scholarly journals TP73 Isoforms (TAp73 and ΔNp73) Are Overexpressed in Acute Myeloid Leukemias and Potential Therapeutic Targets to Enhance Anti-Leukemia Activities of Bcl-2 and MDM2 Inhibitors

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2629-2629
Author(s):  
Yuki Nishida ◽  
Jo Ishizawa ◽  
Vivian Ruvolo ◽  
Michael Andreeff
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
De Novo ◽  
Hematopoietic Cells ◽  
Mrna Levels ◽  
Advisory Committees ◽  
Myeloid Leukemias ◽  
Equity Ownership ◽  
De Novo Aml ◽  
Mdm2 Inhibitor

Abstract Background TP73 is one of the TP53 family transcription factors and generates two isoforms, the transactivation p73 (TAp73) and the N-terminally truncated ΔNp73. TAp73 shares a homologous N-terminal activation domain with p53 and has similar pro-apoptotic function to p53. ΔNp73 lacks an activation domain and has activities distinct from TAp73. ΔNp73 has a dominant negative effect on the DNA binding of TAp73 and more importantly, of p53, since the DNA binding domain is homologous with that of TAp73 and highly similar to that of p53. In acute myeloid leukemias (AML), TP73 has been reported to be expressed except in acute promyelocytic leukemias. However, the association of TP73 isoforms with clinical and genetic characteristics and the regulation of the isoforms in AML have not been explored. Results We determined copy numbers of ΔNp73 and TAp73 mRNA levels in 78 AML samples including 31 de novo AML using droplet digital PCR (ddPCR), which allows to determine the absolute quantity of the isoforms expressed, and investigated their clinical and biological relevance. ΔNp73 and TAp73 expression was detected in 93.6% and 98.7% of AML samples at variable levels (mean ± SEM, 10.6 ± 5.0, and 106.6 ± 33.7 copies/µL, for ΔNp73 and TAp73, respectively). ΔNp73 and TAp73 mRNA levels were highly correlated (R2 = 0.72, P < 0.0001). Normal peripheral blood mononuclear cells and CD34+ hematopoietic cells showed little or no ΔNp73 and TAp73 expression (0.09 ± 0.09 and 0.42 ± 0.35 copies/µL, respectively), demonstrating that expression of ΔNp73 and TAp73 is 100 - 1,000 fold higher in AML as compared to normal hematopoietic cells. These data collectively suggests that transcriptional systems of both isoforms in AML cells are abnormally activated. Disease status (de novo or relapsed/refractory) and cytogenetic abnormalities did not correlate with ΔNp73 and TAp73 levels. However, AML with IDH1/2 mutations had 8.5-fold lower ΔNp73 expression than those with wild-type IDH1/2 (1.8 ± 0.8 vs 15.4 ± 7.7 copies/µL, P = 0.0069), with a similar trend for TAp73 (49.0 ± 20.3 vs 138.6 ± 51.4 copies/µL, P = 0.056). For de novo AML samples, those with DNMT3a and NRAS mutations had significantly higher ΔNp73, but not TAp73, than those without these mutations (21.6 ± 18.2 vs 2.5 ± 1.2 copies/µL, P = 0.017 and 5.6 ± 2.5 vs 9.7 ± 8.0 copies/µL, P = 0.047, respectively). These findings suggest that ΔNp73 and TAp73 can be differentially regulated in AML based on mutation status. To further explore the regulation of TP73 isoforms, we used MDM2 inhibitor Nutlin-3a to induce p53 which is a transcriptional inducer of ΔNp73. Indeed, MDM2 inhibition increased p73 protein levels, and knockdown of both TAp73 and ΔNp73 in AML cells enhanced apoptosis induction by Nutlin-3a (specific annexin V induction by 5 uM Nutlin-3a, 21.9 ± 1.3% vs 61.3 ± 5.2%, P = 0.0084 in OCI-AML3 cells with vector control vs Shp73, respectively), possibly due to the silencing of ΔNp73. AML cells with IDH1/2 mutations are more dependent on Bcl-2 than those without (Chan, Nat Med 2015). Intriguingly, (R)-2HG, the oncometabolite of mutant IDH1/2, reduced both TAp73 and ΔNp73 in AML cells and increased susceptibility to the Bcl-2 inhibitor ABT-199. These results imply a potential mechanism that regulates p73 isoforms by histone methylation or other epigenetic modifications in AML. Conclusion Absolute quantitation of TP73 isoforms by ddPCR revealed high expression in AML cells compared to normal hematopoietic cells. The repressed expression of TP73 isoforms in AML cells with IDH1/2 mutations or by the oncometabolite (R)-2HG suggests that epigenetic modifications through (R)-2HG can regulate TP73 transcription and enhance the anti-leukemia effect by Bcl-2 inhibition. Finally, downregulation of TP73 isoforms enhances the efficacy of MDM2 inhibitor in AML, suggesting a potential therapeutic strategy to enhance MDM2 inhibitor-mediated p53 activation. Disclosures Andreeff: Amgen: Consultancy, Research Funding; Oncolyze: Equity Ownership; Oncoceutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Astra Zeneca: Research Funding; Aptose: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; United Therapeutics: Patents & Royalties: GD2 inhibition in breast cancer ; SentiBio: Equity Ownership; Reata: Equity Ownership; Eutropics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy; Daiichi-Sankyo: Consultancy, Patents & Royalties: MDM2 inhibitor activity patent, Research Funding.

scholarly journals p53 Mediated Bone Marrow Mesenchymal Stem Cell Expansion Supports Acute Myeloid Leukemia Development

