bluuebunny/crossref_metadata_2025 huggingface dataset:
CSIG-04. UNCOUPLING OF ETS1 FROM MAPK PATHWAY SIGNALS AS RESISTANCE MECHANISM TOWARDS BRAF INHIBITORS IN BRAF-MUTATED CHILDHOOD GLIOMA
Authors: Gabler Lisa , Lötsch-Gojo Daniela , Kirchhofer Dominik , Laemmerer Anna , Mayr Lisa , Pirker Christine , Jaunecker Carola , Kastler Lucia , Azizi Amedeo A , Dorfer Christian , Czech Thomas , Haberler Christine , Peyrl Andreas , Slavc Irene , Spiegl-Kreinecker Sabine , Roessler Karl , Gojo Johannes , Berger Walter
Published: November 2021

BACKGROUND

High-grade gliomas are among the most aggressive brain tumors across all age groups. BRAF is within the most frequently altered genes in pediatric glioma, sometimes connected with telomerase reverse transcriptase (TERT) promoter mutations, predicting a particularly aggressive course of disease. Precision medicine approaches targeting the MAPK pathway have shown promising results in patients with BRAF-mutated glioma. Although acquired insensitivity to BRAF inhibitors appears as major issue for therapy failure, underlying molecular mechanisms are still poorly understood.

METHODS

Cell models from an anaplastic pleomorphic xanthoastrocytoma with BRAF V600E and TERT promoter mutations and the recurrent tumor, operated following MAPK pathway-targeting therapy, were established. Furthermore, a dabrafenib-resistant subline of the recurrent tumor was generated. The patient-derived cell models were genetically characterized using array-based genomic hybridization (aCGH). Sensitivity of the cells towards different MAPK pathway inhibitors was tested. Basal expression and activation of MAPK pathway and downstream signals were analyzed by qRT-PCR and Western blots.

RESULTS

Screening a panel of both primary and immortalized glioma cell models with different BRAF and TERT promoter status revealed significantly induced MAPK pathway activation and enhanced TERT levels in BRAF V600E and TERT promoter double-mutant gliomas. Furthermore, cells with both mutations were hyper-sensitive towards BRAF-targeting agents and BRAF inhibition resulted in reduced TERT levels. ETS1 expression was strongly increased in the recurrent tumor and identified as important player in telomerase re-activation. aCGH revealed gains of chromosomal regions encoding for different ETS-factors in the dabrafenib-resistant subline. Western blot analyses suggested a BRAF/ERK-independent survival mechanism in the dabrafenib-resistant subline. Accordingly, dabrafenib insensitivity triggered cross-resistance towards the MEK inhibitor trametinib. Uncoupled from the MAPK pathway, ETS1 expression was further upregulated in the dabrafenib-resistant subline. CONSLUSION: Taken together, our data demonstrate that MAPK-independent ETS transcription factor upregulation is a central mechanism of BRAF inhibitor therapy failure in BRAF-mutated pediatric glioma patients.
CSIG-13. A DYNAMIC CAUSAL MODEL OF GLIOBLASTOMA STEM CELL SIGNALING PREDICTS EFFECTS OF KINASE INHIBITORS
Authors: Holzapple Emilee , Miskov-Zivanov Natasa , Cochran Brent
Published: November 2021

Glioblastomas and glioblastoma stem cells are heterogeneous with respect to mutations, gene expression, and response to drugs. To make predictive responses of individual GBM stem cell lines to kinase inhibitors, we have constructed a causal model of glioblastoma stem cell signaling. The core model was built starting from pathways identified from TCGA mutation data with the addition of the Jak/STAT, Hedgehog, and Notch pathways. Elements and relations between them were validated and extended using the PCNet interaction database and the INDRA database which includes machine read extractions from the biomedical literature. The result is a high confidence executable model consisting of 209 elements (proteins, genes, RNAs) and 370 regulatory logic rules between the elements. Stochastic simulations of the model provide dynamic (quantile) changes in time and responses to perturbations. The output simulates activity of individual nodes as well as cell cycle progression, apoptosis, and differentiation. To simulate the responses of individual cell lines to kinase inhibitors, the model was initialized using DNA sequencing data, RNA-seq, and reverse phase protein array (RPPA) data from each cell line. Comparing the results of the simulations to the drug responses of 11 different kinase targets in 3 cell lines, the model was 88% accurate in predicting effects on growth and survival. The model was further tested by comparing the effects of Mek inhibition of each of the cell lines in the model to the results observed in the RPPA data which overlap by 127 elements. In this case, there was less than 65% concordance between the model and the data for individual nodes. Discrepancies between the model predictions and the data are being investigated to determine whether the model logic or extent needs to be revised to improve the model. This modeling approach is a step toward developing algorithms for personalized therapeutics for GBM.
CSIG-18. HYPERMETHYLATION OF SLIT-ROBO PATHWAY GENES RESULTS IN INACTIVATION IN GLIOMA PROGRESSION
Authors: Kerstetter-Fogle Amber , Harris Peggy , Hoffman Harry , Sloan Anthony , Elder Theresa , Couce Marta , Barnholtz-Sloan Jill , Sloan Andrew
Published: November 2021

INTRODUCTION

Glioblastomas (GBM) are the most common and malignant primary brain tumors. Their rapid growth and invasion into neuronal parenchyma is devastating, with limited treatment options. Genomic alterations have been extensively studied in gliomas tumors, including aberrations of the Slit-Robo pathway genes. The Slit family of secreted proteins modulates migration of somatic cells during development and mediate their effect by binding to its receptor Roundabout (Robo). Genes in the Slit-Robo pathways have been shown to be inactivated by promoter hypermethylation in a number of human cancers. We hypothesize that Slit-Robo signaling pathways are modulated via promotor methylation, controlling GBM malignancy and regulating the invasive capacity of glioma stem cells (GSCs).

METHODS

We characterized expression of mRNA and protein via real-time PCR and Western blots in primary GBM tissue. We then assessed whether epigenetic alterations correlate with Slit-Robo expression by conducting in vitro demethylation assays in patient derived GSCs followed by real-time PCR. We conducted invasion assays to elucidate the role of Slit in GSC invasion.

