Exportin-1 (XPO1) Inhibition Sequesters p53 from MDM2 and MDM4 and Is Highly Synergistic with MDM2 Inhibition in Inducing Apoptosis in Wild-Type p53 Acute Myeloid Leukemias

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 23-24
Author(s):  
Yuki Nishida ◽  
Jo Ishizawa ◽  
Edward Ayoub ◽  
Rafael Heinz Montoya ◽  
Vivian Ruvolo ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Combination Treatment ◽  
Research Funding ◽  
Combined Treatment ◽  
Wild Type ◽  
Advisory Committees ◽  
Ki 67 ◽  
Protein Levels ◽  
Dual Inhibition ◽  
Mdm2 Inhibitor

The tumor suppressor p53 is inactivated in virtually all cancers, including leukemias, by mutations or deletion of the TP53 gene, or overexpression of negative regulators (e.g., MDM2, MDM4, and XPO1). MDM2 and MDM4 are frequently overexpressed in acute myeloid leukemia (AML), with the highest MDM4 expression as compared to other malignancies. XPO1 transports ~300 proteins, including p53, from the nucleus to the cytoplasm and MDM2 is also a cargo protein transported by XPO1.We previously reported high synergism by MDM2 and XPO1 inhibition in AML (Kojima et al., Blood 2013), with the underlying mechanism yet to be fully investigated. Wp53 was highly accumulated in the nucleus by combined treatment in OCI-AML3 and primary AML cells with MDM2 inhibitor milademetan (DS-3032b) and XPO1 inhibitor selinexor (KPT-330), compared to treatment with individual drugs. Upon MDM2 and XPO1 inhibition, MDM2 was exclusively localized in the cytoplasm, not in the nucleus. Intriguingly, MDM4 also localized exclusively in the cytoplasm, and the dual inhibition markedly reduced the level of cytoplasmic MDM4 (Fig.1). Data suggest that the dual inhibition of MDM2 and XPO1 maximizes the transcriptional activity of p53 by sequestering MDM2 and MDM4 in the cytoplasm, with massive p53 induction in the nucleus. Indeed, the combination treatment dramatically induced p53 targets CDKN1A and MDM2 (i.e.,55-fold and 25-fold, respectively). WPathway analysis from RNA seq of OCI-AML3 cells treated with milademetan, selinexor, and the combination revealed the TP53 pathway was the top upregulated pathway compared with control, or single agent treatments. E2F targets, G2M checkpoint genes and MYC targets were the principal downregulated pathways by the combination treatment. Cell cycle analysis measuring EdU/DNA, Ki-67, p53, p21, and active caspase-3 revealed elimination of S-phase and a population with the highest Ki-67 levels at G2/M phase, with increased percentages of cells in G0 and G2/M phases. The combination treatment markedly reduced Ki-67 levels, suggesting the disruption of DNA synthesis and cell cycle arrest. Furthermore, p53 and p21 levels were increased in both G0 and G2/M cells, along with increased active caspase-3 levels, suggesting apoptosis induction in both highly proliferating and quiescent AML cells. WNext to validate c-Myc inhibition by the combination treatment, we used OCI-AML3 cells transduced with shRNA control (ShC) and shRNA for p53 (Shp53), and MOLM-13 cells with wild-type p53 (WT) and with TP53 p.R248W/R213* mutation (MT), obtained through long-term exposure to MDM2 inhibitor. c-Myc protein levels were significantly reduced in OCI-AML3 ShC cells and MOLM-13 WT cells, but not in OCI-AML3 Shp53 cells or MOLM-13 MT cells. Combined treatment synergistically reduced MYC mRNA and c-Myc protein levels both in the cytoplasm and the nucleus. Consistently, the combination treatment reduced c-Myc levels in primary AML cells with wild-type TP53 as opposed to those with TP53 mutations. Overexpression of c-Myc in OCI-AML3 cells conferred increased susceptibility to the combination treatment. Finally, c-Myc protein levels at baseline had negative correlation with the respective ED50 concentrations that induced apoptosis in 50% of AML blasts. In conclusion: we identified strikingly increased transcriptional activity of p53 which was retained in the nucleus and sequestration of MDM2 in the cytoplasm as novel mechanisms of combined MDM2/XPO1 inhibition. In addition, high c-Myc baseline levels were associated with response to the combinatorial treatment, which also markedly reduced nuclear and cytoplasmic c-Myc levels due to MYC repression by p53 activation. These findings support the translation of combined MDM2 and XPO1 inhibition into clinical trials. Disclosures Daver: Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Lesegretain:Daiichi-Sankyo Inc.: Current Employment. Shacham:Karyopharm: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties: (8999996, 9079865, 9714226, PCT/US12/048319, and I574957) on hydrazide containing nuclear transport modulators and uses, and pending patents PCT/US12/048319, 499/2012, PI20102724, and 2012000928) . Andreeff:Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy.

scholarly journals Dual Inhibition of MDM2 and XPO1 Synergizes to Induce Apoptosis in Acute Myeloid Leukemia Progenitor Cells with Wild-Type TP53 through Nuclear Accumulation of p53 and Suppression of c-Myc

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2556-2556
Author(s):  
Yuki Nishida ◽  
Jo Ishizawa ◽  
Vivian Ruvolo ◽  
Kensuke Kojima ◽  
Rafael Heinz Montoya ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Combined Treatment ◽  
Wild Type ◽  
Advisory Committees ◽  
Protein Levels ◽  
Equity Ownership ◽  
Wild Type P53 ◽  
Mdm2 Inhibitor ◽  
Acute Myeloid

