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  • 11
    In: Molecular Cancer Therapeutics, American Association for Cancer Research (AACR), Vol. 22, No. 12_Supplement ( 2023-12-01), p. A148-A148
    Abstract: Radiation therapy (RT) is an important non-surgical clinical treatment for glioblastoma (GBM) and brain metastases, but inherent radio-resistance can limit the efficacy in many patients. The Ataxia Telangiectasia Mutated (ATM) protein critically regulates radiotherapy-mediated DNA damage repair pathways, and defects in this kinase can lead to profound radiosensitivity. In this study, the efficacy of the highly potent ATM inhibitor WSD0628 was evaluated in GBM and melanoma brain metastasis patient derived xenografts (PDXs).  In short term explant cultures of three PDXs, WSD0628 robustly suppressed RT-induced autophosphorylation of ATM at serine 1981 and ATM-mediated phosphorylation of Chk2 at threonine-68 and KAP1 at serine-824, with maximal inhibition at 100 nM. Similarly, RT-induced gH2AX foci were significantly reduced when combined with WSD0628 in the GBM43 cells. Consistent with the importance of ATM in the DNA damage response after radiation, WSD0628 significantly increased the radiosensitivity of U251 cells in clonogenic survival assays (0nM vs. 30nM at 5Gy, p & lt;0.01). To evaluate the optimal duration of drug exposure, WSD0628 was removed from U251 cells at various intervals following irradiation with 5 Gy. Using clonogenic survival as a readout, a 10-fold increase in cytotoxicity was observed with an 8 hour drug exposure, with progressively increasing cytotoxicity gains with exposures up to 24 hours. In vivo efficacy of WSD0628 was evaluated in multiple intracranial PDX models. In an initial dose-ranging study, robust radiosensitization was observed in GBM43 treated with 2 Gy x 5 fractions combined with 5 mg/kg WSD0628 (20 day survival extension) or 10mg/kg WSD0628 (39 day with 10 mg/kg; p & lt;0.01 for both dose levels). Moreover, a single dose of 12.5 Gy combined with 10 mg/kg WSD0628 had profound impact on treatment efficacy in the melanoma brain metastasis M12 PDX: at 180 days post-treatment, all mice in the combination group were electively euthanized, while median survival for sham or RT alone was 17d and 49d, respectively. Histologic analysis identified large intracranial tumors in all sham and RT-only treated mice, but only a small accumulation of melanotic cells without obvious tumor in the combination-treated mice. Immunohistochemical staining of NeuN and GFAP in the combination-treated mice showed preserved neuronal density at the 180-post treatment timepoint and minimal reactive gliosis within the ‘tumor scar’. An ongoing study is comparing this single-fraction 12.5 Gy regimen to a 2.4 Gy x 10 fraction regimen alone or in combination with WSD0628. Collectively, this study demonstrates the potential for profound radiosensitizing effects of WSD0628 in combination without obvious neuronal toxicity and has provided the scientific rational for the first-in-man study of this combination in recurrent GBM (NCT05917145) at Mayo Clinic. Citation Format: Zhiyi Xue, Ann C. Mladek, Sneha Rathi, Danielle M. Burgenske, Shiv K. Gupta, Brett L. Carlson, Zeng Hu, Lauren L Ott, Katrina K. Bakken, Rachael A. Vaubel, William F Elmquist, Wei Zhong, Jann N Sarkaria. The radiosensitizing effects of the novel brain penetrant and potent ATM inhibitor WSD0628 in glioblastoma and melanoma patient derived xenografts [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A148.
