TRAIL Is Active Against Leukemia Stem Cells and Leukemia-Initiating Cells of Children with Acute Lymphoblastic Leukemia

Abstract Abstract 2953 Cancer stem cells represent the most important target cells for anti-tumor therapy as they are uniquely capable to maintain tumor growth and to induce relapse. For sustained anti-tumor activity, anti-cancer therapy has to address and eliminate cancer stem cells. Unfortunately in acute lymphoblastic leukemia (ALL), cancer stem cells / leukemia stem cells (LSCs) can not be reliably defined by cell surface markers complicating studies on cancer stem cells. To overcome this obstacle, we used the functional definition of CSCs as surrogate and studied leukemia-initiating cells (LICs) by their name-defining capability to initiate leukemia in immune-compromised mice. TRAIL (TNF-related apoptosis-inducing ligand) is a member of the TNF family which induces apoptosis in a wide variety of tumor cells while sparing normal cells. TRAIL represents an important candidate anti-cancer agent which is currently tested in phase I and II clinical trials, yet its ability to target cancer stem cells is currently unknown. Here we tested the effect of TRAIL on LSCs and LICs using tumor cells from children with precursor B-cell acute lymphoblastic leukemia (pre-B ALL). Primary ALL cells were engrafted and passaged in NSG mice. Cells were freshly isolated from NSG mice and stimulated with TRAIL in vitro for 2 days and afterwards re-engrafted into mice in dilution curves upon limiting dilution transplantation assay comparing non-treated with TRAIL-treated cells and using about 25 mice per stimulation. After 12–16 weeks, mice were evaluated for leukemic engraftment by staining for leukemia cells in organs like bone marrow, spleen, liver and blood using FACscan analysis and immune histochemistry. In all 3 pre-B ALL samples tested, in vitro treatment with TRAIL prior to transplantation of cells into mice significantly reduced their engraftment capability. TRAIL disabled leukemic engraftment by > 95 % in all 3 samples. Accordingly, in vitro TRAIL treatment significantly increased the time to engraftment and completely disabled engraftment below a defined threshold. In a second, additive approach, TRAIL was used in a preclinical mouse model. Pre-B ALL samples were engrafted in NSG mice and leukemia-bearing mice were treated with TRAIL systemically at 7.5 mg / kg daily i.p. for 10 days. In this preclinical in vivo model, TRAIL treatment completely cured a proportion of animals harbouring patient-derived pre-B ALL xenografts. Taken together, TRAIL significantly disabled the leukemia-initiating function of LICs from patient-derived pre-B ALL xenografts in vitro and that TRAIL eliminated leukemia together with its LSCs in vivo. Although the methods used do not allow the study of signalling mechanisms, TRAIL might most probably have induced apoptosis in LICs and LSCs. Our data show that it is feasible, although technically demanding, to test the apoptosis sensitivity of LICs and LSCs. We conclude from these data that TRAIL constitutes an attractive future drug for treatment of ALL. Disclosures: No relevant conflicts of interest to declare.

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Leukemia-initiating cells of patient-derived acute lymphoblastic leukemia xenografts are sensitive toward TRAIL

Blood ◽

10.1182/blood-2011-08-370114 ◽

2012 ◽

Vol 119 (18) ◽

pp. 4224-4227 ◽

Cited By ~ 16

Author(s):

Catarina Castro Alves ◽

Nadia Terziyska ◽

Michaela Grunert ◽

Sibylle Gündisch ◽

Ulrike Graubner ◽

...

Keyword(s):

Stem Cells ◽

Acute Lymphoblastic Leukemia ◽

Cancer Stem Cells ◽

Lymphoblastic Leukemia ◽

Target Cells ◽

Nsg Mice ◽

Candidate Drug ◽

Cell Acute Lymphoblastic Leukemia

Abstract Cancer stem cells represent the most important target cells for antitumor therapy. TRAIL (TNF-related apoptosis-inducing ligand) is a potential anticancer agent that induces apoptosis in a wide variety of tumor cells, but its ability to target cancer stem cells is currently unknown. Here we investigated whether TRAIL targets leukemia-initiating cells. Limiting dilution transplantation assays were performed on xenografts from pediatric patients with precursor B-cell acute lymphoblastic leukemia (pre-B ALL) in NSG mice. In vitro treatment of xenograft cells with TRAIL significantly reduced and delayed their engraftment and procrastinated animal death from leukemia. Systemic TRAIL treatment of mice injected with patient-derived pre-B ALL xenograft cells abrogated leukemia in 3 of 5 mice in 1 sample. In conclusion, our data suggest that TRAIL targets leukemia-initiating cells derived from pre-B ALL xenografts in vitro and in vivo, and hence constitutes an attractive candidate drug for treatment of ALL.