Background. MDM2 is frequently overexpressed in acute myeloid leukemias (AML) and suppresses p53-mediated apoptosis while p53 mutations are relatively rare in AML. MDM2 inhibitors as a monotherapy have shown limited efficacy in clinical trials in AML (~25% response rate) (Andreeff, Clin Cancer Res 2015). XPO1 transports around 300 proteins, including p53 and other tumor suppressors, from the nucleus to the cytoplasm. Overexpression of XPO1 is associated with unfavorable outcomes in AML (Kojima, Blood 2013). p53 activation or XPO1 inhibition have been reported to decrease c-Myc protein levels through diverse mechanisms (Porter Mol Cell 2017 and Tabe PLoSOne 2015). Objective: We investigated anti-leukemia effect of dual MDM2 and XPO1 inhibition, with the intent to maximize the pro-apoptotic functions of p53, using the MDM2 inhibitor milademetan (Daiichi-Sankyo), and selinexor, a recently FDA-approved XPO1 inhibitor or its analog eltanexor (Karyopharm). Results: Treatment with milademetan and selinexor (1:1 molar ratio) induced synergistic apoptosis in AML cell lines with wild-type p53 (ED50, 89.3 ± 18.6 nM, combination index (CI), 0.60 ± 0.08). Activity in p53 mutant AML required 40-fold higher ED50 (3572 ± 1986 nM), reflected in an antagonistic CI of 6.94 ± 3.06. Knockdown of wild-type p53 by shRNA in OCI-AML3 (OCI-AML3 shp53) cells or presence of TP53 mutation (p.R248W) in MOLM-13 cells eliminated the synergistic effects, suggesting that normal p53 function is a major determinant of sensitivity to combined treatment. Next, we treated primary AML samples with milademetan and selinexor or eltanexor and observed that effects were mutation-agnostic (e.g. RAS and FLT3) except for TP53. Combined treatment significantly reduced AUC determined by absolute live cell numbers compared to each drug alone, and induced synergistic apoptosis in primary AML samples with wild-type p53 (ED50 values, 27.2 - 937.4 nM, CI, 0.51 ± 0.07), with similar efficacies in complex and non-complex karyotype AMLs (279.6 ± 94.7 vs 256.6 ± 56.4 nM, P = 0.84). In contrast, combined treatment showed antagonistic effects in primary AML samples with loss-of-function TP53 mutations (CI > 1.0). Immature CD34+CD38- AML cells were more susceptible to combined treatment than CD34- AML cells (apoptosis induction, 76.2 ± 6.7% vs 47.5 ± 6.8%, P = 0.0002) Mechanistically, combined inhibition increased p53 protein levels and accumulated p53 but not MDM2 protein in the nucleus compared to each drug alone. Combined treatment induced more TP53 target genes (MDM2, CDKN1A, BBC3, FAS and Bax) in OCI-AML3 cells with control shRNA compared with OCI-AML3 shp53 cells. Combinatorial inhibition showed much enhanced reduction of c-Myc mRNA and protein levels in OCI-AML3 shC cells compared with OCI-AML3 shp53 cells (82% vs 32%). In confirmation, combined inhibition reduced c-Myc protein levels profoundly in wild-type p53 primary AMLs (ANOVA P < 0.0001). In contrast, c-Myc reduction was not observed in primary AMLs with p53-inactivating mutations. Intriguingly, OCI-AML3 cells overexpressing c-Myc by lentiviral transduction showed greater sensitivity to XPO1 inhibitors and the combination compared to empty-vector controls, and baseline levels of c-Myc protein also negatively correlated with ED50 for combined treatment in primary AML samples (Spearman R = -0.5357, P = 0.0422). Conclusion: These preclinical data suggest that dual inhibition of MDM2 and XPO1 induces synergistic apoptosis through accumulation of nuclear p53 and suppression of c-Myc in wild-type p53 AMLs. A clinical trial testing this concept in AML is under development. Disclosures 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. Daver:Novartis: Consultancy, Research Funding; Agios: Consultancy; Jazz: Consultancy; Hanmi Pharm Co., Ltd.: Research Funding; Pfizer: Consultancy, Research Funding; Astellas: Consultancy; Immunogen: Consultancy, Research Funding; Forty-Seven: Consultancy; Abbvie: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Servier: Research Funding; Incyte: Consultancy, Research Funding; NOHLA: Research Funding; Glycomimetics: Research Funding; BMS: Consultancy, Research Funding; Karyopharm: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Celgene: Consultancy; Otsuka: Consultancy. Lesegretain:Daiichi-Sankyo Inc.: Employment, Equity Ownership. Shacham:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Andreeff:NIH/NCI: Research Funding; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Amgen: Consultancy; AstaZeneca: Consultancy; 6 Dimensions Capital: Consultancy; Reata: Equity Ownership; Aptose: Equity Ownership; Eutropics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Oncoceutics: Equity Ownership; Oncolyze: Equity Ownership; Breast Cancer Research Foundation: Research Funding; CPRIT: Research Funding; 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; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Leukemia Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; 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; Jazz Pharmaceuticals: Consultancy.

scholarly journals Synergistic Anti-Leukemic Activity with Combination of FLT3 Inhibitor Quizartinib and MDM2 Inhibitor Milademetan in FLT3-ITD Mutant/p53 Wild-Type Acute Myeloid Leukemia Models

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2720-2720 ◽  
Author(s):  
Michael Andreeff ◽  
Weiguo Zhang ◽  
Prasanna Kumar ◽  
Oleg Zernovak ◽  
Naval G. Daver ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Cell Lines ◽  
Combination Treatment ◽  
Research Funding ◽  
Single Agent ◽  
Wild Type ◽  
Advisory Committees ◽  
Mouse Xenograft Model ◽  
Equity Ownership ◽  
Mdm2 Inhibitor

