bluuebunny/crossref_metadata_2025 huggingface dataset:
CTNI-37. ISOEFFECTIVE HYPOFRACTIONATION FOR ELDERLY OR FRAIL PATIENTS WITH A NEWLY DIAGNOSED GLIOBLASTOMA: A POOLED INTERNATIONAL STUDY
Authors: Perlow Haley , Yang Michael , Klamer Brett , Matsui Jennifer , Marrazzo Livia , Detti Beatrice , Scorrsetti Marta , Clerici Elena , Arnett Andrea , Beyer Sasha , Ammirati Mario , Chakravarti Arnab , Raval Raju , Navarria Pierina , Scoccianti Silvia , Grecula John , Palmer Joshua
Published: November 2021

PURPOSE

The standard of care (SOC) for elderly or frail glioblastoma (GBM) patients is 40 Gy in 15 fraction radiotherapy. However, this regimen has a lower BED compared to the Stupp regimen, 60 Gy in 30 fractions. We hypothesize that isoeffective hypofractionated radiation of 52.5 Gy in 15 fractions (BED equivalent to Stupp) will have superior survival compared to standard of care.

METHODS

Elderly GBM patients treated with 52.5 Gy in 15 fractions were pooled from 2 phase II studies, 1 phase 1 and a prospective observation study. Overall survival (OS) and progression free survival (PFS) were defined as the time elapsed between surgery/biopsy and death from any cause or progression. Univariate and multivariate analyses were performed.

RESULTS

62 newly-diagnosed patients were eligible for this analysis. Median follow-up was 10 months. The median OS and PFS was 10.3 and 6.9 mos, respectively. Patients with KPS ≥ 70 and < 70 had a median OS of 15.3 and 9.5 mos. No survival difference was seen between unmethylated and methylated patients with a median OS of 10.2 and 10.3 months, respectively. Multivariable analysis demonstrated that concurrent chemotherapy was an independent prognostic factor for improved PFS and OS. Grade 3 neurologic toxicity was seen in 2 patients (3.2%).

CONCLUSION

This is the first pooled, prospective analysis of elderly/frail GBM patients treated with dose-escalated hypofractionated radiation. Treatment was well tolerated and demonstrated excellent OS and PFS, exceeding that from prior elderly trials (Roa; 6.5 mo [poor KPS]/Perry; 9.3mo [good KPS]). This treatment regimen gives the elderly population an alternative to Stupp that is not de-escalating therapy. Future prospective trials are needed to validate these results.
CTNI-41. INITIAL RESULTS OF A PHASE I WINDOW OF OPPORTUNITY TRIAL EVALUATING A FIRST-IN-CLASS CD29 INHIBITOR, OS2966, IN RECURRENT HIGH-GRADE GLIOMA
Authors: Liu James , Nwagwu Chibueze D , Immidisetti Amanda V , Bukanowska Gabriela , Carbonell Anne-Marie , Vogelbaum Michael
Published: November 2021

BACKGROUND

OS2966 is a first-in-class, humanized and deimmunized monoclonal antibody which antagonizes CD29/β1integrin, a mechanosignaling receptor prominently upregulated in glioblastoma. Preclinical studies in mice and non-human primates have demonstrated safety and encouraging efficacy. A two-part, ascending concentration, phase I clinical trial was therefore initiated to evaluate the safety and feasibility of delivering OS2966 directly to the site of disease via convection-enhanced delivery (CED) in recurrent high-grade glioma patients.

METHODS

This study has a 2-part design: In part 1, patients undergo stereotactic tumor biopsy followed by placement of a multiport CED catheter for delivery of OS2966 to the bulk contrast enhancing tumor. Subsequently, patients undergo a clinically-indicated tumor resection followed by placement of two CED catheters and delivery of OS2966 to the surrounding tumor-infiltrated brain. A unique concentration-based accelerated titration design is utilized for dose escalation. Given availability of pre and post infusion samples, pharmacodynamic data will be analyzed to explore mechanism of action of OS2966.

RESULTS

Two subjects have been treated at two corresponding dose levels (0.2mg/mL and 0.4 mg/mL). No dose-limiting toxicity or unexpected safety issues have been identified. To date, reported adverse events were mild (i.e., grade 1) and consistent with underlying disease and surgical procedures. No adverse events were attributed to OS2966 or CED catheter placement. Further, no clinically significant changes from baseline neurological exam have been noted for either patient through initial follow-up. Maximal tumor coverage and concomitant gross total resection were achieved for both patients. Tumor volume measured 1.63 cm3 and 16 cm3 for Patient 1 and 2 respectively with an intratumoral Vd/Vi ratio of 1.3. and 0.94. Pharmacodynamic analysis via tissue-level biomarkers is ongoing and will be presented.

