Intracranial Xenograft Model Research Articles

Claudin-3 facilitates the progression and mediates the tumorigenic effects of TGF-β in glioblastoma multiforme.

Glioblastoma multiforme (GBM) is a significantly malignant and lethal brain tumor with an average survival time of less than 12months. Several researches had shown that Claudin-3 (CLDN3) is overexpressed in various cancers and might be important in their growth and spread. In this study, we used qRT-PCR, western blotting, immunohistochemistry, and immunofluorescence staining assays to investigate the expression levels of various proteins. To explore the proliferation abilities of GBM cells, we conducted the CCK-8 and EdU-DNA formation assays. Wound healing and transwell assays were used to investigate the capacities of invasion and migration of GBM cells. Additionally, we constructed an intracranial xenograft model of GBM to study the in vivo role of CLDN3. Our study devoted to investigate the function of CLDN3 in the pathogenesis and progression of GBM. Our study revealed that CLDN3 was upregulated in GBM and could stimulate tumor cell growth and epithelial-mesenchymal transition (EMT) in both laboratory and animal models. We also discovered that CLDN3 expression could be triggered by transforming growth factor-β (TGF-β) and reduced by specific inhibitors of the TGF-β signaling pathway, such as ITD-1. Further analysis revealed that increased CLDN3 levels enhanced TGF-β-induced growth and EMT in GBM cells, while reducing CLDN3 levels weakened these effects. Our study demonstrated the function of CLDN3 in facilitating GBM growth and metastasis and indicated its involvement in the tumorigenic effects of TGF-β. Developing specific inhibitors of CLDN3 might, therefore, represent a promising new approach for treating this devastating disease.

PLK3 promotes the proneural-mesenchymal transition in glioblastoma via transcriptional regulation of C5AR1.

Accumulating evidence suggests that polo-like kinase 3 (PLK3) plays an essential role in tumor cells and induces cell proliferation and may have implications for the prognosis of various cancers. We sought to define the role of PLK3-dependent proneural-mesenchymal transition (PMT) in the glioblastoma (GBM) therapy. We analyzed the expression data for PLK3 by using the TCGA database. PLK3 expression in GBM cell lines was determined by qRT-PCR and Western blotting. PLK3 levels were modulated using Lentivirus infection, and the effects on symptoms, tumor volume, and survival in mice intracranial xenograft models were determined. Irradiation (IR) was performed to induce PMT. PLK3 expression was significantly elevated in mesenchymal subtype GBM and promoted tumor proliferation in GBM. Additionally enriched PLK3 expression could be associated with poor prognosis in GBM patients compared with those who have lower PLK3 expression. Mechanically, PLK3-dependent PMT induced radioresistance in GBM cells via transcriptional regulation of complement C5a receptor 1 (C5AR1). In therapeutic experiments conducted in vitro, targeting PLK3 by using small molecule inhibitor decreased tumor growth and radioresistance of GBM cells both in vitro and in vivo. PLK3-C5AR1 axis induced PMT thus enhanced radioresistance in GBM and could become a novel potential therapeutic target for GBM.

A complex of Wnt/planar cell polarity signaling components Vangl1 and Fzd7 drives glioblastoma multiforme malignant properties

Targeting common oncogenic drivers of glioblastoma multiforme (GBM) in patients has remained largely ineffective, raising the possibility that alternative pathways may contribute to tumor aggressiveness. Here we demonstrate that Vangl1 and Fzd7, components of the non-canonical Wnt planar cell polarity (Wnt/PCP) signaling pathway, promote GBM malignancy by driving cellular proliferation, migration, and invasiveness, and engage Rho GTPases to promote cytoskeletal rearrangements and actin dynamics in migrating GBM cells. Mechanistically, we uncover the existence of a novel Vangl1/Fzd7 complex at the leading edge of migrating GBM cells and propose that this complex is critical for the recruitment of downstream effectors to promote tumor progression. Moreover, we observe that depletion of FZD7 results in a striking suppression of tumor growth and latency and extends overall survival in an intracranial mouse xenograft model. Our observations support a novel mechanism by which Wnt/PCP components Vangl1 and Fzd7 form a complex at the leading edge of migratory GBM cells to engage downstream effectors that promote actin cytoskeletal rearrangements dynamics. Our findings suggest that interference with Wnt/PCP pathway function may offer a novel therapeutic strategy for patients diagnosed with GBM.

CFT7455, a novel IKZF1/3 degrader, demonstrates potent activity in peripheral and CNS models of NHL as a single agent or in combination with clinically approved agents