Abstract Background: MDM2, a negative regulator of the tumor suppressor p53, is overexpressed in several cancers including hematological malignancies. Disrupting the MDM2-p53 interaction represents an attractive approach to treat cancers expressing wild-type functional p53. Anticancer activity of small molecule MDM2 inhibitor milademetan (DS-3032b) has been demonstrated in preclinical studies and in a phase 1 trial in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome. Quizartinib is a highly selective and potent FLT3 inhibitor that has demonstrated single-agent activity and improvement in overall survival in a phase 3 clinical study in relapsed/refractory AML with FLT3-internal tandem duplication (FLT3-ITD) mutations. We present here the preclinical studies exploring the rationale and molecular basis for the combination of quizartinib and milademetan for the treatment of FLT3-ITD mutant/TP53 wild-type AML. Methods: We investigated the effect of quizartinib and milademetan combination on cell viability and apoptosis in established AML cell lines, including MV-4-11, MOLM-13 and MOLM-14, which harbor FLT3-ITD mutations and wild type TP53. Cells were treated with quizartinib and milademetan at specified concentrations; cell viability and caspase activation were determined by chemiluminescent assays, and annexin V positive fractions were determined by flow cytometry. We further investigated the effect of the combination of quizartinib and the murine specific MDM2 inhibitor DS-5272 in murine leukemia cell lines Ba/F3-FLT3-ITD, Ba/F3-FLT3-ITD+F691L and Ba/F3-FLT3-ITD+D835Y, which harbor FLT3-ITD, ITD plus F691L and ITD plus D835Y mutations, respectively. F691L or D835Y mutations are associated with resistance to FLT3-targeted AML therapy. In vivo efficacy of combination treatment was investigated in subcutaneous and intravenous xenograft models generated in male NOD/SCID mice inoculated with MOLM-13 and MV-4-11 human AML cells. Results: Combination treatment with milademetan (or DS-5272) and quizartinib demonstrated synergistic anti-leukemic activity compared to the respective single-agent treatments in FLT3 mutated and TP53 wild type cells. Combination indices (CIs) were 0.25 ± 0.06, 0.61 ± 0.03, 0.62 ± 0.06, 0.29 ± 0.004 and 0.50 ± 0.03, respectively, in MV-4-11, MOLM-13, MOLM-14, Ba/F3-FLT3-ITD+F691L and D835Y cell lines, all of which harbor FLT3-ITD or ITD plus TKD point mutations. The combination regimen triggered synergistic pro-apoptotic effect in a p53-dependent manner as shown by annexin-V staining and caspase 3/7 assays. Mechanistically, the combination treatment resulted in significant suppression of phospho-FLT3, phospho-ERK and phospho-AKT and anti-apoptotic Bcl2 family proteins (eg, Mcl-1), as well as up-regulation of p53, p21 and pro-apoptotic protein PUMA, compared to single agent treatments. Of note, the combination regimen also exerted a synergistic pro-apoptotic effect on venetoclax (BCL-2 inhibitor)-resistant MOLM-13 cells (CI: 0.39 ± 0.04) through profound suppression of Mcl-1. In an in vivo study using the MOLM-13 subcutaneous mouse xenograft model, quizartinib at 0.5 and 1 mg/kg and milademetan at 25 and 50 mg/kg demonstrated a significant tumor growth inhibition compared with vehicle treatment or respective single-agent treatments. In MV-4-11 intravenous mouse xenograft model, the combination of quizartinib plus milademetan showed a significantly prolonged survival, with no animal death in the combination group during the study period, compared to respective single agent treatments and untreated control (Figure). Conclusion: Synergistic anti-leukemic activity was observed for quizartinib plus milademetan combination treatment in preclinical AML models. A phase I clinical trial of quizartinib/milademetan combination therapy in patients with FLT3-ITD mutant AML is underway. Figure. Effects of quizartinib, milademetan and their combination on survival of mice intravenously inoculated with human MV-4-11 AML cells Disclosures Andreeff: Oncoceutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy; Aptose: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Eutropics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Research Funding; United Therapeutics: Patents & Royalties: GD2 inhibition in breast cancer ; Oncolyze: Equity Ownership; Astra Zeneca: Research Funding; Reata: Equity Ownership; Daiichi-Sankyo: Consultancy, Patents & Royalties: MDM2 inhibitor activity patent, Research Funding; SentiBio: Equity Ownership. Kumar:Daiichi Sankyo: Employment, Equity Ownership. Zernovak:Daiichi Sankyo: Employment, Equity Ownership. Daver:Pfizer: Research Funding; ImmunoGen: Consultancy; Otsuka: Consultancy; Karyopharm: Research Funding; Alexion: Consultancy; ARIAD: Research Funding; Daiichi-Sankyo: Research Funding; BMS: Research Funding; Karyopharm: Consultancy; Novartis: Consultancy; Novartis: Research Funding; Incyte: Research Funding; Kiromic: Research Funding; Sunesis: Research Funding; Incyte: Consultancy; Pfizer: Consultancy; Sunesis: Consultancy. Isoyama:Daiichi SANKYO CO., LTD.: Employment. Iwanaga:Daiichi Sankyo Co., Ltd.: Employment. Togashi:Daiichi SANKYO CO., LTD.: Employment. Seki:Daiichi Sankyo Co., Ltd.: Employment.

scholarly journals A Phase 1 Study of Milademetan in Combination with Quizartinib in Patients with Newly Diagnosed (ND) or Relapsed/Refractory (R/R) FLT3-ITD Acute Myeloid Leukemia (AML)

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1389-1389 ◽  
Author(s):  
Naval G. Daver ◽  
Weiguo Zhang ◽  
Richard Graydon ◽  
Vikas K Dawra ◽  
Jingdong Xie ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Phase 1 ◽  
Wild Type ◽  
Phase 1 Study ◽  
Advisory Committees ◽  
Once Daily ◽  
Flt3 Inhibitor ◽  
Equity Ownership ◽  
Mdm2 Inhibitor

Background: FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations occur in ≈ 25% of patients with AML and are associated with poor prognosis. Quizartinib is a once-daily, oral, highly potent and selective FLT3 inhibitor. In the phase 3 QuANTUM-R trial (NCT02039726; Cortes et al. Lancet Oncol 2019), quizartinib prolonged overall survival compared with salvage chemotherapy in patients with R/R FLT3-ITD AML. Murine double minute 2 (MDM2), an E3 ubiquitin ligase, negatively regulates the p53 tumor suppressor and has been shown to be upregulated in patients with AML; TP53 mutations in AML are infrequent except within complex karyotypes. Milademetan, a novel and specific MDM2 inhibitor, showed activity in an ongoing phase 1 trial in patients with AML or myelodysplastic syndromes (MDS) [DiNardo et al. ASH 2016, abstract 593]. Preclinical studies have shown that quizartinib plus milademetan may act synergistically to target FLT3-ITD and restore p53 activity in FLT3-ITD/TP53 wild-type AML [Andreeff et al. ASH 2018, abstract 2720]. Targeting MDM2 may restore p53 activity in cell signaling pathways altered by FLT3-ITD in patients with wild-type TP53 AML. Methods: This open-label, 2-part, phase 1 study (NCT03552029) evaluates quizartinib in combination with milademetan in patients with FLT3-ITD AML. Key inclusion criteria comprise a diagnosis of FLT3-ITD AML (de novo or secondary to MDS) and adequate renal, hepatic, and clotting functions. Key exclusion criteria include acute promyelocytic leukemia, prior treatment with a MDM2 inhibitor, QTcF interval &gt; 450 ms, significant cardiovascular disease, and unresolved toxicities from prior therapies. Dose-escalation (part 1) comprises patients with R/R AML. In part 1, quizartinib will be administered once daily in 28-day cycles, at 3 proposed levels (30, 40, and 60 mg) with appropriate dose modifications based on QTcF monitoring and concomitant use of strong CYP3A inhibitors. Milademetan will be administered on days 1-14 of each 28-day cycle, at 3 proposed levels (90, 120, and 160 mg). Dose escalation will be guided by modified continual reassessment with overdose control. The primary objectives of part 1 are to evaluate the safety and tolerability, optimum dosing schedule, maximum tolerated dose (MTD), and recommended dosing for the expansion (RDE) cohort. Dose expansion (part 2) comprises a cohort of patients with R/R FLT3-ITD AML who have not received &gt; 1 salvage therapy and not received &gt; 1 prior FLT3 inhibitor, and a second cohort including ND patients with FLT3-ITD AML who are unfit for intensive chemotherapy. Patients in part 2 will be treated with quizartinib plus milademetan at the RDE doses identified in part 1. The objectives of part 2 are to confirm the safety and tolerability of quizartinib plus milademetan at RDE and identify the recommended phase 2 dose. Pharmacokinetics and preliminary assessment of efficacy are also being evaluated as secondary outcomes. Pharmacodynamic and biomarker assessments such as leukemic stem cell numbers, STAT5 downstream signaling, minimal residual disease measured by flow cytometry, and gene mutations will be evaluated as exploratory endpoints. Approximately 24 to 36 dose-limiting toxicity-evaluable patients are needed in part 1 to determine the MTDs and the RDE; approximately 40 patients per cohort will be treated at the RDE in part 2. This study is currently recruiting at multiple sites in the United States for part 1; recruitment for part 2 may be expanded to additional sites worldwide as necessary. Disclosures Daver: Jazz: Consultancy; Glycomimetics: Research Funding; Immunogen: Consultancy, Research Funding; Forty-Seven: Consultancy; Novartis: Consultancy, Research Funding; Servier: Research Funding; Karyopharm: Consultancy, Research Funding; Celgene: Consultancy; Abbvie: Consultancy, Research Funding; Agios: Consultancy; Daiichi Sankyo: Consultancy, Research Funding; Otsuka: Consultancy; BMS: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Hanmi Pharm Co., Ltd.: Research Funding; Genentech: Consultancy, Research Funding; Astellas: Consultancy; Incyte: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; NOHLA: Research Funding. Graydon:Daiichi Sankyo, Inc.: Employment. Dawra:Daiichi Sankyo, Inc.: Employment; Pfizer Inc: Employment. Xie:Daiichi Sankyo, Inc.: Employment. Kumar:Daiichi Sankyo, Inc.: Employment, Equity Ownership. Andreeff:Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy; Amgen: Consultancy; AstaZeneca: Consultancy; 6 Dimensions Capital: Consultancy; Reata: Equity Ownership; Aptose: Equity Ownership; Eutropics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Oncoceutics: Equity Ownership; Oncolyze: Equity Ownership; Breast Cancer Research Foundation: Research Funding; CPRIT: Research Funding; NIH/NCI: Research Funding; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees; 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.