    Type of Medium: Online Resource
    ISSN: 1538-8514
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2023
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  • 12
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 76, No. 14_Supplement ( 2016-07-15), p. 340-340
    Abstract: BACKGROUND: Talazoparib (TAL) is a potent poly (ADP-ribose) polymerase (PARP) inhibitor that robustly enhances in vitro sensitivity to temozolomide (TMZ) in several tumor models. We assessed the in vitro and in vivo efficacy of TAL combined with TMZ in glioblastoma (GBM) models. METHODS: Established glioma cell lines (T98G, U251) and the GBM12 patient derived xenograft (PDX) line were treated in vitro with TAL (1-10 nM) ± TMZ (2-300 μM). Antitumor efficacy was assessed with CyQUANT, clonogenic and primary neurosphere assays; cell cycle analysis with flow cytometry; DNA damage signaling with phospho-specific western blots for pKap1, pChk1, pChk2 and fluorescent immunocytochemistry for γH2AX and replication protein A foci. Brain and plasma concentrations of TAL in wild-type (WT), Mdr1a/b(-/-), Bcrp(-/-) and Mdr1a/b(-/-)Bcrp(-/-) knockout (KO) mice were assessed with LC-MS/MS. The tolerability of TAL (0.05 - 0.30 mg/kg/day orally, divided twice daily (div. bid)) and TMZ (5-50 mg/kg/day orally) was tested in athymic nude mice. Subsequently, in vivo combination TAL/TMZ efficacy was assessed with survival analyses in intracranial and flank GBM12 PDX models. RESULTS: TAL 1-3 nM sensitizes the TMZ resistant T98G glioma cell line to TMZ at high TMZ concentrations (30-300 μM) and is associated with G2 cell cycle arrest and enhanced DNA damage signaling. TAL 1-3 nM also enhances the cytotoxic efficacy of lower concentrations of TMZ (10-30 μM) in the TMZ sensitive U251 cell line. At least 3 nM TAL is required to enhance the in vitro efficacy of low TMZ concentrations (2-10 μM) in the TMZ sensitive GBM12 PDX line. PK studies in non-tumor bearing WT FVB mice treated with a single dose of TAL 0.15 mg/kg revealed mean brain and plasma concentrations of 0.49 ng/g (1.3 nM) and 25.5 ng/ml (67.1 nM) respectively at 2 hours. The mean brain/plasma ratio at 2 hours was unchanged in Bcrp(-/-) KO mice compared to WT mice (1.2% vs. 2.0%), but was significantly increased in Mdr1a/b(-/-) KO mice (22.8%) and Mdr1a/b(-/-)Bcrp(-/-) KO mice (23.9%). Standard doses of TMZ (50 mg/kg/day, days 1-5) combined with low doses of TAL (0.05 mg/kg/day, div. bid) were toxic in nude mice. Higher doses of TAL (0.30 mg/kg/day, div. bid) required substantial TMZ dose reductions (5 mg/kg/day, days 1-5) for tolerability. The addition of TAL (0.30 mg/kg/day, div. bid) to low-dose TMZ (5 mg/kg/day) prolonged tumor stasis in flank GBM12 xenografts (median time to endpoint 76 vs. 50 days, p = 0.005). However this regimen was ineffective in intracranial GBM12 xenografts (median survival 37 vs. 30 days, p = 0.93). CONCLUSIONS: TAL is a potent PARP inhibitor that enhances the efficacy of TMZ in both in vitro GBM models and flank GBM12 PDX models, but not in the corresponding GBM12 intracranial xenografts. This lack of intracranial efficacy is associated with limited brain distribution due to active efflux mediated by Mdr1 at the blood-brain barrier. Citation Format: Sani H. Kizilbash, Kenneth Chang, Shiv K. Gupta, Ryo Kawashima, Karen Parrish, Ann C. Mladek, Brett L. Carlson, Katrina K. Bakken, Mark A. Schroeder, Gaspar J. Kitange, Paul A. Decker, Yuqiao Shen, William F. Elmquist, Jann N. Sarkaria. Talazoparib enhances low-dose temozolomide efficacy in flank glioblastoma models, but intracranial efficacy is constrained by limited brain distribution. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 340.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2016
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  • 13
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2015
    In:  Cancer Research Vol. 75, No. 15_Supplement ( 2015-08-01), p. 3505-3505
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 75, No. 15_Supplement ( 2015-08-01), p. 3505-3505