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 523-523
Author(s):  
Rasoul Pourebrahimabadi ◽  
Zoe Alaniz ◽  
Lauren B Ostermann ◽  
Hung Alex Luong ◽  
Rafael Heinz Montoya ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Board Of Directors ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Osteoblast Differentiation ◽  
Hematopoietic Cells ◽  
Advisory Committees ◽  
Equity Ownership ◽  
Mdm2 Inhibitor ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a heterogeneous disease that develops within a complex microenvironment. Reciprocal interactions between the bone marrow mesenchymal stem/stromal cells (BM-MSCs) and AML cells can promote AML progression and resistance to chemotherapy (Jacamo et al., 2014). We have recently reported that BM-MSCs derived from AML patients (n=103) highly express p53 and p21 compared to their normal counterparts (n=73 p&lt;0.0001) (Hematologica, 2018). To assess the function of p53 in BM-MSCs, we generated traceable lineage specific mouse models targeting Mdm2 or Trp53 alleles in MSCs (Osx-Cre;mTmG;p53fl/fl and Osx-Cre;mTmG;Mdm2fl/+) or hematopoietic cells (Vav-Cre;mTmG;p53fl/fl and Vav-Cre;mTmG;Mdm2fl/+). Homozygote deletion of Mdm2 (Osx-Cre;Mdm2fl/fl) resulted in death at birth and displayed skeletal defects as well as lack of intramedullary hematopoiesis. Heterozygote deletion of Mdm2 in MSCs was dispensable for normal hematopoiesis in adult mice, however, resulted in bone marrow failure and thrombocytopenia after irradiation. Homozygote deletion of Mdm2 in hematopoietic cells (Vav-Cre;Mdm2fl/fl) was embryonically lethal but the heterozygotes were radiosensitive. We next sought to examine if p53 levels in BM-MSCs change after cellular stress imposed by AML. We generated a traceable syngeneic AML model using AML-ETO leukemia cells transplanted into Osx-Cre;mTmG mice. We found that p53 was highly induced in BM-MSCs of AML mice, further confirming our findings in primary patient samples. The population of BM-MSCs was significantly increased in bone marrow Osx-Cre;mTmG transplanted with syngeneic AML cells. Tunnel staining of bone marrow samples in this traceable syngeneic AML model showed a block in apoptosis of BM-MSCs suggesting that the expansion of BM-MSCs in AML is partly due to inhibition of apoptosis. As the leukemia progressed the number of Td-Tomato positive cells which represents hematopoietic lineage and endothelial cells were significantly decreased indicating failure of normal hematopoiesis induced by leukemia. SA-β-gal activity was significantly induced in osteoblasts derived from leukemia mice in comparison to normal mice further supporting our observation in human leukemia samples that AML induces senescence of BM-MSCs. To examine the effect of p53 on the senescence associated secretory profile (SASP) of BM-MSCs, we measured fifteen SASP cytokines by qPCR and found significant decrease in Ccl4, Cxcl12, S100a8, Il6 and Il1b upon p53 deletion in BM-MSCs (Osx-Cre;mTmG;p53fl/fl) compared to p53 wildtype mice. To functionally evaluate the effects of p53 in BM-MSCs on AML, we deleted p53 in BM-MSCs (Osx-Cre;mTmG;p53fl/fl) and transplanted them with syngeneic AML-ETO-Turquoise AML cells. Deletion of p53 in BM-MSCs strongly inhibited the expansion of BM-MSCs in AML and resulted in osteoblast differentiation. This suggests that expansion of BM-MSCs in AML is dependent on p53 and that deletion of p53 results in osteoblast differentiation of BM-MSCs. Importantly, deletion of p53 in BM-MSCs significantly increased the survival of AML mice. We further evaluated the effect of a Mdm2 inhibitor, DS-5272, on BM-MSCs in our traceable mouse models. DS-5272 treatment of Osx-cre;Mdm2fl/+ mice resulted in complete loss of normal hematopoietic cells indicating a non-cell autonomous regulation of apoptosis of hematopoietic cells mediated by p53 in BM-MSCs. Loss of p53 in BM-MSCs (Osx-Cre;p53fl/fl) completely rescued hematopoietic failure following Mdm2 inhibitor treatment. In conclusion, we identified p53 activation as a novel mechanism by which BM-MSCs regulate proliferation and apoptosis of hematopoietic cells. This knowledge highlights a new mechanism of hematopoietic failure after AML therapy and informs new therapeutic strategies to eliminate AML. Disclosures Khoury: Angle: Research Funding; Stemline Therapeutics: Research Funding; Kiromic: Research Funding. Bueso-Ramos:Incyte: Consultancy. Andreeff:BiolineRx: Membership on an entity's Board of Directors or advisory committees; CLL Foundation: Membership on an entity's Board of Directors or advisory committees; NCI-RDCRN (Rare Disease Cliln Network): Membership on an entity's Board of Directors or advisory committees; Leukemia Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; German Research Council: Membership on an entity's Board of Directors or advisory committees; NCI-CTEP: Membership on an entity's Board of Directors or advisory committees; Cancer UK: Membership on an entity's Board of Directors or advisory committees; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees; NIH/NCI: Research Funding; CPRIT: Research Funding; Breast Cancer Research Foundation: Research Funding; Oncolyze: Equity Ownership; Oncoceutics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Eutropics: Equity Ownership; Aptose: Equity Ownership; Reata: Equity Ownership; 6 Dimensions Capital: Consultancy; AstaZeneca: Consultancy; Amgen: Consultancy; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy. OffLabel Disclosure: Mdm2 inhibitor-DS 5272

scholarly journals Single-Cell Mutational Profiling of Clonal Evolution in De Novo AML during Therapy and Relapse

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1469-1469
Author(s):  
Alexey Aleshin ◽  
Robert Durruthy-Durruthy ◽  
M. Ryan Corces ◽  
Melissa Stafford ◽  
Michaela Liedtke ◽  
...  
Keyword(s):  
Single Cell ◽  
Board Of Directors ◽  
Research Funding ◽  
De Novo ◽  
Sequencing Data ◽  
Employment Equity ◽  
Advisory Committees ◽  
Single Cell Sequencing ◽  
Equity Ownership ◽  
De Novo Aml

Abstract Background: De novo acute myeloid leukemia (AML) is a molecularly heterogeneous disorder with clinically variable outcomes. Recent studies on the mutational landscape of AML have been informative in better stratifying risk of relapse. However, bulk sequencing techniques have been limited in their ability to delineate the true complexity of tumoral molecular heterogeneity and allow for efficient identification of drug resistant subclones. Here, we applied high-throughput single cell sequencing technique to identify patterns of clonal heterogeneity and evolution in longitudinal samples from patients with AML undergoing induction chemotherapy. Methods: Matched diagnosis, remission, and relapse samples were examined for 20 de novo AML cases including 15 relapsed and 5 non-relapsed controls. Mutational bulk sequencing was performed by NGS panel sequencing and exome sequencing was available in select cases. Single cell processing was performed using the Tapestri (Mission Bio) platform. Briefly, individual cells were isolated using a microfluidic approach, followed by barcoding and genomic DNA amplification for individual cancer cells confined to droplets. Barcodes were then used to reassemble the genetic profiles of cells from next generation sequencing data. We applied this approach to individual AML samples, genotyping the most clinically relevant loci across upwards of 10,000 individual cells. Results: Targeted single-cell sequencing was able to recapitulate bulk sequencing data from both peripheral blood and bone marrow aspirate samples. We observed high concordance between bulk VAFs and sample level VAFs derived from single cell sequencing data. Additionally, single cell analysis allowed for resolution of subclonal architecture and tumor phylogenetic evolution beyond what was predicted from bulk sequencing alone. Rare subclones associated with disease relapse, were identified in initial diagnostic samples that were frequently under the limit of detection of bulk NGS. Conclusions:Taken together, our results suggest a greater degree of heterogeneity in de novo AML samples than suggested with bulk sequencing methods alone and shows the utility of single-cell sequencing for longitudinal monitoring and identification of resistant clones prior to therapy initiation in select patients. We show here that this approach is a feasible and effective way to identify and track heterogeneous populations of cells in AML and may be valuable for MRD identification. Disclosures Aleshin: Mission Bio, Inc.: Consultancy; Natera, Inc.: Employment. Durruthy-Durruthy:Mission Bio, Inc.: Employment, Equity Ownership. Liedtke:Prothena: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech/Roche: Research Funding; Caelum: Membership on an entity's Board of Directors or advisory committees; Amgen/Onyx: Consultancy, Honoraria, Research Funding; BlueBirdBio: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; celgene: Research Funding. Medeiros:Celgene: Consultancy, Research Funding; Genentech: Employment. Eastburn:Mission Bio, Inc.: Employment, Equity Ownership.

