Patient-derived Glioblastoma Cell Lines Research Articles

Elucidating the cellular uptake mechanisms of heptamethine cyanine dye analogues for their use as an anticancer drug-carrier molecule for the treatment of glioblastoma.

The development of chemotherapies for glioblastoma is hindered by their limited bioavailability and toxicity on normal brain function. To overcome these limitations, we investigated the structure-dependent activity of heptamethine cyanine dyes (HMCD), a group of tumour-specific and BBB permeable near-infrared fluorescent dyes, in both commercial (U87MG) and patient-derived GBM cell lines. HMCD analogues with strongly ionisable sulphonic acid groups were not taken up by patient-derived GBM cells, but were taken up by the U87MG cell line. HMCD uptake relies on a combination of transporter uptake through organic anion-transporting polypeptides (OATPs) and endocytosis into GBM cells. The uptake of HMCDs was not affected by p-glycoprotein efflux in GBM cells. Finally, we demonstrate structure-dependent cytotoxic activity at high concentrations (EC50 : 1-100 μM), likely due to mitochondrial damage-induced apoptosis. An in vivo orthotopic glioblastoma model highlights tumour-specific accumulation of our lead HMCD, MHI-148, for up to 7 days following a single intraperitoneal injection. These studies suggest that strongly ionisable groups like sulphonic acids hamper the cellular uptake of HMCDs in patient-derived GBM cell lines, highlighting cell line-specific differences in HMCD uptake. We envisage these findings will help in the design and structural modifications of HMCDs for drug-delivery applications for glioblastoma.

Inhibition of MZF1/c-MYC Axis by Cantharidin Impairs Cell Proliferation in Glioblastoma

Myeloid zinc finger 1 (MZF1), also known as zinc finger protein 42, is a zinc finger transcription factor, belonging to the Krüppel-like family that has been implicated in several types of malignancies, including glioblastoma multiforme (GBM). MZF1 is reportedly an oncogenic gene that promotes tumor progression. Moreover, higher expression of MZF1 has been associated with a worse overall survival rate among patients with GBM. Thus, MZF1 may be a promising target for therapeutic interventions. Cantharidin (CTD) has been traditionally used in Chinese medicine to induce apoptosis and inhibit cancer cell proliferation; however, the mechanism by which CTD inhibits cell proliferation remains unclear. In this study, we found that the expression of MZF1 was higher in GBM tissues than in adjacent normal tissues and low-grade gliomas. Additionally, the patient-derived GBM cells and GBM cell lines presented higher levels of MZF1 than normal human astrocytes. We demonstrated that CTD had greater anti-proliferative effects on GBM than a derivative of CTD, norcantharidin (NCTD). MZF1 expression was strongly suppressed by CTD treatment. Furthermore, MZF1 enhanced the proliferation of GBM cells and upregulated the expression of c-MYC, whereas these effects were reversed by CTD treatment. The results of our study suggest that CTD may be a promising therapeutic agent for patients with GBM and suggest a promising direction for further investigation.

IMMU-15. HUMAN ALLOGENIC γδ T CELLS KILL PATIENT-DERIVED GLIOBLASTOMA CELLS IN A PVR- AND DNAM-1-DEPENDENT MANNER

Abstract Background Adoptive transfer of γδ T cells is a novel immunotherapeutic approach to glioblastoma. Few recent studies have shown the efficacy of γδ T cells against glioblastoma, but no previous studies have identified the ligand–receptor interactions between γδ T cells and glioblastoma cells. Here, we identify those ligand–receptor interactions and provide a basis for using γδ T cells to treat glioblastoma. METHODS Vγ9Vδ2 T cells were generated from peripheral blood mononuclear cells of healthy donors using artificial antigen presenting cells. MICA, ULBP, PVR and Nectin expression in 10 patient-derived glioblastoma (PDG) cell lines were analyzed. The in vitro cytokine secretion from the γδ T cells and their cytotoxicity toward the PDG cell lines were also analyzed. The in vivo anti-tumor effects were evaluated using a U87 orthotopic xenograft glioblastoma model. RESULTS Expression of ligands and cytotoxicity of the γδ T cells varied among the PDG cell lines. Interestingly, cytotoxicity correlated significantly with the PVR expression of the PDG cells. IFN-γ and granzyme B secretion levels were significantly higher when γδ T cells were co-cultured with high PVR–expressing PDG cells than when they were co-cultured with low PVR–expressing PDG cells. Blocking DNAM-1 resulted in a decrease in γδ T cell–mediated cytotoxicity and cytokine secretion. Intratumoral injection of γδ T cells showed anti-tumor effects in an orthotopic mouse model. Conclusions Allogenic γδ T cells showed potent anti-tumor effects on glioblastoma in a PVR- and DNAM-1-dependent manner. Our findings will facilitate the development of clinical strategies using γδ T cells for glioblastoma treatment.