    Abstract: Glioblastoma multiforme (GBM) is an aggressive and fatal disease commonly treated with radiation and temozolomide (TMZ), but emergence of therapy resistance invariably limits treatment efficacy. Inhibition of Poly-ADP ribose polymerases 1 and 2 (PARP1/2) sensitizes GBM cells, and inhibitors of PARP are emerging as combination partners with TMZ. However, limited brain penetration precludes use of several promising PARP inhibitors in GBM. BGB-290 is a relatively new and potent PARP inhibitor that crosses the blood brain barrier with a brain to plasma ratio of ∼0.2. The focus of the present study was to evaluate antitumor effects of BGB-290, as single agent or in combination with TMZ, in patient derived GBM xenografts and glioma cell lines. In a biochemical assay, low doses (30-100 nM) of BGB-290 suppressed PARP activity, while single agent anti-tumor activity of BGB-290 was modest and restricted to concentrations above 3 μM. Combinations of 0.1 μM BGB-290 with 10 μM TMZ significantly diminished primary neurosphere formation in a patient-derived xenograft line, GBM12, decreasing relative neurosphere count to 3.1 ± 1.3% as compared to 9.2 ± 3.1% with TMZ alone, p = 0.03. Consistent with a mechanism involving disruption of DNA repair, treatment of GBM12 cells with TMZ and BGB-290 combination resulted in robust γH2AX foci formation and a synergistic increase in DNA damage signaling as compared to TMZ or BGB-290 alone. TMZ-sensitizing effects of BGB-290 were heterogeneous in TMZ-resistant (GBM12TMZ) sublines that were developed previously by in vivo selection of parental GBM12 with cyclical TMZ therapy. The average neurosphere formation across 4 resistant sublines lacking MGMT expression after 100 μM TMZ only was 75.3 ± 9.0% versus 14.9 ± 7.4% with TMZ and 0.1 μM BGB-290, p & lt;0.01. In contrast, 2 MGMT overexpressing sublines were much less sensitive to the combination with relative neurospheres 91.9 ± 5.2% versus 73.2 ± 9.2% respectively, p & lt; 0.01. Next Gen Sequencing revealed discrete non-synonymous somatic mutations in the mismatch repair pathway of GBM12TMZ sublines lacking MGMT, which led us to examine the relationship between mismatch repair and sensitizing effects of PARP inhibition. Silencing Msh2 resulted in marked TMZ resistance in U251 cells (94.7± 5.4% relative growth with 100 μM TMZ), while co-treatment with 0.1 μM BGB-290 and 100 μM TMZ decreased growth to 23.5 ± 9.6% (p & lt;0.01), which is similar sensitivity to TMZ alone in U251 parental cells. In an initial in vivo study with orthotopic GBM12 xenografts, administration of BGB-290 at 3 mg/kg twice per day combined with 25 mg/kg TMZ extended survival of animals beyond 300 days (80% survival at day 320), while in the group treated with TMZ alone 80% animals were moribund before day 150. In conclusion, BGB-290 is a promising PARP inhibitor with high potency, cytotoxicity and favorable in vivo efficacy in TMZ sensitive and possibly a subset of recurrent TMZ resistant GBM. Citation Format: Shiv K. Gupta, Brett L. Carlson, Mark A. Schroeder, Katrina K. Bakken, Ann C. Tuma, Jann N. Sarkaria. Inhibition of PARP activity by BGB-290 potentiates efficacy of temozolomide in patient derived xenografts of glioblastoma multiforme. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3505. doi:10.1158/1538-7445.AM2015-3505
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2015
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  • 14
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 80, No. 16_Supplement ( 2020-08-15), p. 6506-6506