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Drug Screening of Primary Human Pediatric Pre-B Cell Acute Lymphoblastic Leukemia (pre-B ALL) Cells in Their Stromal Niche

Blood ◽

10.1182/blood.v120.21.4295.4295 ◽

2012 ◽

Vol 120 (21) ◽

pp. 4295-4295

Author(s):

Jae-Hung Shieh ◽

Tsann-Long Su ◽

Jason Shieh ◽

Malcolm A.S. Moore

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Acute Lymphoblastic Leukemia ◽

Culture System ◽

Lymphoblastic Leukemia ◽

Nsg Mice ◽

Cd34 Cells ◽

Cell Acute Lymphoblastic Leukemia

Abstract Abstract 4295 Pre-B cell acute lymphoblastic leukemia (pre-B ALL) is the most common leukemia in children and is treatable. However, no in vitro nor in vivo models are available to investigate their pathophysiology other than a number of established cell lines that grow in the absence of any cytokine dependence or stromal interaction. We developed a serum-free MS-5 cell (a murine bone marrow stromal cell line) co-culture system that is capable of expanding human primary pre-B ALL CD34+CD19+ cells in vitro. To define a population of pre-B ALL initiating cells, our study reveals that a sorted CD34bright population displays a slow proliferation and maintains a high % of CD34+ cells. In contrast, CD34dim cells/CD34− cells fraction shows a higher proliferation but expanded cells lost CD34 antigens. A group of alkylating molecules (BO-1055, -1090, 1099, -1393 and -1509) was evaluated for proliferation of the pre-B ALL CD34+ cells, the pre-B ALL CD34− cells, human mesenchymal stem cells (hMSC), murine MSC (MS-5 cells and Op9 cells), human bone marrow derived endothelial cells (BMEC), and human cord blood (CB) CD34+ cells, as well as for a week 5 cobblestones area forming (CAFC) assay with CB CD34+ cells. BO-1055 molecule efficiently suppressed the growth of pre-B ALL CD34+ cells (IC50 = 0.29 μM) and CD34− cells (IC50 = 0.31 μM). In contrast, IC50 of BMEC, MSC, CB CD34+ cells and CAFC are >10, >25, 8, and >5 μM, respectively. Pre-B ALL cells expressing green fluorescent protein (GFP) and luciferase (GFP-Lu-pre-B ALL) were created, and a xenograft of the GFP-Lu-pre-B ALL cells to NOD/SCID IL2R gamma null (NSG) mice was established. The in vivo effect of BO-1055 to the GFP-Lu-pre-B ALL cells in NSG mice is under investigation. Our stromal culture system supports primary pre-B ALL cells and closely recapitulates the growth of primary human pre-B ALL cells in their niche in vivo. Based on this co-culture system, we identified BO-1055 as a potential therapeutic agent with an excellent toxicity window between pre-B ALL cells and normal tissues including BMEC, MSC and hematopoietic progenitor/stem cells. The in vitro stromal co-culture system combined with the xenograft model of GFP-Lu-pre-B ALL cells provides an efficient and powerful method to screen new drugs for pre-B ALL therapy. Disclosures: No relevant conflicts of interest to declare.

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Anlotinib exerts anti‐cancer efficiency on lung cancer stem cells in vitro and in vivo through reducing NF‐κB activity

Journal of Cellular and Molecular Medicine ◽

10.1111/jcmm.16564 ◽

2021 ◽

Author(s):

Zhuohong Li ◽

Juncai Tian ◽

Lei Du ◽

Ying Gao ◽

Yao Wang ◽

...