RESULTS

The Cancer Genome Atlas indicates a negative correlation between Robo2 expression and glioma patient survival (17.1 months versus 37.4 months; p < 1.4E-4). We discovered differential expression of the Slit (1-3) and Robo (2, 3) genes and protein of up to 8-fold between grades 3 and 4 astrocytomas (8.34 versus 4.73 density). Treating patient derived glioma stem cells with 5-aza-2-deoxycytidine results in induction in Slit-Robo gene expression ranging from 5 – 40-fold (p < 0.01). Addition of Slit 2 and 3 in an invasion assay induced migration of GSCs in a differential and concentration dependent manner of 10 - 25% (p < 0.05).

CONCLUSIONS

Our results suggest that promoter methylation and gene expression of the Slit-Robo genes correlates with protein expression, tumor invasiveness, and prognosis and a potential therapeutic target.
CSIG-29. TRIBBLES-1 (TRIB1) INCREASES TUMOR FORMATION IN AN ORTHOTOPIC MOUSE MODELS BY PROMOTING SURVIVAL OF GBM CELLS AND TREATMENT RESISTANCE
Authors: Singh Karnika , Han Chunhua , Fleming Jessica , McElroy Joseph , Kumar Ashok , Sebastian Ebin , Bell Erica , Robe Pierre , Haque Jahar , Chakravarti Arnab
Published: November 2021

INTRODUCTION

Glioblastoma (GBM) is the most aggressive CNS tumor with an average survival of about 15 months after diagnosis. The current gold standard therapy comprises radiation therapy (RT) and concurrent and adjuvant temozolamide (TMZ). Due to poor prognosis, novel therapeutic targets need to be identified for drug development. To this end, we identified TRIB1 through correlative studies using patient derived methylation data from an institutional cohort as a novel therapeutic target. TRIB1 is a Ser/Thr pseudokinase that functions as a scaffold for the degradation of its substrates and activates Akt and MEK oncogenic pathways. In this study, we show that TRIB1 promoted GBM progression by upregulating survival pathways and reducing RT/TMZ-induced cell death.

MATERIALS AND METHODS

In vitro functional validation was performed by overexpression and knockdown approaches. GBM patient derived (PDX) cell lines overexpressing the TRIB1 transgene were used to create an orthotopic tumor model for in vivo studies. Mice were monitored for changes in tumor volume and overall survival. Stable cell lines were generated by puromycin selection. Western blotting was utilized to detect protein levels.

RESULTS

Mice inoculated with PDX cells overexpressing TRIB1 transgene had increased tumor volume and worse overall survival compared to the empty vector control. We also observed that TRIB1 overexpression caused decreased apoptosis of PDX cell lines after RT/TMZ treatment. Additionally, an increase in the phosphorylation of ERK and Akt was also noted after TRIB1 overexpression. Consistent with these observations, TRIB1 knockdown sensitized the cells towards radiation and caused decreased Akt phosphorylation/activation as well.

CONCLUSION

TRIB1 overexpression decreases overall survival of xenograft bearing mice and promotes GBM cell survival by upregulating survival signaling pathways. This compromises the effects of RT/TMZ therapy, which is reversed after TRIB1 knockdown. Targeting of TRIB1 may reduce oncogenic signaling in GBM cells and therefore would sensitize them towards RT/TMZ therapy.
CSIG-30. TARGETING TELOMERASE VIA MEK INHIBITION IN AGGRESSIVE TERT PROMOTER MUTATED BRAIN TUMORS
Authors: Lötsch-Gojo Daniela , Gabler Lisa , Jaunecker Carola , Fürnweger Kerstin , Bruckner Katharina , Mayr Lisa , Madlener Sibylle , Kirchhofer Dominik , Spiegl-Kreinecker Sabine , Roessler Karl , Berger Walter , Gojo Johannes
Published: November 2021

Activating point mutations within the TERT promoter (C228T or C250T) account for the most frequent alteration in aggressive brain tumors. Presence of these alterations results in the generation of binding sites for E-twenty-six (ETS) transcription factors accompanied by enhanced TERT expression. Accordingly, TERT promoter mutations foster cellular immortalization and subsequently tumor aggressiveness. Due to the limitation of treatment options in aggressive brain tumors, including glioblastoma and medulloblastoma, new therapeutic targets need to be discovered. As we previously described a strong interaction of oncogenic MEK/ETS signaling and TERT promoter mutations, we hypothesize that inhibition of these factors halters cell immortalization in TERT-driven brain tumors. Our study included three TERT promoter wild-type (TERTwt), six mutated (TERTmut) glioblastoma and three TERTmut medulloblastoma cell models and tested the effect of MEK inhibitors (U0126 and trametinib) and the ETS inhibitor YK-4-279 on cell viability and clone formation. Cellular senescence upon treatment was evaluated by beta-galactosidase assays. Impact on TERT mRNA expression and TERT promoter activity were analyzed by quantitative real-time PCR and luciferase reporter assays, respectively. Furthermore, the effects on MAPK- and PI3K pathway activation were evaluated by Western blot. Amongst the investigated inhibitors, tumor cells harboring C228T mutation were distinctly more sensitive against trametinib as compared to TERTwt and C250T TERTmut cells. Similar effects were observed on clonogenicity upon long-term exposure to this inhibitor. Regarding MAPK signaling activation, trametinib treatment completely blocked ERK phosphorylation in every cell model, while activation of ETS1 was more effectively reduced in C228T TERTmutcells. Accordingly, exposure to trametinib reduced TERT expression and promoter activity accompanied by induction of cellular senescence in cells with C228T mutation. Impact of trametinib is currently investigated in preclinical experiments using TERTmut brain tumor models. Summarizing, MEK inhibition represents a novel strategy to overcome cell immortalization especially in C228T TERTmut brain tumors.
CSIG-31. MULTI-OMICS TO EDGE INTO PRECISION MEDICINE FOR DIPG
Authors: Tang Nanyun , Leskoske Kristin , Garcia-Mansfield Krystine , Sharma Ritin , Tolson Hannah , Pirrotte Patrick , Berens Michael
Published: November 2021