Immunomodulatory drugs, such as pomalidomide and lenalidomide are approved for the treatment of multiple subtypes of NHL. These drugs induce an interaction between Ikaros family zinc finger proteins 1 and 3 (IKZF1/3) and cereblon (CRBN), an E3 ligase, resulting in IKZF1/3 degradation. Clinically, immunomodulatory drugs are active as single agents or when used in combination with several classes of targeted therapies, in both first line and relapsed/refractory NHL subtypes. We previously described the preclinical characterization of CFT7455 as a novel IKZF1/3 degrader with 800-fold increased potency over pomalidomide in CRBN binding. We demonstrated that this increased activity translates into dramatically greater efficacy compared to pomalidomide in cellular and in vivo preclinical models of multiple myeloma and NHL. Here we show that the increased catalytic activity and improved potency of CFT7455 also translates into potent anti-tumor activity as a single agent or in combination with clinically approved agents in multiple in vivo models of NHL. In addition, the enhanced activity of CFT7455 demonstrates CNS activity in both the Raji and OCI-Ly10 intracranial xenograft models. CFT7455 (100 µg/kg/day) led to a significant increase in survival probability in comparison to pomalidomide (3000 µg/kg/day) and two investigational IKZF1/3 degraders in both models. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Aggressive T-cell non-Hodgkin lymphoma, Molecular Targeted Therapies Conflicts of interests pertinent to the abstract. M. J. Thomenius Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics S. Perino Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics J. Kirby Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics R. Agafonov Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics P. Chaturvedi Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics S. Eron Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics A. Good Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics J. A. Hart Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics M. He Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics A. Phillips Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics D. A. Proia Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics J. A. Henderson Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics C. Nasveschuk Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics S. L. Fisher Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics R. M. Pollock Employment or leadership position: C4 Therapeutics Stock ownership: C4 Therapeutics

Ursolic acid nanoparticles for glioblastoma therapy

BackgroundGlioblastoma multiforme (GBM) is the most common and fatal primary tumor in the central nervous system (CNS). The effect of chemotherapy of GBM is limited due to the existence of blood-brain barrier (BBB). The aim of this study is to develop self-assembled nanoparticles (NPs) of ursolic acid (UA) for GBM treatment. MethodsUA NPs were synthesized by solvent volatilization method. Western blot analysis fluorescent staining and flow cytometry were launched to explore the anti-glioblastoma mechanism of UA NPs. The antitumor effects of UA NPs were further confirmed in vivo using intracranial xenograft models. ResultsUA were successfully prepared. In vitro, UA NPs could significantly increase the protein levels of cleaved-caspase 3 and LC3-II to strongly eliminate glioblastoma cells through autophagy and apoptosis. In the intracranial xenograft models, UA NPs could further effectively enter the BBB, and greatly improve the survival time of the mice. ConclusionsWe successfully synthesized UA NPs which could effectively enter the BBB and show strong anti-tumor effect which may have great potential in the treatment of human glioblastoma.

Abstract LB330: FHND5071: a selective RET inhibitor with unique pharmacokinetic profile

Abstract Background: Gene rearrangements (fusions) and mutations in RET have the potential to be oncogenic drivers and have been observed in a variety of tumors types. Selective RET inhibitors selpercatinib and pralsetinib have been approved for patients with RET-altered cancers. FHND5071 is a novel kinase inhibitor which specifically targets RET activated forms and has unique pharmacokinetic profile. Methods: The pharmacological profile of FHND5071 have been confirmed in in vitro and in vivo evaluations, including enzyme and cell-based assays, PK/PD study, and RET-dependent tumor models. Results: In enzymatic assays, FHND5071 potently inhibited RET wild type, RET fusions and mutations with the IC50 of 4.47~19.26 nM and demonstrated 89-fold selectivity over KDR (VEGFR-2). FHND5071-M2, the active metabolite identified in pre-clinical pharmacokinetics, had the same potency as FHND5071. In cellular settings, FHND5071 inhibited the proliferation of Ba/F3 engineered cells (RET WT, RET V804M, RET M918T) and inhibited RET phosphorylation in HEK-293 engineered cells (WT, V804M, RET M918T, KIF5B-RET, CCDC6-RET) with the similar potency compared with selpercatinib. In PK/PD study (Ba/F3 KIF5B-RET allograft model), compared with selpercatinib, FHND5071 had longer Tmax and MRT in plasma and tumor tissue. FHND5071 preferred to be distributed into tissues. The exposure of FHND5071 in tumor tissue (AUC0-t) was ~28 times that of selpercatinib and the concentration of FHND5071 in brain tissue was ~33 times that of selpercatinib at 4 h after dosing. Meanwhile, after FHND5071 administration, RET phosphorylation and the downstream signaling protein (pAKT, pErk1/2) were significantly inhibited in tumor tissue and the inhibition was maintained for 24 h at least. But the duration of inhibition with selpercatinib was shorter than that of FHND5071. In tumor models, FHND5071 exhibited significant anti-tumor efficacy in Ba/F3 KIF5B-RET model at oral dose levels ≥3 mg/kg once daily (QD) without inducing significant toxicity. FHND5071 QD exhibited similar anti-tumor activity as selpercatinib administrated twice a day (BID) at 30 mg/kg. 30 mg/kg FHND5071 (QD) demonstrated significant anti-tumor efficacy with 100% TGI in patient-derived xenograft models (colorectal cancer with CCDC6-RET and ovarian cancer with NCOA4-RET). In CCDC6-RET intracranial xenograft model, 30 mg/kg FHND5071 (QD) significant prolonged life time of model mice. The median survival time was 56 days and the increase in life-span was 51% (p<0.005 compared with the vehicle group). Conclusions: FHND5071 demonstrated excellent selectivity and anti-tumor efficacy. The unique pharmacokinetic profile of FHND5071 supported the frequency of once-a-day dosing and better efficacy in target organ and brain tumor in clinical. FHND5071 has received IND approval from NMPA and FDA. It is currently in the dose-escalation segment of a first-in-human phase 1 trial for patients with RET-driven solid tumors. Citation Format: Yongqiang Zhu, Jia Wang, Minghong Shang. FHND5071: a selective RET inhibitor with unique pharmacokinetic profile [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB330.

