgamma 1 (PLCG1) as a specific target of the AE fusion protein that is induced after AE binding to intergenic regulatory DNA elements. Genetic inactivation of PLCG1 in murine and human AML inhibited AML1-ETO dependent self-renewal programs, leukemic proliferation, and leukemia maintenance in vivo. In contrast, PLCG1 was dispensable for normal hematopoietic stem and progenitor cell function. These findings are extended to and confirmed by pharmacologic perturbation of Ca++-signaling in AML1-ETO AML cells, indicating that the PLCG1 pathway poses an important therapeutic target for AML1-ETO+ leukemic stem cells.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood.2021012778

Language: English

Publisher: American Society of Hematology

Publication Date: 2022

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 128, No. 22 ( 2016-12-02), p. 1202-1202

Abstract: Several genes and signaling pathways control the fine balance between self-renewal and differentiation in hematopoietic stem cells and potentially also in leukemic stem cells (LSC). Phospholipase C family members are key mediators of calcium signaling which play an important role in differentiation and proliferation of immune cells but also contribute to malignant transformation and tumorigenesis. Plcg1 is highly expressed in hematopoietic stem- and progenitor cells and also in myeloid leukemia. Plcg1 gets activated by cell extrinsic receptor stimulation and integrates signals from the cell surface. Its influence on proliferation and differentiation of hematopoietic cells may be largely independent of other bone fide mediators of self-renewal and stem cell viability such as STAT-, MEK-ERK or AKT-signaling. To which extent Plcg1-dependent signal integration is required for function and maintenance of leukemic stem cells remained so far elusive. Genetic inactivation of Plcg1 by RNAi in human AML cell lines led to decreased proliferative capacity. Likewise, knockdown of Plcg1 in AML1-ETO (AML1ETO9a) transformed murine LSK-cells resulted in reduced colony formation and decreased re-plating capacity. In order to validate these findings and to investigate the impact of Plcg1 on myeloid leukemia stem cell function, we generated a conditional knockout mouse model for Plcg1 with Exons 3-5 being flanked with loxP sites. Excision of the respective sequence by activation of a Cre-recombinase resulted in complete loss of a functional protein and transcript. LSK-cells from Plcg1f/f and Plcg1+/+ littermate controls were retrovirally infected with two different oncogenes: either MLL-AF9 (MA9-GFP) or AML1-ETO9a in combination with KRAS (AE9a/KRAS-GFP). Primary recipient mice were injected with GFP+ LSK-cells and monitored for disease development. GFP+ Kit+ cells were isolated from leukemic mice and transduced with a Cre-recombinase, followed by plating in methylcellulose. Inactivation of Plcg1 in AE9a/KRAS transformed cells significantly reduced the number of colonies and decreased re-plating capacity to three rounds. Loss of Pclg1 in MA9 transformed LSC resulted in decreased colony numbers and colony size, however, re-plating capacity was not affected to a major extent. To assess for the requirement of Plcg1 in maintenance of fully developed leukemia, we injected equal numbers of GFP+ Kit+ cells (Plcg1-/- or Plcg1+/+) into sublethally irradiated secondary recipients. Inactivation of Plcg1 was highly deleterious for AE9a/KRAS induced AML-LSC and reduced disease penetrance by more than 85%. Depletion of Plcg1 in MA9 transformed cells delayed AML development and significantly prolonged survival of recipient mice. Leukemias that developed from Plcg1-/- donors showed complete excision of Plcg1, indicating, that Plcg1 deficient leukemia can develop in an MLL-AF9 driven background. However, when transplanting MA9 transformed Plcg1-/- or Plcg1+/+ bone marrow cells into tertiary recipient mice, loss of Plcg1 significantly delayed disease progression and reduced disease penetrance. To quantify this loss of leukemic stem cells, we performed limiting dilution analysis using purified LSCs from diseased Plcg1-/- or Plcg1+/+ MA9 secondary recipient mice. LSC frequency was markedly reduced in tertiary recipients of Plcg1-depleted LSCs (1 in 78,000 Plcg1-/- vs. 1 in 3,000 Plcg1+/+). Genetic inactivation of Plcg1 in LSCs derived from primary recipient mice (either MA9 or AE9a/KRAS driven AML) led to induction of differentiation as assessed by cell morphology and immunophenotyping, and this effect was more pronounced in AE9a/KRAS transformed cells. To investigate whether transcriptional effectors of Plcg1 signaling affect the fine balance between self-renewal in MA9- and AE9a/KRAS-driven leukemia, we performed whole transcriptome analysis (RNAseq) on sorted LSCs. Ongoing analyses address the functional difference between AML-ETO and MLL-AF9 driven disease and elucidate on distinct patterns of activated gene sets depending on the oncogenic background. Taken together, Plcg1 is required for maintenance of myeloid leukemia stem cells. Understanding of its relevance in LSC biology and function may offer the opportunity to develop this relevant signaling node as a target structure in AML. Disclosures No relevant conflicts of interest to declare.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood.V128.22.1202.1202