scholarly journals Clonal Expansion of Mutant p53 Clones By MDM2 Inhibition in Acute Myeloid Leukemias

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 27-28
Author(s):  
Yuki Nishida ◽  
Rafael Heinz Montoya ◽  
Kiyomi Morita ◽  
Tomoyuki Tanaka ◽  
Feng Wang ◽  
...  
Keyword(s):  
Single Cell ◽  
Board Of Directors ◽  
Research Funding ◽  
Drug Exposure ◽  
Single Agent ◽  
Wild Type ◽  
Advisory Committees ◽  
Tp53 Mutations ◽  
Mdm2 Inhibitor ◽  
Acute Myeloid

MDM2 inhibition by small molecules as a means of restoring p53 function has shown clinical activity against acute myeloid leukemia (AML) (Andreeff, Clin Cancer Res 2015). However, we and others have found increased variant allele frequencies (VAFs) of TP53 mutations in AML cells after treatment with MDM2 inhibitors, either as monotherapy or in combination with other agents (Daver ASH 2019), which suggests that MDM2 inhibition selects preexisting clones or generates de novo clones with TP53 mutations. We performed a long-term culture of AML cells (MOLM-13, an AML cell line with wild-type p53 and FLT3-ITD) treated with increasing concentrations of an MDM2 inhibitor idasanutlin (up to 320 nM, less than 10% concentration of Cmax) (Selleck). We obtained MDM2 inhibitor-resistant (R) AML cells after 96 days of the drug exposure and found that the resistant cells harbor hotspot TP53 p.R248W (R248W) mutation. We next isolated single cell clones from MOLM-13 R cells by limiting dilution, and obtained twelve subclones (subclones #1-12 in order of development). All clones carried the same R248W mutation. To determine clonal patterns of these cells, we performed single cell DNA sequencing (scDNAseq) of MOLM-13 parental, R and subclone #1 and #2 (SC1 and SC2) cells using the MissionBio Tapestry system covering 125 amplicons of 19 genes frequently mutated in AML. scDNAseq identified FLT3-ITD mutations in all cells analyzed, as expected. In the parental cells we identified only 0.02% cells (1/ 5,240) with the identical R248W mutation found in MOLM-13 R cells. MOLM-13 R cells had only 0.6% of wild-type TP53 cells, 51% carrying R248W only, and 43% R248W/R213* mutation (R248W/R213*). SC1 and SC2 cells had 1% and 99% of R248W and R248W/R213* clones, respectively (Fig.1). Seven other mutations were detected by scDNAseq. Results suggest that MDM2 inhibition can accelerate the selection of TP53-mutant AML cells in vitro. Of note, the parental cells had remained mostly p53 wild-type, where the subclone with mutant R248W did not have a growth advantage over other cells. Next we analyzed patient samples enrolled in the phase 1 clinical trial (NCT02319369) for the MDM2 inhibitor milademetan (DS-3032b; Daiichi-Sankyo) in relapsed/refractory AML or high-risk MDS patients. Fifty seven patients were treated with single agent milademetan in the study. All but one patient had wild-type TP53 as determined by NGS at baseline. One patient (1.8%) had a TP53 p.R213* mutation at baseline with VAF of 91%. Four patients (7%) developed different TP53 mutations (R248Q, R248W, P250fs, V122fs and V274L), with increasing VAFs that were not detected at baseline to 19% average, ranging from 11% to 28% post treatment, One patient (anonymized ID 1001-1005) developed both, R248Q and R248W mutations, detected at cycle 2 day1 (C2D1, day 29). The pre-existing R213* mutation detected in one patient persisted with increased VAF after treatment (91% to 100%). To detect p53 mutations with higher sensitivity than NGS, we performed droplet digital PCR (ddPCR) for R248W/Q and R273H in samples from two patients. ddPCR detected 0.46% and 0.62% of R248Q and R248W mutations, respectively, at baseline, which were not detected by NGS, with increased VAFs of 18.2 and 27.6% at C2D1, respectively. ddPCR detected additional R273H mutations with VAFs of 0.08% and 0.18% at baseline, and 2.2% and 2.6% in these patients at C2D1, respectively. Conclusion: Data suggest that MDM2 inhibition selects rare AML subpopulations with TP53 mutations and careful monitoring of patients treated with MDM2 inhibitors with sensitive methods to detect TP53 mutant clones is warranted. This finding also points to the need to develop strategies to prevent/suppress these clones early on. Disclosures Kumar: Daiichi-Sankyo Inc.: Current Employment. Patel:Daiichi-Sankyo Inc.: Current Employment. Dos Santos:Daiichi Sankyo, Inc.: Current Employment. DiNardo:Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Novartis: Consultancy; ImmuneOnc: Honoraria; Calithera: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Notable Labs: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Research Funding; MedImmune: Honoraria; Jazz: Honoraria; Agios: Consultancy, Honoraria, Research Funding; Takeda: Honoraria; Syros: Honoraria. Andreeff:Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding.