Keyword(s):

Lung Cancer ◽

Stem Cells ◽

Cancer Stem Cells ◽

Anti Cancer ◽

Lung Cancer Stem Cells

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Copper-Complexed Melphalan (MOC*M), a Member of a New Class of Anti-Leukemic and Anti-Tumouric Substances for Treatment of Primary and Relapsed Acute Lymphoblastic Leukemia in Childhood.

Blood ◽

10.1182/blood.v106.11.4457.4457 ◽

2005 ◽

Vol 106 (11) ◽

pp. 4457-4457

Author(s):

Aram Prokop ◽

Corazon Frias ◽

Guenter Henze ◽

Swetlana Sadolinnaya ◽

Valeriy Tatarskiy

Keyword(s):

Acute Lymphoblastic Leukemia ◽

Tumor Cells ◽

Dna Fragmentation ◽

Lymphoblastic Leukemia ◽

Model Systems ◽

Cytostatic Drugs ◽

Cytostatic Agents ◽

New Class

Abstract Acute lymphoblastic leukemia (ALL) is the most frequent malignant disease of childhood. Despite a relatively good prognosis (survival 80 %), approximately ¼ of the patients suffer from relapses with a much poorer prognosis (survival 40 %). If a complete remission through chemotherapy is not achieved, the patients will not survive. Thus, the search for new cytostatic substances which can break the resistance against conventional cytostatic drugs is of great interest. We developed a new class of copper-containing cytostatic agents with apoptosis-inducing properties. The present study deals with 20 children, who suffer from de novo ALL or relapsed ALL. In vitro measurement of DNA-fragmentation in primary lymphoblasts of the children showed, that the copper-complexed cytostatic drugs are considerably more effective, compared to conventional analogues and other cytostatic drugs (cytarabine p<0.002, vincristine p< 0.006) used against childhood ALL. Furthermore, the new copper-containing analogues overcome drug resistance against doxorubicin (p<0.001) in vitro. In addition, the prototype of copper-complexed drug analogues, MOC*M, a melphalan-copper-acetoacetonate-complex, has synergistic effects in apoptosis induction combined with melphalan or conventional drugs in therapy of ALL in childhood like vincristin, doxorubicin and cytarabine. Experiments revealed that MOC*M specifically induces apoptosis, as evidenced by DNA fragmentation and dissipation of the mitochondrial membrane potential. MOC*M induces cell death, which was functionally characterized by the use of different cellular model systems being devoid of defined molecular parts of the apoptosis machinery. MOC*M triggers apoptosis in a Bcl-2-independent manner in the multi-resistant melanoma cell line MelHO with a 30-fold over-expression of Bcl-2. In vitro and in vivo experiments on mice with tumors sarcom S-180, melanoma B-16 and adenocarcenom in the large intestine proved a high anti-tumor activity of MOC*M with anti-metastasis and immunizing properties without any side effects in kidney or liver. Thus, MOC*M is able to prolong the life of animals with leucosis L-1210 and P-388. We could show that the accumulation of the tritium-labelled MOC*M compounds took place mainly in the tumor cells in vivo. Moreover, MOC*M is also inhibiting glycolysis in the tumor cells. The result of pre-clinical tests with MOC*M preparations, tested on a limited quota of oncological patients with different tumors, was a very large spectrum of anti-tumor and anti-leukemic activities. Further MOC*M has an immense tolerability in vivo. All in all, copper-containing cytostatic drugs comprise an innovative, highly promising class of cytostatic agents for cancer and leukemia therapy, especially for the therapy of relapsed ALL in childhood.

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In Vitro Culture Reveals Microenvironment-Dependent Growth, Heterogeneity and Hierarchical Structure of Primary Human Pediatric Pre-B Cell Acute Lymphoblastic Leukemia (pre-B ALL) Cells

Blood ◽

10.1182/blood.v118.21.1483.1483 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1483-1483

Author(s):

Jae Hung Shieh ◽

Peter G Steinherz ◽

Jason Shieh ◽

Malcolm A.S. Moore

Keyword(s):