DIPG is an incurable pediatric brain tumor with 80% of patients harboring H3F3A (H3.3) mutation that substitutes methionine for lysine at position 27 (K27M), resulting in global depletion of H3.3K27 me3 (trimethylation). These histone mutations modify the epigenome and alter oncogenic transcription, causing oncogenic insults to progenitor cells in early neurodevelopment (1). To determine the reprogramming pathways in the cell context of H3.3K27M tumors, we conducted LC-MS based proteomic and phosphoproteomic analysis on seven patient-derived DIPG cell lines. Three normal neuronal stem cell lines were included as non-tumor brain cells for comparison. Pathway analysis identified 29 pathways that are significantly altered in DIPG compared to normal brain cells at both the protein abundance and phosphosite level. Notably, AKT and MAPK associated PI3K signaling, VEGF signaling, mTOR signaling, and HIF1a signaling were differentially active in H3.3K27M tumors compared to healthy control cell lines. We saw significantly higher activity of multiple kinases involved in axon guidance and cytoskeletal remodeling in DIPG, such as PTK2B, DYRK2, TTBK2 and MARK2. This is the first time to report an increased abundance and kinase activity of PYK2 protein (coded by PTK2B), a close homologue of FAK and its associated signaling in DIPG. PYK2 has been proposed to act in concert with Src to link Gi- or Gq-coupled receptors with the mitogen-activated protein (MAP) kinase signaling pathway (2). Because of the shared signaling across kinase pathways, targeting activated PYK2 in DIPG may complement inhibitors of other dysregulated signaling networks in DIPG such as MAPK2, VEGFR, PI3K and Src. Our data also found that IL13RA2 was upregulated in DIPG. We conclude that for H3 K27M DIPG tumors, campaigns to target PYK2, MAPK2, VEGFR, PI3K, Src and IL13Ra2 using small molecules that traverse the blood brain barrier loom as promising opportunities for drug development.
CSIG-32. microRNA 211, A POTENTIAL THERAPEUTIC AGENT FOR GROUP 3 MEDULLOBLASTOMA IN CHILDREN
Authors: Katsushima Keisuke , Lee Bongyong , Yuan Menglang , Kunhiraman Haritha , Stapleton Stacie , Jallo George , Raabe Eric , Eberhart Charles , Perera Ranjan
Published: November 2021

Medulloblastoma (MB) is a central nervous system (CNS) tumor that predominantly affects children and requires aggressive therapy. Affected individuals often suffer from treatment-related side-effects and treatment-resistant recurrences associated with high morbidity and mortality rates. There are four major molecular MB subgroups: wingless-type (Wnt)-activated, sonic hedgehog (Shh)-activated, group III (G3), and group IV (G4) MBs. While the molecular pathology of Wnt- and Shh-activated MBs is well defined, rather less is known about G3 and G4 MB's genetic basis, so their molecular diagnosis and consequent management have remained challenging. MBs develop through various genetic, epigenetic, and non-coding (nc)RNA-related mechanisms, with the role of ncRNAs, particularly microRNAs, in MB tumor growth is poorly defined. We addressed this knowledge gap with an exemplar of microRNA-211 (miR-211) implicated in G3 MB tumor growth. Compared to other MB subgroups, miR-211 is significantly downregulated in G3 MB cell lines, underscoring its important role as a therapeutic agent and a biomarker. miR-211 overexpression in G3 MB cells significantly reduced cell proliferation, invasion, 3D colony formation, and induced apoptosis. Oxygen consumption rates are higher in engineered cells, and we postulate that miR-211 is involved in G3 MB mitochondrial energy metabolism. miR-211 expressed G3 MB cells injected into mouse cerebella produce smaller tumors than those derived from parental cells. We applied single-cell RNA sequencing and immune histochemical assays to characterize tumors to identify the molecular mechanism of miR-211- driven tumor reduction in G3 MBs, and our preliminary results support that miR-211 is an attractive therapeutic agent to treat this aggressive MB subtype.
RADT-07. DETERMINATION OF THE OPTIMAL TIME INTERVAL BETWEEN POST-OPERATIVE MRI AND CT SIMULATION FOR STEREOTACTIC RADIOSURGERY PLANNING
Authors: Panse Drishti , Rogers Aubrey , Farhangi Edward , Péris-Celda Maria , Adil Khaled
Published: November 2021

BACKGROUND

The incidence of brain metastasis is approximately 200,000 worldwide annually. Stereotactic radiation therapy of post-operative cavity reduces local recurrence. Surgical cavity size changes significantly with 96.5% demonstrating volumetric change during post-operative period. We sought to define the optimal time interval that preserved the volumetric dimensions between the post-surgical MRI and the CT simulation used for stereotactic radiosurgery planning.

METHODS

Seven patients with brain metastasis that underwent surgical resection and stereotactic radiation treatment at Albany Medical Center from February 2019 to April 2020 were included in the study. A total of 8 target lesions were included. Brain lab planning system was used for contouring the target volume. A postoperative MRI within 24-48 hours after surgery was obtained. 3 patients required an additional interim MRI 16-50 days after surgery. The planning CT simulation was performed 2 days prior and up to 15 days after the post-operative/interim MRI and target volumes were compared.

RESULTS

The average volume of the post-surgical cavity contoured by the neurosurgeons on the post-operative/interim MRI was 15.96 cc (± 7.79 cc, range of 6.54 -24.9 cc). The average volume of the post-surgical cavity contoured by the radiation oncologists on the planning CT was 15.71 (± 7.49 cc, range of 6.53 -24.31 cc). There was no noticeable change in volume size between post-operative/interim MRI and planning CT up to the period of 15 days.

LIMITATION

This was a retrospective pilot study with a small sample size and patients recruited from a single center.