Pro-drug Nanoparticle Loaded Supramolecular Hydrogels for Drug Delivery to IDH1 Wild-Type Glioblastoma

Abstract AIMS A hyaluronic acid-based hydrogel with mechanical properties comparable to human brain tissue is being investigated as an implantable drug-delivery vehicle for post-surgical treatment of IDH1 wild-type glioblastoma (GBM). Hydrogels are to be loaded with polymeric pro-drug nanoparticles to enable controlled drug release and increased drug penetration through brain parenchyma for enhanced treatment of residual disease within and beyond the invasive margin. METHOD A panel of patient-derived glioblastoma cell lines resected from tumour core and invasive margin, have been used to generate tumour spheroids. Chemotherapeutic drug screening has been performed to select lead compounds for formulation and gel loading. Synergies of drug combinations have been studied for potential combination loading. Upcoming work will investigate nanoparticle internalisation, spheroid penetration and prodrug nanoparticle potency. Nanoparticle loaded hydrogels are then to be studied for validation of effective in vitro application. RESULTS Current results demonstrate that patient-derived cell lines can generate robust, reproducible tumour spheroids with diameters approx. 350-400 µm. Patient-to-patient differences in drug potencies were observed, with differences also noted between counterpart core and marginal cells from the same patients, illustrating the importance of using patient-derived cells and distinct regional cells to study heterogenous disease such as GBM. Drug combination experiments indicated synergy of topoisomerase I inhibitor (Irinotecan) with PARP inhibitor (Ola-parib). Interestingly, combination of PARP inhibition with topoisomerase II inhibitors (Doxorubicin, Etoposide) was found not synergistic. CONCLUSION Together, data gathered on single drug and drug-drug combinations will inform upcoming formulation and in vitro application of hydrogels planned, with eventual translation to pre-clinical in vivo models.

P10.04.A The development of a potent, tumour-specific heptamethine cyanine dye-palbociclib conjugate with novel mechanisms of action for the treatment of glioblastoma

Abstract Background Glioblastoma is the most common and aggressive primary brain tumour in adults. The development of anti-cancer agents for brain tumours is challenged by the blood-brain barrier and the resistance conferred by the local tumour microenvironment. Heptamethine cyanine dyes (HMCDs) are a class of near-infrared fluorescence compounds that have recently emerged as promising agents for drug delivery Material and Methods We conjugated palbociclib, a cyclin-dependent kinase 4/6 inhibitor to the HMCD, MHI 148 for the treatment of GBM. Patient-derived GBM cell lines were established from surgically resected biopsy GBM tissue. Results High-throughput drug screening revealed an almost 100-fold increase in cytotoxicity of the palbociclib-MHI 148 conjugate compared to palbociclib alone. Moreover, the palbociclib-MHI 148 conjugate was synergistic with radiation, but not with temozolomide. Further analysis revealed the palbociclib-MHI 148 conjugate was superior to other cyclin-dependent kinase inhibitors in vitro. The shift of palbociclib from cytostatic to cytotoxic when conjugated to MHI 148 prompted further investigation. We revealed that palbociclib-MHI 148-dependent inhibition of cell-cycle progression resulted in increased DNA damage. This preceded increased transcription of key extrinsic apoptosis genes and caused a time-dependent upregulation of TNFR1 endocytosis-dependent cell death signalling. Notably, inhibition of endocytosis and siRNA knockdown of TNFR1 prevented palbociclib-MHI 148-induced cell death. Conclusion: These results highlight a novel mechanism of action of palbociclib when conjugated to MHI-148 that induced autocrine-driven TNFR1-mediated apoptosis. In addition, we highlight the potential application of HMCDs in repurposing tyrosine kinase inhibitors, to overcome the current limitations preventing the expansion of second-line treatment options for GBM.

