scholarly journals Germline Runx1 Mutations Induce Inflammation in Hematopoietic Stem and Progenitor Cells and Predispose to Hematologic Malignancies

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2201-2201
Author(s):  
Mohd Hafiz Ahmad ◽  
Mahesh Hegde ◽  
Waihay J. Wong ◽  
Andrew Dunbar ◽  
Anneliese Carrascoso ◽  
...  

Abstract Patients with Familial Platelet disorder (FPD) have a germline RUNX1 mutation and are at high risk to developing hematologic malignancies (HM), primarily myelodysplastic syndrome and acute myeloid leukemia (lifetime risk~40%). To understand how germline RUNX1 mutations predispose to HM in vivo, we developed a Runx1 R188Q/+ mouse strain , mimicking the FPD-associated R201Q missense mutation. Analysis of the bone marrow cells in Runx1 R188Q/+ mice revealed a significant increase in the total number of bone marrow cells. Immunophenotypic analysis using Sca-1 and Cd86 markers revealed a significant increase in Sca-1 expression in hematopoietic stem and multi-potential progenitor cells, indicating a systemic inflammation in the bone marrow. In addition, the frequency of common-myeloid, granulocytic-monocytic and granulocytic progenitor cells were found significantly increased in the Runx1 R188Q/+ bone marrow. Accordingly, their colony-forming unit capacity was increased when compared to wildtype controls (wt/Runx1 R188Q/+ CFU average = 45/85), indicating a myeloid bias. The number and size of platelets were not altered in Runx1 R188Q/+ mice. However, platelet function was significantly reduced. The activation of the Cd41/Cd61 fibrinogen receptor complex in membrane after thrombin treatment was reduced in Runx1 R188Q/+ platelets. Similarly, the translocation of P-selectin by alpha granules and the secretion of serotonin by the dense granules were also reduced. Hematopoietic progenitor cells isolated from Runx1 R188Q/+ mice revealed a significant reduction in DNA-damage repair response in vitro. Quantitative analysis of nuclei with 53bp1-positive foci in response to ionizing radiation showed a marked increase in 53bp1-positive foci in Runx1 R188Q/+ nuclei, suggesting that Runx1 R188Q/+ cells have a defective repair of double strand DNA breaks. Furthermore, expression of DNA-damage repair pathway-associated Pmaip1 (Noxa) was significantly reduced in irradiated Runx1 R188Q/+ hematopoietic progenitor cells. To understand underlying mechanism responsible for the observed myeloid bias in Runx1 R188Q/+ cells, transcription profiling analysis was performed in myeloid progenitors from wildtype and Runx1 R188Q/+ mice, utilizing RNA-sequencing. A total of 39 genes were significantly deregulated (> 1.5 FC; FDR<0.05), including 8 up- and 31 down-regulated genes. The expression of three repressed genes with important function in hematopoietic differentiation and malignancy (Cdh1, Gja1, and Fcer1a) were validated by qRT-PCR. To study the FPD-associated pre-leukemic process in vivo, wildtype and Runx1 R188Q/+ mice were monitored for 20 months. Although Runx1 R188Q/+ mice remained healthy for 18 months, somatic mutations in their leukocytes were evident at 12 months. Targeted sequencing of 578 cancer genes (mIMPACT panel) in leukocyte DNA of two Runx1 R188Q/+ mice identified somatic mutations in Kdm6a, Setd1b, Amer1, and Esco1 (variant allele frequencies between 0.5% and 2.8%). These mutations were confirmed at stable frequency for eight following months. Since loss of the second Runx1 allele is a frequent somatic event in progression to FPD/HM, we evaluated the predisposition to HM in Mx1Cre-Runx1 R188Q/fl mice over time. Unlike Runx1 R188Q/+ mice, Runx1 R188Q/Δ mice succumbed to myeloid leukemia with a median latency of 37.5 weeks and full penetrance. In addition, the expression of oncogenic Nras-G12D, in Runx1 R188Q/Δ mice reduced the median latency to 14.7 weeks. These studies demonstrate that FPD-associated Runx1 germline mutations induce inflammation in hematopoietic stem cells, induce myeloid expansion with defective DNA-damage response and predispose to HM over time. These studies suggest that anti-inflammatory therapies in pre-symptomatic FPD patients may reduce clonal expansion and predisposition to HM. Disclosures Ebert: Exo Therapeutics: Membership on an entity's Board of Directors or advisory committees; Skyhawk Therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Deerfield: Research Funding; GRAIL: Consultancy. Levine: Isoplexis: Membership on an entity's Board of Directors or advisory committees; Auron: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Membership on an entity's Board of Directors or advisory committees; Zentalis: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; QIAGEN: Membership on an entity's Board of Directors or advisory committees; Ajax: Membership on an entity's Board of Directors or advisory committees; Imago: Membership on an entity's Board of Directors or advisory committees; Mission Bio: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria; Prelude: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Lilly: Honoraria; Morphosys: Consultancy; Roche: Honoraria, Research Funding; Incyte: Consultancy; Astellas: Consultancy; Amgen: Honoraria.