Efficacy of Single-Agent Decitabine in Relapsed and Primary Refractory (rel/ref) Acute Myeloid Leukemia (AML)

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2518-2518
Author(s):  
Andrew Hantel ◽  
Niloufer Khan ◽  
Richard A. Larson ◽  
Lucy A. Godley ◽  
Michael J. Thirman ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Genetic Risk ◽  
Research Funding ◽  
De Novo ◽  
Median Number ◽  
Advisory Committees ◽  
Secondary Aml ◽  
Induction Regimen ◽  
De Novo Aml ◽  
Wbc Count

Abstract Introduction Improving therapy for rel/ref AML remains a challenge. Decitabine, a DNA methyl-transferase inhibitor, initially showed promise in AML as a 5-day, first-line induction regimen and more recently as a 10-day regimen in older and unfit patients (1). However, little is known about the activity of decitabine in the rel/ref patient population despite increased use. Therefore, we sought to analyze the outcomes of these pts treated at our institution. Methods To obtain data regarding decitabine efficacy in rel/ref AML, we performed a retrospective analysis of outcomes following decitabine treatment in 34 adult pts treated at The University of Chicago from January 2009 to June 2014. Permission to access patient charts was granted by the medical centerÕs Institutional Review Board. AML was defined by WHO criteria, genetic risk grouping and complete remission (CR) was according to ELN classification; PR was defined as >50% decrease in bone marrow blasts and normalization of blood counts. Rel/ref AML was defined as either having had a prior CR with recurrence of disease or having received a prior induction regimen (1-2 cycles) without CR. Results Median pt age was 62 yrs (range, 18-81) and 60% were male. Median Charlson comorbidity index (CCI) was 5 (range, 0-8); 29% had ECOG performance status 0-1 and 71% had >2. 21 pts (62%) had de novo AML (7 with myelodysplasia-related changes), 3 (9%) had therapy-related myeloid neoplasm (t-MN), and 10 (29%) had secondary AML after myelodysplastic syndrome. 6% were in the ELN favorable genetic group, 3% intermediate-I, 18% intermediate-II, and 67% adverse; 2 cases were unevaluable. The median number of prior treatment regimens was three. 9% had received prior azacitidine, 85% had received prior HiDAC, and 38% had a prior allogeneic stem cell transplant (SCT). 34 pts received a total of 71 cycles of decitabine, 20 mg/m2 daily, in 5 or 10-day cycles every 28 days. All patients received 10-day courses, 91% had an initial 10-day course, and 74% had only 10-day courses. The median number of cycles per pt was 2; 59% received >1 cycle. 7 (21%) achieved CR and 4 (12%) had a partial response (PR), for an overall response rate (OR) of 33%. Responses occurred in 24% of pts with de novo AML, 66% with t-MN, and 50% with secondary AML. Intermediate and adverse group pts had OR of 14% and 39%, respectively. All pts achieving CR did so after 1 cycle; PR required a median of 3 cycles. Pts who achieved CR or PR had a significantly lower pretreatment WBC count (median, 9.5 vs 49.5 x 103/µL in non-responders; p=0.015) and blast percentage (44 vs 59.4; p=0.035) than those who did not. Pts with secondary AML or t-MN had a higher probability of OR compared to those with de novo AML (54 vs 23%; p=0.042). Median overall survival (OS) of all pts was 256 days; prior SCT was associated with reduced OS (p=0.017). When comparing de novo to secondary AML & t-MN, 1-year OS was not significantly different (Figure 1). Responders had a significantly longer OS (median, 622 days vs 278 days for non-responders; p=0.012). Age, race, CCI, ECOG PS, genetic risk group, prior HiDAC, dysplasia, azacitidine, and number of prior treatments did not impact OR or OS. 16 (47%) pts proceeded to SCT. During treatment, 70% had a grade 3-4 non-hematologic toxicity (based on NCI CTACE v4.0); the most common was fatigue. The median number of hospitalizations for complications per patient was 2 (range, 0-7). Causes of hospitalization were febrile neutropenia (40%), infection (22%), cytopenias (18%), rash (6%), acute kidney injury (6%), and 8% were for other causes. Conclusion Decitabine treatment of 34 adults with rel/ref AML resulted in an OR of 33% (21% CR) and allowed nearly one-half of these pts to proceed to SCT. All pts achieving CR did so after 1 cycle. Responding pts had improved OS over those without response (p=0.012). Interestingly, secondary AML or t-MN were 7.8 times more likely to achieve a response compared to de novo AML (p=0.046); lower WBC count and marrow blast percentage also correlated with higher OR. Further delineation of molecular subsets associated with response to decitabine should be evaluated in a larger prospective trial in this high-risk AML population. Citation 1. Blum KA, et al. Phase I trial of low dose decitabine targeting DNA hypermethylation in patients with chronic lymphocytic leukaemia and non-Hodgkin lymphoma: dose-limiting myelosuppression without evidence of DNA hypomethylation. Br J of Haem. Jul 2010;150(2):189-195. Figure 1. Figure 1. Disclosures Off Label Use: Decitabine is indicated for treatment of MDS but is often used to treat newly diagnosed or relapsed/refractory AML. In this study we analyzed results of patients with AML who were treated with decitabine in the relapsed/refractory setting.. Thirman:AbbVie: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Gilead: Research Funding; Merck: Research Funding; AbbVie: Research Funding; Gilead: Research Funding; Merck: Research Funding. Odenike:Sunesis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Liu:Astra Zeneca/Medimmune: Consultancy; Pfizer: Consultancy; Astra Zeneca/Medimmune: Consultancy; Pfizer: Consultancy. Stock:Gilead: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Exome Array Analyses Identify Low-Frequency Germline Variants Associated with Increased Risk of AML in a HLA-Matched Unrelated Donor Blood and Marrow Transplant Population

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 42-42
Author(s):  
Alyssa I. Clay ◽  
Theresa Hahn ◽  
Qianqian Zhu ◽  
Li Yan ◽  
Leah Preus ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
De Novo ◽  
Association Studies ◽  
Low Frequency ◽  
Hematologic Malignancies ◽  
Unrelated Donor ◽  
Advisory Committees ◽  
De Novo Aml ◽  
Normal Cytogenetics