scholarly journals TP73 As Novel Determinant of Resistance to BCL-2 Inhibition in Acute Myeloid Leukemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1251-1251
Author(s):  
Yuki Nishida ◽  
Jo Ishizawa ◽  
Vivian Ruvolo ◽  
Feng Wang ◽  
Koichi Takahashi ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Mrna Levels ◽  
Wild Type ◽  
Advisory Committees ◽  
Protein Levels ◽  
Enhanced Sensitivity ◽  
Equity Ownership ◽  
Acute Myeloid

Background. BCL-2 inhibition is a novel and highly effective treatment modality in acute myeloid leukemias (AML). AML patients with IDH1/2 mutations are highly sensitive to BCL-2 inhibition by venetoclax (VEN) (Chen et al Nat Med 2015). High expression levels of the BCL-2 family proteins MCL-1 or BCL-XL, or knockout of TP53 have been reported to confer resistance to BCL-2 inhibition (Pan et al. Cancer Cell 2017, Nechiporuk et al. Cancer Discov 2019). p73 is one of the p53 family transcription factors and generates two isoforms, transactivation p73 (TAp73) and the N-terminally truncated ΔNp73. TAp73 shares a homologous N-terminal activation domain with p53 and has pro-apoptotic function similar to p53. ΔNp73 lacks an activation domain and has a dominant negative effect on the DNA binding of TAp73 and more importantly, of p53.TP73 is expressed in AML except in acute promyelocytic leukemias. However, the associations of TP73 isoforms with clinical and genetic characteristics or sensitivity to BCL-2 inhibition in AML have not been explored. Results. We determined copy numbers of TAp73 and ΔNp73 mRNA levels in AML samples (N = 78) and normal CD34+ hematopoietic cells (HPC) using droplet digital PCR and investigated their clinical and biological relevance. Both TP73 isoforms were expressed in AML, with TAp73 expression being 50-fold higher in AML than in CD34+ HPC (P = 0.027); no difference seen for ΔNp73 (P = 0.80), suggesting that TAp73 is aberrantly expressed in AML cells. ΔNp73 and TAp73 mRNA levels were highly correlated (R2 = 0.72, P < 0.0001). AML samples had 10-fold more abundant TAp73 than ΔNp73 mRNA levels (P = 0.0017) and isoforms were not associated with disease status (de novo vs relapsed/refractory) or cytogenetic groups, and were mutation-agnostic, except for IDH1/2. IDH1/2 mutant AML showed lower levels of TAp73 and ΔNp73 than those with wild-type IDH1/2 (P = 0.06 and P = 0.007 for TAp73 and ΔNp73, respectively). In a separate dataset, we observed repressed TP73 in IDH1/2 mutant vs. wild-type AML samples (P = 0.073) by RNAseq analysis (N = 47). Mechanistically, treatment with cell permeable octyl-(R)-2HG, the oncometabolite of mutant IDH1/2, reduced both TAp73 and ΔNp73 and increased susceptibility to VEN. Lentiviral knockdown of p73 in OCI-AML3 cells resulted in enhanced sensitivity to VEN with no significant changes in MCL-1 and p53 protein levels, or TP53 targets (MDM2, CDKN1A, FAS and BBC3). VEN resistant AML cells (MOLM-13 and MV4;11) generated through long-term culture with VEN expressed highly elevated TP73 mRNA and protein levels without significant changes in p53 or TP53 target changes, suggesting that elevated p73 could confer resistance to VEN independent of p53 function (Figure). Knockdown of TP73 showed increased protein levels of SDHB, UQCRC2 and ATP5A, components of mitochondrial respiratory chain complex II, III and V, indicating increased dependency on oxdative phosphorylation by depleting p73. Overexpression of TAp73α by lentiviral gene transfer minimally increased VEN-induced apoptosis, while ΔNp73γ overexpression conferred striking resistance to VEN in MOLM-13 cells, suggesting p73 isoform-specific dependency of VEN sensitivity/resistance. The combination of 5'-azacitidine (5'-aza) and VEN decreased ΔNp73 level by 50%. Conclusion. Repression of TP73 in IDH1/2 mutant AML, and downregulation of TP73 by the oncometabolite 2-HG were associated with enhanced sensitivity to VEN, suggesting that TP73 determines AML susceptibility to BCL-2 inhibition. VEN resistant cells massively overexpressed TP73, and TP73 knockdown restored sensitivity to VEN. Specifically, overexpression of the ΔNp73γ isoform resulted in induced VEN resistance. ΔNp73 levels were also reduced by combining VEN with 5'-aza. Results may explain the high sensitivity of IDH1/2 mutant AML to VEN as consequence of downregulation of TP73 by 2-HG, and establish the mechanism of synergistic effect by VEN + 5'-aza combination and overexpression of p73 as a novel resistance mechanism to BCL-2 inhibition. Disclosures 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. Takahashi:Symbio Pharmaceuticals: Consultancy. Carter:Amgen: Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding. Andreeff:BiolineRx: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy; Amgen: Consultancy; AstaZeneca: Consultancy; 6 Dimensions Capital: Consultancy; Reata: Equity Ownership; Aptose: Equity Ownership; 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; 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; Oncoceutics: Equity Ownership; Breast Cancer Research Foundation: Research Funding; CPRIT: Research Funding; NIH/NCI: Research Funding; Oncolyze: Equity Ownership; Eutropics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

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

The CSF3R T618I Mutation Found In Chronic Neutrophilic Leukemia Removes An O-Linked Glycosylation Site and Increases Receptor Dimerization

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 270-270
Author(s):  
Julia E. Maxson ◽  
Jason Gotlib ◽  
Daniel A. Pollyea ◽  
Angela G. Fleischman ◽  
Anupriya Agarwal ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Board Of Directors ◽  
Research Funding ◽  
Conflicts Of Interest ◽  
Glycosylation Site ◽  
Wild Type ◽  
Advisory Committees ◽  
Advisory Boards ◽  
Financial Interest ◽  
Truncation Mutant