CONCLUSION

There is no change in size of the cavity volume for up to 15 days between post-operative/interim MRI and planning CT. This knowledge will help understand the optimal time interval between post-operative MRI and CT simulation for the stereotactic radiation therapy planning.
RADT-26. PROTON VERSUS PHOTON CRANIOSPINAL IRRADIATION FOR ADULT MEDULLOBLASTOMA: A DOSIMETRIC AND TOXICITY ANALYSIS
Authors: Breen William , Geno Connie , Harmsen William , Brown Paul , Waddle Mark , Qian Jing , Burns Terence , Ruff Michael , Neth Bryan , Yan Elizabeth , Laack Nadia , Mahajan Anita
Published: November 2021

Medulloblastoma is a posterior fossa tumor rarely diagnosed in adults. Treatment includes craniospinal irradiation (CSI). Proton CSI is increasingly utilized to decrease radiation dose to normal tissues, despite the lack of randomized data demonstrating decreased toxicity compared to photon CSI. This single institution retrospective study of 39 adult medulloblastoma patients includes nineteen patients treated with photon CSI prior to 2015, and twenty treated with proton CSI thereafter. Median age was 28 years (range 18-66). Molecular subtype was most commonly sonic hedgehog (68%). The most common fractionation schedule was 36 Gy CSI in 20 fractions (85% of photon and 58% of proton patients) with a boost to 54-55.8 Gy (92%). Proton CSI delivered significantly lower mean doses to the cochleae (median 32 Gy vs. 44 Gy), lacrimal glands (8 vs. 36 Gy), lens (2 vs. 28 Gy), parotid glands (3 vs. 26 Gy), pharyngeal constrictors (6 vs. 15 Gy), esophagus (2 vs. 29 Gy), heart (0 vs. 14 Gy), lungs (1 vs. 7 Gy), liver (0.1 vs. 7 Gy), and skin (38 vs. 51 Gy) (all p< 0.001). Patients receiving proton CSI had significantly lower rates of acute dysphagia of any grade (5% vs. 35%, p= 0.044) and decreased median weight loss during radiation (+1.0 vs. -2.8 kg, p= 0.011). Acute hospitalization was associated with increased weight loss (p= 0.009). Median follow-up was 2.9 and 12.9 years for proton and photon patients, respectively, limiting late toxicity and outcome comparisons. At last follow-up five photon patients had died (two of progressive disease, three without recurrence ages 41-63) and 21% had experienced major cardiovascular events. At 10 years, 89% were alive and 82% were recurrence free. In conclusion, this study demonstrates dosimetric improvements with proton CSI, potentially leading to decreased acute toxicity including dysphagia and weight loss during treatment.
RADT-30. MULTISESSION RADIOSURGERY ALONE FOR TREATMENT OF PRESUMED MENINGIOMAS: AN INTERIM REPORT FROM A SINGLE INSTITUTION PROTOCOL
Authors: Carrasquilla Michael , Tai Alexander , Forsthoefel Matthew , Wang Edina , Lei Siyuan , Campbell Lloyd , Suy Simeng , Harris Breant , Azumi Norio , Berkowitz Frank , Voyadzis Jean-Marc , Kalhorn Christopher , Jean Walter , McGrail Kevin , Collins Sean , Collins Brian
Published: November 2021

PURPOSE

Meningiomas are the most commonly diagnosed primary intracranial tumor. Resection and single-fraction radiosurgery are treatment options with well-established long-term outcomes data. Multisession radiosurgery is an alternative treatment option with promising early results. However, mature outcomes literature does not yet exist. In this study, we report our institution’s interim results on the efficacy and safety of 5-fraction radiosurgery alone for radiographically diagnosed meningiomas.

MATERIALS AND METHODS

Between 2005-2015 all patients who completed treatment on a single institution protocol utilizing 5-fraction robotic radiosurgery alone for the treatment of progressing radiographically diagnosed meningiomas were eligible for inclusion. Local control was calculated using the Kaplan-Meier Method.

RESULTS

Forty-four consecutive predominately female patients (84%) ranging in age from 33-85 (median: 59) were included in the present study. Median tumor volume was 4.05mm3 (range: 0.94-15.4mm3) and the majority of tumors were located at the base of skull (66%). A median dose of 25Gy (range: 25Gy-35Gy), was delivered to a median isodose line of 82%, (range: 70%-90%) over a median of 7 days (range: 5-11 days). Acute toxicity was minimal with 7 patients (15%) requiring a short course of steroids for symptomatic edema during treatment. Of 16 patients who presented with a cranial nerve deficit, symptom improvement was noted in 11 patients (69%). No permanent treatment related toxicity was noted in our cohort. The median radiographic follow-up was 6.9 years (range: 0.5-14.8 years). The 5 and 8-year local control rates were 100% and 95%. The median time to local failure (n=2) in our cohort was 8.2 years.

CONCLUSIONS

The treatment of radiographically diagnosed meningiomas with 5-fraction robotic radiosurgery provides excellent local control to date, with low rates of acute and late toxicity. However, with late failures noted in our series, continued follow-up is needed to determine the optimal dose required for long-term tumor control.
CTIM-03. AUTOLOGOUS ADOPTIVE IMMUNE-CELL THERAPY ELICITED A DURABLE RESPONSE WITH ENHANCED IMMUNE REACTION SIGNATURES IN PATIENTS WITH RECURRENT GLIOBLASTOMA: AN OPEN LABEL, PHASE I/IIA TRIAL
Authors: Lim Jaejoon , Park Young Joon , Ahn Ju Won , Sim Jeong Min , Kim Suwan , Hwang Sojung , Sung Kyungsu , Cho Kyunggi
Published: November 2021