P02.03.B Drug repurposing screen reveals glioblastoma cell line susceptibility to statins

Abstract Background The standard therapy for glioblastoma patients is tumor resection followed by radiotherapy and temozolomide chemotherapy. Although glioblastoma has been extensively molecularly profiled along with other cancers, this knowledge has not yet been translated into improved survival outcomes. We used a bioinformatics approach to identify potential novel therapeutic strategies for glioblastoma. Objectives: Comprehensive online datasets which have assessed up to 1376 cancer cell lines in multiple ways were interrogated to identify potential drug candidates for glioblastoma. Material and Methods Datasets included were from the cancer cell line encyclopedia (mRNA expression), the Achillies project (cell viability following Crispr-Cas9 knockout) and PRISM (drug treatment). A t-test comparing cell viability of glioblastoma cell lines versus other cancers was used to identify potential drug candidates, followed by the use of multiple statistical tools to investigate potential mechanism of action and status of biomarkers. Results Fluvastatin and pitavastatin were amongst the drugs with the most significant effects against glioblastoma cell lines while also being FDA approved. These effects were found in both glioblastoma cells and other cancer types with a mesenchymal-like expression phenotype. The anti-cancer properties of statins have previously been attributed to the inhibition of HMG-Coa reductase. Here, we found their effects correlated with the gene knockout of UBIAD1. We tested the effects of statins on patient-derived glioblastoma cell lines with a mesenchymal (n = 2) and non-mesenchymal phenotype (n=2). Mesenchymal-like glioblastoma cells lines were found to be more susceptible to statins. Conclusion Statins appeared to be especially effective against glioblastoma lines and the effect could be linked to the direct or indirect inhibition of UBIAD1. In vitro validation of this finding is ongoing.

In-Vitro Use of Verteporfin for Photodynamic Therapy in Glioblastoma

BackgroundStummer et al. established fluorescence-guided surgery (FGS) for glioblastoma (GBM) using 5-aminolevulinic acid (5-ALA). Its metabolite, protoporphyrin IX (PPIX), is also a photosensitizer and can be used for photodynamic therapy (PDT) using a laser beam of 635 nm. The porphyrin derivate verteporfin (VP) was discovered to have properties to penetrate the brain, pharmacologically target glioma cells, and is approved for PDT of choroidal neovascularization in wet age-related macular degeneration at 689 nm. ObjectiveTo elucidate whether GBM cell lines are susceptible to PDT with second-generation photosensitizer VP. MethodsHuman glioma cell lines LN229, HSR-GBM1, and a low-passage patient-derived GBM cell line P1 were treated with variable concentrations of VP for 24 h, followed by PDT at 689 nm using a diode laser light. Cell viability was measured using the MTT assay and VP uptake was measured using a desktop cytometer. ResultsSignificantly higher cell death following PDT with VP compared to VP treatment alone or no treatment was detected in all cell models (LN229, HSR-GBM1, P1). Flowcytometric measurements revealed a concentration-dependent cellular uptake of VP after 24 h incubation up to 99% at 10 µM (HSR-GBM1). ConclusionThis study demonstrates that PDT with VP causes cell death in GBM cells at marginal concentrations. Additionally, red spectrum fluorescence was detected at therapeutic concentrations in all cell lines, validating the cellular uptake of VP in GBM cells. VP, therefore, is not only a potential drug for targeting GBM pharmacologically but can be used as an optical imaging dye in surgery and photosensitizer to make GBM susceptible to PDT.

Gonadal sex patterns p21-induced cellular senescence in mouse and human glioblastoma

Males exhibit higher incidence and worse prognosis for the majority of cancers, including glioblastoma (GBM). Disparate survival may be related to sex-biased responses to treatment, including radiation. Using a mouse model of GBM, we show that female cells are more sensitive to radiation, and that senescence represents a major component of the radiation therapeutic response in both sexes. Correlation analyses revealed that the CDK inhibitor p21 and irradiation induced senescence were differentially regulated between male and female cells. Indeed, female cellular senescence was more sensitive to changes in p21 levels, a finding that was observed in wildtype and transformed murine astrocytes, as well as patient-derived GBM cell lines. Using a novel Four Core Genotypes model of GBM, we further show that sex differences in p21-induced senescence are patterned during early development by gonadal sex. These data provide a rationale for the further study of sex differences in radiation response and how senescence might be enhanced for radiation sensitization. The determination that p21 and gonadal sex are required for sex differences in radiation response will serve as a foundation for these future mechanistic studies.

The Sesquiterpene Lactone Cynaropicrin Manifests Strong Cytotoxicity in Glioblastoma Cells U-87 MG by Induction of Oxidative Stress.