Language: English

Publisher: American Society of Hematology

Publication Date: 2016

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 134, No. Supplement_1 ( 2019-11-13), p. 4166-4166

Abstract: Introduction. Blast phase (BP) is the terminal and most incurable phase of myelofibrosis (MF) and occurs in a not negligible fraction of patients (pts). In the pre-ruxolitinib (RUX) era, peripheral blasts, thrombocytopenia, unfavorable cytogenetics, and high risk category were identified as predictors of BP. RUX is the standard of care for symptomatic MF; however, information on clinical/laboratory correlates of BP in RUX-treated pts is not available. Aims. The primary objective of the study is to assess real-world data on incidence, risk factors and outcome of BP in RUX-treated MF pts. Methods. A multicentre observational retrospective study on RUX-treated MF pts was conducted in 20 European Hematology Centers. Data were extracted from an electronic database that included consecutive pts treated with RUX from June 2011. Data cut-off was June 2019. Risk category was assessed at RUX start according to the Dynamic International Prognostic Score System (DIPSS) or the Myelofibrosis Secondary to PV and ET Collaboration Prognostic Model (MYSEC-PM) in pts with post-Polycythemia Vera (PV)/post-Essential Thrombocythemia (ET) MF (secondary MF, SMF). A time-to-event (BP) analysis was conducted with Fine & Gray model with death/time of stem cell transplant as competing risks. Variables tested for association with BP were: age≥65yr, sex, transfusion-dependency, PLT 〈 150x109/l, peripheral blasts ≥3%, marrow fibrosis grade, CALR-unmutated genotype, unfavorable karyotype, spleen length (≥10 cm), total symptoms score (≥20), previous hydroxyurea (HU), alkylating agents, and interferon (IFN) use, time from MF diagnosis to RUX start, and PV/ET duration. Cumulative Incidence Function among risk categories for DIPSS and MYSEC-PM was calculated applying the Gray's model. Results . Overall, 589 MF pts were included and observed for 1833 pt-yrs from RUX start (median, 35.4 mos). Diagnosis was PMF in 304 pts (51.6%), PPV-MF in 164 pts (27.8%) or PET-MF in 121 (20.6%); 58.4% males. Molecular status was: JAK2V617F (82.5%), CALR (11.3%) and MPLW515K/L (1.1%); 5.1% were triple negatives. Overall, 368 (62.5%) pts received ≥1 cytoreductive therapy before RUX, specifically: HU, n. 357; alkylating agents, n. 47; anagrelide, n. 33; and IFN, n. 29. Median time from MF diagnosis to RUX start was 1.3 yrs. DIPSS for the whole cohort was: INT-1 (52.9%), INT-2 (40.1%), and HIGH (7%). DIPSS distribution in PMF pts was: INT-1 (47.8%), INT-2 (45.7%), and HIGH (6.5%), while SMF pts were categorized at LOW (11.1%), INT-1 (43.1%), INT-2 (31.2%) and HIGH (14.6%) risk according to the MYSEC-PM. Overall, 65 (11%) developed BP. In 61 pts, BP caused RUX withdrawal after a median time of 1.2 yrs (0.7-6.2); in 4 pts BP occurred after RUX stop (median time: 2.4 yrs). BP incidence rate was 3.6 x100 pt-yrs and was comparable in PMF and SMF (p=0.1). In univariate analysis, the probability of BP evolution for the PMF cohort was significantly reduced by previous IFN use (p=0.001). In SMF, predictors for BP in univariate analysis were PLT 〈 150 x109/l (p=0.001), blasts ≥3% (p=0.002), grade 3 marrow fibrosis (p=0.03) and PV/ET duration ≥ 10 yrs (p=0.02); previous IFN significantly reduced the risk of BP (p=0.02). In multivariable analysis, PLT 〈 150 x109/l (HR 2.4, 95% CI 1.1-5.4, p=0.03), blasts ≥3% (HR 