Acute Lymphoblastic Leukemia ◽

B Cell ◽

Hierarchical Structure ◽

Culture System ◽

Lymphoblastic Leukemia ◽

Nsg Mice ◽

Cd34 Antigen ◽

Cell Acute Lymphoblastic Leukemia

Abstract Abstract 1483 In Vitro culture reveals microenvironment-dependent growth, heterogeneity and hierarchical structure of primary human pediatric pre-B cell acute lymphoblastic leukemia (pre-B ALL) cells. J.-H. Shieh1, P. Steinherz2, J Shieh3 and M. A.S. Moore1. 1Moore Laboratory. Cell Biology Program and 2Leukemia and Lymphoma Studies, Department of Pediatrics, Memorial-Sloan Kettering Cancer Center, New York, NY. 3Department of Biology, Brandeis Univ., Waltham, MA Pre-B cell acute lymphoblastic leukemia (pre-B ALL) is the most common leukemia in children. Although this pediatric pre-B ALLs are treatable, no in vitro nor in vivo models are available to investigate their pathophysiology other than a number of established cell lines that grow in the absence of any cytokine dependence or stromal interaction. To address this issue, we systemically evaluated the effects of various tissue culture parameters to the growth of primary pre-B ALL cells. A serum-free MS-5 cells (a murine bone marrow stromal cell line) co-culture system is capable of expanding the pre-B ALL CD34+CD19+ cells and supporting their differentiation to CD34−CD19+ B cells. This expansion requires a contact between the stromal cells and the pre-B ALL cells, and is inhibited by fetal bovine serum and IL-6 in a dose-dependent manner. c-Kit ligand and Flt3 ligand can reverse the IL-6 inhibition. Expansion of individual CD34+CD19+ cells revealed a hierarchical structure with respect to CD34 antigen expression and an heterogeneity in cell proliferation. When the pre-B ALL cells were sorted into CD34dim and CD34bright populations, the CD34dim cells were capable of a faster proliferation but gradually lost their CD34 antigen. In contrast, the CD34bright cells were more slowly proliferating and retained their CD34 antigen. We transduced the B-ALL cells with a fusion gene expressing green fluorescent protein (GFP) and luciferase (GFP-Lu-pre-B ALL). These GFP-Lu-pre-B ALL cells display the similar in vitro characteristics and in vivo xenograftment to NOD/SCID IL2R gamma null (NSG) mice as the non-transduced pre-B ALL cells. One hundred, 103, 104 or 105 GFP-LU-pre-B ALL CD34+ cells were i.v. transplanted to NSG mice. Both 104 and 105 cells resulted in the engraftment of the leukemia cells in limbs and cranium as judged by imaging after 6 weeks, and 103 cells engrafted after 13 weeks. When the 105 cells-transplanted mice were sacrificed after 14 weeks, the harvested peripheral blood, spleen (3–4×108cells/spleen) and bone marrow (5−10×106 cells/femur) displayed 2–3%, 51–55% and 75–81% of human CD34+CD19+ cells, respectively. Human CD34−CD19+ cells were 1–2%, 12–13% and 15–21%, respectively. Therefore, our stromal culture system supports leukemic stem cell/leukemia initiating cell proliferation and closely recapitulates the growth of primary human pre-B ALL cells in their niche in vivo, and reveals the heterogeneity and hierarchical structure of human pre-B ALL cells. The in vitro stromal co-culture system combined with the xenograft model of GFP-Lu-pre-B ALL cells provides powerful tools to dissect the pathophysiology of human pre-B ALL, and to screen new drugs for pre-B ALL therapy. Disclosures: No relevant conflicts of interest to declare.

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Comparative Study of Obinutuzumab (GA101) Vs. Rituximab Against CD20+ rituximab-Sensitive and -Resistant Burkitt (BL) and Acute Lymphoblastic Leukemia (B-ALL): Potential Targeted Therapy in Patients with High Risk BL and Pre-B-ALL

Blood ◽

10.1182/blood.v124.21.2251.2251 ◽

2014 ◽

Vol 124 (21) ◽

pp. 2251-2251 ◽

Cited By ~ 3

Author(s):

Aradhana Awasthi ◽

Janet Ayello ◽

Carmella van de Ven ◽

Mona Elmacken ◽

Christopher Reggio ◽

...