Cynaropicrin has shown a wide range of pharmacological properties, such as antitumor action. Here, we showed the inhibitory effect of Cyn on human glioblastoma cell U-87 MG growth. According to the IC50 values, Cyn 4, 8 and 10 µM displayed a significant cytotoxicity, as confirmed by the cell count and MTT assay. Furthermore, Cyn completely abolished the ability of U-87 MG to form colonies and induced drastic morphological changes. Interestingly, pretreatment with ROS scavenger N-acetylcysteine 3 mM reversed the cytotoxicity induced by Cyn 25 µM and preserved the cells by morphological changes. Therefore, oxidative stress induction was evaluated at low 8- and high 25-µM concentrations in U-87 MG, as demonstrated by the quantitative and qualitative analysis of ROS. A prolonged increase in ROS generation under Cyn 25 µM exposure was followed by the loss of the mitochondrial membrane potential in treated U-87 MG cells. An acute treatment with Cyn 25 µM induced Cyt c release, as revealed by immunofluorescence staining and the activation of cell death pathways, apoptosis and autophagy. On the other hand, chronic treatment with Cyn 8 µM induced senescence, as revealed by the increase in SA-β-Gal activity. Moreover, at this concentration, Cyn led to ERK dephosphorylation accompanied by a relevant reduction of the NF-κB p65 subunit. Finally, the combined effect of TMZ and Cyn resulted in synergistic cytotoxicity, as evaluated by the Bliss additivity model. The strong cytotoxicity of Cyn was also confirmed on IDH1 mutant U-87 MG cells and patient-derived IDH wild-type glioblastoma cell lines NULU and ZAR. In conclusion, given the high toxicity at minimal concentrations, the high inhibition of tumor cell growth and synergy with the standard drug for glioblastoma TMZ, Cyn could be proposed as a potential adjuvant for the treatment of glioblastoma.

Abstract 5498: Plinabulin, a novel tubulin targeting agent, collapses the proinvasion tumor microtube network in primary and recurrent patient derived glioblastoma cell lines to inhibit neurosphere invasion and survival

Abstract Glioblastoma multiforme (GBM) is the most common adult primary brain malignancy. Aggressive, diffuse invasion is regulated by a dynamic cytoskeleton and significantly contributes to poor survival. Intraparenchymal tumor cell dissemination prevents complete surgical resection and compromises essential brain functions. Invasive cells are inherently less sensitive to traditional cytotoxic therapies. Recent investigation into targeted therapies has failed to address invasion/cytoskeleton based GBM therapy resistance. Furthermore, established GBM cell line modeling in 2 or 3 dimensions (3D) does not capture the genetic diversity or clinical relevance of patient derived primary (1') GBM cell lines, which may uncover/predict differential responses in tumors to novel therapies. Cytoskeleton remodeling and cell invasion in patient-derived primary GBM cells generates unique structures called tumor microtubes (TMs) not seen in established, cultured GBM cell lines. TMs are ultralong, pro-invasive, tubulin-enriched protrusions that promote chemo- and radioresistance in GBM patient derived primary cells. Using our extensive GBM cell line biobank derived from 1' and/or therapy resistant recurrent (2') tumors, we investigated the effects of a novel drug targeting the microtubule cytoskeleton. Plinabulin is a tubulin targeting agent that crosses the blood brain barrier and demonstrated anticancer efficacy in Phase III trial patients with non-small cell lung carcinoma. Plinabulin also has antiproliferative properties in 2D GBM cells. Here, we evaluate the efficacy of plinabulin treatment upon 3D neurosphere viability and invasion in 5 GBM 1' and 2' recurrent patient derived cell lines. Within 24h of matrigel embedding, 3D GBM patient neurospheres generate robust pro-invasive TMs. Plinabulin treatment (10-30 nM) at embedding followed by drug washout after 24h eliminated existing TMs and inhibited single cell invasion (>80% relative to controls) in both 1' and 2' GBM patient neurospheres. Cell survival was significantly reduced in plinabulin treated neurospheres (>30 nM). Plinabulin efficacy was evaluated in a clinically relevant therapeutic ITR model: GBM patient neurospheres invaded (I) for 48h to establish TM networks; were treated (T) with 1-50 nM plinabulin for 24h prior to drug washout; and recovered (R) for 96h. In 1', 2', or matched 1' and 2' cell line pairs from the same patient, 10-40 nM plinabulin sustained invasion inhibition (>90%) through 96h post washout and completely blocked TM extension relative to controls, consistent with established clinical concentrations of plinabulin. This study reveals plinabulin as a potent GBM therapeutic targeting pro-invasion TM networks and survival in 1' and therapy resistant 2' GBM patient cell lines. Citation Format: Kathryn M. Eisenmann, Kenneth Lloyd, Krista M. Pettee, Kathryn N. Becker, Jason Schroeder, Kevin Reinard, James R. Tonra, Ramon Mohanlal, Lan Huang. Plinabulin, a novel tubulin targeting agent, collapses the proinvasion tumor microtube network in primary and recurrent patient derived glioblastoma cell lines to inhibit neurosphere invasion and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5498.