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 33-33
Author(s):  
Akira Chiba ◽  
Yosuke Masamoto ◽  
Hideaki Mizuno ◽  
Mineo Kurokawa

Acute myeloid leukemia (AML) with high expression of a transcriptional factor, Ecotropic viral integration site 1 (EVI1), is associated with extremely poor prognosis. EVI1 is, however, also essential for maintaining normal hematopoietic stem cells (HSCs), rendering it potentially difficult to target this molecule. To overcome this therapeutic difficulty, it is important to comprehensively elucidate differentially regulated downstream targets between normal and leukemia cells. In this study, we searched downstream targets of EVI1 in normal hematopoiesis by combining a chromatin immunoprecipitation sequence (ChIP-seq) and RNA-sequence (RNA-seq) analysis using a mouse hematopoietic cell line 32D-cl3 with high EVI1 expression. We deleted Evi1 using CRISPR/Cas9 in 32D-cl3 cells. Evi1 knock-out (KO) 32D-cl3 cells showed comparable cell growth with parental cells in the presence of IL-3, which enables them to proliferate permanently without differentiation. When they are allowed to differentiate by adding G-CSF, the number of KO cells decreased sharply at day 5-6, compared with parental 32D-cl3 cells. Along with the decreased cell number, KO cells also demonstrated higher positive rate of Gr-1 at day 7, a typical marker of differentiation into granulocytes, indicating accelerated differentiation of KO cells. These results indicated that EVI1 is required to maintain undifferentiated status of 32D-cl3 cells in a differentiation-permissive conditions, which can model normal hematopoiesis. We knocked in 3×FLAG tag at the 3' end of the Evi1 gene to perform ChIP-seq using anti-FLAG antibody. By using these knock-in cells, ChIP-seq was performed on day 0 and day 3 of G-CSF treatment, when they had started to differentiate with still maintained EVI1 expression. The peaks observed in undifferentiated day 0 sample were considered to contain a group of genes involved in undifferentiated hematopoietic cells in cooperation with EVI1. Genes associated HDAC class I, RAC1 signaling were enriched in these genes. To investigate the functional implications of the result of ChIP-seq, RNA-seq data using two clones of KO cells and parental cells were combined. We found that 152 genes were significantly up-regulated, and 155 genes were down-regulated in the KO cells, with false discovery rate less than 0.05. Twenty-four genes were identified by extracting common genes between ChIP-seq and RNA-seq; namely, genes which had day 0-specific peaks in ChIP-seq, and whose expression were decreased in the KO cells. In order to further examine the physiological implications of 24 genes in vivo, we referred to the results of RNA-seq using murine bone marrow transplantation model, where murine hematopoietic progenitor cells retrovirally transduced with Evi1 were transplanted into irradiated syngeneic mice, finally leading to AML after a long latency. Samples obtained early after post transplantation and those after AML onset were compared to those of normal hematopoietic progenitor cells. Among the above 24 genes, the expression of 5 genes was increased early after transplantation and decreased after the onset of AML, that is, these genes were up-regulated by EVI1 but don't seem to be involved in AML maintenance. We functionally validated the role of these genes in 32D-cl3 cells. Of the above, CRISPR/Cas9-mediated knock-out of Gfi1(Growth Factor Independent 1 Transcriptional Repressor) and Mfsd2b (Major facilitator superfamily domain containing 2B) in 32D-cl3 cells led to high Gr-1 positivity at day 7 like Evi1-KO cells, suggesting that these genes are involved in the functions of EVI1 in the normal hematopoiesis. The mRNA expression of these genes was compared in LSK (Lineage- Sca1+ c-kit+) cells from the bone marrow of Evi1 conditional knockout (cKO) mice and control mice. The expression of Gfi1 and Mfsd2b was decreased in LSK cells from Evi1 cKO mice. Furthermore, retroviral expression of Gfi1 in LSK cells restored the reduced colony-forming ability of Evi1 cKO cells. These results collectively suggest that GFI1 is regulated by EVI1 and is involved in the function of EVI1 regulating the stemness of hematopoietic stem and progenitor cells in normal hematopoiesis. These findings provide us with the novel insights on EVI1-mediated HSC maintenance as well as on the therapeutic strategy that specifically targets leukemia-specific EVI1 effectors while preserving normal hematopoiesis. Disclosures Kurokawa: Shire Plc: Speakers Bureau; Jansen Pharmaceutical: Speakers Bureau; Ono: Research Funding, Speakers Bureau; Boehringer Ingelheim: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Eisai: Research Funding, Speakers Bureau; Sumitomo Dainippon Pharma: Research Funding, Speakers Bureau; Teijin: Research Funding; Takeda: Research Funding, Speakers Bureau; Kyowa Kirin: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas: Research Funding, Speakers Bureau; Otsuka: Research Funding, Speakers Bureau; Pfizer: Research Funding; Sanwa-Kagaku: Consultancy; MSD: Consultancy, Research Funding, Speakers Bureau; Chugai: Consultancy, Research Funding, Speakers Bureau; Bioverativ Japan: Consultancy; Celgene: Consultancy, Speakers Bureau; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Nippon Shinyaku: Research Funding, Speakers Bureau.