A Cell Type Selective YM155 Prodrug Targets Receptor-Interacting Protein Kinase 2 to Induce Brain Cancer Cell Death.

Glioblastoma (GBM) is the most prevalent and aggressive primary central nervous system (CNS) malignancy. YM155 is a highly potent broad-spectrum anti-cancer drug that was derived from a phenotypic screen for functional inhibitors of survivin expression, but for which the relevant biomolecular target remains unknown. Presumably as a result of its lack of cell-type selectivity, YM155 has suffered from tolerability issues in the clinic. Based on its structural similarity to the GBM-selective prodrug RIPGBM, here, we report the design, synthesis, and characterization of a prodrug form of YM155, termed aYM155. aYM155 displays potent cell killing activity against a broad panel of patient-derived GBM cancer stem-like cells (IC50 = 0.7-10 nM), as well as EGFR-amplified and EGFR variant III-expressing (EGFRvIII) cell lines (IC50 = 3.8-36 nM), and becomes activated in a cell-type-dependent manner. Mass spectrometry-based analysis indicates that enhanced cell-type selectivity results from relative rates of prodrug activation in transformed versus non-transformed cell types. The prodrug strategy also facilitates transport into the brain (brain-to-plasma ratio, aYM155 = 0.56; YM155 = BLQ). In addition, we determine that the survivin-suppressing and apoptosis-inducing activities of YM155 involve its interaction with receptor-interacting protein kinase 2 (RIPK2). In an orthotopic intracranial GBM xenograft model, aYM155 prodrug significantly inhibits brain tumor growth in vivo, which correlates with cell-type selective survivin-based pharmacodynamic effects.

Abstract 1146: Tepotinib treatment inhibits tumor growth and affects tumor permeability in an intracranial PDX model of MET-amplified NSCLC brain metastasis

Abstract Background: Tepotinib is approved to treat patients with NSCLC harboring MET exon 14 skipping. We previously provided preclinical proof of concept for tepotinib to treat NSCLC metastasized to the brain (Friese-Hamim M, et al. Lung Cancer 2022;163:77-86). Here, we report a detailed analysis of the effects of high-dose tepotinib in preclinical models of MET-amplified NSCLC brain metastases. Experimental methods: Using the previously reported intracranial MET-amplified patient-derived xenograft (PDX) models (LU5349 and LU5406), we measured the effects of tepotinib at the clinically relevant dose of 125 mg/kg QD and above (300 mg/kg QD) or a vehicle control on plasma concentrations, tumor growth (by T2-weighted MRI), intra-tumoral compound distribution (by MALDI MSI) and tumor vasculature (by DCE-MRI for Ktrans, a measure of tumor permeability), as well as biomarkers in tumor tissue (pMET, pAKT, Ki67, endoglin, caspase-3, and MoIgG). For model LU5349, animals were imaged on the day before euthanasia at Day (D) 0, 6 and 16 of treatment (n=10 per time point). Results: Plasma concentrations of tepotinib 2 hours after the final administration at each time point were not proportional by dose, indicating a limited absorption at the higher dose. By D16, tumor measurements (±SD) in tepotinib-treated mice (5.5 ± 3.4 mm3) were approximately 20-fold smaller than those in control mice (109.3 ± 50.1 mm3). At the lower dosing level, concentrations of tepotinib within the tumor regions decreased from 12 ± 6.4 µM (D0) to 3.2 ± 2.7 µM (D6) and then increased to 4.6 ± 1.2 µM (D16). In the higher dose group, concentrations of tepotinib in tumor regions decreased from 15.1 ± 8.7 µM (D0) to 6.8 ± 2.9 µM (D6) and then to 4.5 ± 3.6 µM (D16). Concentrations of tepotinib were below the limit of detection in non-tumor regions. Ktrans of the tumor was also affected by tepotinib treatment. While there was an apparent decline in mean Ktrans over time in control tumors (7.4 ± 3.0 × 10−2 s−1 [D0], 6.4 ± 2.8 × 10−2 s−1 [D6], 5.6 ± 3.5 × 10−2 s−1 [D16]), tepotinib treatment caused a further reduction at both the lower (7.8 ± 3.2 × 10−2 s−1 [D0], 2.9 ± 1.3 × 10−2 s−1 [D6], 2.7 ± 1.4 × 10−2 s−1 [D16]) and higher dose (8.0 ± 3.0 × 10−2 s−1 [D0], 2.7 ± 1.1 × 10−2 s−1 [D6], 2.9 ± 1.2 × 10−2 s−1 [D16]), indicating potential anti-vascular effects in the tumor. Conclusions: These preclinical analyses of tepotinib treatment of MET-amplified NSCLC brain metastases provide new insights, considering the observed tumor regression, the compound’s distribution to tumor versus non-tumor brain tissue and anti-vascular effects (via DCE-MRI), which may provide a predictive biomarker of response and patient survival. A possible causal association between reduced vascular permeability and the restricted distribution of tepotinib to tumor regions may exist. Analyses of the second PDX model and tumor biomarkers are ongoing and will be presented. Citation Format: Anderson Clark, Joachim Albers, Patrick McConville, Sylwia A. Stopka, Michael S. Regan, Marina DiPiazza, Nathalie Y.R. Agar. Tepotinib treatment inhibits tumor growth and affects tumor permeability in an intracranial PDX model of MET-amplified NSCLC brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1146.