    Abstract: The efficacy of standard radiation therapy (RT) in glioblastoma (GBM) is limited, and there is a strong rationale to develop effective radiosensitizing agents. ATM is a key regulator of DNA damage induced by RT, and small molecule ATM inhibitors have shown radio-sensitizing effects in cancer cells, and may improve radio-sensitivity in GBM. Here, we evaluated the brain penetrant ATM inhibitor AZD1390 in combination with RT in GBM cell lines and patient derived xenografts (PDXs). AZD1390 (30 nM and higher) suppressed ionizing radiation-(5 Gy, IR) induced phosphorylation of ATM-Serine1981 and downstream signaling proteins Kap1, Chk2 and H2AX in GBM established cell lines (U251 and U87) and PDX lines (GBM12, GBM39 and GBM43). In cell cycle analysis, 30nM AZD1390 enhanced the IR induced G2/M arrest in U251 (80.6% with AZD1390/IR vs. 64.6% with IR alone, p= 0.01) and PDX lines GBM43 (61.9% vs. 25.7%, p= 0.01) and GBM39 (40.9% vs. 25.4%, p= 0.01). Moreover, in a U251 clonogenic survival assay, AZD1390 sensitized cells to IR-(5 Gy) induced killing (0.24% survival with AZD1390/RT vs. 2.3% with IR alone, P=0.01). For in vivo radiation combination studies, mice with established orthotopic tumors were irradiated to the cerebrum through opposed laterals with a 225 kVp stereotactic animal irradiator. While the hard palate and upper tongue were in the radiation target, the oropharynx and hypopharynx were spared with this radiation set up. A pilot study of RT combined with AZD1390 was evaluated in mice with established U251 orthotopic tumors using cohorts of 5 mice per arm. AZD1390 was given concurrently with conventionally fractionated radiation (2 Gy x 5 fractions) at a dose of 20 mg/kg PO delivered either daily or twice daily, with or without the efflux inhibitor elacridar. RT alone was well tolerated with minimal weight loss but was ineffective (median survival 30 days vs. 33 days in control group, p=0.5). In contrast, all of the RT/AZD1390 treatment arms exhibited enhanced but tolerable weight loss and had significant extension in symptom-free survival that currently extends beyond 65 days (median survival no reached). In conclusion, AZD1390 is an effective radio-sensitizer in vitro, and survival benefit from AZD1390 combined with conventionally fractionated RT in U251 models is encouraging. Further evaluation of efficacy across additional PDX models and careful analysis of the pharmacodynamic effects in tumor vs. normal tissues will be important to understand the therapeutic window for this agent in combination with RT. Citation Format: Jiajia Chen, Shiv K. Gupta, Gaspar J. Kitange, Ann C. Mladek, Brett L. Carlson, Lihong He, Zeng Hu, Katrina K. Bakken, Danielle M. Burgenske, Margaret A. Connors, Jann N. Sarkaria. Targeting ATM with AZD1390 for radio-sensitization of glioblastoma patient derived xenografts [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6506.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2020
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  • 15
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 22, No. Supplement_2 ( 2020-11-09), p. ii89-ii89
    Abstract: There is an unmet need to identify novel targets that can sensitize temozolomide (TMZ) or prevent resistance in GBM. We have demonstrated that retinoblastoma binding protein 4 (RBBP4) interacts with p300 to modulate expression of genes involved in homologous recombination (HR), including RAD51. In vitro, RBBP4- or p300-shRNA significantly sensitized TMZ in patient derived xenograft (PDX) GBM43 cells (relative fluorescence for 100µM TMZ treated control shNT cells was 0.89 ± 0.1 vs 0.47± 0.09 and 0.39 ± 0.01 for shRBBP4 and shp300, respectively (p & lt; 0.01)). TMZ sensitization increased DNA damage signaling through phosphorylation of KAP1 (p-KAP1) and p-CHK1. Moreover, RBBP4- or p300-shRNA delayed the repair of TMZ-induced DSBs evidenced by persistent gH2AX. Silencing RBBP4 or p300 reduced acetylation of lysine 27 of histone H3 (H3K27Ac) within promoters of HR genes regulated by RBBP4/p300 complex. Thus, RBBP4/p300 complex controls gene expression through p300-mediated histone acetyltransferase (HAT) activity, suggesting that p300 inhibitors could sensitize GBM to TMZ. Accordingly, CBP/p300 inhibitor CPI1612 significantly suppressed H3K27Ac and HR repair genes, including RAD51. Moreover, CPI1612 sensitized TMZ in GBM43 (synergy score = 258), and TMZ/CPI1612 significantly suppressed growth of GBM39 PDX