CONCLUSION

Initial data demonstrates the safety and feasibility of direct intracranial delivery of OS2966.
DDRE-01. CDK PATHWAY INHIBITION WITH ABEMACICLIB IMPROVES INTRACRANIAL AND EXTRACRANIAL RESPONSE TO CHECKPOINT BLOCKADE IN PRE-CLINICAL MODELS OF MELANOMA BRAIN METASTASIS
Authors: Nayyar Naema , Singh Mohini , de Sauvage Magali , Dahal Ashish , Brehm Michael , Brastianos Priscilla
Published: November 2021

While immune checkpoint inhibitors (ICI) have revolutionized treatment of metastatic melanoma, few of the 75% of patients who develop brain metastases benefit from immunotherapy. Inhibition of CDK4/6 pathway – altered in ~90% of melanoma patients – can reportedly increase tumor inflammation and sensitize extracranial tumors to ICI. To determine whether intracranial melanoma can be similarly sensitized, we studied efficacy of combination CDK4/6 inhibitor Abemaciclib and ICI in immunocompetent mouse models of melanoma brain metastases bearing concurrent intracranial and extracranial tumors. 8-week-old female C57BL/6 mice received subcutaneous injections of 2x105 YUMM1.7 or B16-F10 melanoma cells 3 days prior to intracranial injections of 5x104 YUMM1.7 cells or 5x103 B16-F10 cells respectively. Mice were randomized into 6 treatment groups (n=5-7/group): Abemaciclib alone, anti-PD-1 monotherapy, anti-PD-1 and anti-CTLA4 combined (combination ICI), Abemaciclib and anti-PD-1, Abemaciclib combined with anti-PD-1 and anti-CTLA4 (triple therapy), and treatment with vehicle and isotype-matched antibodies as control. In mice bearing YUMM1.7 tumors, subcutaneous tumor growth was significantly reduced compared to control in mice treated with Abemaciclib alone (p< 0.05), combination ICI (p< 0.05) and triple therapy (p< 0.05). However, improvement in survival was only observed with triple therapy (p=0.039) compared to control group. In mice bearing B16-F10 tumors, we observed striking reduction in subcutaneous tumor growth in mice treated with Abemaciclib and anti-PD-1 compared to control-treated mice (p=0.0016) or to mice receiving anti-PD-1 monotherapy (p=0.000056). This further corresponded to a significant increase in survival of Abemaciclib and anti-PD-1 treated mice compared to control (p=0.02). Additionally, we observed improved survival in mice treated with combination ICI (p=0.006) or triple therapy (p=0.01). These results indicate CDK4/6 inhibition with Abemaciclib can improve both extracranial and intracranial responses to ICI and sensitize melanoma brain metastases to immunotherapy. Our pre-clinical findings warrant further investigation to determine whether this combination approach can improve patient outcomes.
DDRE-07. TARGETING TUMOR HYPOXIA AND MITOCHONDRIAL METABOLISM WITH ANTI-PARASITIC DRUGS AS AN APPROACH TO IMPROVE THE RADIOSENSITIVITY OF DIFFUSE INTRINSIC PONTINE GLIOMA
Authors: Mudassar Faiqa , Chang Cecilia , Ing Prunella , Cook Kristina , O'Neill Geraldine , Shen Han , Hau Eric
Published: November 2021

Diffuse intrinsic pontine glioma (DIPG) is an incurable pediatric brain tumor with a median survival of 12 months. Current management is limited to radiotherapy; however, the tumor recurs secondary to radioresistance. Tumor hypoxia appears to be one of the major contributors to radioresistance of DIPG, as oxygenation is critical to successful radiotherapy treatment. Therefore, strategies to alleviate hypoxia could enhance the effectiveness of radiotherapy and result in improved survival outcomes of patients with DIPG. Recent approaches to target tumor hypoxia are predicated on inhibiting mitochondrial respiration of the tumors to decrease oxygen consumption rate (OCR) and increase oxygenation. Here, we aimed to identify a safe but potent mitochondrial inhibitor that could decrease OCR and hypoxia, and improve the radiosensitivity of DIPG. A subset of anti-parasitic drugs (atovaquone, ivermectin, quinacrine, mefloquine and proguanil) which are known mitochondrial inhibitors were studied against a panel of patient-derived DIPG cell lines. We assessed their antiproliferative effects, OCR inhibition and radiosensitising efficacy using cell proliferation, extracellular flux and colony formation assays. Among the five tested drug candidates, atovaquone was found to be the most potent OCR inhibitor with minimal antiproliferative effects on DIPG cultures. It also decreased hypoxia in 3-dimensional DIPG neurospheres, reduced the expression of hypoxia-inducible factor-1α and improved the radiosensitivity of neurospheres of DIPG. Its anti-mitochondrial role was further confirmed by inhibition of various mitochondrial parameters and increase in reactive oxygen species. Overall, these results provide promising in vitro evidence of atovaquone as a hypoxia modifier and radiosensitiser in DIPG and pave a way for rapid translation to in vivo studies.
DDRE-11. SECOND GENERATION IDO INHIBITORS FOR IMPROVING IMMUNOTHERAPEUTIC EFFICACY IN PATIENTS WITH GLIOBLASTOMA
Authors: Bollu Lakshmi , Bommi Prashant , Wainwright Derek , Ladomersky Erik , Zhai Lijie , Bell April , Lauing Kristen
Published: November 2021