Blood ◽  
2000 ◽  
Vol 95 (2) ◽  
pp. 700-704 ◽  
Author(s):  
Kimberly A. Gush ◽  
Kai-Ling Fu ◽  
Markus Grompe ◽  
Christopher E. Walsh

Fanconi anemia (FA) is a genetic disorder characterized by bone marrow failure, congenital anomalies, and a predisposition to malignancy. FA cells demonstrate hypersensitivity to DNA cross-linking agents, such as mitomycin C (MMC). Mice with a targeted disruption of the FANCC gene (fancc −/− nullizygous mice) exhibit many of the characteristic features of FA and provide a valuable tool for testing novel therapeutic strategies. We have exploited the inherent hypersensitivity offancc −/− hematopoietic cells to assay for phenotypic correction following transfer of the FANCC complementary DNA (cDNA) into bone marrow cells. Murine fancc −/− bone marrow cells were transduced with the use of retrovirus carrying the humanfancc cDNA and injected into lethally irradiated recipients. Mitomycin C (MMC) dosing, known to induce pancytopenia, was used to challenge the transplanted animals. Phenotypic correction was determined by assessment of peripheral blood counts. Mice that received cells transduced with virus carrying the wild-type gene maintained normal blood counts following MMC administration. All nullizygous control animals receiving MMC exhibited pancytopenia shortly before death. Clonogenic assay and polymerase chain reaction analysis confirmed gene transfer of progenitor cells. These results indicate that selective pressure promotes in vivo enrichment offancc-transduced hematopoietic stem/progenitor cells. In addition, MMC resistance coupled with detection of the transgene in secondary recipients suggests transduction and phenotypic correction of long-term repopulating stem cells.


Author(s):  
Ramya Dewi Mathialagan ◽  
Zariyantey Abd Hamid ◽  
Qing Min Ng ◽  
Nor Fadilah Rajab ◽  
Salwati Shuib ◽  
...  

Hematopoietic stem/progenitor cells (HSPCs) are susceptible to benzene-induced genotoxicity. However, little is known about the mechanism of DNA damage response affecting lineage-committed progenitors for myeloid, erythroid, and lymphoid. Here, we investigated the genotoxicity of a benzene metabolite, 1,4-benzoquinone (1,4-BQ), in HSPCs using oxidative stress and lineage-directed approaches. Mouse bone marrow cells (BMCs) were exposed to 1,4-BQ (1.25–12 μM) for 24 h, followed by oxidative stress and genotoxicity assessments. Then, the genotoxicity of 1,4-BQ in lineage-committed progenitors was evaluated using colony forming cell assay following 7–14 days of culture. 1,4-BQ exposure causes significant decreases (p < 0.05) in glutathione level and superoxide dismutase activity, along with significant increases (p < 0.05) in levels of malondialdehyde and protein carbonyls. 1,4-BQ exposure induces DNA damage in BMCs by significantly (p < 0.05) increased percentages of DNA in tail at 7 and 12 μM and tail moment at 12 μM. We found crucial differences in genotoxic susceptibility based on percentages of DNA in tail between lineage-committed progenitors. Myeloid and pre-B lymphoid progenitors appeared to acquire significant DNA damage as compared with the control starting from a low concentration of 1,4-BQ exposure (2.5 µM). In contrast, the erythroid progenitor showed significant damage as compared with the control starting at 5 µM 1,4-BQ. Meanwhile, a significant (p < 0.05) increase in tail moment was only notable at 7 µM and 12 µM 1,4-BQ exposure for all progenitors. Benzene could mediate hematological disorders by promoting bone marrow oxidative stress and lineage-specific genotoxicity targeting HSPCs.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1293-1293
Author(s):  
Hong Qian ◽  
Sten Eirik W. Jacobsen ◽  
Marja Ekblom

Abstract Within the bone marrow environment, adhesive interactions between stromal cells and extracellular matrix molecules are required for stem and progenitor cell survival, proliferation and differentiation as well as their transmigration between bone marrow (BM) and the circulation. This regulation is mediated by cell surface adhesion receptors. In experimental mouse stem cell transplantation models, several classes of cell adhesion receptors have been shown to be involved in the homing and engraftment of stem and progenitor cells in BM. We have previously found that integrin a6 mediates human hematopoietic stem and progenitor cell adhesion to and migration on its specific ligands, laminin-8 and laminin-10/11 in vitro (Gu et al, Blood, 2003; 101:877). Using FACS analysis, the integrin a6 chain was now found to be ubiquitously (>95%) expressed in mouse hematopoietic stem and progenitor cells (lin−Sca-1+c-Kit+, lin−Sca-1+c-Kit+CD34+) both in adult bone marrow and in fetal liver. In vitro, about 70% of mouse BM lin−Sca-1+c-Kit+ cells adhered to laminin-10/11 and 40% adhered to laminin-8. This adhesion was mediated by integrin a6b1 receptor, as shown by functional blocking monoclonal antibodies. We also used a functional blocking monoclonal antibody (GoH3) against integrin a6 to analyse the role of the integrin a6 receptor for the in vivo homing of hematopoietic stem and progenitor cells. We found that the integrin a6 antibody inhibited the homing of bone marrow progenitors (CFU-C) into BM of lethally irradiated recipients. The number of homed CFU-C was reduced by about 40% as compared to cells incubated with an isotype matched control antibody. To study homing of long-term repopulating stem cells (LTR), antibody treated bone marrow cells were first injected intravenously into lethally irradiated primary recipients. After three hours, bone marrow cells of the primary recipients were analysed by competitive repopulation assay in secondary recipients. Blood analysis 16 weeks after transplantation revealed an 80% reduction of stem cell activity of integrin a6 antibody treated cells as compared to cells treated with control antibody. These results suggest that integrin a6 plays an important role for hematopoietic stem and progenitor cell homing in vivo.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3401-3401
Author(s):  
Rebecca L Porter ◽  
Mary A Georger ◽  
Laura M Calvi

