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  • 1
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 22, No. Supplement_2 ( 2020-11-09), p. ii86-ii86
    Abstract: Radio-resistance mechanisms limit the benefit of radiation therapy (RT) for melanoma brain metastases. A key pathway for radiation-induced DNA double-strand break repair is non-homologous end joining, which is critically mediated by DNA-dependent protein kinase (DNA-PKcs). Here we evaluated radio-sensitizing effects of M3814, a selective oral inhibitor of DNA-PKcs, in patient-derived xenografts (PDXs) of melanoma brain metastases. In a clonogenic survival assay, M3841 augmented RT-induced killing of M12 cells at concentrations of ≥300 nM, and a minimum of 16 h exposure with ~300 nM M3814 was required for effective sensitization. M3814 inhibited RT-induced (5 Gy) auto-phosphorylation of serine-2056 of DNA-PKcs in primary cultures of M12, M15 and M27 PDX lines. Interestingly, inhibition of RT-induced DNA-PKcs by M3814 coincided with increased KAP1 phosphorylation, a DNA damage signaling regulated via ATM. Persistent γH2AX foci were observed in 28% M12 cells at 24 hours after co-treatment with M3814 and RT as compared to 12% cells following RT alone. In vivo pharmacokinetic analysis after single oral dose of 20 mg/kg M3814, showed reasonably short half-life (~2.44 hours) and poor brain distribution in wild-type FBV mice (Kpuu, 0.027). Consistent with an efflux liability, brain distribution of M3814 in triple knockout mice for BCRP/MDR1A/B was ~11 fold higher (Kpuu, 0.215). Compared to normal brain, much higher M3814 concentrations were detected in intracranially implanted M12 tumors (~23 fold and ~20 fold) 2 and 6 hours after a single oral dose of 50mg/kg respectively. The relative exclusion of M3814 from normal brain as compared to brain metastases suggests that this drug may have a favorable toxicity profile when combined with radiation for treatment of melanoma brain metastases, and this hypothesis is being tested in ongoing efficacy studies.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2020
    detail.hit.zdb_id: 2094060-9
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  • 2
    In: Neuro-Oncology Advances, Oxford University Press (OUP), Vol. 4, No. 1 ( 2022-01-01)
    Abstract: EGFR targeting antibody-drug conjugates (ADCs) are highly effective against EGFR-amplified tumors, but poor distribution across the blood–brain barrier (BBB) limits their efficacy in glioblastoma (GBM) when administered systemically. We studied whether convection-enhanced delivery (CED) can be used to safely infuse ADCs into orthotopic patient-derived xenograft (PDX) models of EGFRvIII mutant GBM. Methods The efficacy of the EGFR-targeted ADCs depatuxizumab mafodotin (Depatux-M) and Serclutamab talirine (Ser-T) was evaluated in vitro and in vivo. CED was performed in nontumor and tumor-bearing mice. Immunostaining was used to evaluate ADC distribution, pharmacodynamic effects, and normal cell toxicity. Results Dose-finding studies in orthotopic GBM6 identified single infusion of 2 μg Ser-T and 60 μg Depatux-M as safe and effective associated with extended survival prolongation ( & gt;300 days and 95 days, respectively). However, with serial infusions every 21 days, four Ser-T doses controlled tumor growth but was associated with lethal toxicity approximately 7 days after the final infusion. Limiting dosing to two infusions in GBM108 provided profound median survival extension of over 200 days. In contrast, four Depatux-M CED doses were well tolerated and significantly extended survival in both GBM6 (158 days) and GBM108 (310 days). In a toxicity analysis, Ser-T resulted in a profound loss in NeuN+ cells and markedly elevated GFAP staining, while Depatux-M was associated only with modest elevation in GFAP staining. Conclusion CED of Depatux-M is well tolerated and results in extended survival in orthotopic GBM PDXs. In contrast, CED of Ser-T was associated with a much narrower therapeutic window.