Keyword(s):

Cell Death ◽

Acute Lymphoblastic Leukemia ◽

B Cell ◽

Children And Adolescents ◽

Nk Cells ◽

Tumor Cells ◽

Lymphoblastic Leukemia ◽

Tumor Burden

Abstract Background: Aggressive non-Hodgkin lymphoma (NHL) represents >90% of all NHL that occur in children and adolescents. Among all NHLs, Burkitt Lymphoma (BL) is the most common NHL in children and adolescents and has an excellent prognosis (≥80% 5 yrs, EFS) following short but intense multi-agent chemotherapy (Cairo et al. Blood, 2007). Patients who relapse with CD20+ B-NHL and B cell Acute lymphoblastic leukemia (B-ALL) have a dismal prognosis, often associated with chemotherapy resistance and may require alternative therapeutic strategies (Cairo et al. JCO, 2012, Barth/Cairo et al. BJH, 2013). Rituximab (RTX) in combination with FAB 96 chemotherapy is a safe and well-tolerated and is associated with >90% EFS in children with newly diagnosed and advanced mature B-Cell NHL (Goldman/Cairo et al. Leukemia, 2013). Resistance to RTX, however, may predispose patients with CD20+ B-NHL/ALL to an increase risk of relapse and/or disease progression (Barth/Cairo et al. BJH, 2012; Tsai et al. Cl. Can. Res, 2012,). Obinutuzumab, a novel glycoengineered type II CD20 antibody, has been shown to enhance cell death and ADCC vs. RTX (Herter et al, Clinc Canc Res, 2013), and was recently approved by FDA and EMA for first line treatment of CLL in combination with chlorambucil. Objective: To evaluate anti-tumor activity of obinutuzumab vs RTX against RTX resistant and sensitive BL and pre-B-ALL tumor targets in-vitro and in-vivo in xenografted NSG mice. Methods: Raji (CD20+) and Loucy (T-ALL, CD20-), (ATCC, Manhass, VA), U698-M (CD20+, DSMZ, Germany) and Raji-4RH (provided by M. Barth, Roswell Park Cancer Institute) were cultured in RPMI with 10% FBS. For in-vitro studies, tumor cells were incubated with 100 µg/ml obinutuzumab (supplied by Christian Klein, PhD, Roche Research & Early Development, Zurich), and/or RTX for 24 hrs. Cell death was evaluated by staining with AnnexinV/7AAD and analysis by flow-cytometry. Loucy cells (CD20-) were used as the negative control. ADCC were performed with K562-IL-15-41BBL expanded NK cells (Ayello/Cairo et al. ASH, 2010) at 20:1 effector: target ratio (E: T, n=3) using an europium release assay (Perkin-Elmer).The lentiviral construct, pSico PolII-eGFP-Luc2, was transfected into Raji, Raji 4RH (RTX resistant), U698M and Loucy for in vivo evaluation by BLI. Six to 8 week old female NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ), mice, bred in-house under pathogen free conditions, were divided into 5 groups: PBS only (control), isotype control (IgG), obinutuzumab 10 mg/kg, obinutuzumab (30 mg/kg), and RTX (30 mg/kg). Mice were xenografted with intravenous injections of Luc+ Raji, Raji4RH, U698M and Loucy cells at 5x106 tumor cells/mouse. 6-8 days after tumor cell injection, mice were then injected every 7 days with the respective therapy for 8 weeks. Mice were monitored for tumor burden and survival for up to 12 weeks ( approx. 80 days) via bioluminescent imaging (BLI) using the IVIS Spectrum system. Results: Obinutuzumab compared to RTX (100 mg/ml, 24hrs), significantly enhanced cell death in Raji 45.1±3.3% vs 32.7±6.8%, (p=0.005), Raji4RH 15.8±2.2% vs 2.1±1.5% (p=0.001) and U698-M 40.5±2.9 % vs 26.36±2.6% (p=0.001) n=6. Obinutuzumab vs RTX also elicited a significant increase ADCC with K562-IL15-41BBL expanded NK cells, in Raji 73.8±8.1% vs 56.81±4.6% (p=0.001), Raji-4RH 40.0±1.6% vs 0.5±1.1%, (p=0.001), and U-698-M 70.0±6 % vs. 45.56± 0.1% (p=0.001) n=3. Further, we found that, in vivo, obinutuzumab was significantly more effective than RTX when administered at the same doses in BL (RTX resistant/sensitive) and pre-B-ALL xenografts. Overall survival in mice receiving 30 mg/kg of obinutuzumab was significantly increased when compared to mice receiving 30 mg/kg of RTX in BL; Raji (p=0.05), Raji4RH (p=0.024) and U698-M (p=0.03) (Figure1: A, B and C). Conclusion: Obinutuzumab significantly enhances cell death and NK mediates ADCC in sensitive and RTX resistant CD20+ B-NHL and B-ALL compared to RTX. These preliminary studies also demonstrate that RTX sensitive/resistant BL and pre-B-ALL xenografted mice display significantly increased survival when given 30 mg/kg of obinutuzumab and decreased tumor burden in BL and Pre-B-ALL xenografts compared to an equal dose of RTX. Obinutuzumab may be a novel agent to investigate as adjuvant therapy in patients with relapsed refractory CD20+ B-NHL and/or B-ALL. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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STEM-26. SMALL MOLECULE DRUG CBL0137 INHIBITS THE FACT COMPLEX AND SENSITIZES GLIOBLASTOMA CANCER STEM CELLS TO RADIOTHERAPY