Abstract 3097: Prodrugs of a 1-hydroxy-2-oxopiperidin-3-yl phosphonate enolase inhibitor for the treatment of ENO1-deleted cancers

Abstract Cancers harboring homozygous deletion of the glycolytic enzyme enolase 1 (ENO1) are selectively vulnerable to inhibition of the paralogous isoform, enolase 2 (ENO2). We previously identified and characterized a competitive, small molecule phosphonate inhibitor of ENO2, 1-hydroxy-2-oxopiperidin-3-yl phosphonate (HEX), and its lipophilic bis-ester prodrug (POMHEX) in an ENO1-deleted intracranial orthotopic xenograft model of glioblastoma. Treatment with either HEX (150 mg/kg IV/IP) or POMHEX (20 mg/kg IV/IP) yielded tumor regression even after drug discontinuation. However, due to the poor pharmacokinetics of esterase-labile POMHEX, we synthesized a library of novel phosphonate prodrugs with distinct mechanisms of bioactivation and assessed their potency in D423 (ENO1-/-) cells. By conducting a prodrug structure activity relationship (SAR) study, we found that phosphonoamidate esters were efficiently bioactivated in ENO1-deleted glioma cells, while canonical McGuigan (ProTide) prodrugs were not. Other strategies, including salicylic alcohol (cycloSal) and lipid prodrugs of HEX, exhibited low micromolar IC50 values in ENO1-deleted glioma cells and improved stability in human serum over POMHEX. En route, we developed a novel class of aliphatic amine/ester prodrugs that can be broadly applied to efficiently deliver phosph(on)ate pharmacophores in cells. The activity of select prodrugs was also probed using the NCI-60 cell line screen, supporting its use to examine the relationship between prodrugs and cell line-dependent bioactivation. In sum, we have developed a novel class of phosph(on)ate prodrugs that is efficiently bioactivated in cells in vitro. Our prodrug SAR study disputes the common notion that ProTides are universally advantageous promoieties on phosph(on)ate pharmacophores and we provide mechanistic rationale for this observation with HEX. Finally, we show that the cycloSal prodrug yields efficient intracellular delivery of HEX in vitro, with a mechanism of bioactivation consistent with the GBM microenvironment, making this promoiety promising for further evaluation in vivo. Citation Format: Victoria C. Yan, Cong-Dat Pham, Elliot S. Ballato, Kristine L. Yang, Sunada Khadka, Yasaman Barektain, Prakriti Shrestha, Theresa Tran, Anton H. Poral, Mykia Washington, Sudhir Raghavan, Barbara Czako, Federica Pisaneschi, Yu-Hsi Lin, Nikunj Satani, Naima Hammoudi, Jeffrey J. Ackroyd, Dimitra K. Georgiou, Steven W. Millward, Florian L. Muller. Prodrugs of a 1-hydroxy-2-oxopiperidin-3-yl phosphonate enolase inhibitor for the treatment of ENO1-deleted cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3097.

Abstract 6185: Debio 0123 is a selective WEE1 inhibitor that effectively penetrates the brain and demonstrates anti-tumor activity in preclinical models of glioblastoma

Abstract Background: Glioblastoma (GBM) is one of the most aggressive and hard-to-treat cancers with a 5-year survival rate of 5.8%, in part due to the presence of the blood brain barrier (BBB) that prevents most therapeutics from reaching the tumors at efficacious concentrations. Debio 0123 is a WEE1 inhibitor that has previously shown significant preclinical efficacy in combination with DNA damaging agents or radiotherapy and is currently being investigated in phase 1 clinical studies either as a monotherapy or in combination with carboplatin. Herein we present data that demonstrates Debio 0123 effectively penetrates in to the brain and subsequently leads to anti-tumor activity in GBM models both in vitro and in vivo as a monotherapy or in combination with standard-of-care therapies (SOC). Methods: Radio- and chemo-sensitizing effects of Debio 0123 were evaluated in GBM cell lines in vitro using standard clonogenic assays or cytotoxicity assays. In vivo, distribution and bioanalysis studies were performed to determine the amount of Debio 0123 present in the different parts of the brain and intracranially implanted tumors. Efficacy of Debio 0123 as monotherapy or in combination with the SOC, temozolomide (TMZ), was further assessed in vivo in U87MG-luc intracranial or subcutaneous xenograft models. Results: In vitro, Debio 0123 in combination with radiation enhanced cell death in GBM cell lines and reduced TMZ IC50 in primary GBM cell lines. In vivo studies demonstrated substantial Debio 0123 brain penetration in mice, rats and monkeys, with mean brain-to-plasma concentration ratios of ~0.6 and 1.52 and 4, respectively. Furthermore, a mean tumor-to-plasma ratio of 0.62 was determined in orthotopically implanted brain tumors in mice. In efficacy studies, Debio 0123 administered at 30 or 60mg/kg every day for 28 days displayed significant anti-tumor activity in a GBM xenograft model U87-MG implanted in immunodeficient mice either subcutaneously, with up to 57.5% tumor growth inhibition, or orthotopically in the brain, with up to 73.7% tumor growth inhibition. Finally, efficacy of Debio 0123 in combination with TMZ was also assessed in intracranially transplanted U87-MG tumors. Here, TMZ was highly active, however, the combination of Debio 0123 and TMZ resulted in significantly enhanced anti-tumor activity leading to sustained complete regressions in 75% of animals for up to 100 days and was well tolerated throughout the 28-day treatment. Conclusion: These results demonstrate that following oral administration, Debio 0123 effectively crosses the BBB, has significant efficacy as a monotherapy and improves response to standard-of-care chemo or radiotherapy in preclinical models. Collectively, these data highlight Debio 0123 as a promising candidate for further clinical development in GBM patients that may provide improved response to SOC therapy. Citation Format: Luke Piggott, Noemie Luong, Frederic Massiere, Annett Kunze, Christophe Chardonnens, Anne Vaslin. Debio 0123 is a selective WEE1 inhibitor that effectively penetrates the brain and demonstrates anti-tumor activity in preclinical models of glioblastoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6185.