Abstract LB507: Towards elucidating the role of RNA modifications in cancer by improving the quantitative accuracy of mass spectrometric profiling of RNA modifications

Abstract The molecular structure of both coding and non-coding RNA is frequently altered by the enzymatic activity of either writer or eraser of RNA modifications. Since the RNA functions are dependent on its molecular structure, cellular activities that involve specific RNA molecule(s) can potentially be regulated by the reversible nature of RNA modifications. There are more than 140 known RNA modifications. Mass spectrometry is a proven technique for the identification of RNA modifications. However, due to the lack of ribonucleoside standards and biases in normalizing the level of RNA modifications, it remains a challenge to perform the quantitative analysis of multiple RNA modifications that may co-exist in a biological sample. Our group has recently developed a method for standard-free quantitative epitranscriptomic profiling (SqEP) that allows us using mass spectrometry to accurately determine the abundancy of each detectable RNA modification without using any ribonucleoside standards to calibrate the detection signals. Thus, the SqEP method can be used for the untargeted analysis of RNA modifications. It also allows us to directly compare the level of different RNA modifications that are detectable in an individual cell line. This is an important feature for studying the relationships between various RNA modifications. Using glioblastoma (GBM) as our model, the results from using the SqEP method to determine the level of specific RNA modifications in patient-derived GBM cell lines were shown to be more accurate than the existing methods, and complied with the gene expression data from GBM patients that are available in the Cancer Genome Atlas (TCGA) program. Citation Format: Norman H. Chiu, Jennifer H. Simpson, Renata L. Fleming, Jian Teng, Bakhos A. Tannous. Towards elucidating the role of RNA modifications in cancer by improving the quantitative accuracy of mass spectrometric profiling of RNA modifications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB507.

Abstract 1842: Drug repurposing screen reveals glioblastoma cell line susceptibility to statins

Abstract Background: The standard therapy for glioblastoma patients is tumor resection followed by radiotherapy and temozolomide chemotherapy. Although glioblastoma has been extensively molecularly profiled along with other cancers, this knowledge has not yet been translated into improved survival outcomes. We used a bioinformatics approach to identify potential novel therapeutic strategies for glioblastoma. Objectives: Comprehensive online datasets which have assessed up to 1376 cancer cell lines in multiple ways were interrogated to identify potential drug candidates for glioblastoma. Methods: Datasets included were from the cancer cell line encyclopedia (mRNA expression), the Achillies project (cell viability following Crispr-Cas9 knockout) and PRISM (drug treatment). A t-test comparing cell viability of glioblastoma cell lines versus other cancers was used to identify potential drug candidates, followed by the use of multiple statistical tools to investigate potential mechanism of action and status of biomarkers. Results: Fluvastatin and pitavastatin were amongst the drugs with the most significant effects against glioblastoma cell lines while also being FDA approved. These effects were found in both glioblastoma cells and other cancer types with a mesenchymal-like expression phenotype. The anti-cancer properties of statins have previously been attributed to the inhibition of HMG-Coa reductase. Here, we found their effects correlated with the gene knockout of UBIAD1, which participates in non-mitochondrial ubiquinone and menaquinone-4 synthesis. We tested the effects of statins on patient-derived glioblastoma cell lines with a mesenchymal (n = 2) and non-mesenchymal phenotype (n=2). Mesenchymal-like glioblastoma cells lines were found to be particularly susceptible to multiple statins. Conclusion: Statins appeared to be especially effective against glioblastoma lines and the effect could be linked to the direct or indirect inhibition of UBIAD1. In vitro validation of this finding is ongoing. Citation Format: Dylan S. Harwood, Signe R. Michaelsen, Bjarne W. Kristensen. Drug repurposing screen reveals glioblastoma cell line susceptibility to statins [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1842.