Abstract Both genome wide association studies (GWAS) of common variation and exome wide association studies (EXWAS) of rare variation have successfully identified disease susceptibility variants for a variety of diseases. One GWAS of inherited susceptibility to Acute Myeloid Leukemia (AML) has been conducted, but no EXWAS have been performed to measure risk of AML attributable to low-frequency constitutional genetic variation. We performed the first EXWAS of risk of AML as a nested case-control study in the DISCOVeRY-BMT (Determining the Influence of Susceptibility Conveying Variants Related to one-Year mortality after BMT) cohorts. The DISCOVeRY-BMT parent study examined transplant-related mortality in leukemia patients undergoing unrelated donor allogeneic BMT. To identify low frequency variants and genes contributing to increased susceptibility to AML we used genotype data from the Illumina HumanExome BeadChip typed in the DISCOVeRY-BMT cohorts; the HumanExome BeadChip contains 242,901 variants, which are mainly protein-coding variants. The optimal sequence kernel association test (SKAT-O) was used to analyze gene-level associations with risk of AML. These gene-based tests evaluate the cumulative effects of multiple single gene variants on risk of AML. Analyses were performed in all European American AML cases and two subtypes: 1) de novo AML, 2) de novo AML with normal cytogenetics. Models were adjusted for age at transplant and principal components to control for population stratification. For gene-based tests at least 2 variants with minor allele frequency (MAF) ≤ 5%, were required to be present in the gene. This yielded a total of 13,687 genes tested, and a Bonferroni corrected significance level of P<3.65 x 10-6. Association tests were performed in 1,189 AML cases reported to CIBMTR 2000-08 (Cohort 1) and 327 AML cases reported to CIBMTR from 2009-11 (Cohort 2). Controls in Cohorts 1 (n=1,986) and 2 (n= 515) were 10/10 HLA-matched unrelated donors who passed a comprehensive medical exam and deemed healthy. We used metaSKAT to combine Cohorts 1 and 2 and obtain p-values of association with AML. We present the results of gene-level tests significant in both cohorts. The likely pathogenicity of these variants was determined in silico using SIFT, PolyPhen and MutationTaster. Patient characteristics are in Table 1. DNMT3A, on chromosome 2, was associated in the gene-based test with risk of AML (Pmeta=1.70x10-9, Table 2). Three missense variants at MAF <1% comprise both overall AML and de novo AML gene-based association: exm177559 (Asn->Ser), exm177507 (Arg->His), and exm177543 (Arg->Trp). Normal cytogenetics de novo AML gene-based assocations consisted of only 2 of these variants: exm177559 and exm177507 (Table 2). While prevalence of exm177507 is <1% for all AML cases, in de novo AML with normal cytogenetics the MAF was higher at 3%. The other 2 variants had a MAF<1% irrespective of subtype. Somatically, DNMT3A is most frequently mutated in hematologic malignancies, with >30% of de novo AML cases with a normal karyotype and >10% of MDS patients having DNMT3A mutations. Although these are germline gene associations all three of the variants found have been reported somatically in hematologic malignancies. In 200 AML cases from The Cancer Genome Atlas (TCGA) p.R882H (represented as exm177507 on the exome chip) was a frequent somatic mutation (25%). Exm177543 (p.R635W) and exm177559 (p.N501S) are reported in the Catalogue of Somatic Mutations in Cancer (COSMIC) as somatic mutations involved in hematopoietic and lymphoid tissue in both cell lines and humans. Exm177507 and exm177543 show evidence of pathogenicity in all three in silico tools, while exm177559 was reported as deleterious and disease causing by Sift and MutationTaster, respectively. Our results show that multiple potentially pathogenic missense germline variants in DNMT3A comprise the gene-based association with AML, specifically de novo AML with normal cytogenetics. Given the functional nature of these variants it is possible germline risk stratification could be informative in determining AML risk, and subsequently development of AML harboring DNMT3A mutations. Confirmation of these findings in additional cohorts could have implications for individualized risk screening, prediction and prognosis. Additional cytogenetic subgroup analyses, including treatment-related AML, are underway. Disclosures Hahn: Novartis: Equity Ownership; NIH: Research Funding. McCarthy:Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; The Binding Site: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gamida Cell: Honoraria, Membership on an entity's Board of Directors or advisory committees. Sucheston-Campbell:NIH/NCI: Research Funding.

The Effect of Eltrombopag on Platelet Resistance to Apoptosis: The Role of the Bcl-Xl Pathway

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1158-1158
Author(s):  
W. Beau Mitchell ◽  
Michele N Edison ◽  
Mariana P Pinheiro ◽  
Nayla Boulad ◽  
Bethan Psaila ◽  
...  
Keyword(s):  
Platelet Count ◽  
Board Of Directors ◽  
Research Funding ◽  
De Novo ◽  
Apoptosis Resistance ◽  
Advisory Committees ◽  
Apoptotic Pathway ◽  
Akt Activation ◽  
Platelet Counts ◽  
Equity Ownership

Abstract Abstract 1158 INTRODUCTION: Immune thrombocytopenia (ITP) is typically characterized by increased platelet destruction and reduced platelet production. Eltrombopag and Romiplostim are thrombopoietin receptor (TPO-R) agonists that are known to increase platelet counts in patients with ITP by stimulating thrombopoiesis. Platelets also express TPO-R on their surface, but it is unknown whether the thrombopoietin mimetics (TPO-M) have a direct effect on the circulating platelets. Although controversial, in a very small number of ITP patients, TPO-M agents may increase platelet counts in 2–5 days, earlier than would be expected from de novo megakaryocytopoiesis. Platelet survival is hypothesized to be mediated by two molecular intermediates in an apoptotic pathway, Bcl-xL and Bak. Bcl-xL/Bak protein expression in megakaryocytes is regulated in part by TPO-mediated activation of Akt pathways through Jak2 and Stat5. We hypothesized that an increase in platelet count in the first week of treatment might be mediated by TPO-R signaling, resulting in decreased platelet apoptosis. This study explored whether Eltrombopag or Romiplostim treatment has anti-apoptotic effects on platelets of patients with ITP. METHODS: Following a treatment wash out period, 75 mg of Eltrombopag once daily or 10 mcg/kg weekly of Romiplostim was initiated for 2 weeks. Blood counts were measured on days 1, 3, 5, 8, 10, 12, and 15. Platelet function and survival was assessed on days 1, 8, and 15 by: immature platelet fraction (IPF), glycocalicin index, Bcl-xL inhibitor (ABT-737) assay, measurement of Bcl-xL by western blot, measurement of several members of the Bcl-xL Akt mediated, apoptotic pathway by flow cytometry (FACS), bleeding score, measurement of thrombin-anti-thrombin complexes (TATs), and quantification of microparticles. RESULTS: Eight of 10 patients responded to treatment with Eltrombopag with a platelet count ≥ 50,000/μL, and 6 of the 8 responders at least doubled their counts during the 2 weeks of treatment. All 3 patients treated with Romiplostim responded with platelet count ≥ 50,000/μL. In both treatment groups there was a significant increase in median platelet count (p<0.001), median large platelet count (p<0.01), and median absolute IPF (A-IPF, p<0.01), while there was no significant change in median % IPF. The dose of ABT-737 required to kill half of the platelets in the sample (IC50) in the Eltrombopag group was lower in patients at day 1 than in non-ITP controls, and there was an increase in resistance to apoptosis between days 1 and 8, but these changes did not reach statistical significance. Between days 8 and 15 the IC50 declined to pre-treatment levels. In the Romiplostim group there was no significant difference in IC50 between the control and the patients over the 2 weeks of study. There was no significant correlation between the platelet counts and the IC50 values. FACS analysis of members of the AKT signal transduction pathway revealed increased activation of each of the markers between days 1 and 8, followed by a decrease between days 8 and 15. The levels of Bcl-xL and phosphor-AKT(308) decreased from day 1 to day 15. The other lab tests are pending. DISCUSSION: Because the A-IPF increased by less than the platelet increase and because the lifespan of the A-IPF is not known, it is unclear if the platelet count increase is solely a result of increased platelet production. Platelet lifespan may be enhanced by Eltrombopag treatment as there was a parallel albeit transient increase in AKT activation markers and platelet apoptosis resistance in the Eltrombopag group. Treatment with Romiplostim did not appear to affect apoptosis resistance although it did result in transient AKT activation. Our data suggest that platelets are more resistant to apoptosis when the levels of anti-apoptotic factors (eg. PTEN, Phospho-GSK3β) involved in the AKT/Bcl-xL pathway are greatest despite a concomitant increase in pro-apoptotic factors (eg. Bak, Bax). Since both the increased AKT activation and apoptotic resistance returned to baseline at day 15, megakaryocytes and platelets already present at the start of treatment may respond differently than those generated de novo in the presence of TPO mimetics. Disclosures: Bussel: Portola: Consultancy; Eisai: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; GlaxoSmithKline: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Cangene: Research Funding; Genzyme: Research Funding; Immunomedics: Research Funding; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Shionogi: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sysmex: Research Funding.