Abstract Abstract 3401 Hematopoietic stem and progenitor cells (HSPCs) are responsible for the continual production of all mature blood cells during homeostasis and times of stress. These cells are known to be regulated in part by the bone marrow microenvironment in which they reside. We have previously reported that the microenvironmentally-produced factor Prostaglandin E2 (PGE2) expands HSPCs when administered systemically in naïve mice (Porter, Frisch et. al., Blood, 2009). However, the mechanism mediating this expansion remains unclear. Here, we demonstrate that in vivo PGE2 treatment inhibits apoptosis of HSPCs in naïve mice, as measured by Annexin V staining (p=0.0083, n=6–7 mice/group) and detection of active-Caspase 3 (p=0.01, n=6–7 mice/group). These data suggest that inhibition of apoptosis is at least one mechanism by which PGE2 expands HSPCs. Since PGE2 is a local mediator of injury and is known to play a protective role in other cell types, we hypothesized that it could be an important microenvironmental regulator of HSPCs during times of injury. Thus, these studies explored the role of PGE2 signaling in the bone marrow following myelosuppressive injury using a radiation injury model. Endogenous PGE2 levels in the bone marrow increased 2.9-fold in response to a sub-lethal dose of 6.5 Gy total body irradiation (TBI)(p=0.0004, n=3–11 mice/group). This increase in PGE2 correlated with up-regulation of microenvironmental Cyclooxygenase-2 (Cox-2) mRNA (p=0.0048) and protein levels at 24 and 72 hr post-TBI, respectively. Further augmentation of prostaglandin signaling following 6.5 Gy TBI by administration of exogenous 16,16-dimethyl-PGE2 (dmPGE2) enhanced the survival of functional HSPCs acutely after injury. At 24 hr post-TBI, the bone marrow of dmPGE2-treated animals contained significantly more LSK cells (p=0.0037, n=13 mice/group) and colony forming unit-spleen cells (p=0.037, n=5 mice/group). Competitive transplantation assays at 72 hr post-TBI demonstrated that bone marrow cells from irradiated dmPGE2-treated mice exhibited increased repopulating activity compared with cells from vehicle-treated mice. Taken together, these results indicate that dmPGE2 treatment post-TBI increases survival of functional HSPCs. Since PGE2 can inhibit apoptosis of HSPCs in naïve mice, the effect of dmPGE2 post-TBI on apoptosis was also investigated. HSPCs isolated from mice 24 hr post-TBI demonstrated statistically significant down-regulation of several pro-apoptotic genes and up-regulation of anti-apoptotic genes in dmPGE2-treated animals (3 separate experiments with n=4–8 mice/group in each), suggesting that dmPGE2 initiates an anti-apoptotic program in HSPCs following injury. Notably, there was no significant change in expression of the anti-apoptotic gene Survivin, which has previously been reported to increase in response to ex vivo dmPGE2 treatment of bone marrow cells (Hoggatt et. al., Blood, 2009), suggesting differential effects of dmPGE2 in vivo and/or in an injury setting. Additionally, to ensure that this inhibition of apoptosis was not merely increasing survival of damaged and non-functional HSPCs, the effect of early treatment with dmPGE2 post-TBI on hematopoietic recovery was assayed by monitoring peripheral blood counts. Interestingly, dmPGE2 treatment in the first 72 hr post-TBI significantly accelerated recovery of platelet levels and hematocrit compared with injured vehicle-treated mice (n=12 mice/group). Immunohistochemical analysis of the bone marrow of dmPGE2-treated mice also exhibited a dramatic activation of Cox-2 in the bone marrow microenvironment. This suggests that the beneficial effect of dmPGE2 treatment following injury may occur, both through direct stimulation of hematopoietic cells and also via activation of the HSC niche. In summary, these data indicate that PGE2 is a critical microenvironmental regulator of hematopoietic cells in response to injury. Exploitation of the dmPGE2-induced initiation of an anti-apoptotic program in HSPCs may represent a useful method to increase survival of these cells after sub-lethal radiation injury. Further, amplification of prostaglandin signaling by treatment with PGE2 agonists may also represent a novel approach to meaningfully accelerate recovery of peripheral blood counts in patients with hematopoietic system injury during a vulnerable time when few therapeutic options are currently available. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 513-513
Author(s):  
Pekka Jaako ◽  
Shubhranshu Debnath ◽  
Karin Olsson ◽  
Axel Schambach ◽  
Christopher Baum ◽  
...  