Neuro-Oncology ◽

10.1093/neuonc/noaa215.843 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii201-ii202

Author(s):

Miranda Tallman ◽

Abigail Zalenski ◽

Amanda Deighen ◽

Morgan Schrock ◽

Sherry Mortach ◽

...

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

High Rate ◽

Orthotopic Model ◽

In Vivo Models ◽

Specific Cytotoxicity ◽

Treatment Paradigm ◽

Cancer Agent

Abstract Glioblastoma (GBM) is a malignant brain tumor with nearly universal recurrence. GBM cancer stem cells (CSCs), a subpopulation of radio- and chemo-resistant cancer cells capable of self-renewal, contribute to the high rate of recurrence. The anti-cancer agent, CBL0137, inhibits the FACT (facilitates chromatin transcription) complex leading to cancer cell specific cytotoxicity. Here, we show that CBL0137 sensitized GBM CSCs to radiotherapy using both in vitro and in vivo models. Treatment of CBL0137 combined with radiotherapy led to increased DNA damage in GBM patient specimens and failure to resolve the damage led to decreased cell viability. Using clonogenic assays, we confirmed that CBL0137 radiosensitized the CSCs. To validate that combination therapy impacted CSCs, we used an in vivo subcutaneous model and showed a decrease in the frequency of cancer stem cells present in tumors as well as decreased tumor volume. Using an orthotopic model of GBM, we confirmed that treatment with CBL0137 followed by radiotherapy led to significantly increased survival compared to either treatment alone. Radiotherapy remains a critical component of patient care for GBM, even though there exists a resistant subpopulation. Radio-sensitizing agents, including CBL0137, pose an exciting treatment paradigm to increase the efficacy of irradiation, especially by inclusively targeting CSCs.

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BRD4 PROTAC degrader ARV-825 inhibits T-cell acute lymphoblastic leukemia by targeting 'Undruggable' Myc-pathway genes

Cancer Cell International ◽

10.1186/s12935-021-01908-w ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Shuiyan Wu ◽

You Jiang ◽

Yi Hong ◽

Xinran Chu ◽

Zimu Zhang ◽

...

Keyword(s):