scholarly journals CUL1: Novel Therapeutic Target in Myeloid Neoplasms Harboring -7/Del(7q)

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1281-1281
Author(s):  
Vera Adema ◽  
Cassandra M Kerr ◽  
Sunisa Kongkiatkamon ◽  
Jibran Durrani ◽  
Hassan Awada ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Board Of Directors ◽  
Research Funding ◽  
Synthetic Lethality ◽  
Mrna Levels ◽  
Healthy Individuals ◽  
Selective Toxicity ◽  
Advisory Committees ◽  
Proliferative Effect ◽  
Equity Ownership

Lenalidomide (LEN) has established a new paradigm of targeted therapy in MDS. The mechanistic underpinnings of LEN efficacy are related to the synthetic lethality of this agent through its ability to bind cereblon (CRBN). LEN induces degradation of CK1α, which is encoded by the CSNK1A1 gene located on the del(5q) CDR, whereby haploinsufficient levels of this gene allow for selective toxicity to deletion mutants. Another common cytogenetic abnormality present in patients with myeloid neoplasia (MN) is -7/del(7q). To date no selective therapies exist for -7/del(7q), an urgent unfulfilled need, given the poor prognosis associated with this cytogenetic abnormality. We were interested to explore if this same notion of selective toxicity may be possible in del(7q) myeloid patients and sought to screen drugs for this focused population. From a large cohort of patients with MN (n=3,328), we found -7/del(7q) in 10% (n=316) of patients. We first identified a signature pattern of haploinsufficient genes on -7/del(7q) based on NGS. We then searched for haploinsufficient genes which, if targeted by investigational drugs, could provide a therapeutic window for selected MN subtypes in analogy to LEN in del(5q). For the purpose of our analysis, haploinsufficient expression was defined as <25th %tile of the mRNA levels seen in healthy individuals (Kerr, ASH 2019). Among others, we identified haploinsufficiency in CUL1 (7q36.1). CUL1 is a tumor suppressor gene, and is a well-characterized target of neddylation inhibitors. CUL1 had haploinsufficient mRNA levels in 92% of the patients compared to healthy individuals (n=64; log2 CPM 25th %tile expression= 4.966; P<.0001). Similarly, in primary AML (Beat AML; n=37) CUL1 was haploinsufficient in 81% of the cases compared to healthy individuals (n=21; log2 CPM 25th %tile expression= 6.182; P<.0001). Given that the 7q36.1 region involves CUL1 and EZH2, we investigated the interrelation between these 2 genes. Cases with overlapping microdeletions involving CUL1 and EZH2 have been previously described. A 25.4-kb microdeletion encompassing the last exon of EZH2 and the 3′ region of CUL1 has been found in Weaver syndrome, a congenital growth disorder caused by mutations in genes of the PRC2 complex (EED, SUZ12). Distinct from EZH2, CUL1 is rarely mutated in MN; only 2 mutations have been described (TCGAAML: N141S; E241D). Unexpectedly, in our cohort EZH2 had haploinsufficient expression in 97% of the patients compared to healthy individuals (n=64; log2 CPM 25th %tile expression= 6.042; P<.0001). CUL1 and EZH2 low expressors had a significantly (P<.001) higher expression of CDKN1A (p21), another target of neddylation inhibitors. CUL1 low expressors had significantly increased expression of other key cell cycle control factors regulated by CUL1 e.g., p27 (P=.003), c-myc (P=.007), β-catenin (P<.0001), mTOR (P<.0001), as well as the ubiquitin promoter p-IκBα (P=.0017). We previously evaluated the global impact of impairing cullins-neddylation by using MLN4924 (Pevonedistat) on the AML proteome and established a rationale for its combination with azacytidine (AZA) in vivo. MLN4924 elicits an anti-proliferative effect (IC50: 1 μM) in del(7q) AML cells KG-1; an effect that was doubled when MLN4924 was combined with AZA. Available databases of drug sensitivity (cancerrx) summarize the MLN4924 anti-proliferative effect on 721 cancer cells (0.02<IC50 [μM]>97) with sensitivity levels of KG-1 in the lower μM ranges. Our analysis also identified changes in death box-RNA-helicases (DDX41, DDX24,DDX54) and DNA binding proteins (CHD3), opening the possibility that MLN4924 might lead to degradation of key proteins implicated in the pathogenesis of MDS/ AML. The therapeutic index was confirmed by the absence of toxicity to normal CD34+ cells which were unresponsive to MLN4924 because they lack the expression of NEDD8-activating enzyme (NAE) (major target of MLN4924). In contrast to normal cells, NAE is highly expressed in myeloid cancer cells. In an ongoing dose-escalation study of MLN4924 plus AZA, 1 patient with -7 had stable disease after 6 cycles of therapy and 2 patients with del(7q) achieved complete and partial remissions. In sum, we propose that MN with -7/del(7q) abnormalities might represent a patient population genetically hypersensitive to synthetic lethality by neddylation inhibitors. Disclosures Hutter: MLL Munich Leukemia Laboratory: Employment. Advani:Glycomimetics: Consultancy, Research Funding; Kite Pharmaceuticals: Consultancy; Macrogenics: Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Research Funding; Abbvie: Research Funding. Kelly:Novartis, Bayer, Janssen, Pharmacyclics, Celgene, Astrazeneca, Seattle Genetics: Honoraria, Speakers Bureau; Genentech, Verastem: Consultancy; Takeda: Research Funding. Saunthararajah:Novo Nordisk: Consultancy; EpiDestiny: Consultancy, Equity Ownership, Patents & Royalties. Meggendorfer:MLL Munich Leukemia Laboratory: Employment. Sekeres:Celgene: Membership on an entity's Board of Directors or advisory committees; Millenium: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees. Savona:AbbVie: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Patents & Royalties; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Selvita: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sunesis: Research Funding. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Maciejewski:Alexion: Consultancy; Novartis: Consultancy.

scholarly journals BRCA1/2 Containing Complex 3 (BRCC36) Is Recurrently Mutated in AML with t(8;21) and Associated with Increased Sensitivity to Chemotherapy through Impairment of the DNA Damage Repair Pathway