INTRODUCTION

Indoleamine 2,3-dioxygenase 1 (IDO; IDO1) is a rate-limiting enzyme that metabolizes tryptophan and is expressed in >90% of patient-resected glioblastoma (GBM). IDO-mediated tryptophan metabolism has been the proposed mechanism for suppressing the immune response in GBM. Recently, we discovered that IDO also possesses non-enzymic functions that contribute to suppress the anti-GBM immune response. This finding motivated us to develop IDO-Proteolysis Targeting Chimeras (IDO-PROTACs) to degrade IDO protein rather than simply inhibiting IDO enzyme activity.

METHODS

Western blot analysis was used to determine IDO-PROTAC efficiency of IDO protein degradation among human and mouse GBM cell lines and PDX. Our lead IDO-PROTAC was tested for toxicity, blood brain barrier penetration, and pharmacokinetics (PK) in wild-type C57BL/6 mice.

RESULTS

IDO-PROTACs degrade IDO protein in both tumor and non-tumor cells with a DC50 value of ~0.5µM in human GBM tumor cells. Biolayer interferometry (BLI) studies show that IDO-PROTAC forms a binary complex with IDO protein with similar affinity comparable to parental compound – BMS986205. IDO-PROTACs induced IDO ubiquitination and the pretreatment with ubiquitin proteasome inhibitors, MG132 or MLN4924, inhibited IDO protein degradation. In vivo toxicity studies showed that treatment with IDO-PROTAC at 25 mg/kg for 3-weeks did not develop any apparent toxicity in C57BL/6 mice. PK analysis revealed that IDO-PROTAC bioavailabilty reached a peak serum and brain concentration within 30 minutes after intraperitoneal administration.

CONCLUSIONS

This study developed a lead IDO-PROTAC compound that efficiently degrades IDO protein in human GBM cells with a moderate bioavailability and blood-brain barrier (BBB) penetration. Future work will focus on the enhancement of BBB penetration, increased bioavailability, and route of administration to improve IDO-PROTAC potency for combination with other forms of immunotherapy for GBM patient treatment.
DDRE-44. TIRABRUTINIB MONOTHERAPY FOR RELAPSED PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA: HIGH RESPONSE RATE, COMMON SKIN-RELATED DISORDERS, AND DURABLE REMISSION IN A SUBSET OF PATIENTS
Authors: Sasaki Nobuyoshi , Kobayashi Keiichi , Saito Kuniaki , Onoda Ryo , Seiya Yousuke , Yamagishi Yuki , Suzuki Saki , Nakatomi Hirofumi , Shiokawa Yoshiaki , Nagane Motoo
Published: November 2021

BACKGROUNDS

Prognosis of relapsed primary central nervous system lymphoma (rPCNSL) is poor ranging between 2.2 and 16 months, and the optimal treatment strategy has not been established. Tirabrutinib is a second generation Bruton’s tyrosine kinase (BTK) inhibitor, approved by the Japanese Pharmaceutical and Medical Devices Agency (PMDA) for relapsed and refractory (r/r) PCNSL in March 2020. While an overall response rate (ORR) of 64% and progression-free survival (PFS) of 2.9 months was reported in a phase 1/2 study, the real-world treatment results of rPCNSL treated with tirabrutinib have not been investigated yet.

METHODS

Treatment results of rPCNSL patients treated with tirabrutinib at the author’s institution including response rate, PFS, overall survival (OS), and toxicity profiles were retrospectively analyzed.