cells compared with either drug alone (confluence (%) was 92 ± 1.0 (DMSO), 76.5 ± 4.6 (10 µM TMZ), 62 ± 3.4 (10 nM CPI1612) and 21.9 ± 3.2 (TMZ 10 µM/CPI-CPI1612 10 nM). CPI1612 enhanced TMZ-induced DSBs with increased damage signaling through p- KAP1 and persistent gH2AX. Pharmacodynamics studies in GBM39 orthotopic mice models revealed that oral CPI1612 penetrates the brain and accumulate in tumor regions and suppresses H3K27Ac without significant weight loss in mice that received placebo, TMZ, CPI1612 alone or combined TMZ/CPI-1612, demonstrating good animal tolerability. Collectively, these findings are encouraging that CBP/p300 inhibition by the brain penetrant CPI-1612 is a potential strategy for enhancing the efficacy of TMZ in GBM.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2020
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  • 16
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 81, No. 14 ( 2021-07-15), p. 3930-3941
    Abstract: Human tissue samples commonly preserved as formalin-fixed paraffin-embedded (FFPE) tissues after diagnostic or surgical procedures in the clinic represent an invaluable source of clinical specimens for in-depth characterization of signaling networks to assess therapeutic options. Tyrosine phosphorylation (pTyr) plays a fundamental role in cellular processes and is commonly dysregulated in cancer but has not been studied to date in FFPE samples. In addition, pTyr analysis that may otherwise inform therapeutic interventions for patients has been limited by the requirement for large amounts of frozen tissue. Here we describe a method for highly sensitive, quantitative analysis of pTyr signaling networks, with hundreds of sites quantified from one to two 10-μm sections of FFPE tissue specimens. A combination of optimized magnetic bead–based sample processing, optimized pTyr enrichment strategies, and tandem mass tag multiplexing enabled in-depth coverage of pTyr signaling networks from small amounts of input material. Phosphotyrosine profiles of flash-frozen and FFPE tissues derived from the same tumors suggested that FFPE tissues preserve pTyr signaling characteristics in patient-derived xenografts and archived clinical specimens. pTyr analysis of FFPE tissue sections from breast cancer tumors as well as lung cancer tumors highlighted patient-specific oncogenic driving kinases, indicating potential targeted therapies for each patient. These data suggest the capability for direct translational insight from pTyr analysis of small amounts of FFPE tumor tissue specimens. Significance: This study reports a highly sensitive method utilizing FFPE tissues to identify dysregulated signaling networks in patient tumors, opening the door for direct translational insights from FFPE tumor tissue banks in hospitals.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2021
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  • 17
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 24, No. 3 ( 2022-03-12), p. 384-395
    Abstract: Glioblastoma (GBM) is an incurable disease with few approved therapeutic interventions. Radiation therapy (RT) and temozolomide (TMZ) remain the standards of care. The efficacy and optimal deployment schedule of the orally bioavailable small-molecule tumor checkpoint controller lisavanbulin alone, and in combination with, standards of care were assessed using a panel of IDH-wildtype GBM patient-derived xenografts. Methods Mice bearing intracranial tumors received lisavanbulin +/−RT +/−TMZ and followed for survival. Lisavanbulin concentrations in plasma and brain were determined by liquid chromatography with tandem mass spectrometry, while flow cytometry was used for cell cycle analysis. Results Lisavanbulin monotherapy showed significant benefit (P & lt; .01) in 9 of 14 PDXs tested (median survival extension 9%-84%) and brain-to-plasma ratios of 1.3 and 1.6 at 2- and 6-hours postdose, respectively, validating previous data suggesting significant exposure in the brain. Prolonged lisavanbulin dosing