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1487-1487
Author(s):  
Tatjana Meyer ◽  
Nikolaus Jahn ◽  
Anna Dolnik ◽  
Peter Paschka ◽  
Verena I. Gaidzik ◽  
...  
Keyword(s):  
Dna Damage ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
De Novo ◽  
Dna Damage Repair ◽  
Advisory Committees ◽  
Data Set ◽  
Damage Repair ◽  
De Novo Aml

Abstract Introduction BRCA1/BRCA2-containing complex 3 (BRCC36) is a Lys63-specific deubiquitinating enzyme (DUB) involved in DNA damage repair. Mutations in BRCC36 have been identified in 2-3% of patients with myelodysplastic syndromes (MDS) and secondary AML (sAML). The role of BRCC36 mutations in de novo AML and their impact on DNA damage-inducing cytotoxic chemotherapy sensitivity is not clear. Aim We aimed to determine the incidence of BRCC36 mutations in AML and their impact on outcome and drug sensitivity in vitro. Methods We analyzed the entire coding region of BRCC36 for mutations in 191 AML cases with t(8;21) (q22;q22.1) and 95 cases with inv(16) (p13.1q22) using a customized targeted sequencing panel. Data for de novo AML was derived from The Cancer Genome Atlas Research Network (TCGA) data set (NEJM 2013). Lentiviral CRISPR/Cas9 was used to inactivate BRCC36 in t(8;21)-positive AML cell lines - Kasumi-1 and SKNO-1 - and murine hematopoietic stem and progenitor cells (LSKs). Knockout was confirmed by a cleavage assay as well as Western blot. AML1-ETO-9a was expressed by a retroviral vector. Cell lines and LSK cells were treated with different concentrations of doxorubicin or cytarabine and their viability was assessed seven days post treatment. DNA damage was assessed through phospho-γH2AX staining using flow-cytometry. Results BRCC36 mutations were identified in 7 out of 191 patients (3.7%) with t(8;21) AML and none of 95 patients with inv(16). In the TCGA data set one out of 200 patients (0.5%) with de novo AML had a BRCC36 mutation. This patient had a complex karyotype and would be considered as secondary AML with myelodysplastic-associated changes according to the 2016 WHO classification. Six of the 7 mutations were missense or nonsense mutations that were predicted to be deleterious to BRCC36 function. One mutation affected a splice site at exon 6, resulting in an impaired splicing capability. With intensive standard chemotherapy all patients with BRCC36 mutations achieved a complete remission and had an estimated relapse-free and overall survival of 100% after a median follow up of 4.2 years. Given its role in DNA damage repair, we hypothesized that BRCC36 inactivation sensitizes AML cells to DNA-damage inducing drugs. In order to test this, we generated BRCC36 knockout Kasumi-1 and SKNO-1 cell lines using CRISPR-Cas9. BRCC36 inactivation had no impact on cell growth on either of the cell lines. However, we found that BRCC36 knockout cells were significantly more sensitive to doxorubicin as compared to the parental cells with normal BRCC36. This was accompanied by a significant increase in DNA damage as assessed by phospho-γH2AX in BRCC36 knockout vs control cells after doxorubicin treatment. In contrast, BRCC36 inactivation had no impact on cytarabine sensitivity. We next assessed drug sensitivity in primary murine leukemic cells expressing AML1-ETO-9a. Again, inactivation of BRCC36 resulted in a significant higher sensitivity to doxorubicin but not cytarabine. Conclusion We found BRCC36 to be recurrently mutated in t(8;21)-positive AML Inactivation of BRCC36 was associated with impairment of the DNA damage repair pathway and thus higher sensitivity to DNA damage-inducing chemotherapy. This might be also reflected by the favorable clinical outcome of patients with BRCC36 mutated t(8;21)-positive AML, a finding which has to be confirmed in a large patient cohort. Disclosures Paschka: Pfizer: Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Travel support; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Otsuka: Membership on an entity's Board of Directors or advisory committees; Sunesis: Membership on an entity's Board of Directors or advisory committees; Jazz: Speakers Bureau; Amgen: Other: Travel support; Janssen: Other: Travel support; Bristol-Meyers Squibb: Other: Travel support, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Travel support; Astex: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees. Bullinger:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Speakers Bureau; Bayer Oncology: Research Funding; Sanofi: Research Funding, Speakers Bureau; Janssen: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Döhner:Novartis: Consultancy, Honoraria, Research Funding; Jazz: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Janssen: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Pfizer: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Janssen: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Pfizer: Research Funding; Agios: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Agios: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Seattle Genetics: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Sunesis: Consultancy, Honoraria, Research Funding.

scholarly journals Targeting Misfolded p53 and p53 Aggregation to Overcome Resistance to Apoptosis in Acute Myeloid Leukemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3786-3786
Author(s):  
Michael Andreeff ◽  
Jianfang Zeng ◽  
Alice Soragni ◽  
Vivian Ruvolo ◽  
Bing Z Carter ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Protein Aggregation ◽  
Board Of Directors ◽  
Protein Misfolding ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Advisory Committees ◽  
Equity Ownership ◽  
Mdm2 Inhibitor ◽  
Acute Myeloid