Glioblastoma multiforme (GBM) is an aggressive malignancy classified by the World Health Organization as a grade IV glioma. Despite the availability of aggressive standard therapies, most patients experience recurrence, for which there are currently no effective treatments. We aimed to conduct a phase I/IIa clinical trial to investigate the safety and efficacy of adoptive, ex-vivo-expanded, and activated natural killer cells and T lymphocytes from peripheral blood mononuclear cells of patients with recurrent GBM. This study was a single-arm, open-label, investigator-initiated trial on 14 patients recruited between 2013 and 2017. The immune cells were administered via intravenous injection 24 times at 2-week intervals after surgical resection or biopsy. The safety and clinical efficacy of this therapy was examined by assessing adverse events and comparing 2-year overall survival (OS). Transcriptomic analysis of tumor tissues was performed using NanoString to identify the mechanism of therapeutic efficacy. No grade 4 or 5 severe adverse events were observed. The most common treatment-related adverse events were grade 1 or 2 in severity. The most severe adverse event was grade 3 fever. Median OS was 22.5 months, and the median progression-free survival was 10 months. Five patients were alive for over 2 years and showed durable response with enhanced immune reaction transcriptomic signatures without clinical decline until the last follow-up after completion of the therapy. In conclusion, autologous adoptive immune-cell therapy was safe and showed durable response in patients with enhanced immune reaction signatures. This therapy may be effective for recurrent GBM patients with high immune response in their tumor microenvironments. Trial registration: The Korea Clinical Research Information Service database: KCT0003815, Registered 18 April 2019, retrospectively registered.
CTIM-10. REPRODUCIBILITY OF CLINICAL TRIALS USING CMV-TARGETED DENDRITIC CELL VACCINES IN PATIENTS WITH GLIOBLASTOMA
Authors: Batich Kristen , Mitchell Duane , Healy Patrick , Herndon James , Broadwater Gloria , Michael Gunn , Huang Min-Nung , Hotchkiss Kelly , Sanchez-Perez Luis , Nair Smita , Congdon Kendra , Norberg Pam , Weinhold Kent , Archer Gary , Reap Elizabeth , Xie Weihua , Shipes Steven , Albrecht Emily , Peters Katherine , Randazzo Dina , Johnson Margaret , Landi Daniel , Desjardins Annick , Friedman Henry , Vlahovic Gordana , Reardon David , Vredenburgh James , Bigner Darell , Khasraw Mustafa , McLendon Roger , Thompson Eric , Cook Steven , Fecci Peter , Codd Patrick , Floyd Scott , Reitman Zachary , Kirkpatrick John , Friedman Allan , Ashley David M , Sampson John
Published: November 2021

INTRODUCTION

Vaccination with dendritic cells (DCs) fares poorly in primary and recurrent glioblastoma (GBM). Moreover, GBM vaccine trials are often underpowered due to limited sample size.

METHODS

To address these limitations, we conducted three sequential clinical trials utilizing Cytomegalovirus (CMV)-specific DC vaccines in patients with primary GBM. Autologous DCs were generated and electroporated with mRNA encoding for the CMV protein pp65. Serial vaccination was given throughout adjuvant temozolomide cycles, and 111Indium radiolabeling was implemented to assess migration efficiency of DC vaccines. Patients were followed for median overall survival (mOS) and OS.

RESULTS

Our initial study was the phase II ATTAC study (NCT00639639; total n=12) with 6 patients randomized to vaccine site preconditioning with tetanus-diphtheria (Td) toxoid. This led to an expanded cohort trial (ATTAC-GM; NCT00639639) of 11 patients receiving CMV DC vaccines containing granulocyte-macrophage colony-stimulating factor (GM-CSF). Follow-up data from ATTAC and ATTAC-GM revealed 5-year OS rates of 33.3% (mOS 38.3 months; CI95 17.5-undefined) and 36.4% (mOS 37.7 months; CI95 18.2-109.1), respectively. ATTAC additionally revealed a significant increase in DC migration to draining lymph nodes following Td preconditioning (P=0.049). Increased DC migration was associated with OS (Cox proportional hazards model, HR=0.820, P=0.023). Td-mediated increased migration has been recapitulated in our larger confirmatory trial ELEVATE (NCT02366728) of 43 patients randomized to preconditioning (Wilcoxon rank sum, Td n=24, unpulsed DC n=19; 24h, P=0.031 and 48h, P=0.0195). In ELEVATE, median follow-up of 42.2 months revealed significantly longer OS in patients randomized to Td (P=0.026). The 3-year OS for Td-treated patients in ELEVATE was 34% (CI95 19-63%) compared to 6% given unpulsed DCs (CI95 1-42%).

CONCLUSION

We report reproducibility of our findings across three sequential clinical trials using CMV pp65 DCs. Despite their small numbers, these successive trials demonstrate consistent survival outcomes, thus supporting the efficacy of CMV DC vaccine therapy in GBM.
CTIM-11. PHASE 2 STUDY OF SL-701, A NOVEL IMMUNOTHERAPY, IN ADULTS WITH RECURRENT GBM: A HIGH PARAMETER FLOW CYTOMETRY ANALYSIS OF CD8+ T CELLS AND POTENTIAL IMPLICATIONS FOR PATIENT ENRICHMENT STRATEGIES
Authors: Peereboom David , Lindsay Ross , Badruddoja Michael , Nabors L Burt , Kumthekar Priya , Lieberman Frank , Tran David , Phuphanich Surasak , Schiff David , Sherman Jonathan , Butowski Nicholas , Dunbar Erin , Fink Karen , Iwamoto Fabio , Moertel Christopher , Schulder Michael , Walbert Tobias , Habboubi Nassir , Grzegorzewski Krzysztof , Brooks Christopher , Reardon David
Published: November 2021

Treatment of glioblastoma (GBM) remains a critical challenge and unmet medical need due to limited treatment options. SL-701 is a novel immunotherapy comprised of synthetic peptides designed to elicit a target-specific anti-tumor immune response against the GBM antigens IL-13Rα2, ephrinA2, and survivin. A multicenter, 2-stage, phase 2 clinical trial (NCT02078648) that evaluated the safety and efficacy of SL-701 in 74 adults with recurrent GBM was previously reported. This report describes preliminary data to suggest a correlation of immunocompetence to clinical outcome. In stage 2 (SL-701 + bevacizumab + poly-ICLC) the overall survival at 12 months was 50%. Two of 28 patients enrolled in stage 2 achieved CR (duration of response: 7.8 and 8.8 months) and 2 achieved PR (duration of response: 7.9 and 8.8 months). In a preliminary analysis to assess CD8+ T-cell responses, long-term survivors were comprised largely of subjects with an SL-701-induced target-specific CD8+ T-cell response, indicating a potential correlation of immunocompetence to clinical outcome. By week 24, SL-701-induced target-specific CD8+ T cells expressing IFNg were detected in 8 of 27 patients (30%) who had sufficient samples, with co-expression of PD-1, TIM3, and LAG3 detected in 4 patients. To further understand the T-cell response to SL-701, deep sequencing of target-specific CD8+ T cells using whole transcriptome-based molecular cytometry and high parameter (25+ color) flow cytometry is currently underway and updated data will be reported.
CTIM-15. FIRST-IN-HUMAN PHASE 1 STUDY OF CD200 ACTIVATION RECEPTOR-LIGAND (CD200AR-L) AND ALLOGENEIC TUMOR LYSATE VACCINE IMMUNOTHERAPY FOR RECURRENT GLIOBLASTOMA: INITIAL RESULTS FROM AN ONGOING CLINICAL TRIAL
Authors: Neil Elizabeth , Eaton Anne , Lunn Shannon , Nelson Kristen , Greengard Emily , Moertel Christopher , Olin Michael
Published: November 2021