from RT start until moribund was required for maximal benefit (GBM6: median survival lisavanbulin/RT 90 vs. RT alone 69 days, P = .0001; GBM150: lisavanbulin/RT 143 days vs. RT alone 73 days, P = .06). Similar observations were seen with RT/TMZ combinations (GBM39: RT/TMZ/lisavanbulin 502 days vs. RT/TMZ 249 days, P = .0001; GBM26: RT/TMZ/lisavanbulin 172 days vs. RT/TMZ 121 days, P = .04). Immunohistochemical analyses showed a significant increase in phospho-histone H3 with lisavanbulin treatment (P = .01). Conclusions Lisavanbulin demonstrated excellent brain penetration, significant extension of survival alone or in RT or RT/TMZ combinations, and was associated with mitotic arrest. These data provide a strong clinical rationale for testing lisavanbulin in combination with RT or RT/TMZ in GBM patients.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
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  • 18
    In: Molecular Cancer Therapeutics, American Association for Cancer Research (AACR), Vol. 18, No. 12_Supplement ( 2019-12-01), p. C096-C096
    Abstract: Lisavanbulin (LIS; BAL101553) is the prodrug of BAL27862, a microtubule-binding, tumor checkpoint controller and potential radiosensitizer. These studies evaluated optimal integration of LIS with standard of care radiation therapy (RT) and/or temozolomide (TMZ) using GBM PDX models. Distribution across the blood brain barrier was evaluated after a single 30 mg/kg oral LIS dose, and concentrations of the active metabolite BAL27862 were measured by liquid chromatography-tandem mass spectrometry. Similar BAL27862 concentrations were detected in the brain (B) and plasma (P) at both two (B:P ratio 1.29) and six hours (B:P ratio 1.64) post-dose. An in vivo screen of LIS monotherapy across 14 orthotopic GBM PDX models showed significant survival benefit (p & lt;0.01) in seven models (median survival extension 24-87%). Extending from these results, LIS was evaluated in several of the sensitive models in combination with RT +/- TMZ. Two MGMT unmethylated PDXs, GBM6 and GBM150, were treated with vehicle or two weeks of RT +/- LIS. LIS dosing during the RT dosing period did not significantly improve median survival in either line (GBM6 survival with RT 54 days vs RT/LIS 58 days, p=0.16; GBM150 RT 86 days vs RT/LIS 101 days, p=0.21). However, prolonged LIS dosing from the start of RT until mice reached a moribund state demonstrated added benefit (GBM6 median 90 days vs RT 69 days, p=0.0001; GBM150 median 143 days vs RT 73 days, p=0.06). In GBM6, prolonged LIS dosing also significantly extended survival when combined with 2 weeks of RT/TMZ (median 101 days vs 66 days, p & lt;0.0001), while LIS alone or RT/TMZ resulted in similar median survivals (63 days vs 66 days, respectively; p=0.68). This same RT/TMZ/LIS benefit was not seen in the MGMT methylated GBM12. Subsequent experiments were performed to evaluate integration of prolonged LIS dosing with concurrent RT/TMZ followed by 3 cycles of adjuvant TMZ (‘Stupp’ regimen). In MGMT methylated GBM39, LIS alone did not significantly extend survival, but LIS addition to the Stupp regimen doubled median survival (Stupp 249 days vs Stupp/LIS 502 days, p=0.0001). GBM150 demonstrated equal benefit from LIS alone or Stupp regimen (median 118 days vs 123 days, p=0.49). Stupp/LIS showed no additional survival benefit (median 98 days, p=0.97). In a second MGMT unmethylated, TMZ-resistant GBM26 PDX, LIS alone or combined with the Stupp regimen provided significant survival benefit: median survival 53 days for vehicle vs. 80 days for LIS (p=0.0001), 114 days for RT only (p & lt;0.0001), 147 days for RT/LIS (p=0.30 relative to RT), 121 days for ‘Stupp’ regimen alone (p=0.57 relative to RT), and 172 days for Stupp/LIS (p=0.04 relative to Stupp). A follow-up GBM39 study revealed a significant increase in the mitotic marker phospho-histone H3 with LIS treatment relative to vehicle-treated controls (p=0.01) while Ki67 levels were similar (p=0.15). This suggests that LIS induces