Abstract 1822: Selective inhibition of ZCCHC11/ZCCHC6 TUTases with genetic and pharmacological tools supports a role in glioblastoma cell growth

Abstract The purpose of the study was to determine if genetic and pharmacological inhibition of terminal uridyltransferases (TUTases) ZCCHC11 and ZCCHC6 could modulate Glioblastoma (GBM) cell growth in vitro. ZCCHC11 (also known as TUT4 and TENT3A) and ZCCHC6 (also known as TUT7 and TENT3B) catalyze uridylation of diverse RNA species. Recent evidence indicates that genetic perturbation of ZCCHC11/6 expression can disrupt cell proliferation of both immortalized and patient-derived primary GBM cell lines (Kim et al., Mol Cell 2020). We confirmed that genetic inhibition of ZCCHC11/6 with siRNA or CRISPR can decrease viability of U-87 MG and A-172 GBM cell lines, and we identified DK-MG as another GBM cell line with sensitivity to ZCCHC11/6 knockdown. Herein, we report the first novel, potent, and selective inhibitor of ZCCHC11/6, TS-1. Biochemically, TS-1 can block ZCCHC11/6-mediated uridylation of an RNA substrate in vitro (IC50 = 0.65 nM for recombinant ZCCHC11 protein; IC50 = 9.6 nM for recombinant ZCCHC6 protein). ZCCHC11/6 inhibitor TS-1 could decrease cell viability in U-87 MG, A-172 and DK-MG cells (cell viability IC50s ranging between 0.7-1.5 μM) and induce apoptosis and cell cycle arrest. A cellular assay detecting uridylation of miR-191 as a marker for ZCCHC11/6 activity was developed and validated. TS-1 strongly decreased uridylation of miR-191 in U-87 MG, A-172 and DK-MG cells (IC50 ranging between 10-40 nM). In contrast, TS-2, a weakly active enantiomer of TS-1 (enzyme IC50 = 0.15 μM and 1.8 μM against ZCCHC11 and ZCCHC6, respectively), had less impact on cell viability, apoptosis, cell cycle and uridylation in cells. In conclusion, we have verified ZCCHC11/6-dependency in a set of GBM cell lines and we have also developed a first-in class potent and selective small molecule that reduces in vitro Glioblastoma cell proliferation through selective inhibition of TUTases activity. Citation Format: Robinson Triboulet, Khikmet Sadykov, Jessica L. Johnson, Andrew R. Snyder, Sarah K. Knutson, Pavan Kumar, Christopher B. Mayo, Dillon Hawley, Andrew Madanjian, Ross L. Stein, David M. Wilson, Darren M. Harvey, Shomir Ghosh, Robert M. Campbell. Selective inhibition of ZCCHC11/ZCCHC6 TUTases with genetic and pharmacological tools supports a role in glioblastoma cell growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1822.

A phase I/IIa, open-label, multicenter, non-randomized clinical trial to assess the safety and efficacy of CYNK-001 in combination with recombinant human interleukin 2 in adults with recurrent resection eligible IDH1 wild-type glioblastoma (GBM).

TPS2080 Background: CYNK-001 is a CD56+CD3- enriched, off-the-shelf, allogeneic natural killer (NK) cell product expanded from placental CD34 cells. CYNK-001 exhibits in vitro cytotoxicity against patient-derived GBM cell lines and secretes cytolytic cytokines during co-culture with cancer cells. CYNK-001 administered via the intracranial (IC) route exhibited in vivo antitumor activity in a U-87MG orthotopic mouse model. Methods: A Phase I/IIa clinical trial is enrolling IDH1 wild-type GBM patients at first or second recurrence with contrast-enhancing measurable disease (per RANO criteria) who are candidate for surgical resection. Screening MRI scans for inclusion are performed within 14 days prior to Day -5 lymphodepletion with Cyclophosphamide 900mg/m2 and fludarabine 30mg/m2 plus mesna. Using a standard 3+3 dose escalation schema, patients will receive the first cycle of CYNK-001 intravenously (IV) at an initial dose of 2.4 x109 cells on Days 1, 8 and 15 after lymphodepletion. Cell supportive IL-2 at 6M IU administered SQ on Days 1, 3, 5, 8, 10, 12, and 15 within 3 hours prior to CYNK-001 IV infusion where applicable. Cycle 2 begins with surgical resection on Day 22 in which CYNK-001 is administered directly into the tumor cavity wall at an initial dose of 100 x106 NK cells and an Ommaya catheter placement. Subsequent CYNK-001 IC administrations via the Ommaya are on days 29 and 36 with 6M IU IL-2 SQ. DLT is evaluated for all dosing cohorts from day 1 to 7 days post last dose of cycle 2. Once a maximum tolerated dose is identified, a safety lead-in cohort with an additional 3 cycles of CYNK-001 IC will be administered prior to initiating the Phase IIa portion of the study. Endpoints: The primary endpoint is dose-limiting toxicity for the Phase I analysis and 6-month progression free survival post tumor resection for the Phase IIa component. Post-resected tumor tissue will be characterized for effector immune cell function and immune suppression with assessments directed at CYNK-001 tumor distribution using methodology developed at Celularity Inc. Approximately 66 patients are planned for this Phase I/IIa study. Approximately 66 patients are planned for this Phase I/IIa study. Clinical trial information: NCT05218408.