Abstract Abstract 513 Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia associated with physical abnormalities and predisposition to cancer. Mutations in genes that encode ribosomal proteins have been identified in approximately 60–70 % of the patients. Among these genes, ribosomal protein S19 (RPS19) is the most common DBA gene (25 % of the cases). Current DBA therapies involve risks for serious side effects and a high proportion of deaths are treatment-related underscoring the need for novel therapies. We have previously demonstrated that enforced expression of RPS19 improves the proliferation, erythroid colony-forming potential and differentiation of patient derived RPS19-deficient hematopoietic progenitor cells in vitro (Hamaguchi, Blood 2002; Hamaguchi, Mol Ther 2003). Furthermore, RPS19 overexpression enhances the engraftment and erythroid differentiation of patient-derived hematopoietic stem and progenitor cells when transplanted into immunocompromised mice (Flygare, Exp Hematol 2008). Collectively these studies suggest the feasibility of gene therapy in the treatment of RPS19-deficient DBA. In the current project we have assessed the therapeutic efficacy of gene therapy using a mouse model for RPS19-deficient DBA (Jaako, Blood 2011; Jaako, Blood 2012). This model contains an Rps19-targeting shRNA (shRNA-D) that is expressed by a doxycycline-responsive promoter located downstream of Collagen A1 gene. Transgenic animals were bred either heterozygous or homozygous for the shRNA-D in order to generate two models with intermediate or severe Rps19 deficiency, respectively. Indeed, following transplantation, the administration of doxycycline to the recipients with homozygous shRNA-D bone marrow results in an acute and lethal bone marrow failure, while the heterozygous shRNA-D recipients develop a mild and chronic phenotype. We employed lentiviral vectors harboring a codon-optimized human RPS19 cDNA driven by the SFFV promoter, followed by IRES and GFP (SFFV-RPS19). A similar vector without the RPS19 cDNA was used as a control (SFFV-GFP). To assess the therapeutic potential of the SFFV-RPS19 vector in vivo, transduced c-Kit enriched bone marrow cells from control and homozygous shRNA-D mice were injected into lethally irradiated wild-type mice. Based on the percentage of GFP-positive cells, transduction efficiencies varied between 40 % and 60 %. Three months after transplantation, recipient mice were administered doxycycline in order to induce Rps19 deficiency. After two weeks of doxycycline administration, the recipients transplanted with SFFV-RPS19 or SFFV-GFP control cells showed no differences in blood cellularity. Remarkably, at the same time-point the recipients with SFFV-GFP homozygous shRNA-D bone marrow showed a dramatic decrease in blood cellularity that led to death, while the recipients with SFFV-RPS19 shRNA-D bone marrow showed nearly normal blood cellularity. These results demonstrate the potential of enforced expression of RPS19 to reverse the severe anemia and bone marrow failure in DBA. To assess the reconstitution advantage of transduced hematopoietic stem and progenitor cells with time, we performed similar experiments with heterozygous shRNA-D bone marrow cells. We monitored the percentage of GFP-positive myeloid cells in the peripheral blood, which provides a dynamic read-out for bone marrow activity. After four months of doxycycline administration, the mean percentage of GFP-positive cells in the recipients with SFFV-RPS19 heterozygous shRNA-D bone marrow increased to 97 %, while no similar advantage was observed in the recipients with SFFV-RPS19 or SFFV-GFP control bone marrow, or SFFV-GFP heterozygous shRNA-D bone marrow. Consistently, SFFV-RPS19 conferred a reconstitution advantage over the non-transduced cells in the bone marrow. Furthermore, SFFV-RPS19 reversed the hypocellular bone marrow observed in the SFFV-GFP heterozygous shRNA-D recipients. Taken together, using mouse models for RPS19-deficient DBA, we demonstrate that the enforced expression of RPS19 rescues the lethal bone marrow failure and confers a strong reconstitution advantage in vivo. These results provide a proof-of-principle for gene therapy in the treatment of RPS19-deficient DBA. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 689-689
Author(s):  
John S. Welch ◽  
Allegra Petti ◽  
Christopher A. Miller ◽  
Daniel C. Link ◽  
Matthew J. Walter ◽  
...  