Cell Cycle ◽

Cell Proliferation ◽

Acute Lymphoblastic Leukemia ◽

Caspase 3 ◽

Lymphoblastic Leukemia ◽

Rna Seq ◽

Cell Acute Lymphoblastic Leukemia ◽

Bet Protein

Abstract Background T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease with a high risk of induction failure and poor outcomes, with relapse due to drug resistance. Recent studies show that bromodomains and extra-terminal (BET) protein inhibitors are promising anti-cancer agents. ARV-825, comprising a BET inhibitor conjugated with cereblon ligand, was recently developed to attenuate the growth of multiple tumors in vitro and in vivo. However, the functional and molecular mechanisms of ARV-825 in T-ALL remain unclear. This study aimed to investigate the therapeutic efficacy and potential mechanism of ARV-825 in T-ALL. Methods Expression of the BRD4 were determined in pediatric T-ALL samples and differential gene expression after ARV-825 treatment was explored by RNA-seq and quantitative reverse transcription-polymerase chain reaction. T-ALL cell viability was measured by CCK8 assay after ARV-825 administration. Cell cycle was analyzed by propidium iodide (PI) staining and apoptosis was assessed by Annexin V/PI staining. BRD4, BRD3 and BRD2 proteins were detected by western blot in cells treated with ARV-825. The effect of ARV-825 on T-ALL cells was analyzed in vivo. The functional and molecular pathways involved in ARV-825 treatment of T-ALL were verified by western blot and chromatin immunoprecipitation (ChIP). Results BRD4 expression was higher in pediatric T-ALL samples compared with T-cells from healthy donors. High BRD4 expression indicated a poor outcome. ARV-825 suppressed cell proliferation in vitro by arresting the cell cycle and inducing apoptosis, with elevated poly-ADP ribose polymerase and cleaved caspase 3. BRD4, BRD3, and BRD2 were degraded in line with reduced cereblon expression in T-ALL cells. ARV-825 had a lower IC50 in T-ALL cells compared with JQ1, dBET1 and OTX015. ARV-825 perturbed the H3K27Ac-Myc pathway and reduced c-Myc protein levels in T-ALL cells according to RNA-seq and ChIP. In the T-ALL xenograft model, ARV-825 significantly reduced tumor growth and led to the dysregulation of Ki67 and cleaved caspase 3. Moreover, ARV-825 inhibited cell proliferation by depleting BET and c-Myc proteins in vitro and in vivo. Conclusions BRD4 indicates a poor prognosis in T-ALL. The BRD4 degrader ARV-825 can effectively suppress the proliferation and promote apoptosis of T-ALL cells via BET protein depletion and c-Myc inhibition, thus providing a new strategy for the treatment of T-ALL.

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STEM-20. RADIO-SENSITIZING GLIOBLASTOMA CANCER STEM CELLS BY INHIBITION OF FACT

Neuro-Oncology ◽

10.1093/neuonc/noz175.993 ◽

2019 ◽

Vol 21 (Supplement_6) ◽

pp. vi237-vi238

Author(s):

Miranda Montgomery ◽

Abigail Zalenski ◽

Amanda Deighen ◽

Sherry Mortach ◽

Treg Grubb ◽

...

Keyword(s):

Stem Cells ◽

Dna Damage ◽

Cancer Stem Cells ◽

Combination Therapy ◽

High Rate ◽

Primary Role ◽

Cancer Cell Growth ◽

Treatment Paradigm

Abstract Glioblastoma (GBM) has a particularly high rate of recurrence with a 5-year overall survival rate of approximately 5%. This is in part due to a sub-population of cancer stem cells (CSC), which are both radioresistant and chemotherapeutically resistant to conventional treatments. Here we investigated CBL0137, a small molecule form of curaxin, in combination with radiotherapy as a means to radiosensitize CSCs. CBL0137 sequesters FACT (facilitates chromatin transcription) complex to chromatin, which leads to activation of p53 and inhibition of NF-κB. This sequestering of FACT results in cytotoxicity especially within tumor cells and prevents FACT from performing its primary role as a histone chaperone, as well as inhibits its part in the DNA damage response pathway. We show that when combined with radiotherapy, CBL0137 administration limited the ability of CSCs to identify and repair damaged DNA. CSCs treated in vitro with CBL0137 and irradiation showed an increased inhibition of cancer cell growth and decreased viability compared to irradiation or drug alone. Combination therapy also showed more DNA damage in the CSCs than with either agent alone. Based on our in vitro evidence for the efficacy of combination therapy to target CSCs, we moved forward to test the treatment in vivo. Using a subcutaneous model, we show that the amount of CD133+ cells (a marker for GMB CSCs) was reduced in irradiation plus CBL0137 compared to either treatment alone. Survival studies demonstrated that irradiation plus CBL0137 compared to irradiation alone or CBL0137 alone increase lifespan. Here we show the ability of CBL0137, in combination with irradiation, to target patient GBM CSCs both in vitro and in vivo. This work establishes a new treatment paradigm for GBM that inclusively targets CSCs and may ultimately reduce tumor recurrence.

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