Transcriptomic Profiling of DNA Damage Response in Patient-Derived Glioblastoma Cells before and after Radiation and Temozolomide Treatment

Glioblastoma is a highly aggressive, invasive and treatment-resistant tumour. The DNA damage response (DDR) provides tumour cells with enhanced ability to activate cell cycle arrest and repair treatment-induced DNA damage. We studied the expression of DDR, its relationship with standard treatment response and patient survival, and its activation after treatment. The transcriptomic profile of DDR pathways was characterised within a cohort of isocitrate dehydrogenase (IDH) wild-type glioblastoma from The Cancer Genome Atlas (TCGA) and 12 patient-derived glioblastoma cell lines. The relationship between DDR expression and patient survival and cell line response to temozolomide (TMZ) or radiation therapy (RT) was assessed. Finally, the expression of 84 DDR genes was examined in glioblastoma cells treated with TMZ and/or RT. Although distinct DDR cluster groups were apparent in the TCGA cohort and cell lines, no significant differences in OS and treatment response were observed. At the gene level, the high expression of ATP23, RAD51C and RPA3 independently associated with poor prognosis in glioblastoma patients. Finally, we observed a substantial upregulation of DDR genes after treatment with TMZ and/or RT, particularly in RT-treated glioblastoma cells, peaking within 24 h after treatment. Our results confirm the potential influence of DDR genes in patient outcome. The observation of DDR genes in response to TMZ and RT gives insight into the global response of DDR pathways after adjuvant treatment in glioblastoma, which may have utility in determining DDR targets for inhibition.

MicroRNA 3928 Suppresses Glioblastoma through Downregulation of Several Oncogenes and Upregulation of p53.

Glioblastoma (GBM) is the most frequent and lethal primary malignant brain tumor. Despite decades of research, therapeutic advances that significantly prolong life are non-existent. In recent years, microRNAs (miRNAs) have been a focus of study in the pathobiology of cancer because of their ability to simultaneously regulate multiple genes. The aim of this study was to determine the functional and mechanistic effects of miR-3928 in GBM both in vitro and in vivo. To the best of our knowledge, this is the first article investigating the role of miR-3928 in GBM. We measured endogenous miR-3928 expression levels in a panel of patient-derived GBM tissue samples and cell lines. We found that GBM tissue samples and cell lines express lower levels of miR-3928 than normal brain cortex and astrocytes, respectively. Therefore, we hypothesized that miR-3928 is a tumor suppressive microRNA. We verified this hypothesis by showing that exogenous expression of miR-3928 has a strong inhibitory effect on both cell growth and invasiveness of GBM cells. Stable ex vivo overexpression of miR-3928 in GBM cells led to a reduction in tumor size in nude mice xenografts. We identified many targets (MDM2, CD44, DDX3X, HMGA2, CCND1, BRAF, ATOH8, and BMI1) of miR-3928. Interestingly, inhibition of the oncogene MDM2 also led to an upregulation of wild-type p53 expression and phosphorylation. In conclusion, we find that miR-3928, through the downregulation of several oncogenes and upregulation and activation of wild-type p53, is a strong tumor suppressor in GBM. Furthermore, the fact that miR-3928 can target many important dysregulated proteins in GBM suggests it might be a “master” regulatory microRNA that could be therapeutically exploited.

USF1/CD90 signaling in maintaining glioblastoma stem cells and tumor-associated macrophages adhesion.