Abstract To determine how AML subclonal architecture changes during decitabine treatment, and whether specific mutations might correlate with sensitivity vs. resistance to decitabine, we performed exome sequencing at multiple time points during single agent decitabine therapy. We enrolled 69 patients with either AML (age ≥ 60, or with relapsed/refractory disease, N = 45) or MDS (N = 24) on a phase I clinical trial. All subjects were treated with decitabine 20 mg/m2 on days 1-10 of 28 day cycles. With a median follow-up of 13.7 months, the intention to treat clinical response (complete remission with or without complete count recovery: CR/CRi) is 40%, with survival correlating with response (median survival - CR/CRi: 583 days; partial response/stable disease (PR/SD): 260 days; progressive disease (PD) or failure to complete cycle 1: 36 days, p < 0.0001). We performed exome sequencing on unfractionated bone marrow cells at diagnosis (day 0), cycle 1 day 10, cycle 1 day 28, cycle 2 day 28, and, when possible, during remission and at clinical relapse/progression. We have completed sequencing analysis for the first 34 cases (outcomes: 5 CR, 15 CRi, 3 PR, 8 SD, and 3 PD). Several important themes have emerged, as follows: 1) We correlated mutation status at diagnosis with clinical response. All six patients with TP53 mutations obtained clinical CR or CRi, and exome analysis demonstrated near complete elimination of the TP53- associated founding clones by the end of cycle 2 (p < 0.03). Long-term outcomes were similar in these patients compared with other patients who achieved CR/CRi: four patients relapsed after 8, 9, 10, or 17 cycles; 1 patient is doing well post-transplant; and one patient died of an infectious complication after cycle 2. No other mutations were significantly associated with clinical response or with consistent mutation clearance. 2) We observed a reduction in blast counts, which preceded mutation elimination in fourteen cases with CR, CRi or PR. This suggests that decitabine may induce morphological blast differentiation in vivo prior to mutation elimination. 3) In eight of nine cases with a clinical response followed by relapse, clinical progression was associated with expansion of a pre-existing subclone. We have not yet observed any recurrent mutations that reliably predict whether a subclone will contribute to relapse. Intriguingly, in two of these cases, the relapse-associated subclone was detectable at diagnosis and was eliminated more slowly than the founding clone mutations, suggesting that this subclone harbored intrinsic decitabine-resistance. 4) Complete remission can occur with concomitant non-malignant, clonal hematopoiesis. In three cases with a CR, a new clonal population was selected for during the remission. In two of these cases, there were no shared mutations between the founding clone and the emergent, non-malignant, clonal hematopoiesis, suggesting that these clones were unrelated. 5) Mutational architecture is generally stable, but differential chemo-sensitivity can be detected even between subclones in the same patient. In ten cases with PR or SD, we observed minimal shifts within the mutational burden over the course of eight weeks, suggesting that "clonal drift" is a relatively slow process. However, in four cases with SD, what appeared clinically to be simple persistent disease was in fact a dynamic elimination of one subclone, and its replacement by a different subclone. Similarly, in three cases with CRi, we observed rapid clearance of a subclone with slower clearance of the founding clone, again suggesting differential chemo-sensitivity among subclones. 6) Finally, we correlated pharmacologic markers with clinical outcomes. We observed no correlation between steady-state plasma decitabine levels and clinical responses. Using Illumina 450k methylation arrays, we observed a correlation between response and the extent of decitabine-induced hypomethylation in total bone marrow cells that persisted on cycle 1 day 28 (p < 0.01), but not on cycle 1 day 10 (p < 0.1). In summary, these data reveal that response to decitabine is associated with morphologic blast clearance before mutations are eliminated, that relapse is associated with subclonal outgrowth that may be identified early in the treatment course, and that TP53 mutations may be predictive of rapid clinical responses, although, like most responses to decitabine, these are not necessarily durable. Disclosures Off Label Use: Decitabine treatment of AML.. Uy:Novartis: Research Funding. Oh:CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees. Abboud:Novartis: Research Funding; Gerson Lehman Group: Consultancy; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Pfizer: Research Funding; Merck: Research Funding; Teva Pharmaceuticals: Research Funding. Cashen:Celgene: Speakers Bureau. Schroeder:Celgene: Other: Azacitidine provided for this trial by Celgene; Incyte: Consultancy. Jacoby:Sunesis: Research Funding; Novo Nordisk: Consultancy.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1462-1462
Author(s):  
Lindsay Meg Gurska ◽  
Rachel Okabe ◽  
Meng Maxine Tong ◽  
Daniel Choi ◽  
Kristina Ames ◽  
...  

Abstract The Philadelphia-chromosome negative myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF), are clonal hematopoietic stem cell disorders characterized by the proliferation of one or more myeloid lineage compartments. Activation of JAK/STAT signaling is a major driver of all Ph-negative MPNs. During disease progression, MPN patients experience increased pro-inflammatory cytokine secretion, leading to remodeling of the bone marrow microenvironment and subsequent fibrosis. The JAK inhibitor ruxolitinib is an approved targeted therapy for MPN patients and has shown promise in its ability to reduce splenomegaly and the cytokine storm observed in patients. However, JAK inhibitors alone are not sufficient to reduce bone marrow fibrosis or to eliminate the JAK2-mutated clone. Furthermore, JAK inhibitor persistence, or reactivation of JAK/STAT signaling upon chronic JAK inhibitor treatment, has been observed in both MPN mouse models and MPN patients. Therefore, there is an urgent need for new treatment options in MPN. The tyrosine kinase RON, a member of the MET kinase family, has well-characterized roles in erythroblast proliferation and pro-inflammatory cytokine production. RON can be phosphorylated by JAK2 to stimulate erythroblast proliferation. However, the role of RON in MPN pathogenesis is unknown. We found that the ALK/MET/RON/ROS1 inhibitor crizotinib inhibited colony formation by MPN patient CD34+ cells, regardless of their disease subtype, mutation status, or JAK2 inhibitor treatment history (Figure 1A). To determine whether this is due to inhibition of the JAK/STAT signaling pathway, we performed phospho-flow cytometry of STAT3 and STAT5 in myelofibrosis patient erythroblasts treated with crizotinib ex vivo as well as Western blot analysis in the JAK2-mutated cell lines SET2 and HEL. We found that crizotinib inhibits the phosphorylation of JAK2, STAT3, and STAT5 (Figure 1B). Since crizotinib has not been reported to directly inhibit JAK2, we asked whether these effects of crizotinib in MPN cells could be explained by RON inhibition. Consistent with this hypothesis, we observed that shRNA knockdown of multiple RON isoforms also decreases the phosphorylation of JAK2, STAT5, and STAT3 in HEL cells (Figure 1C-D). To determine whether crizotinib can alter the MPN disease course in vivo, we tested crizotinib by oral gavage in the MPLW515L bone marrow transplant murine model of myelofibrosis at 100mg/kg daily for 2 weeks. We showed that crizotinib decreased the disease burden of MPL-W515L mice, as evidenced by decreased spleen and liver weights (Figure 1E). To determine the effects of RON genetic deletion on MPN pathogenesis, we tested whether genetic deletion of Stk (mouse gene for RON) impairs disease progression in the JAK2V617F bone marrow transplant MPN model by transplanting Stk-/- c-Kit+ bone marrow cells transduced with the JAK2V617F-GFP retrovirus into lethally irradiated recipients. We observed a significant delay in disease onset in Stk-/- transplant recipients compared to WT controls (Figure 1F). However, we found that Stk-/- mice have normal numbers of hematopoietic stem and progenitor cells, and normal bone marrow myeloid colony forming capacity, suggesting that RON is a safe therapeutic target. To determine whether RON plays a role in the JAK inhibitor persistence phenotype, we generated persistent cells by treating SET2 cells with increasing doses of ruxolitinib over 8 weeks, and confirmed persistent proliferation and JAK/STAT activation. Interestingly, we found that RON phosphorylation is enhanced in JAK inhibitor persistent cells, and that dual inhibition of RON and JAK2 overcomes JAK inhibitor persistence in SET2 cells (Figure 1G-H), suggesting that RON may potentiate the JAK2 persistence phenotype in response to ruxolitinib. Importantly, we showed by immunoprecipitation that phospho-RON and phospho-JAK2 physically interact in JAK inhibitor persistent SET2 cells, and that this interaction is disrupted by crizotinib (Figure 1I). In summary, our data demonstrate that RON kinase is a novel mediator of JAK/STAT signaling in MPNs, and that it plays a particularly important role in JAK inhibitor persistence. Our work suggests that therapeutic strategies to inhibit RON, such as crizotinib, should be investigated in MPN patients. Figure 1 Figure 1. Disclosures Halmos: Guardant Health: Membership on an entity's Board of Directors or advisory committees; Apollomics: Membership on an entity's Board of Directors or advisory committees; TPT: Membership on an entity's Board of Directors or advisory committees; Eli-Lilly: Research Funding; Advaxis: Research Funding; Blueprint: Research Funding; Elevation: Research Funding; Mirati: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer-Ingelheim: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding. Gritsman: iOnctura: Research Funding.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1442-1442
Author(s):  
Xiangmeng Wang ◽  
Po Yee Mak ◽  
Wencai Ma ◽  
Xiaoping Su ◽  
Hong Mu ◽  
...  