RESULTS

Eleven patients were identified (median age: 73 [range: 50-83], median PFS: 70 [range: 40-90]). Response was CR in four (36.4%), PR in five (45.4%), PD in two (18.2%) patients, providing with an ORR of 81.8%. At a median follow up of 25.7 months, relapse was observed in seven patients (63.6%), and median PFS was 3.0 months. Durable remission of more than six months was obtained in four patients (36.4%). As for toxicities, six patients (54.5%) had skin-related disorders, which lead to tirabrutinib interruption in two (18.2%), dose reduction in three (27.3%), and discontinuation in two patients (18.2%). Grade 3/4 hematological toxicities were grade 4 neutropenia in one, and grade 3 lymphopenia in five patients (45.4%). No deaths have been observed.

DISCUSSION

Tirabrutinib monotherapy achieved a high response rate in rPCNSL, while skin-related disorders appeared to be the major obstacle leading to treatment interruption or discontinuation. Overall median PFS was in line with the phase 1/2 study. A subset of patients achieved durable remission, suggesting its strong benefit in certain patients. Further investigation of predictive biomarkers for response to tirabrutinib is warranted.
DDRE-46. REDUCED CANCER CELL SENSITIVITY TO TUMOR TREATING FIELDS (TTFields) THROUGH ACTIVATION OF THE PI3K/AKT/mTOR SIGNALING PATHWAY CAN BE MITIGATED USING PI3K INHIBITORS OR PI3K/mTOR DUAL INHIBITORS
Authors: Klein-Goldberg Anat , Voloshin Tali , Zemer-Tov Efrat , Paz Rom , Koren Lilach , Wainer-Katsir Kerem , Volodin Alexandra , Koltun Bella , Brant Boris , Haber Adi , Giladi Moshe , Weinberg Uri , Palti Yoram
Published: November 2021

INTRODUCTION

Tumor Treating Fields (TTFields) therapy is an approved anti-cancer treatment modality applied non-invasively and loco-regionally to the tumor region. TTFields have been demonstrated to extend life, however, most patients do eventually progress. The current study aimed to identify potential molecular mechanisms involved in reduced cellular sensitivity to TTFields.

METHODS

Cancer cells that exhibit reduced sensitivity to TTFields were generated by continuous long duration application of TTFields (7 or 13 days, depending on the cell line). Changes in cellular signaling pathways were evaluated in ovarian A2780 and glioblastoma U-87 MG cancer cells exposed to long-term relative to short-term (3 or 7 days, depending on the cell line) treatment with TTFields using Luminex multiplex assay followed by Western blot validation. The relevance of the affected pathways was confirmed through evaluation of the response to long-term application of TTFields in combination with pharmacological pathway inhibitors by measuring cell counts, apoptosis, and clonogenicity. Relevant pathway markers in tumor sections from tumor-bearing rats treated with TTFields were examined using immunohistochemistry.

RESULTS

Continuous long-term application of TTFields reduced cellular sensitivity to TTFields and was accompanied by increased levels of phosphorylated AKT, mTOR and additional proteins from the PI3K/AKT/mTOR signaling pathway. Increased phosphorylation of AKT was also evident in tumor sections from rats treated with TTFields. Concomitant use of TTFields with PI3K inhibitors or PI3K/mTOR dual inhibitors sensitized A2780 cells to long-term TTFields application.

CONCLUSION

Our study demonstrates that decreased cancer cell sensitivity to long-term TTFields application is mediated by activation of the PI3K/AKT/mTOR signaling pathway and provides a rationale for further examining the potential benefit of combining TTFields with PI3K or PI3K/mTOR dual inhibitors.
EPID-07. EPIDEMIOLOGICAL CHARACTERISTICS AND SURVIVAL OF PATIENTS WITH DIFFUSE GLIOMA IN BRAZIL: PRELIMINARY RESULTS OF A MULTICENTRIC RETROSPECTIVE STUDY - LACOG 0619
Authors: Yamada Camilla , Vasques Carolina , Coutinho Rodrigo , Maldaun Marcos , Baldotto Clarissa , Viola Fabiana , Maluf Fernando , Santos Vanessa , Pessoa Carolina , Pacheco Patrícia , Matias Danielli , Oliveira Daniela , Peria Fernanda , de Jesus Rafaela , Rebelatto Taiane , Malheiros Suzana
Published: November 2021

INTRODUCTION

In Brazil, most of the 9,196 deaths due to brain cancers in 2017 were gliomas. There is a dearth of epidemiological data on diffuse glioma in Brazil.

METHODS

LACOG 0619 is a multicentric retrospective cohort study, which included patients from nine tertiary oncology centers. Patients aged ≥18 years with histologically proven astrocytoma, oligodendroglioma, oligoastrocytoma or glioblastoma diagnosed from June 2010 to June 2019 were included. The study protocol was approved by each Institutional Review Board.