Glioblastoma stem cells (GSCs) and their interplay with tumor-associated macrophages (TAMs) are responsible for malignant growth and tumor recurrence of glioblastoma multiforme (GBM), but the underlying mechanisms are largely unknown. Cell viability, stemness, migration, and invasion were measured in GSCs after the knockdown of upstream stimulating factor 1 (USF1). Luciferase assay and chromatin immunoprecipitation qPCR were performed to determine the regulation of CD90 by USF1. Immunohistochemistry and immunofluorescent staining were used to examine the expression of USF1 and GSC markers, as well as the crosstalk between GSCs and TAMs. In addition, the interaction between GSCs and TAMs was confirmed using in vivo GBM models. We show that USF1 promotes malignant glioblastoma phenotypes and GSCs-TAMs physical interaction by inducing CD90 expression. USF1 predicts a poor prognosis for glioma patients and is upregulated in patient-derived GSCs and glioblastoma cell lines. USF1 overexpression increases the proliferation, invasion, and neurosphere formation of GSCs and glioblastoma cell lines, while USF1 knockdown exerts an opposite effect. Further mechanistic studies reveal that USF1 promotes GSC stemness by directly regulating CD90 expression. Importantly, CD90 of GSCs functions as an anchor for physical interaction with macrophages. Additionally, the USF1/CD90 signaling axis supports the GSCs and TAMs adhesion and immunosuppressive feature of TAMs, which in turn enhance the stemness of GSCs. Moreover, the overexpression of CD90 restores the stemness property in USF1 knockdown GSCs and its immunosuppressive microenvironment. Our findings indicate that the USF1/CD90 axis might be a potential therapeutic target for the treatment of glioblastoma.

Targeting of the alphav beta3 integrin complex by CAR-T cells leads to rapid regression of diffuse intrinsic pontine glioma and glioblastoma

BackgroundDiffuse intrinsic pontine glioma (DIPG) and glioblastoma (GBM) are two highly aggressive and generally incurable gliomas with little therapeutic advancements made in the past several decades. Despite immense initial success...

Dose-dependent thresholds of dexamethasone destabilize CAR T-cell treatment efficacy.

Chimeric antigen receptor (CAR) T-cell therapy is potentially an effective targeted immunotherapy for glioblastoma, yet there is presently little known about the efficacy of CAR T-cell treatment when combined with the widely used anti-inflammatory and immunosuppressant glucocorticoid, dexamethasone. Here we present a mathematical model-based analysis of three patient-derived glioblastoma cell lines treated in vitro with CAR T-cells and dexamethasone. Advanced in vitro experimental cell killing assay technologies allow for highly resolved temporal dynamics of tumor cells treated with CAR T-cells and dexamethasone, making this a valuable model system for studying the rich dynamics of nonlinear biological processes with translational applications. We model the system as a nonautonomous, two-species predator-prey interaction of tumor cells and CAR T-cells, with explicit time-dependence in the clearance rate of dexamethasone. Using time as a bifurcation parameter, we show that (1) dexamethasone destabilizes coexistence equilibria between CAR T-cells and tumor cells in a dose-dependent manner and (2) as dexamethasone is cleared from the system, a stable coexistence equilibrium returns in the form of a Hopf bifurcation. With the model fit to experimental data, we demonstrate that high concentrations of dexamethasone antagonizes CAR T-cell efficacy by exhausting, or reducing the activity of CAR T-cells, and by promoting tumor cell growth. Finally, we identify a critical threshold in the ratio of CAR T-cell death to CAR T-cell proliferation rates that predicts eventual treatment success or failure that may be used to guide the dose and timing of CAR T-cell therapy in the presence of dexamethasone in patients.

Live-Cell Synchrotron-Based FTIR Evaluation of Metabolic Compounds in Brain Glioblastoma Cell Lines after Riluzole Treatment.

Glioblastoma multiforme (GBM) is the most aggressive brain tumor, characterized by short median survival and an almost 100% tumor-related mortality. The standard of care treatment for newly diagnosed GBM includes surgical resection followed by concomitant radiochemotherapy. The prevention of disease progression fails due to the poor therapeutic effect caused by the great molecular heterogeneity of this tumor. Previously, we exploited synchrotron radiation-based soft X-ray tomography and hard X-ray fluorescence for elemental microimaging of the shock-frozen GBM cells. The present study focuses instead on the biochemical profiling of live GBM cells and provides new insight into tumor heterogenicity. We studied bio-macromolecular changes by exploring the live-cell synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy in a set of three GBM cell lines, including the patient-derived glioblastoma cell line, before and after riluzole treatment, a medicament with potential anticancer properties. SR-FTIR microspectroscopy shows that GBM live cells of different origins recruit different organic compounds. The riluzole treatment of all GBM cell lines mainly affected carbohydrate metabolism and the DNA structure. Lipid structures and protein secondary conformation are affected as well by the riluzole treatment: cellular proteins assumed cross β-sheet conformation while parallel β-sheet conformation was less represented for all GBM cells. Moreover, we hope that a new live-cell approach for GBM simultaneous treatment and examination can be devised to target cancer cells more specifically, i.e., future therapies can develop more specific treatments according to the specific bio-macromolecular signature of each tumor type.