BACKGROUND

Poor efficacy and adverse events limit the use of immunotherapy in the treatment of glioblastoma. CD200AR-L, a novel immunotherapy targeting multiple checkpoints with a single peptide inhibitory ligand, activates the immune system by downregulating CD200-inhibitory receptor, PD-1/PD-L1, and CTLA-4.

METHODS

Single-center, first-in-human, dose-escalation phase 1 clinical trial (NCT04642937) utilizing a 3 + 3 design initiated accrual in 12/2020 at dose level-1; CD200AR-L 3.75micrograms/kg/dose administered on days 1 and 2 by intradermal injection after topical imiquimod. On day 2, a fixed dose of an allogeneic vaccine is also injected intradermally. Induction Phase consists of this injection series weekly for 4 weeks with monitoring for dose-limiting toxicity through day 28.

RESULTS

Between 12/2020 to 3/2021, 6 patients were enrolled on dose level-1; aged 37-65 years, 4 men, all with KPS >/= 80, and 3 patients on daily dexamethasone (4mg (n=2), 2mg (n=1)). Five were at first recurrence, 1 at second and 5 had cancers MGMT-promoter unmethylated. All completed the 4 weeks of induction. One dose-limiting toxicity of a grade-III encephalopathy was observed. Non-dose-limiting grade-III toxicities included, lymphopenia (n=1) and immunotherapy-related intracranial edema (IrICE) (n=2). IrICE symptoms were temporarily mitigated with ‘bevacizumab rescue protocol.’ No patients had local injection site reactions. Three patients are off study for radiographic disease progression confirmed on pathology (n=1) and radiographic disease progression with progressive neurological decline (n=2). Completed investigational hematologic immune monitoring for 4/6 patients revealed, that between weeks 2 and 4 post-vaccination, evidence of immune stimulation with an increase in CD4/8 T-cells, natural killer, and natural killer T-cells. There was also a reduction in immunosuppressants noted by a decrease in PD-1/PD-L1 and CTLA-4 expression on CD4/8 T-cells, CD14, CD11c, and myeloid-derived suppressor cells.

CONCLUSION

Initial dosing of CD200AR-L was well tolerated with early positive signal of immunological effect. Enrollment continues, now at dose level-2; CD200AR-L at 5micrograms/kg/dose.
CTIM-24. RANDOMIZED TRIAL OF NEOADJUVANT VACCINATION WITH TUMOR-CELL LYSATE INDUCES T CELL RESPONSE IN LOW-GRADE GLIOMAS
Authors: Taylor Jennie , Ogino Hirokazu , Nejo Takahide , Gibson David , Watchmaker Payal , Okada Kaori , Saijo Atsuro , Tedesco Meghan , Shai Anny , Wong Cynthia , Rabbitt Jane , Olin Michael , Moertel Christopher , Nishioka Yasuhiko , Salazar Andres , Molinaro Annette , Phillips Joanna , Butowski Nicholas , Clarke Jennifer , Oberheim-Bush Nancy Ann , Hervey-Jumper Shawn , Theodosopoulos Philip , Chang Susan , Berger Mitchel , Okada Hideho
Published: November 2021

BACKGROUND

The prognosis of WHO grade II low-grade gliomas (LGG) is varied with potential for long survival.Given their relatively intact immune system and slow growth rate, vaccines are an attractive treatment strategy for LGG in an attempt to defer more toxic treatments. The goals of this pilot study were to evaluate safety and immunological effects of vaccination with GBM6-AD, an allogeneic glioblastoma stem cell line lysate, with poly-ICLC in LGG.

METHODS

Eligible patients were ≥ 18 years old, ≥ 70 KPS, with recurrent LGG or imaging consistent with LGG, and amenable to resection. Patients were randomized to vaccine prior to surgery (Arm 1) or not (Arm 2) and all received adjuvant vaccine. Co-primary outcomes were safety and immune response in the tumor, with exploratory outcomes of survival and immunologic effects in peripheral blood.

RESULTS

A total of 17 eligible patients were evaluable – nine into Arm 1 and eight into Arm 2. Median age was 33 years, with median time from initial diagnosis of 4.7 years (0 – 20). Two patients (11.8%) previously received radiotherapy and seven (41.2%) prior systemic therapy. No dose limiting toxicities or grade 3 AEs were observed. Neoadjuvant vaccination induced up regulation of type-1 cytokines and chemokines in peripheral blood, and CD8+ T cell clones that reacted to the vaccine were also detected in the tumor. Median follow-up time from first post-operative vaccine was 20.8 months with median PFS of 11.0 months and time to change in therapy of 23.7 months. Of the six patients to receive additional treatment, three had second surgery only one confirming malignant progression to anaplastic oligodendroglioma.