Development and validation of a glioma-associated mesenchymal stem cell-related gene prognostic index for predicting prognosis and guiding individualized therapy in glioma

BackgroundRecent studies have demonstrated that glioma-associated mesenchymal stem cells (GA-MSCs) are implicated in the regulation of glioma malignant progression. However, the prognostic value of GA-MSCs has not been comprehensively explored in glioma.MethodsWe extracted GA-MSCs from glioma tissues, established intracranial xenograft models in nude mice, and obtained GA-MSC-related genes (GA-MSCRGs) by using microarrays. The transcriptome data and clinical information of glioma patients were obtained from the CGGA and TCGA databases. We screened 8 prognostic GA-MSCRGs to construct a prognostic index by using the multivariate Cox regression method. The validity of the GA-MSCRGPI was verified in the training (CGGA693) and validation (TCGA and CGGA325) cohorts. The expression patterns of these 8 GA-MSCRGs were validated in 78 glioma tissue specimens by using a qRT‒PCR assay.ResultsGA-MSCs were successfully isolated from glioma tissues. Based on intracranial xenograft models and transcriptome microarray screening, 8 genes (MCM7, CDK6, ORC1, CCL20, TNFRSF12A, POLA1, TRAF1 and TIAM1) were selected for the construction of a GA-MSC-related gene prognostic index (GA-MSCRGPI). In both the training and validation cohorts, high GA-MSCRGPI patients showed an inferior survival outcome compared with low GA-MSCRGPI patients. A nomogram was established based on independent prognostic indicators (age, WHO grade and GA-MSCRGPI) and exhibited a strong forecasting ability for overall survival (OS). Moreover, we found that the GA-MSCRGPI could evaluate the prognosis of glioma patients undergoing chemoradiotherapy. The high GA-MSCRGPI group exhibited higher immune, stromal and ESTIMATE scores; lower tumor purity; higher infiltration of Tregs and M2-type macrophages; fewer activated NK cells; and higher expression of immune checkpoints. Tumor Immune Dysfunction and Exclusion (TIDE) showed that the high GA-MSCRGPI group had more responders to ICI therapy. The results of the genetic mutation profile and tumor mutation burden (TMB) in different GA-MSCRGPI subgroups further supplement GA-MSCRGPI-related mechanisms. Finally, the expression patterns of 8 selected GA-MSCRGs in GA-MSCRGPI were correlated with glioma WHO grades to a certain extent.ConclusionThe constructed GA-MSCRGPI could predict prognosis and guide individualized therapy in glioma patients.

Sitagliptin inhibits the survival, stemness and autophagy of glioma cells, and enhances temozolomide cytotoxicity

The standard regimen treatment has improved GBM outcomes, but the survival rate of patients is still unsatisfactory. Temozolomide (TMZ) resistance is one of main reasons limiting the therapeutic efficacy of GBM. However, there are currently no TMZ-sensitizing drugs available in the clinic. Here we aimed to study whether the antidiabetic drug Sitagliptin can inhibit the survival, stemness and autophagy of GBM cells, and thus enhance TMZ cytotoxicity. We used CCK-8, EdU, colony formation, TUNEL and flow cytometry assays to assess cell proliferation and apoptosis; sphere formation and limiting dilution assays to measure self-renewal and stemness of glioma stem cells (GSCs); Western blot, qRT-PCR or immunohistochemical analysis to measure the expression of proliferation or stem cell markers; Western blot/fluorescent analysis of LC3 and other molecules to evaluate autophagy formation and degradation in glioma cells. We found that Sitagliptin inhibited proliferation and induced apoptosis in GBM cells and suppressed self-renewal and stemness of GSCs. The in vitro findings were further confirmed in glioma intracranial xenograft models. Sitagliptin administration prolonged the survival time of tumor-bearing mice. Sitagliptin could inhibit TMZ-induced protective autophagy and enhance the cytotoxicity of TMZ in glioma cells. In addition, Sitagliptin acted as a dipeptidyl peptidase 4 inhibitor in glioma as well as in diabetes, but it did not affect the blood glucose level and body weight of mice. These findings suggest that Sitagliptin with established pharmacologic and safety profiles could be repurposed as an antiglioma drug to overcome TMZ resistance, providing a new option for GBM therapy.