Abstract Background We have recently identified mutations in Colony Stimulating Factor 3 Receptor (CSF3R, aka GCSFR) in ∼60% of chronic neutrophilic leukemia (CNL) and atypical chronic myeloid leukemia (aCML) patients (Maxson et al, NEJM 2013). These mutations fall into two categories: membrane proximal point mutations (the most common of which is T618I) and truncation mutations. Drug and siRNA screening of primary patient samples revealed that the two classes of CSF3R mutations exhibit differential sensitivity to inhibition of SRC or JAK kinases. CSF3R truncation mutations conferred sensitivity to SRC family kinase inhibition, while CSF3R membrane proximal mutations (T618I) conferred sensitivity to JAK kinase inhibition. A patient with the T618I membrane proximal mutation responded to treatment with the FDA approved JAK inhibitor, ruxolitinib. CSF3R truncation mutations have also been observed in a subset of severe congenital neutropenia patients who are at high risk for development of acute myeloid leukemia. Prior studies in this context have shown that truncation mutations result in loss of endocytic and degradation motifs, leading to increased expression of the receptor. The differences in signaling and drug sensitivity of these mutation classes suggest that membrane proximal mutations may activate CSF3R signaling through a distinct, as-yet unknown mechanism. Furthermore, a subset of CNL patients harbor both membrane proximal and truncation mutations on the same allele, though the consequences of these compound mutations are not yet known. Methods CSF3R expression level and banding pattern were assessed by immunoblot of lysates from 293T17 cells transfected with wild type, membrane proximal mutant, or truncation mutant CSF3R. O-linked glycosylation was removed from the receptor by treatment with O-glycosidase and neuraminidase. Ligand independence of the CSF3R mutants was analyzed in murine interleukin-3 (IL3)-dependent Ba/F3 cells. CSF3R dimerization was assessed by co-transfecting CSF3R-Flag and CSF3R-V5 tagged constructs and then immunoprecipitating CSF3R-Flag and detecting co-immunoprecipitation of the CSF3R-V5 by immunoblot. Transforming potential of the CSF3R compound mutations relative to the corresponding point or truncation mutations was assessed by analyzing IL3-independent growth of Ba/F3 cells or mouse bone marrow colony formation. Results To better understand the functional and biochemical differences between membrane proximal and truncation mutant CSF3R, we examined transformation potential, requirement for ligand, and expression patterns in Ba/F3 and 293T17 cells. We found membrane proximal mutations to exhibit rapid transformation potential and ligand independence, while truncation mutations exhibited delayed transformation and ligand hypersensitivity. Unlike the truncation mutations, which induce dramatic overexpression of CSF3R, the T618I mutation did not result in overexpression of the receptor but instead induced a shifted banding pattern, indicative of altered protein modification. We examined the amino acid sequence surrounding the membrane proximal mutations and found residue T618 to be part of a consensus motif for O-glycosylation, wherein wild type CSF3R is O-glycosylated and the T618I mutation abrogates this O-glycosylation event. Furthermore, the T618I mutation exhibited increased receptor dimerization compared to wild type CSF3R, which likely explains its ligand independence. Finally, we found that CSF3R compound mutations have increased transforming potential in Ba/F3 and murine bone marrow colony assays compared with either class of single mutation, further underscoring the different mechanisms of action of the membrane proximal and truncation mutations. Conclusion CSF3R represents a promising therapeutic target for patients with CNL. We show that T618I, the most common CSF3R mutation in CNL, is part of an O-linked glycosylation site. Mutation of this residue leads to loss of O-linked glycosylation and represents a novel mechanism of homodimeric cytokine receptor activation. CSF3R compound mutations are more rapidly transforming relative to the membrane proximal or truncation mutations alone, warranting their further investigation for patient prognosis and therapy. Disclosures: Off Label Use: Ruxolitinib - a JAK1/2 inhibitor that we propose can be used off-label for disease management of CSF3R-mutant neutrophilic leukemia. Gotlib:Incyte: Membership on an entity’s Board of Directors or advisory committees, Research Funding, Travel Support Other. Fleischman:Incyte: Speakers Bureau. Collins:Genoptix: Membership on an entity’s Board of Directors or advisory committees. Oh:Incyte Corporation: Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau. Deininger:Novartis: Advisory Boards, Advisory Boards Other, Consultancy, Research Funding; Ariad Pharmaceuticals: Advisory Boards, Advisory Boards Other, Consultancy; Bristol-Myers Squibb: Advisory Boards Other, Consultancy, Research Funding; Celgene: Research Funding; Gilead Sciences: Research Funding. Druker:Bristol-Myers Squibb: PI or co-investigator on BMS clinical trials. OHSU and Dr. Druker have a financial interest in MolecularMD. OHSU has licensed technology used in some of these clinical trials to MolecularMD. Potential conflicts of interest are managed by OHSU. Other; Novartis: PI or co-investigator on Novartis clinical trials. OHSU and Dr. Druker have a financial interest in MolecularMD. OHSU has licensed technology used in some of these clinical trials to MolecularMD. Potential conflicts of interest are managed by OHSU., PI or co-investigator on Novartis clinical trials. OHSU and Dr. Druker have a financial interest in MolecularMD. OHSU has licensed technology used in some of these clinical trials to MolecularMD. Potential conflicts of interest are managed by OHSU. Other; Incyte: PI or co-investigator on clinical trials., PI or co-investigator on clinical trials. Other. Tyner:Incyte Corporation: Research Funding.

Response to Treatment Among SF3B1 Mutated Myelodysplastic Syndromes (MDS): A Case-Control Study from the MDS Clinical Research Consortium (MDS CRC)

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1697-1697 ◽  
Author(s):  
Rami S. Komrokji ◽  
Amy E. DeZern ◽  
Katrina Zell ◽  
Najla H. Al Ali ◽  
Eric Padron ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Lower Risk ◽  
Research Funding ◽  
Somatic Mutations ◽  
Response To Treatment ◽  
Wild Type ◽  
Advisory Committees ◽  
Baseline Characteristics ◽  
Matching Criteria