Abstract Wnt/β-catenin signaling regulates self-renewal and proliferation of AML cells and is critical in AML initiation and progression. Overexpression of β-catenin is associated with poor prognosis. We previously reported that inhibition of Wnt/β-catenin signaling by C-82, a selective inhibitor of β-catenin/CBP, exerts anti-leukemia activity and synergistically potentiates FLT3 inhibitors in FLT3-mutated AML cells and stem/progenitor cells in vitro and in vivo (Jiang X et al., Clin Cancer Res, 2018, 24:2417). BCL-2 is a critical survival factor for AML cells and stem/progenitor cells and ABT-199 (Venetoclax), a selective BCL-2 inhibitor, has shown clinical activity in various hematological malignancies. However, when used alone, its efficacy in AML is limited. We and others have reported that ABT-199 can induce drug resistance by upregulating MCL-1, another key survival protein for AML stem/progenitor cells (Pan R et al., Cancer Cell 2017, 32:748; Lin KH et al, Sci Rep. 2016, 6:27696). We performed RNA Microarrays in OCI-AML3 cells treated with C-82, ABT-199, or the combination and found that both C-82 and the combination downregulated multiple genes, including Rac1. It was recently reported that inhibition of Rac1 by the pharmacological Rac1 inhibitor ZINC69391 decreased MCL-1 expression in AML cell line HL-60 cells (Cabrera M et al, Oncotarget. 2017, 8:98509). We therefore hypothesized that inhibiting β-catenin by C-82 may potentiate BCL-2 inhibitor ABT-199 via downregulating Rac1/MCL-1. To investigate the effects of simultaneously targeting β-catenin and BCL-2, we treated AML cell lines and primary patient samples with C-82 and ABT-199 and found that inhibition of Wnt/β-catenin signaling significantly enhanced the potency of ABT-199 in AML cell lines, even when AML cells were co-cultured with mesenchymal stromal cells (MSCs). The combination of C-82 and ABT-199 also synergistically killed primary AML cells (P<0.001 vs control, C-82, and ABT-199) in 10 out of 11 samples (CI=0.394±0.063, n=10). This synergy was also shown when AML cells were co-cultured with MSCs (P<0.001 vs control, C-82, and ABT-199) in all 11 samples (CI=0.390±0.065, n=11). Importantly, the combination also synergistically killed CD34+ AML stem/progenitor cells cultured alone or co-cultured with MSCs. To examine the effect of C-82 and ABT-199 combination in vivo, we generated a patient-derived xenograft (PDX) model from an AML patient who had mutations in NPM1, FLT3 (FLT3-ITD), TET2, DNMT3A, and WT1 genes and a complex karyotype. The combination synergistically killed the PDX cells in vitro even under MSC co-culture conditions. After PDX cells had engrafted in NSG (NOD-SCID IL2Rgnull) mice, the mice were randomized into 4 groups (n=10/group) and treated with vehicle, C-82 (80 mg/kg, daily i.p injection), ABT-199 (100 mg/kg, daily oral gavage), or the combination for 30 days. Results showed that all treatments decreased circulating blasts (P=0.009 for C-82, P<0.0001 for ABT-199 and the combination) and that the combination was more effective than each single agent (P<0.001 vs C-82 or ABT-199) at 2 weeks of therapy. The combination also significantly decreased the leukemia burden in mouse spleens compared with controls (P=0.0046) and single agent treated groups (P=0.032 or P=0.020 vs C-82 or ABT-199, respectively) at the end of the treatment. However, the combination did not prolong survival time, likely in part due to toxicity. Dose modifications are ongoing. These results suggest that targeting Wnt/β-catenin and BCL-2, both essential for AML cell and stem cell survival, has synergistic activity via Rac1-mediated MCL-1 inhibition and could be developed into a novel combinatorial therapy for AML. Disclosures Andreeff: SentiBio: Equity Ownership; Oncolyze: Equity Ownership; Oncoceutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy; Amgen: Consultancy, Research Funding; Eutropics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Patents & Royalties: MDM2 inhibitor activity patent, Research Funding; Aptose: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Reata: Equity Ownership; Astra Zeneca: Research Funding; Celgene: Consultancy; United Therapeutics: Patents & Royalties: GD2 inhibition in breast cancer . Carter:novartis: Research Funding; AstraZeneca: Research Funding.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1874-1874 ◽  
Author(s):  
Irene M. Ghobrial ◽  
Ranjit Banwait ◽  
Abdel Kareem Azab ◽  
Phong Quang ◽  
Jacob P. Laubach ◽  
...  