CONCLUSION

Treatment was well-tolerated with no regimen-limiting toxicity. GBM6-AD plus poly-ICLC induced effector CD8+ T cell response in peripheral blood and enables some vaccine-reactive CD8+ T cells to migrate into the TME. Further investigation is warranted.
CTIM-29. CLINICAL EVALUATION OF CHLOROTOXIN-DIRECTED CAR T CELLS FOR PATIENTS WITH RECURRENT GLIOBLASTOMA
Authors: Brown Christine , Blanchard M Suzette , Aftabizadeh Maryam , Hibbard Jonathan , Dodia Ramsinh , Lingaraju Chetan Raj , Starr Renate , D'Apuzzo Massimo , Forman Stephen J , Portnow Jana , Ressler Julie A , Stiller Tracey , Barva Baishakhi , Kilpatrick Julie , McNamara Paige , Wagner Jamie R , Wang Dongrui , Barish Michael , Badie Behnam
Published: November 2021

Chlorotoxin (CLTX), a peptide component of scorpion venom, exhibits selective and broad binding to glioblastoma (GBM) and other tumors with minimal activity against non-malignant cells. We have developed a novel CAR that utilizes CLTX as the tumor targeting domain. Preclinical studies established that CLTX-CAR T cells target GBM through recognition of a receptor complex incorporating membrane-bound matrix metalloprotease-2 (MMP-2). Here, we report initial clinical findings for our phase I trial evaluating safety and bioactivity of CLTX-CAR T cells in patients with MMP2+ recurrent GBM (NCT04214392). Weekly infusions of CLTX-CAR T cells are delivered locoregionally, either directly into the tumor cavity (ICT; Arm 1), or in combination with intracerebroventricular (ICV) delivery (dual ICT/ICV; Arm 2). At this interim analysis, four participants have received at least three cycles of CLTX-CAR T cells ICT (Arm 1; 3-8 cycles) at dose level 1 (DL1; 4M, 20M, 20M CAR T cells per cycle). None of the participants experienced dose limiting toxicity (DLT) during the DLT evaluation period of 28-days, although one participant experienced a serious adverse event of grade 3 cerebral edema, possibly attributed to CAR T cells. Overall, Arm 1-DL1 was well-tolerated, and the next patient cohort will be treated on Arm 2-DL1 (dual ICT/ICV; 8M, 40M, 40M CAR T cells per cycle), as per protocol design. Disease response was assessed by RANO, overall survival, and time to progression; three of four participants achieved a best response of stable disease. Liquid biopsy detected persistent CAR T cells in the tumor cavity throughout treatment, suggesting that the therapeutic cells are not immunogenic. Ongoing studies are evaluating biomarkers of response and resistance, including CAR T cell activation and inflammatory cytokines. This clinical study provides first-in-human evidence for the safety and feasibility of CLTX-CAR T cells as a new class of toxin-based CARs for treatment of GBM.
CTIM-32. IMMUNE CHECKPOINT INHIBITOR NIVOLUMAB IN PEOPLE WITH RECURRENT SELECT RARE CNS CANCERS: RESULTS OF INTERIM ANALYSIS IN A HEAVILY PRETREATED COHORT
Authors: Penas-Prado Marta , Yuan Ying , Wall Kathleen , Vera Elizabeth , Ikiddeh-Barnes Ukeme , Blackburn Katie , Chambers Claudia , Ratnam Nivi , Frederico Stephen , Acquaye Alvina , Aldape Kenneth , Briceno Nicole , Choi Anna , Christ Alexa , Jammula Varna , Leeper Heather , Levine Jason , Lindsley Matthew , Reyes Jennifer , Roche Kayla , Rogers James , Timmer Michael , Boris Lisa , Burton Eric , Lollo Nicole , Panzer Marissa , Polskin Lily , Pillai Valentina , Quezado Martha , Theeler Brett , Wu Jing , Armstrong Terri , Gilbert Mark
Published: November 2021

INTRODUCTION

Standard and experimental therapies for patients with rare CNS tumors are scarce. Nivolumab (PD-1 inhibitor) is approved for several non-CNS cancers. This ongoing Phase II trial (NCT03173950) will determine the efficacy of nivolumab in adults with recurrence/progression of one of 11 selected rare primary CNS tumors. Efficacy is measured by Disease Control Rate (DCR; confirmed CR/PR or durable SD for ≥ 6 months) in 2 cohorts: heavily and non-heavily pretreated patients (heavily pretreated: ≥ 3 prior therapies; non-heavily pretreated: ≤ 2). We report efficacy and safety results of a preplanned interim analysis in the heavily pretreated cohort.

METHODS

Eligibility includes recurrence/progression of an eligible tumor; age ≥ 18 years; tumor tissue available for histopathology, molecular and immune profiling; KPS ≥ 70; and no steroids at study entry. A total of 150 evaluable patients will be enrolled (75 to each cohort). Prior therapies include radiation and/or standard or investigational drugs. Nivolumab treatment is 240 mg IV every 2 weeks (4 doses); then 480 mg every 4 weeks (14 additional doses). Interim analysis was planned when sample size reached 32 in each cohort.

RESULTS

As of March 10, 2021, DCR exceeded the minimum required for interim analysis in the heavily pretreated cohort. Among 30 patients, 4 achieved SD > 6 months (medulloblastoma, anaplastic ependymoma, myxopapillary ependymoma, metastatic atypical meningioma). Safety profile (related AEs): grade 3 = 7; grade 4 = 1. Most frequent grade 3-5 AEs regardless of attribution: tumor progression (6); anemia, hydrocephalus, lymphopenia (3 each); cerebral edema, headache (2 each).

CONCLUSION

DCR exceeded the “go” boundary (i.e., > 2) in the heavily pretreated cohort. Nivolumab showed safety profile consistent with other studies. This cohort will continue to stage 2 and complete total accrual of 75 patients. The trial is currently being expanded to 10 additional sites across the BTTC/NCI-CONNECT consortium.
CTNI-02. NERATINIB FOR TREATMENT OF LEPTOMENINGEAL METASTASES FROM HER2-POSITIVE BREAST CANCER IN EXTENDED ACCESS PROGRAM: PRELIMINARY RESULTS
Authors: Pellerino Alessia , Palmiero Rosa , Bruno Francesco , Muscolino Erminia , Franchino Federica , Rudà Roberta , Soffietti Riccardo
Published: November 2021

INTRODUCTION

The aim of the study was to evaluate the activity of neratinib in LM from HER2-positive BC after the failure of multiple lines of treatment.