Abstract Introduction Somatic mutations in SF3B1 ,a gene encoding a core component of RNA splicing machinery, have been identified in patients (pts) with myelodysplastic syndrome (MDS). The SF3B1 mutation (MT) is more commonly detected in pts with ring sideroblasts (RS) morphology and is associated with favorable outcome. The pattern of response among SF3B1 mutated MDS pts to available treatment options, including erythropoiesis stimulating agents (ESA), hypomethylating agents (HMA) and lenalidomide is not known. The distinct underlying disease biology among such pts may alter response to treatment. Methods Pts treated at MDS CRC institutions with MT vs wild-type SF3B1 (WT) controls were matched 1:2. Matching criteria were age at diagnosis, year of diagnosis and International Prognostic Scoring System (IPSS) category at diagnosis. IPSS category was split into two groups (Low or Int-1 vs. Int-2 or High). Matching was performed using the R package by calculating a propensity score, which was then used to determine the two most similar WT SF3B1 patients for each SF3B1-mutated pt, without replacement. Additionally, to be included in the population, pts also had to have been treated with one of the following: ESAs, HMA, or lenalidomide. Response to treatment was evaluated by international Working Group criteria (IWG 2006) and classified as response if hematological improvement or better was achieved (HI+). Survival was calculated from date of treatment until date of death or last known follow-up, unless otherwise noted. Results: We identified 48 Pts with MT and 96 matched controls. Table 1 summarizes baseline characteristics comparing MT vs WT SF3B1 cohorts. SF3B1 MT was detected more often in association with RS, as expected. The majority of pts had lower-risk disease by IPSS and revised IPSS (IPSS-R). Pts with MT had higher platelets than controls. The most common concomitant somatic mutations observed were TET2 (30%), DNMT3A (21%), and ASXL1 (7%). Median follow-up time from diagnosis was 35 months (mo). Median overall survival (OS) from diagnosis was significantly longer for patients with SF3B1 MT (108.5 mo (68.8, NA)) than wild-type controls (28.3 mo (22.3, 36.4); p < 0.001). Patients with an SF3B1 MT had a decreased hazard of death (hazard ratio [HR]: 0.49 (95% confidence limits [95% CL]: 0.29, 0.84); p = 0.009) ESA was the first line therapy for 43 pts (88%) with MT and 55 WT Pts (56%). For ESA treated pts, 14 out 40 MT Pts responded (35%) compared to 9/56 among WT Pts (16%), p 0.032. Among those treated with HMA therapy, 5 out 21 (24%) MT pts responded compared to 11/46 (24%) WT Pts (p 0.99). Finally, for Pts treated with lenalidomide 4/16 (25%) and 4/21 (19%) responded among SF3B1 MT and WT Pts respectively, p 0.7. Conclusions SF3B1 somatic mutation in MDS is commonly associated with RS, lower risk disease, and better OS. Pts with SF3B1 mutation had higher response to ESA compared WT SF3B1. No difference in response to HMA or lenalidomide was observed compared to WT patients. Response rates to lenalidomide and HMA were low in both MT patients and controls. Biologically rational therapies are needed that target this molecular disease subset. Table 1. Baseline characteristics SF3B1 MT (n=48) SF3B1 WT (n=96) P value Age median 65 67 0.6 Gender male 29 (60%) 64(67%) 0.5 Race White 44/45 (98%) 83/90 (92%) 0.34 WHO classification RA RARS RCMD RARS-T Del5 q RAEB-I RAEB-II MDS-U MDS/MPN CMML 3 24 8 4 1 3 3 2 0 0 6 9 17 2 6 10 9 3 11 9 IPSS Low Int-1 Int-2 High 29 (60%) 16 (33%) 3 (6%) 0 21 (22%) 69 (72%) 4 (4%) 2 (2%) < 0.001 IPSS-R Very low Low Intermediate High Very High 15 (31%) 26 (54%) 5 (10%) 2 (4%) 0 11 (11%) 37 (39%) 26 (27%) 18 (19%) 4 (4%) <0.001 Lab values (mean) Hgb Platelets ANC myeloblasts 9.7 274 2.63 1 9.6 108 1.92 2 0.46 <0.001 0.04 0.05 Disclosures Komrokji: Novartis: Research Funding, Speakers Bureau; Celgene: Consultancy, Research Funding; Incyte: Consultancy; Pharmacylics: Speakers Bureau. Padron:Novartis: Speakers Bureau; Incyte: Research Funding. List:Celgene Corporation: Honoraria, Research Funding. Steensma:Incyte: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Onconova: Consultancy. Sekeres:Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; TetraLogic: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees.

Combined Treatment with Lenalidomide (LEN) and Epoetin Alfa (EA) Is Superior to Lenalidomide Alone in Patients with Erythropoietin (Epo)-Refractory, Lower Risk (LR) Non-Deletion 5q [Del(5q)] Myelodysplastic Syndrome (MDS): Results of the E2905 Intergroup Study-an ECOG-ACRIN Cancer Research Group Study, Grant CA180820, and the National Cancer Institute of the National Institutes of Health

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 223-223 ◽  
Author(s):  
Alan F List ◽  
Zhuoxin Sun ◽  
Amit Verma ◽  
John M. Bennett ◽  
Kathy L McGraw ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Board Of Directors ◽  
Research Funding ◽  
Combined Treatment ◽  
Phase Iii ◽  
Advisory Committees ◽  
Median Response ◽  
Erythroid Response ◽  
Receptor Complexes ◽  
Erythroid Precursors