CircNDC80 promotes glioblastoma multiforme tumorigenesis via the miR-139-5p/ECE1 pathway

BackgroundCircular RNAs (circRNAs) have been shown to be essential for the emergence and growth of different cancers. However, further research is required to validate the function of circRNA in glioblastoma (GBM).MethodsCircNDC80 expression in both normal brain tissues (NBTs) and glioma tissues was determined using real-time PCR. The impact of circNDC80 on GBM cell proliferation, migration, and invasion was then confirmed by CCK-8, colony formation, EdU incorporation, Transwell, and wound healing assays. To determine how circNDC80 affects the capacity of glioma stem cells (GSCs) to maintain their stemness and self-renewal, a CellTiter-Glo assay, clonogenic assay and extreme limiting dilution assay were utilized. To ascertain the impact of circNDC80 in vivo, intracranial xenograft models were established.ResultsWhen compared to NBT, glioblastoma tissue had a higher level of circNDC80 expression. In functional assays, circNDC80 promoted glioblastoma cell proliferation, migration, and invasion, while sustaining the stemness and fostering the self-renewal of glioma stem cells. In addition, a dual luciferase reporter assay and circRIP were used to verify that circNDC80 simultaneously affects the expression of ECE1 mRNA by sponging miR-139-5p, and a rescue experiment was used to verify the above results further.ConclusionsAccording to our research, circNDC80 is an oncogenic factor that promotes glioblastoma through the miR-139-5p/ECE1 pathway. This implies that circNDC80 may be employed as a novel therapeutic target and a possible predictive biomarker.

The PARP inhibitor Rucaparib synergizes with radiation to attenuate atypical teratoid rhabdoid tumor growth.

Atypical teratoid rhabdoid tumors (ATRT) are highly aggressive pediatric brain tumors. The available treatments rely on toxic chemotherapy and radiotherapy, which themselves can cause poor outcomes in young patients. Poly (ADP-ribose) polymerases (PARP), multifunctional enzymes which play an important role in DNA damage repair and genome stability have emerged as a new target in cancer therapy. An FDA-approved drug screen revealed that Rucaparib, a PARP inhibitor, is important for ATRT cell growth. This study aims to investigate the effect of Rucaparib treatment in ATRT. This study utilized cell viability, colony formation, flow cytometry, western blot, immunofluorescence, and immunohistochemistry assays to investigate Rucaparib's effectiveness in BT16 and MAF737 ATRT cell lines. In vivo, intracranial orthotopic xenograft model of ATRT was used. BT16 cell line was transduced with a luciferase-expressing vector and injected into the cerebellum of athymic nude mice. Animals were treated with Rucaparib by oral gavaging and irradiated with 2 Gy of radiation for 3 consecutive days. Tumor growth was monitored using In Vivo Imaging System. Rucaparib treatment decreased ATRT cell growth, inhibited clonogenic potential of ATRT cells, induced cell cycle arrest and apoptosis, and led to DNA damage accumulation as shown by increased expression of γH2AX. In vivo, Rucaparib treatment decreased tumor growth, sensitized ATRT cells to radiation and significantly increased mice survival. We demonstrated that Rucaparib has potential to be a new therapeutic strategy for ATRT as seen by its ability to decrease ATRT tumor growth both in vitro and in vivo.

BI-907828, a novel potent MDM2 inhibitor, inhibits glioblastoma brain tumor stem cells in vitro and prolongs survival in orthotopic xenograft mouse models.

The tumor suppressor TP53 (p53) is frequently mutated, and its downstream effectors inactivated in many cancers, including glioblastoma (GBM). In tumors with wild-type status, p53 function is frequently attenuated by alternate mechanisms including amplification and overexpression of its key negative regulator, MDM2. We investigated the efficacy of the MDM2 inhibitor, BI-907828, in GBM patient-derived brain tumor stem cells (BTSCs) with different amplification statuses of MDM2, in vitro and in orthotopic xenograft models. In vitro growth inhibition and on-target efficacy of BI-907828 were assessed by cell viability, co-immunoprecipitation assays, and western blotting. In vivo efficacy of BI-907828 treatments was assessed with qPCR, immunohistochemistry, and in intracranial xenograft models. BI-907828 decreases viability and induces cell death at picomolar concentrations in both MDM2 amplified and normal copy number TP53 wild-type BTSC lines. Restoration of p53 activity, including robust p21 expression and apoptosis induction, was observed in TP53 wild-type but not in TP53 mutant BTSCs. shRNA-mediated knock-down of TP53 in wild-type BTSCs abrogated the effect of BI-907828, confirming the specificity of the inhibitor. Pharmacokinetic-pharmacodynamic studies in orthotopic tumor-bearing severe combined immunodeficiency (SCID) mice demonstrated that a single 50mg/kg p.o. dose of BI-907828 resulted in strong activation of p53 target genes p21 and MIC1. Long-term weekly or bi-weekly treatment with BI-907828 in orthotopic BTSC xenograft models was well-tolerated and improved survival both as a single-agent and in combination with temozolomide, with dose-dependent efficacy observed in the MDM2 amplified model. BI-907828 provides a promising new therapeutic option for patients with TP53 wild-type primary brain tumors.