PATIENTS AND METHODS

Inclusion criteria were as follows: age ≥ 18 years; histological diagnosis of primary HER2-positive BC; newly-diagnosed LM (LANO criteria); KPS ≥ 60; coexistence of BM that have or not received radiotherapy; life expectancy ≥ 3 months; previous drugs, including capecitabine, trastuzumab, T-DM1, pertuzumab, and hormone therapy, were allowed, with the exclusion of lapatinib or other investigational agents. Neratinib was administered 240 mg daily continuously. Primary endpoint was the OS. Secondary endpoints were progression-free survival (PFS), neurological benefit, radiological response rate, and tolerability.

RESULTS

Nine patients with LM have been enrolled with a median age of 44 years, and a median KPS of 80. Median time since LM onset from the diagnosis of primary BC was 42 months, and patients underwent a median number of adjuvant treatments before LM of 3. Three patients developed LM alone, and other 6 had LM associated with multiple BM. Six-months and 1-year OS were 66.7% and 22.3%, respectively, with a median OS of 8 months (95%CI 3-13*). Median PFS was 3.5 months (95%CI 2-6) after the start of treatment. A neurological improvement was reported in 2/9 patients (22.2%), while in other 4/9 patients (44.5%) was achieved a neurological stabilization lasting for a median time of 5 months (95%CI 2-19). The best radiological response was a stable disease in 5/9 patients (55.6%), while no complete or partial were achieved according to LANO criteria. A CSF clearance was observed in 1 patient only (11.1%). Grade III-IV adverse events were not reported, and 2 patients only (22.2%) had mild diarrhea correlated with neratinib.

CONCLUSIONS

Neratinib might be a safe and effective treatment in LM from heavily pretreated HER2-positive BC.
CTNI-03. EXTENDED BENEFITS IN PATIENTS WITH RECURRENT HIGH GRADE GLIOMA THAT CONTINUOUSLY RECEIVE TOCA FC AFTER TOCA 511 TREATMEN
Authors: Walbert Tobias , Damek Denise , Nina L Martinez , Piccioni David , Singer Samuel , Cloughesy Timothy
Published: November 2021

Toca 511 (vocimagene amiretrorepvec) is an investigational nonlytic, retroviral replicating vector (RRV) constructed with a codon-optimized yeast cytosine deaminase (CD) gene. Toca 511 infects cancer cells, and stably delivers CD gene whose protein product converts courses of the prodrug TocaFC (5-fluorocytosine) into 5-fluorouracil (5-FU). Several phase 1 studies and a phase 2/ 3 clinical study tested Toca511 in combination with TocaFC in patients undergoing planned resection for recurrent glioblastoma (rGBM) or anaplastic astrocytoma (rAA). The last trial was completed in 2019, and although the Phase 2/3 study did not meet the primary objective, patients who appeared to benefit from the treatment elected to continue TocaFC through an expanded access or compassionate use pathway. Seven patients continued on treatment: 3 men and 4 women; 5 with rGBM, 2 with rAA. Duration of treatment with TocaFC ranges from 29 months to 7 years and 5 months (average 49.2 months). Six patients who are still on active treatment with TocaFC have either stable disease or complete response. TocaFC is well tolerated in these patients, typical side effects include diarrhea. Some patients with rGBM or rAA appear to benefit from extended TocaFC treatment after Toca511. Individual cases will be discussed.
CTNI-06. TRAM-01: A PHASE 2 STUDY OF TRAMETINIB FOR PATIENTS WITH PEDIATRIC GLIOMA WITH ACTIVATION OF THE MAPK/ERK PATHWAY
Authors: Perreault Sébastien , Larouche Valérie , tabori uri , Hawkins Cynthia , Lippe sarah , Ellezam Benjamin , decarie Jean-Claude , Ospina Luis H , theoret yves , Desjardins Leandra , Metras Marie-Elaine , Sultan serge , Cantin Edith , Routhier Marie-Eve , Caru Maxime , Vairy Stephanie , Legault Geneviève , Bouffet Eric , Lafay-Cousin Lucie , Hukin Juliette , Erker Craig , Jabado Nada
Published: November 2021

BACKGROUND

Pediatric low-grade gliomas (PLGG) are the most frequent brain tumors in children. It is known that the majority of PLGG have activation of the MAPK/ERK pathway.

METHODS

This ongoing multicenter phase II trial includes three progressing/refractory PLGG groups: NF1 patients, KIAA1549-BRAF fusion patients and patients with other activation of the MAPK/ERK pathway (excluding V600E). The primary objective was to evaluate the overall response rate based on RANO criteria after daily oral trametinib administration for 18 cycles, lasting 28 days each. Secondary objectives include the assessment of progression-free survival, tolerability of trametinib, serum levels of trametinib and quality of life evaluation during treatment.

RESULTS

As of February 12 2021, 50 patients have been enrolled (NF1: n=10; KIAA1549-BRAF fusion: n=31; other: n=9 including 5 patients with FGFR1 alterations). Median age is 8.8 years (range 2.4-25.5). Median follow-up is 17.5 months (range 4.7-28.5). Forty-three patients are evaluable. The overall response includes: 4 partial response (PR) (9%), 18 minor response (MR) (42%), 17 stable disease (40%), 4 progressive disease (9%). Median time to response is 5.5 months (range 2.4-13.8). Median duration of response is 6.1 months (range 0.6-26.5). Progression free survival at 12 months is 79.9% (95% CI 68.5-93.6%) and median progression free survival has not yet been reached. Treatment was discontinued for 30 patients: 16 after completing 18 cycles as planned, 5 for progressive disease, 5 for adverse events, 4 for other reasons. A total of 8 patients progressed after discontinuation of treatment including 6 patients (37.5%) that completed 18 cycles. Five of these patients had achieved minor response prior to discontinuation.

CONCLUSION

Trametinib is a potentially effective targeted therapy for patients with recurrent/refractory PLGG. Treatment was overall well tolerated. This ongoing trial will continue to gather data on response rate, duration of response and safety of trametinib for PLGG.