The function of wild-type (wt) p53 in acute myeloid Leukemia (AML) is suppressed by MDM2, MDM4 and XPO-1 (Andreeff et al, Exp Hematol, 2016). We propose that wt p53 protein misfolding and cytosolic localization are contributing to its inactivation in AML. Immunofluorescence staining with OpalR TSA amplification demonstrated that p53 is localized both in the nucleus and in the cytosol of AML cells with prominent para-nuclear accumulation. We show here that misfolded wt p53 is localized mainly in the cytoplasm of AML cells, similar to what we reported for mutant (mt) p53 previously (Zeng et al, Blood, 2016). p53 misfolding promotes its aggregation which was recently reported as a novel mechanism promoting loss of its anti-tumor functions (Xu et al, Nat Chem Biol, 2011; Soragni et al, Cancer Cell, 2016). A pro-aggregating segment in the p53 DNA binding domain is exposed when p53 is misfolded. We showed that ReACp53, a cell permeable peptide designed to inhibit the aggregation of this segment, induced apoptosis in ovarian cancers bearing mt p53 (Soragni et al, Cancer Cell, 2016). We also reported that wt p53 AML cells responded to ReACp53 treatment (Zeng et al, Blood, 2016). ReACp53 eliminated misfolded p53, promoted its mitochondrial translocation and induced rapid apoptosis, suggesting that cytoplasmic misfolded wt p53 is a novel target in AML. MDM2 promotes p53 degradation, and inhibitors of MDM2 such as Nutlin derivatives are currently in trials for AML. These molecules inhibit p53 proteasomal degradation and result in p53-mediated apoptosis, as we demonstrated pre-clinically and in a Phase I trial of RG7112 in AML (Andreeff et al, Clin Cancer Res, 2015). p53 aggregation is initiated by protein misfolding, and progresses with increasing accumulation of misfolded p53. While p53 degradation is promoted by MDM2, binding of MDM2 to p53 causes p53 to misfold (Sasaki et al, J Biol Chem, 2007). This raises concerns about induction of p53 misfolding and consequent aggregation in tumors treated with MDM2 inhibitors, which could diminish therapeutic efficacy. We observed that levels of total and misfolded p53 and protein aggregation as identified by Proteostat positivity were MDM2 inhibitors dose- and time-dependent in wt p53 AML cells. This supports the hypothesis that MDM2 inhibition can cause not only p53 misfolding but also aggregation. Consequently, we show that adding a p53-aggregation inhibitor such as ReACp53 to an MDM2 inhibitor to limit p53 misfolding and aggregation results in increased cytotoxic activity in wt p53 AML. Co-aggregation of mt p53 with p63/p73 proteins carrying similar pro-aggregating segments has been reported (Xu et al, Nat Chem Biol, 2011). Next, we tested whether coaggregation could be an additional factor sequestering and inactivating wt p53. High levels of ΔNp73α, a tumor-promoting isoform of p73, can antagonize p53 function possibly through hetero-tetramer formation (Coutandin et al, Cell Death Differ, 2009), resulting in chemoresistance (Kazushi et al, Subcell Biochem, 2014). We hypothesize that upregulated ΔNp73α could constrain wt p53 through protein co-aggregation causing inactivation. Increased levels of misfolded p53 and protein aggregation were detected in both ΔNp73α-overexpressing HEK293T and MOLM13 (M13) cells. ΔNp73α-overexpressing M13 cells were resistant to MDM2 inhibitor-induced apoptosis compared to controls but sensitive to ReACp53. Treatment with Nutlin-derivatives (RG7388 or DS3032b) did not alter ΔNp73α levels but caused dose- and time-dependent increases in total and misfolded p53 and protein aggregation. HEK293T and M13 cells overexpressing ΔNp73α had higher levels of misfolded and aggregated p53, which we interpret as ΔNp73α providing a "seed" to accelerate p53 co-aggregation due to MDM2 inhibition. This suggests that ΔNp73α-overexpression conferred resistance to MDM2-mediated apoptosis that could be overcome by inhibition of p53 aggregation. Thus, combination of Nutlin derivatives and ReACp53 treatment exerted enhanced cytotoxicity in both cells lines. In conclusion, our data supports cytoplasmic, misfolded wt p53 as a novel target in AML and offers a rationale to combine therapeutic approaches supplementing MDM2 inhibition with p53 aggregation-targeting molecules to increase effectiveness. The model of wt p53 aggregation and coaggregation induced by MDM2 inhibition may apply to other cancer types. Disclosures Andreeff: Oncoceutics: Equity Ownership; Oncolyze: Equity Ownership; Breast Cancer Research Foundation: Research Funding; CPRIT: Research Funding; NIH/NCI: Research Funding; Cancer UK: Membership on an entity's Board of Directors or advisory committees; NCI-CTEP: Membership on an entity's Board of Directors or advisory committees; German Research Council: Membership on an entity's Board of Directors or advisory committees; Leukemia Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; NCI-RDCRN (Rare Disease Cliln Network): Membership on an entity's Board of Directors or advisory committees; CLL Foundation: Membership on an entity's Board of Directors or advisory committees; BiolineRx: Membership on an entity's Board of Directors or advisory committees; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; 6 Dimensions Capital: Consultancy; AstaZeneca: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees; Reata: Equity Ownership; Aptose: Equity Ownership; Eutropics: Equity Ownership. Carter:Amgen: Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding. Ishizawa:Daiichi Sankyo: Patents & Royalties: Joint submission with Daiichi Sankyo for a PTC patent titled "Predictive Gene Signature in Acute Myeloid Leukemia for Therapy with the MDM2 Inhibitor DS-3032b," United States, 62/245667, 10/23/2015, Filed.

scholarly journals A Phase 1 Dose Escalation Study of Milademetan in Combination with 5-Azacitidine (AZA) in Patients with Acute Myeloid Leukemia (AML) or High-Risk Myelodysplastic Syndrome (MDS)

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3932-3932
Author(s):  
Courtney D. DiNardo ◽  
Rebecca Olin ◽  
Jo Ishizawa ◽  
Hiroyuki Sumi ◽  
Jingdong Xie ◽  
...  
Keyword(s):  
High Risk ◽  
Board Of Directors ◽  
Dose Escalation ◽  
Research Funding ◽  
Phase 1 ◽  
Single Agent ◽  
Advisory Committees ◽  
Equity Ownership ◽  
Ecog Ps ◽  
Mdm2 Inhibitor

Background: The tumor suppressor p53, encoded by the TP53 gene, is negatively regulated by murine double minute 2 (MDM2), an E3 ubiquitin ligase. Deregulation of MDM2 results in the degradation of p53, leading to cessation of the protein's multiple tumor-suppressive functions, including the induction of apoptosis and reactivation of aberrantly silenced genes. Although TP53 is not frequently mutated in AML, p53 pathway dysfunction is prevalent, with MDM2 overexpression being frequently observed. Disrupting MDM2's negative regulatory effect to reactivate functional p53 is a promising strategy for the treatment of AML. Milademetan (DS-3032b) is a small-molecule MDM2 inhibitor that disrupts the p53-MDM2 interaction and has demonstrated single-agent activity in preclinical and clinical studies of AML. Survival rates are poor for patients with relapsed/refractory (R/R) AML or high-risk MDS which underpins the rationale for combination treatments to build on the efficacy of available agents. AZA, a hypomethylating agent, is part of the standard of care for AML and MDS. Reactivation of p53-inducible genes with milademetan combined with hypomethylation and direct cytotoxicity with AZA has shown activity in preclinical models of AML. Study Design and Methods: This open-label, 2-part, multicenter, phase 1 dose-escalation and -expansion study (NCT02319369) evaluates milademetan in combination with AZA in patients with R/R AML or high-risk MDS. Key inclusion criteria comprise a diagnosis of R/R AML or high-risk MDS; Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-2; and adequate renal, hepatic, and clotting functions. Additional inclusion criteria for newly diagnosed patients is ineligibility for intensive induction chemotherapy due to advanced age (≥ 75 years), congestive heart failure, or ECOG PS of 3 that is not related to leukemia. Key exclusion criteria include acute promyelocytic leukemia, central nervous system leukemia, unresolved toxicity from previous anticancer therapy, mean QTcF interval >450 ms for males or >470 ms for females, or prior treatment with an MDM2 inhibitor. During part 1 (dose escalation), patients with R/R AML or high-risk MDS receive single-agent milademetan (part 1; completed) or milademetan in combination with AZA at different dose schedules (part 1A; ongoing). Milademetan is administered as a single agent on days 1-21 of each 28-day cycle (21/28 schedule) at a starting dose of 60 mg and escalating to 90, 120, 160, and 210 mg. Less frequent dosing schedules will also be evaluated, starting with the maximum tolerated dose (MTD) determined from the 21/28 schedule. In part 1A, AZA will be administered at 75 mg/m2 subcutaneously or intravenously on days 1-7 of each 28-day cycle, with milademetan treatment on days 5-14 or 8-14. The primary objectives of part 1 are to assess safety and tolerability, determine the MTD of single-agent milademetan and in combination with AZA, and identify the recommended dose for expansion (RDE) for milademetan plus AZA. During part 2 (dose expansion), 3 cohorts of patients with either (1) R/R AML, (2) newly diagnosed AML, or (3) high-risk MDS will receive milademetan in combination with AZA at the RDE. The primary objectives of part 2 are to confirm safety and tolerability, evaluate response to combination treatment, and identify a recommended phase 2 dose. Pharmacokinetics and pharmacodynamics of milademetan as a single agent and in combination with AZA will be evaluated in both parts. Approximately 80 patients are planned to be enrolled in part 1, and up to 40 patients are planned to be enrolled for each cohort in part 2. This study is currently recruiting in the United States. Disclosures DiNardo: agios: Consultancy, Honoraria; medimmune: Honoraria; celgene: Consultancy, Honoraria; syros: Honoraria; jazz: Honoraria; notable labs: Membership on an entity's Board of Directors or advisory committees; daiichi sankyo: Honoraria; abbvie: Consultancy, Honoraria. Olin:Spectrum: Research Funding; Revolution Medicine: Consultancy; Mirati Therapeutics: Research Funding; Genentech: Consultancy, Research Funding; Astellas: Research Funding; Ignyta: Research Funding; Jazz Pharmaceuticals: Consultancy; Novartis: Research Funding; Astrazeneca: Research Funding; Daiichi Sankyo: Research Funding; Clovis: Research Funding. Ishizawa:Daiichi Sankyo: Patents & Royalties: Joint submission with Daiichi Sankyo for a PTC patent titled "Predictive Gene Signature in Acute Myeloid Leukemia for Therapy with the MDM2 Inhibitor DS-3032b," United States, 62/245667, 10/23/2015, Filed. Sumi:Daiichi Sankyo, Inc.: Employment. Xie:Daiichi Sankyo, Inc.: Employment. Kato:Daiichi Sankyo, Inc.: Employment; Celgene: Employment, Equity Ownership. Kumar:Daiichi Sankyo, Inc.: Employment, Equity Ownership. Andreeff:NIH/NCI: Research Funding; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees; Oncoceutics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Oncolyze: Equity Ownership; Breast Cancer Research Foundation: Research Funding; CPRIT: Research Funding; BiolineRx: Membership on an entity's Board of Directors or advisory committees; CLL Foundation: Membership on an entity's Board of Directors or advisory committees; NCI-RDCRN (Rare Disease Cliln Network): Membership on an entity's Board of Directors or advisory committees; Leukemia Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; German Research Council: Membership on an entity's Board of Directors or advisory committees; NCI-CTEP: Membership on an entity's Board of Directors or advisory committees; Cancer UK: Membership on an entity's Board of Directors or advisory committees; Eutropics: Equity Ownership; Aptose: Equity Ownership; Reata: Equity Ownership; 6 Dimensions Capital: Consultancy; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy; Amgen: Consultancy; AstaZeneca: Consultancy.