    Type of Medium: Online Resource
    ISSN: 2632-2498
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 3009682-0
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  • 3
    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
    detail.hit.zdb_id: 2094060-9
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  • 4
    In: Neuro-Oncology Advances, Oxford University Press (OUP), Vol. 5, No. 1 ( 2023-01-01)
    Abstract: Although the epidermal growth factor receptor (EGFR) is a frequent oncogenic driver in glioblastoma (GBM), efforts to therapeutically target this protein have been largely unsuccessful. The present preclinical study evaluated the novel EGFR inhibitor WSD-0922. Methods We employed flank and orthotopic patient-derived xenograft models to characterize WSD-0922 and compare its efficacy to erlotinib, a potent EGFR inhibitor that failed to provide benefit for GBM patients. We performed long-term survival studies and collected short-term tumor, plasma, and whole-brain samples from mice treated with each drug. We utilized mass spectrometry to measure drug concentrations and spatial distribution and to assess the impact of each drug on receptor activity and cellular signaling networks. Results WSD-0922 inhibited EGFR signaling as effectively as erlotinib in in vitro and in vivo models. While WSD-0922 was more CNS penetrant than erlotinib in terms of total concentration, comparable concentrations of both drugs were measured at the tumor site in orthotopic models, and the concentration of free WSD-0922 in the brain was significantly less than the concentration of free erlotinib. WSD-0922 treatment provided a clear survival advantage compared to erlotinib in the GBM39 model, with marked suppression of tumor growth and most mice surviving until the end of the study. WSD-0922 treatment preferentially inhibited phosphorylation of several proteins, including those associated with EGFR inhibitor resistance and cell metabolism. Conclusions WSD-0922 is a highly potent inhibitor of EGFR in GBM, and warrants further evaluation in clinical studies.
    Type of Medium: Online Resource
    ISSN: 2632-2498
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2023
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  • 5
    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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  • 6
    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
    detail.hit.zdb_id: 2062135-8
    SSG: 12
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  • 7
    Online Resource
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    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
    detail.hit.zdb_id: 2062135-8
    SSG: 12
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  • 8
    In: Molecular Cancer Therapeutics, American Association for Cancer Research (AACR), Vol. 22, No. 12_Supplement ( 2023-12-01), p. A002-A002
    Abstract: Large PDX collections provide broad representation of tumor genetics and are commonly used to evaluate the clinical potential of novel therapeutic strategies. In many solid malignancies, profound benefit in PDX preclinical studies has foreshadowed eventual FDA approval of clinically impactful therapeutics. With a lack of corresponding progress in glioblastoma (GBM), the value of PDX testing has been questioned. Mayo Clinic has developed 111 GBM PDXs from newly diagnosed (72 PDX) and recurrent (39 PDX) patients, and over the past 23 years, we have used this collection for extensive in vivo preclinical testing of 145 drugs in both orthotopic and heterotopic settings. As part of this work, the impact of standard of care therapy with temozolomide (TMZ) and bevacizumab was evaluated in orthotopic models using clinically relevant dosing regimens. For each animal study, the ratio of median survival for treated vs. control animals were used to define a ‘survival ratio’ as a normalized metric of benefit. TMZ efficacy was evaluated in 26 newly diagnosed GBM PDXs, with equal representation of MGMT methylated and unmethylated tumors. As expected, MGMT methylated PDXs were much more sensitive to TMZ as compared to unmethylated PDXs (median survival ratio 4.47 vs 1.48, respectively), and similar to clinical experience, 2 MGMT unmethylated PDXs were markedly sensitive to TMZ, while 1 MGMT methylated PDX was relatively resistant. In a more limited study, dose-dense vs. standard TMZ dosing was compared in 7 PDXs (4 MGMT methylated, 3 MGMT unmethylated). In a pooled analysis of all lines, both standard (HR=0.09; 95% CI: 0.06–0.14) and dose-dense TMZ therapy (HR=0.09; 95% CI: 0.06–0.14) were superior to vehicle controls (p & lt;0.001).  Similar to the clinical results in the Phase III randomized RTOG 0525 trial, survival with the dose-dense TMZ was no different than standard dosing (p=0.88, HR=0.98; 95% CI: 0.72-1.32). In an analysis of bevacizumab across 32 PDXs, mice were dosed once a week until moribund, and a minimum overall median survival benefit of 20% was used to define ‘responders’. Thirteen PDXs met this criterion, although the overall survival ratio among this subset was limited (range 1.21-1.65). Only 2 models had a 50% or greater survival benefit. Stratification by disease state (24 newly diagnosed vs 8 recurrent) showed equivalent performance (median survival benefit 1.13 for both). These results are consistent with the limited survival benefit observed with bevacizumab and the RTOG 0825 clinical trial. In summary, the results from these relatively inexpensive PDX studies demonstrate the potential of pre-clinical PDX trials to evaluate the extent of benefit and fraction of responsive PDXs to a novel therapeutic. If analyzed across an ‘adequate’ number of PDXs, these results potentially can be used to identify predictive biomarkers or to compare various treatment regimens prior to clinical testing. Citation Format: Danielle M Burgenske, Ann C Mladek, Katrina K Bakken, Zeng Hu, Brett L Carlson, Paul A Decker, Jeanette E Eckel-Passow, Jann N Sarkaria. The utility of pre-clinical trials in glioblastoma patient-derived xenografts (PDXs) models for informing clinical trial development of therapeutic strategies [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 A002.
    Type of Medium: Online Resource
    ISSN: 1538-8514
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2023
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