EXTH-08. DEVELOPMENT OF NOVEL HISTONE DEMETHYLASE INHIBITOR AGAINST DIPG

Abstract BACKGROUND Diffuse intrinsic pontine glioma (DIPG) is one of most the devastating pediatric brain tumors, and virtually all patients die within two years after diagnosis. It has been shown that targeted inhibition of JMJD3 demethylase activity by GSK-J4 results in restored K27 methylation and a significant delay of tumor progression and prolonged animal survival in intracranial DIPG patient-derived xenograft (PDX) models. Because of its promising anti-tumor activities, GSK-J4 has been used to treat many kinds of tumors in preclinical models including leukemia, lymphoma, neuroblastoma, prostate, and gastric cancer, and DIPG; however, GSK-J4 is not yet in clinical development. The major challenge for GSK-J4 in clinical development is that GSK-J4 is a prodrug and is rapidly converted in vivo to the active drug GSK-J1, which has restricted cellular and brain permeability. Hypothesis: We hypothesize that development of a stable GSK- J1 analog that offers good cellular and brain transport is essential to improving in vivo efficacy and is required for clinical application of this class of compounds. METHODS We developed a novel alcohol derivative of GSK-J1, UR-8, as a lead anti-cancer agent through our screening and drug development activities. RESULTS UR-8 has demonstrated selective cytotoxic activity against human K27M DIPG cells in vitro and apparently transported the brain to a useful extent based on its in vivo bio-distribution and effectiveness. CONCLUSION UR-8 showed greater anti-tumor activity and survival benefit than that obtained by GSK-J4 treatment in intracranial DIPG PDX models.

EXTH-51. HSV-PTENΑ TREATMENT TARGETS GLIOMA STEM CELLS TO REDUCE STEMNESS AND SENSITIZES GLIOBLASTOMA TO IRRADIATION

Abstract Glioblastoma is one of the most lethal and treatment-resistant tumors of the central nervous system. Despite maximal surgical and medical therapy, survival remains dismal with a median of 21 months. Despite advances in treatment, this has only led to modest survival benefit. A significant challenge in treatment of glioblastoma is targeting glioma stem cells (GSCs) which are a source of therapy resistance. Oncolytic viral (OV) therapy is a promising therapy for solid tumors that preferentially targets tumor cells for lysis and an anti-tumor immune response while sparing normal cells. Among all OVs, oncolytic Herpes Simplex Virus (oHSV) is substantially ahead in the clinic, with an oHSV T-VEC approved by the FDA for metastatic melanoma treatment and G47∆ which received conditional approval for the treatment of GBM in Japan. In prior work, our group has demonstrated that PTENα expression by an oHSV (HSV-P10) results in improved long-term survivors in intracranial tumor-bearing mice compared to HSVQ treatment. We aim to elucidate the mechanism of improved therapeutic efficacy of HSV-P10 against GBM and evaluate if HSV-P10 may overcome radio-resistance. RNA sequencing and GSEA analysis of primary human GBM cells infected with control HSVQ or HSV-P10 reveals that while HSVQ virus infection leads to an increase in genes regulating IL6-STAT3 pathway, pivotal in maintaining stemness properties, HSV-P10 infection leads to a reduction. HSV-P10 reduces CD133+/CD44+ stem cells, induces DNA damage and sensitizes the GBM cells to irradiation. Our findings reveal a novel mechanism induced by HSV-P10 in combination with irradiation where HSV-P10 modulates IL6-STAT3 signaling downregulating genes associated with stemness (Nestin, Sox2). HSV-P10 infection in combination with irradiation reduces GSC tumor sphere formation in vitro and sensitizes GBMs to radiotherapy in an intracranial mouse xenograft model. Our findings uncover a possible mechanism to overcome GSC-mediated therapy resistance to improve the therapeutic efficacy for GBM.

DDDR-01. AZD9574 IS A NOVEL, BRAIN PENETRANT PARP-1 SELECTIVE INHIBITOR WITH ACTIVITY IN AN INTRACRANIAL XENOGRAFT MODEL OF TRIPLE NEGATIVE BREAST CARCINOMA WITH HOMOLOGOUS RECOMBINATION REPAIR DEFICIENCY