Abstract Background: Treatment with rhu-Epo ameliorates anemia in a subset of LR-MDS patients, however, effective salvage therapy is limited. LEN promotes erythroid lineage competence and expansion of primitive erythroid precursors in vitro. In the MDS-002 and MDS-005 trials, treatment with LEN improved erythropoiesis, yielding RBC transfusion-independence in 26% of azanucleoside-naïve, transfusion-dependent (TD) LR, non-del(5q) MDS patients for a median of 10.2 and 7.75 months, respectively. We previously reported that LEN restores Epo-responsiveness in MDS progenitors by inducing formation of lipid rafts enriched for signaling competent JAK2/Epo-receptor complexes and excluding large isoforms of the JAK2/lyn kinase-phosphatase CD45 (McGraw K, et. al. PLoS One 2014; Basiorka A, et. al. Cancer Res 2016). In a pilot study of Epo-refractory MDS patients, addition of EA yielded erythroid responses in 28% of patients who were unresponsive to LEN alone, suggesting that LEN may overcome resistance and augment response to rhEpo (Komrokji R, et. al. Blood 2012). To test this hypothesis, we performed a randomized phase III trial comparing treatment with LEN to LEN+EA in LR non-del(5q) MDS patients who were refractory to, or not candidates for treatment with rhEpo. Methods: Patients with Low or Intermediate-1 (Int-1) risk IPSS MDS with hemoglobin <9.5 g/dL who were unresponsive to rhEpo treatment or were TD (>2 units/mo) with serum Epo >500mU/mL were eligible for study. Patients were stratified by serum Epo level and prior rhEpo (EA vs. darbepoetin vs. none) then randomized to treatment with LEN 10 mg/d x21d q4wk (Arm A) or LEN + EA 60,000U SC/wk (Arm B). Primary endpoint was IWG 2006 major erythroid response (MER) rate after 4 cycles. Arm A non-responders were offered cross-over to combined therapy. Secondary endpoints included analysis of response biomarkers. Results: Between April 2009 and May 2016, 248 patients were enrolled and 195 were randomized and will be included in the primary analysis. Interim analysis of 163 patients (Arm A, 81; B, 82) accrued before July 2015 showed that the study met predefined stopping criteria. Baseline characteristics were balanced between arms. Median age was 74 years (range, 47-89) receiving a median of 2 RBC units/mo (0-8). Overall, 64 (39%) patients had Low IPSS risk and 90 (55%) Int-1 risk. Among these, 150 received prior rhuEpo (92%) and 27, azanucleosides (17%). In an ITT analysis, MER rate was significantly higher with combination therapy, Arm B 25.6% (n=21) vs. Arm A 9.9% (n=8) (P=0.015). Among 116 patients evaluable at week 16, 33.3% (20/60) and 14.3% (8/56) achieved MER, respectively (P=0.018), with a median response duration of 25.4 months vs. not reached in Arm A responders. Response to combined treatment was associated with baseline CD45-isoform distribution in erythroid precursors. Patients achieving MER had a significantly lower CD45 RA+RB:RO ratio (median, 1.51) compared to non-responders (median, 4.21; P=0.04), favoring homo-dimerization of the short CD45-RO isoform and inhibition of phosphatase activity. MER rate in Arm B patients with a low isoform ratio (< median) was 72.7% vs. 18.2% in the high ratio group (P=0.03). Thirty-four Arm A non-responders crossed over to combination-therapy with only 1 MER. There was no difference in the frequency or distribution of >Grade 3, non-hematologic AEs. Conclusions: LEN restores sensitivity to rhEpo in Epo-refractory LR-non-del(5q) MDS patients to yield durable and significantly higher rates of erythroid response to combination treatment without added toxicity. Erythroid CD45 isoform profile may serve as a response biomarker for selection of candidates for combination therapy. Disclosures Bennett: Celgne: Membership on an entity's Board of Directors or advisory committees. Altman:Syros: Honoraria; Janssen: Honoraria; BMS: Honoraria; Novartis: Honoraria. Komrokji:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Speakers Bureau. Schiffer:Teva: Other: DSMB member; BMS: Research Funding; Ariad: Research Funding; Pfizer: Other: DSMB member.

Identification of a Factor X-Interactive Site on the Factor VIII A2 Domain

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3760-3760
Author(s):  
Masahiro Takeyama ◽  
Keiji Nogami ◽  
Shoko Furukawa ◽  
Midori Shima
Keyword(s):  
Board Of Directors ◽  
Binding Affinity ◽  
Research Funding ◽  
Cross Linking ◽  
Functional Evaluation ◽  
Dependent Manner ◽  
Wild Type ◽  
Advisory Committees ◽  
Chugai Pharmaceutical ◽  
A2 Domain

Abstract We have experienced a case of acquired hemophilia A with inhibitor recognizing only a factor (F) VIII A2 epitope, and reported the inhibitory mechanism for disappearing FVIII activity (Blood, 124, 4226, 2014). In summary, the patient's inhibitor IgG bound to FVIII A2N (residue 372-562) fragment and inhibited Arg372 cleavage in FVIII by FXa, suggesting that FX(a) bound to FVIII A2 domain. ELISA-based assay showed that FVIII A2 fragment bound to FX (Kd; 338 nM). We hypothesized that FVIII A2 residues 400-429 might be FX binding site according to the 3-D model of FVIII molecule, and prepared synthetic peptides (400-409, 409-419, and 420-429). The 400-409 peptide inhibited the FVIII A2-FX interaction, suggesting that the 400-409 region contributed to FX-interactive site. In this current study, we further performed the localization of a FX-interactive site on the 400-409 region in the A2 domain. A purified FXa generation assay demonstrated the 400-409 peptide decreased the generation of FXa in a dose-dependent manner up to 38% of 100 μM (Ki; 23 ± 9 nM). In comparison, scrambled peptide of 400-409 decreased up to 10% of 100 μM. These data demonstrated that the 400-409 peptide inhibited the generated FXa, suggesting the 400-409 region contributed to regulate the coagulation function. Covalent cross-linking was observed between the biotinylated 400-409 peptide and FX following reaction with EDC (1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide) using SDS-PAGE. This cross-linking formation was blocked by the addition of unlabeled 400-409 peptide. N-terminal sequence analysis of the peptide-FX product demonstrated that two sequential residues (Lys408 and Ser409) could not be detected, supporting that two residues participate in cross-link formation. To confirm the significance of these residues in A2 domain for FX-binding, the mutant forms of the A2 domain, converted to alanine, were expressed in BHK system and purified. Compared with wild type FVIII (Kd; 10 ± 3 nM), the binding affinity of Ser409Ala FVIII mutant for FX was no significant difference (Kd; 14 ± 1 nM) on SPR-based assay. Lys408Ala or Lys408Ala/Ser409Ala double FVIII mutant, however, decreased the binding affinity by 3.6~4.3-fold (Kd; 36 ± 7 or 43 ± 2 nM, respectively), suggesting contribution of Lys408Ala to the binding interaction. For the functional evaluation of the association with FVIII mutants to FX, a FXa generation assay was repeated. Lys408Ala, Ser409Ala, or Lys408Ala/Ser409Ala FVIII mutant reacted with varying concentrations of FX decreased by 1.2~1.6-fold (Km; 53 ± 12, 69 ± 15, or 65 ± 15 nM, respectively) compared to wild type FVIII (Km; 43 ± 9 nM), supporting a contribution of these mutants to Km and overall catalytic efficiency. Vmax values were largely unaffected by the mutations with most values within approximately 30% of the wild-type value. On the other hand, Kcat/Km value of Lys408Ala, Ser409Ala, or Lys408Ala/Ser409Ala FVIII mutant were decreased by 0.5~0.7-fold (Kcat/Km; 1.0, 1.3, or 0.9 nM-1min-1, respectively) compared to wild type FVIII (Kcat/Km; 1.8 nM-1min-1), suggesting low catalytic efficacy of Lys408Ala and Ser409Ala. These results indicate that the 400-409 region in the FVIII A2 domain, and in particular Lys408 and Ser409, may contribute to a unique FX-interactive site. Disclosures Nogami: Chugai Pharmaceutical Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; F. Hoffmann-La Roche Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sysmex Corporation: Patents & Royalties, Research Funding. Shima:Sysmex Corporation: Patents & Royalties, Research Funding; Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; F. Hoffmann-La Roche Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Sign in / Sign up

Export Citation Format

Share Document