3.3, 95% CI 1.4-7.5, p=0.004) and previous IFN (HR 0.1, 95% CI 0.02-0.8, p=0.04) remained significant. High DIPSS risk significantly predicted BP in PMF (p=0.04, HR [95% CI]: 2.6 [1.1-6.5] ) but not in SMF (p=0.40). In this latter cohort, only the MYSEC-PM was associated with BP (p=0.02, HR 1.7 [95% CI]: [1.1-2.8] ) (Fig.1). Estimated HRs, in reference to the lower score category, were: 1.10 for INT-1, 1.82 for INT-2, and 4.04 for HIGH risk. HR for HIGH risk, comparing to all lower risk groups, was 3.53 (95% CI: 1.53-8.11). Overall, 54 (81.8%) BP pts died and median survival was 2.8 mos. Survival after BP was not influenced by type of MF, previous response to RUX, and type of salvage treatment. Conclusions. Thrombocytopenia and peripheral blasts at RUX start identified pts at higher risk of BP in SMF, while previous IFN use was associated with reduced BP evolution in both PMF and SMF, suggesting a possible disease-modifying action of this agent. Also, this analysis supports the ability of MYSEC-PM in predicting BP in pts with SMF. Despite RUX use, outcome after BP remained dismal, confirming the need for newer treatment strategies. Disclosures Palandri: Novartis: Consultancy, Honoraria. Breccia:Incyte: Honoraria; Celgene: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; BMS: Honoraria. Tiribelli:Incyte: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Benevolo:Novartis Pharmaceuticals: Consultancy. Bonifacio:Novartis: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; Incyte: Honoraria; BMS: Honoraria. Iurlo:Pfizer: Honoraria; BMS: Honoraria; Incyte: Honoraria; Novartis: Honoraria. Elli:Novartis: Membership on an entity's Board of Directors or advisory committees. Abruzzese:BMS: Consultancy; Incyte: Consultancy; Novartis: Consultancy; Pfizer: Consultancy. Sgherza:Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Incyte: Honoraria. Cavazzini:Pfize: Honoraria; Incyte: Honoraria; Novartis: Honoraria. Crugnola:Novartis: Honoraria; Incyte: Honoraria. Isidori:Janssen: Honoraria; Novartis: Honoraria; Gilead: Honoraria. Heidel:Novartis: Consultancy, Research Funding; Celgene: Consultancy; CTI: Consultancy. Latagliata:Janssen: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; Celgene: Honoraria. Trawinska:Novartis: Consultancy, Honoraria. Krampera:Janssen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Cuneo:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Abbvie: Honoraria, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Cavo:takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; bms: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; novartis: Honoraria. Palumbo:Novartis: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Amgen: Honoraria; Hospira: Honoraria; Teva: Honoraria.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood-2019-123379

Language: English

Publisher: American Society of Hematology

Publication Date: 2019

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7

In: Blood, American Society of Hematology, Vol. 124, No. 1 ( 2014-07-03), p. 13-23

Abstract: CDK6 is a critical effector of MLL fusions in myeloid leukemogenesis. Genetic and pharmacologic inhibition of CDK6 overcome the differentiation block associated with MLL-rearranged AML.

Type of Medium: Online Resource

ISSN: 0006-4971 , 1528-0020

URL: Article

DOI: 10.1182/blood-2014-02-558114

Language: English

Publisher: American Society of Hematology

Publication Date: 2014

detail.hit.zdb_id: 1468538-3

detail.hit.zdb_id: 80069-7