Remissions after Third Induction Chemotherapy for Primary Non-Responders with Acute Myeloid Leukemia (AML) Are Uncommon and Short-Lived

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2800-2800
Author(s):  
Sara Farshchi Zarabi ◽  
Steven M. Chan ◽  
Vikas Gupta ◽  
Dina Khalaf ◽  
Andrzej Lutynski ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Palliative Care ◽  
Board Of Directors ◽  
Induction Chemotherapy ◽  
Research Funding ◽  
De Novo ◽  
Phase 1 ◽  
Cell Transplant ◽  
Advisory Committees ◽  
De Novo Aml

Abstract The outcome of adult patients with AML who are primary non-responders to two courses of induction chemotherapy is poor. However, the utility of a 3rd induction for a select subgroup of these patients is uncertain. Here, we evaluated the rates of response and survival after a 3rd course of induction chemotherapy for primary non-responders with AML. We identified 98 patients from the Princess Margaret Cancer Centre between May 1999 and March 2015 who were non-responders to induction and reinduction chemotherapy. No-response to re-induction chemotherapy was defined according to the Revised Recommendations of the International Working Group for AML (JCO, 2003) as patients who survived > 7 days post re-induction and had persistent AML in blood or bone marrow (>5%). Median age was 58.3 years [range: 20-76.6]. 50 (51%) were male. 2% had favorable, 18% normal, 18% intermediate, and 48% adverse cytogenetics. 50% had de novo AML, 23% had AML secondary to MDS or MPN, and 17% had therapy-related AML. Induction chemotherapy consisted of "7+3" (n =88), Nove-HiDAC (n=1), Flag-Ida (n= 2), or similar variants (n=7). Reinduction chemotherapy consisted of Nove-HiDAC (n=70), Flag-Ida (n=7), "7+3" (n=1) or other similar variants (n =20). No patients received the same regimen for both induction and reinduction. Of the 98 primary non-responders, 15 received a 3rd induction regimen, while the others received supportive/palliative care ± low-dose chemotherapy (57 pts), or a non-induction clinical trial (26 pts). Average age was 56.4 (sd: 12.9) for patients who received supportive/palliative care and 47.0 (sd: 17.5) for patients who received a 3rd induction (p=0.008). Other baseline characteristics including gender, cytogenetic risk, marrow blast count post 2nd induction, and time between 1st and 2nd induction, did not differ between patients who did and did not receive a 3rd induction. Time to 3rd induction was a median of 54 days [range:36-126] from the start of the 2nd induction. Of the 15 third inductions, 7 were clinical trials evaluating novel agents in combination with induction chemotherapy, while the other 8 were combinations of standard chemotherapeutics (Flag-Ida n=1), AMSA+HiDAC (n=2), Daunorubicin+ HiDAC (n=1), Nove-HiDAC (n=4). Of the 15 patients who received a 3rd induction, 3 (20%) achieved a CR following Nove-HiDAC and Flag-Ida or AMSA+HiDAC chemotherapy, where the Ara-C was given as continuous infusion. 1 patient underwent allogeneic stem cell transplant (SCT) approximately 3.7 months after 3rd induction and remains alive 4.6 years post CR. 2 patients relapsed 2.3 and 4.7 months post CR without having received alloSCT. None of the 12 other patients responded to the 3rd induction and none had prolonged aplasia. 2 of 15 (13%) died during 3rd induction. Among the 83 patients who did not receive a 3rdinduction, 1 achieved a CR after a phase 1 clinical trial (MDM2 inhibitor) and remains in CR 3.6 years following an alloSCT. For patients who survived the immediate post induction period and were discharged from hospital median overall survival from the start of the 2nd induction did not differ between patients who did and did not receive a 3rd induction (276 days [range: 78-1304] vs 181.5 days [range: 47-1855] respectively p= 0.14). Median duration of hospital stay (including subsequent admissions) was longer for patients receiving a 3rd induction compared to those who did not (94 days following start of the 2nd induction [range: 47-169] vs 57 days [range: 51-181], respectively;(p= 0.003)). In summary, remissions after 3rd inductions for primary non-responders are uncommon, and short-lived, suggesting that 3rd inductions should be considered with caution and only when an SCT strategy is in place. Disclosures Gupta: Incyte Corporation: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Schuh:Amgen: Membership on an entity's Board of Directors or advisory committees. Yee:Novartis Canada: Membership on an entity's Board of Directors or advisory committees, Research Funding. Schimmer:Novartis: Honoraria.

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