a mitotic arrest associated with microtubule deregulation. Collectively, these data provide a strong rationale to evaluate lisavanbulin (BAL101553) with RT +/- TMZ in GBM and provided the basis for an ongoing Phase I clinical trial. Citation Format: Danielle M Burgenske, Ann C Mladek, Jenny L Pokorny, Heidi A Lane, Felix Bachmann, Rachael A Vaubel, Mark A Schroeder, Katrina K Bakken, Lihong He, Zeng Hu, Brett L Carlson, Surabhi Talele, Gautham Gampa, Matthew L Kosel, Paul A Decker, Jeanette E Eckel-Passow, William F Elmquist, Jann Sarkaria. Modeling the clinical paradigm of lisavanbulin (BAL101553) deployment in patient-derived xenografts (PDX) of glioblastoma (GBM) [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C096. doi:10.1158/1535-7163.TARG-19-C096
    Type of Medium: Online Resource
    ISSN: 1535-7163 , 1538-8514
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2019
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  • 19
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 80, No. 16_Supplement ( 2020-08-15), p. 4190-4190
    Abstract: Robust function of the p53 tumor suppressor pathway is critical when treating with DNA-damage inducing agents such as radiation therapy (RT), which is a key component of standard care for GBM. MDM2 is an important negative regulator of p53 stability and MDM2 is amplified in approximately 14% of GBM. Based on the concept that suppression of MDM2 can reactivate p53 function and potentially have single agent or combinatorial effects, multiple MDM2 inhibitors have been developed. Here we report in vitro and in vivo efficacy and pharmacodynamic (PD) effects of a BBB-penetrant MDM2-p53 antagonist, BI-MDM2, in GBM patient-derived xenograft (PDX) models. In vitro studies in p53 wild-type (WT) lines with or without MDM2 amplification demonstrate IC50 values in cell viability assays of 2-12 nM in serum-free culture and 5-35 nM in serum-containing culture after seven days of treatment. In vivo studies were performed in p53 WT lines: the MDM2-amplified GBM108, and the non-amplified GBM14, grown as orthotopic tumors in nude mice. Weekly oral treatment at 2 mg/kg of BI-MDM2 doubled median survival (placebo, 28 days (d) vs 2 mg/kg BI-MDM2, 57 d. p & lt;0.0001) while weekly dosing at 10 mg/kg extended the median over 5 fold (176 d. p & lt;0.0001) with half of the mice still living at 223 days post-inoculation. To assess the PD properties of this compound, mice bearing orthotopic GBM108 were treated three weeks after inoculation with a single dose of 2 or 10 mg/kg BI-MDM2. Normal brain, tumor, and plasma were collected at 24 and 48 hours (h) after dosing and downstream p53 transcriptional targets, p21 and PUMA were evaluated by qRT-PCR. p21 mRNA relative quantification detection at 24h increased by 1.5-10.5-fold in the 2 mg/kg group of animals compared to vehicle while the 10 mg/kg dose led to an increase by 2-25 fold compared to vehicle. PUMA was minimally affected by the 2 mg/kg dose but increased 1.2-17-fold over vehicle in the 10 mg/kg group at 24h. The observed increases in p21 and PUMA varied little between the 24 and 48h timepoints. In an orthotopic GBM14 PDX efficacy study, BI-MDM2 was combined with 20 Gy RT delivered in 10 fractions over 2 weeks with dosing limited to 2 weeks of therapy or until mice reached a moribund state. While two doses of 10 mg/kg BI-MDM2 alone had a modest effect on survival (41 d vs 31 d with placebo; p=0.002), continued dosing until moribund further extended median survival (82 d with BI-MDM2; p=0.001). The combination of two doses of BI-MDM2 with 2 weeks of RT extended survival as compared to RT alone (107 d vs. 69 d, respectively; p=0.019), while with extended drug dosing combined with 2 weeks of RT, median survival has not yet been reached ( & gt;125 d). Taken together, these results suggest that BI-MDM2 is a promising therapeutic agent that may provide significant anti-tumor efficacy either alone or in combination with RT in both MDM2 amplified and non-amplified p53 WT patients. Citation Format: Ann C. Mladek Tuma, Shiv Gupta, Surabhi Talele, Afroz Shareef Mohammad, Katrina K. Bakken, Helen He, Zeng Hu, Margaret A. Connors, Danielle M. Burgenske, Brett L. Carlson, William F. Elmquist, Ulrike Weyer-Czernilofsky, Jann N. Sarkaria. A promising blood-brain-barrier penetrant MDM2-p53 antagonist, BI-MDM2, increases survival in orthotopic, glioblastoma patient-derived xenograft models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4190.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2020