Abstract Abstract 1874 INTRODUCTION: This study aimed to determine the safety and activity of plerixafor (CXCR4 inhibitor) in combination with bortezomib as a chemosensitization strategy in multiple myeloma (MM). This was based on our preclinical studies showing that plerixafor (Mozobil, Genzyme Corporation, MA) induces de-adhesion of MM cells and sensitization to bortezomib in preclinical animal models. METHODS: Eligibility criteria included: 1) patients with relapsed or relapsed/refractory MM with 1–5 prior lines of therapy including bortezomib (unless patients were refractory to bortezomib), 2) measurable disease, 3) not receiving chemotherapy > 3 weeks, or biological therapy for MM > 2 weeks prior to study treatment. Eight cohorts with different doses and two treatment schedules were planned. In cohorts 1–5, patients received plerixafor at the recommended dose sq on days 1–6 of each cycle and bortezomib at the recommended dose twice a week on days 3, 6, 10, and 13 every 21 days. To test the hypothesis that higher doses and a different schedule might induce better chemosensitization, in cohort 5b–7 plerixafor was given at the recommended dose sq on days 1, 3, 6, 10, and 13 and bortezomib was given at the recommended dose twice a week on days 3, 6, 10, and 13 every 21 days. Bortezomib was given 60–90 minutes after plerixafor. Patients were assessed after every cycle by modified EBMT/UC criteria. Patients who had a response or stable disease went on to receive a total of 8 cycles with maintenance therapy for patients with at least a minimal response (MR). To examine the in vivo effect of plerixafor and bortezomib on de-adhesion of MM cells and other accessory cells of the bone marrow, peripheral blood samples were obtained from the patients at 0, 1, 2, 3, 4 and 24 hours post-dose on days 1 and 3, and time points 0, 2, and 4 hours post-dose on days 6, 10 and 13 of cycle 1. RESULTS: Twenty-five patients were enrolled in this phase I trial from June 2009 to May 2011. Median age was 60 years (range, 44–85) and median lines of prior therapy were 2 (range, 1–4) with all but 3 patients receiving prior bortezomib. The median number of cycles on therapy was 3 (1–11). Dose limiting toxicities including insomnia, restlessness, and psychosis were observed in two patients at dose level 6 (plerixafor 0.40 mg/kg and bortezomib 1.3 mg/m2). To further explore the safety of maximum tolerated dose, three additional patients were enrolled at dose level 5b (plerixafor 0.32 mg/kg and bortezomib 1.3 mg/m2). Overall, the combination proved to be well tolerated. There were no grade 4 toxicities. Grade 3 toxicities included lymphopenia (40%), hypophosphatemia (20%), anemia (10%), hyponatremia (10%), hypercalcemia (10%), and bone fracture due to myeloma bone disease (10%). One patient came off treatment due to grade 2 painful neuropathy at cycle 5. Twenty-three patients were evaluable for response, including 1 (4%) complete response (CR), 1 (4%) very good partial response (VGPR) and 3 (13%) MR, with an overall response rate (including MR) of 5 (22%) in this relapsed and refractory population. In addition, 15 (65%) patients achieved stable disease (SD), with just 3 (13%) having progressive disease (PD) as their best response. We also examined in vivo mobilization of plasma cells, CD34+ hematopoietic stem cells and other accessory bone marrow cells. Analysis of these samples showed rapid mobilization of plasma cells at 2 hours post-plerixafor with a rapid return to normal levels at 4 and 24 hours post plerixafor. Similar results were observed on days 1 and 3, but less mobilization occurred on the following days. Hematopoietic stem cell mobilization occurred at 4 hours on days 1 and 3, and was less observed with subsequent doses of plerixafor consistent with prior studies. CONCLUSIONS: The combination of plerixafor and bortezomib is generally well tolerated with minimal neuropathy or other toxicities seen to date. The responses observed are encouraging in this relapsed and refractory population. The ability to demonstrate transient de-adhesion of MM cells and accessory cells in vivo in most of the patients indicates that chemosensitization can potentially be achieved in patients with MM using this approach. Further studies are warranted and a phase 2 trial is underway. This study was supported by R01CA133799-01, and by Genzyme Corporation. Disclosures: Ghobrial: Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Noxxon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; Noxxon: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Off Label Use: Plerixafor in myeloma. Munshi:Millennium: 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; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx: Membership on an entity's Board of Directors or advisory committees. Schlossman:Millennium: Consultancy; Celgene: Consultancy. Anderson:Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Acetylon: Equity Ownership. Richardson:Millennium: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees.


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