Abstract The Poly (ADP-ribose) polymerase (PARP) family has numerous essential functions in cellular processes such as transcription, chromatin remodelling, DNA damage response and repair as well as apoptosis. PARP inhibition blocks base excision repair and results in conversion of SSBs to DNA double-strand break (DSBs), the most deleterious form of DNA damage. DSBs can be repaired by homologous recombination repair (HRR) or non-homologous end joining (NHEJ). The physiological importance of HRR is underscored by the observation of genomic instability in HRR-deficient (HRD+) cells and, importantly, the association of cancer predisposition and developmental defects with mutations in HRR genes. PARP1 and PARP2 are required for SSB repair, while PARP1 is also involved in the repair of DNA double-strand breaks (DSBs) and replication fork damage. AZD9574 is a novel brain penetrant PARP1 inhibitor that acts by selectively inhibiting and trapping PARP1 at the sites of SSBs. While AZD9574 inhibited PARP1 enzymatic activity in all tested cell lines irrespective of the HRR status (IC50 range between 0.3 – 2 nM), colony formation assay in isogenic cell lines pairs confirmed higher potency and selectivity towards HRD+ models. In vivo, AZD9574 demonstrated dose-dependent efficacy in a BRCA1 mutant MDA-MB-436 subcutaneous xenograft model. Anti-tumour effects of AZD9574 were manifested by significant growth regressions that were durable after treatment withdrawal. An intracranial xenograft model of breast cancer brain metastases was developed to assess the efficacy of AZD9574 in the context of blood-brain barrier penetrance. Treatment of animals with established intracranial lesions showed sustained tumour growth suppression resulting in a significantly extended survival of tumour-bearing mice. Collectively, we believe that our data support the development of AZD9574 as a potential therapy for patients with HRD+ breast cancer whose disease has spread to the brain.This abstract was previously presented at AACR 2022 (Hamerlik et al, AACR 2022, Abs #3880)

EXTH-103. DISCOVERY AND PHARMACOLOGICAL CHARACTERIZATION OF SKL27969, A NOVEL BRAIN-PENETRATING PRMT5 INHIBITOR WITH STRONG ANTITUMOR ACTIVITY, IN GLIOBLASTOMA AND BRAIN METASTASIS PRECLINICAL MODELS

Abstract Protein arginine methyltransferase 5 (PRMT5), a type II methyltransferase, regulates cellular processes such as survival, proliferation, and apoptosis by inducing symmetric arginine dimethylation of multiple cellular proteins involved in the regulation of cellular transcription and RNA splicing. Elevated tumor PRMT5 protein level has recently been correlated with poor prognosis and poor patient survival in various human cancers, including glioblastoma multiforme (GBM), lung cancer, breast cancer, and ovarian cancer. SKL27969 is a highly selective and potent PRMT5 inhibitor that is designed for brain penetration. It strongly binds to S-adenosylmethionine (SAM)-bound PRMT5/MEP50 (methylosome protein 50), leading to potent cellular symmetric dimethylarginine (SDMA) inhibition with an IC50 of 3.4 nM. Cell line panel profiling of SKL27969 revealed a broad spectrum of anti-proliferative activity in various cancer cell types, including CNS tumors, solid cancers prone to spread to brain, other solid cancers, and hematologic cancers. SKL27969 showed excellent brain exposure, with total and unbound partition coefficient (Kp and Kpuu) values of 6.57 and 1.08, respectively, and high tumor-to-plasma ratio, which resulted in significant survival benefit in orthotopic GBM xenograft models and metastatic brain cancer models such as intracranial xenograft models of non-small cell lung cancer (NSCLC) or triple-negative breast cancer (TNBC). Administration of SKL27969 showed strong tumor growth suppression in subcutaneous xenograft models of GBM, NSCLC, or TNBC. High correlation between tumor and plasma SDMA levels after SKL27969 treatment were observed in the preclinical models. Furthermore, SKL27969 showed potentiation of DNA damage when used in combination with DNA-damaging agents, which may suggest possible benefit as a combination therapy. Given the therapeutic target potential of PRMT5 in glioblastoma and other brain metastatic cancers, and the preclinical efficacy of SKL27969, these results have enabled the initiation of Phase 1/2 open-label, multicenter dose-finding study in patients with advanced solid tumors (NCT05388435).

TAS2940, a novel brain-penetrable pan-ERBB inhibitor, for tumors with HER2 and EGFR aberrations.

Genetic alterations in human epidermal growth factor receptor type 2 (HER2)/epidermal growth factor receptor (EGFR) are commonly associated with breast and lung cancers and glioblastomas. Cancers with avian erythroblastosis oncogene B (ERBB) deregulation are highly metastatic and can cause primary brain tumors. Currently, no pan-ERBB inhibitor with remarkable brain penetration is available. Here, TAS2940, a novel irreversible pan-ERBB inhibitor with improved brain penetrability, was evaluated for its efficacy against several ERBB aberrant cancer models. The selectivity of TAS2940 was evaluated by enzymatic kinase assays. The inhibitory effects of TAS2940 against ERBB genetic alterations were examined using MCF10A cells expressing various HER2 or EGFR mutations and other generic cell lines harboring deregulated ERBB expression. In vivo efficacy of TAS2940 was examined following oral treatment in subcutaneous or intracranial xenograft cancer models. TAS2940 was highly potent against cells harboring HER2/EGFR alterations. TAS2940 could selectively inhibit phosphorylation of targets and the growth of cancer cells with ERBB aberrations in vitro. TAS2940 also inhibited tumor growth in xenograft mouse models with ERBB aberrations: HER2 amplification, HER2/EGFR exon 20 insertions, and EGFR vIII mutation. TAS2940 was effective in the intracranial xenograft models of HER2/EGFR cancers and improved the survival of these mice. TAS2940 has promising therapeutic effects in preclinical study against cancers harboring HER2/EGFR mutations, especially metastatic and primary brain tumors. Our results highlight potential novel strategies against lung cancers with brain metastases harboring HER2/EGFR exon 20 insertions and glioblastomas with EGFR aberrations.