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  • 20
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2019
    In:  Molecular Cancer Therapeutics Vol. 18, No. 12_Supplement ( 2019-12-01), p. C051-C051
    In: Molecular Cancer Therapeutics, American Association for Cancer Research (AACR), Vol. 18, No. 12_Supplement ( 2019-12-01), p. C051-C051
    Abstract: Cell survival following radiation therapy (RT) is critically modulated by multiple DNA damage response pathways including the p53 tumor suppressor, which promotes cell cycle arrest and/or apoptosis in the face of DNA damage. Murine Double Minute 2 (MDM2) targets p53 for degradation and suppresses its functions. The MDM2 locus is amplified in approximately 14% of glioblastoma (GBM) tumors and is a promising target for individualized therapy. In these studies, we tested the MDM2 small molecule inhibitor KRT-232, alone and in combination with RT, in MDM2-amplified and/or p53 wildtype patient-derived xenograft (PDX) models of GBM in vitro and in vivo. KRT-232 suppressed GBM PDX cell explant culture viability in three MDM2-amplified lines (GBM46, 108, and 148) and two non-amplified but p53 wildtype lines (GBM10 and 39) with similar IC50s ranging from 300-800nM in FBS culture conditions. As expected, little suppression was observed in a p53 mutant (GBM43) line. Many drugs have limited distribution in the brain, and to understand limitations surrounding KRT-232, LCMS-MS was used to compare brain and plasma levels of drug in mice. Preliminary pharmacokinetic analysis using FVB wildtype mice compared to mice which maintain triple knockout of the efflux transporters Mdr1a, Mdr1b and Bcrp1–/– (TKO) treated with a single 10 mg/kg oral dose of KRT-232 and harvested 2 hours later demonstrate an 8% brain/plasma ratio of KRT-232 in the TKO mice, while levels were undetectable in WT mice. In light of these data, the efficacy of KRT-232 was initially tested in vivo in an MDM2-amplified GBM108 PDX with an artificially disrupted BBB afforded by VEGFA lentiviral expression. In this model, daily dosing with KRT-232 alone produced a 100 day prolongation in survival as compared to vehicle. In a subsequent experiment, just one week of daily KRT-232 dosing, either alone or in combination with RT, in the control GBM108 PDX with a relatively intact BBB, was remarkably effective; median survival for placebo 22 days, KRT-232 alone 46 days, RT alone 31 days, and the KRT-232/RT combination 77 days. Despite low BBB penetration as determined by pharmacokinetic studies, KRT-232 alone and in combination with RT is an effective treatment in a pre-clinical model of glioblastoma. Future studies will evaluate KRT-232 pharmacodynamic responses as well as PDX orthotopic combination therapy in additional MDM2 amplified and non-amplified/p53 wildtype lines to understand if this therapy can be used in a larger population of GBM tumors. Citation Format: Ann C Mladek, Shiv Gupta, Minjee Kim, Afroz Shareef Mohammad, Katrina K Bakken, Helen He, Zeng Hu, Danielle M Burgenske, Brett L Carlson, William F Elmquist, Jann Sarkaria. MDM2 inhibitor KRT-232 extends survival in glioblastoma patient-derived xenograft models [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C051. doi:10.1158/1535-7163.TARG-19-C051
    Type of Medium: Online Resource
    ISSN: 1535-7163 , 1538-8514
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2019
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    SSG: 12
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