RESULTS

642 patients were included in the analysis. Median age was 51.0 (19-91) years. Most patients were male (n=364, 56.8%), 175 (27.3%) had ECOG 0-1, and 480 (74.8%) had private healthcare insurance. Neurological symptoms were present in 568 (88.5%) patients at diagnosis, and 263 (41.0%) had a history of seizure before surgery. Regarding histology, 361 (56.2%) had glioblastoma, 162 (25.2%) had astrocytoma, 90 (14.0%) had oligodendroglioma, and 23 (3.6%) had glioma NOS. Gross total resection was performed in 168 (26.2%), subtotal resection in 292 (45.5%), biopsy in 108 (16.8%), conventional radiotherapy in 380 (59.2%), and hypofractionation in 44 (6.9%) patients. Concomitant chemoradiotherapy was administered to 370 (57.6%) patients, mostly with temozolamide (n=362, 97.8%). Furthermore, 434 (67.7%) patients received maintenance chemotherapy, 398 with temozolamide (< 6 cycles in 112 [28.4%], 6 cycles in 75 [18.8%], and >6 cycles in 214 [3.8%]). Median follow-up was 29 months (26-33). Median OS according to histology was: 35 months (95%CI 26-46) for glioblastoma, 91 months (95%CI 35-NR) for glioma NOS, and not reached for astrocytoma and oligodendroglioma. Median OS by number of temozolamide maintenance cycles was 18 months (95%CI 15-24) for < 6 cycles and not reached for 6 cycles or more.

CONCLUSIONS

This is the first multicentric cohort evaluating Brazilian patients with diffuse glioma, providing important data on epidemiology, treatment patterns, and survival in the country.
EPID-11. A POPULATION STUDY OF CLINICAL TRIAL ACCRUAL FOR WOMEN AND MINORITIES IN NEURO-ONCOLOGY FOLLOWING THE NIH REVITALIZATION ACT
Authors: Reihl Sheantel , Patil Nirav , Morshed Ramin , Mehari Mulki , Aabedi alexander , Chukwueke Ugonma , Porter Alyx , Fontil Valy , Cioffi Gino , Waite Kristin , Kruchko Carol , Ostrom Quinn , Barnholtz-Sloan Jill , Hervey-Jumper Shawn
Published: November 2021

INTRODUCTION

The NIH Revitalization Act, implemented 29 years ago, set to improve the representation of women and minorities in clinical trials. In this study, we investigate the progress made in neuro-oncology in all phase therapeutic clinical trials for neuro-epithelial central nervous system tumors in comparison to their demographic-specific age-adjusted disease incidence and mortality.

METHODS

Registry study of all published clinical trials for World Health Organization (WHO) defined neuro-epithelial CNS tumors between January 2000 and December 2019. Study participants for trials were obtained from PubMed and ClinicalTrials.gov. Population-based data from the CBTRUS for incidence analyses. SEER-18 Incidence-Based Mortality data was used for mortality analysis. Descriptive statistics, Fisher exact, and c2 tests were used to analyze the data.

RESULTS

Among 662 published clinical trial articles representing 49, 907 accrued participants, 62.5% of study participants were men and 37.5% were women (P< 0.0001) representing a mortality specific over-accrual for men (P= 0.001) and under-accrual for women (P= 0.001). Whites, Asians, Blacks, and Hispanics represented 91.7%, 1.5%, 2.6%, and 1.7% of trial participants. Compared with their US cancer mortality, Blacks (47% of expected mortality, P=.008), Hispanics (17% of expected mortality, P< .001) and Asians (33% of expected mortality, P< .001) were underrepresented compared with Whites (114% of expected mortality, P< .001).

CONCLUSIONS

Nearly 30 years since the Revitalization Act, minorities and women are consistently underrepresented when compared with their demographic-specific incidence and mortality in therapeutic clinical trials for neuroepithelial tumors. This study provides a framework for investigating cancer clinical trial accrual and offers guidance regarding workforce factors associated with enrollment of vulnerable patients.
EPID-22. IMPROVED SHORT-TERM OUTCOMES AND LONG-TERM SURVIVORSHIP IN RELATION TO IMMUNOTHERAPY FOR PATIENTS WITH GLIOBLASTOMA BASED ON ANALYSIS OF THE NATIONAL CANCER DATABASE (NCDB)
Authors: Zhu Ping , Du Xianglin , Tandon Nitin , Esquenazi Yoshua , Zhu Jay-Jiguang
Published: November 2021

OBJECTIVES

To explore the impact of immunotherapy on short-term outcomes and long-term survival rates, and the predictors of immunotherapy receipt in patients with glioblastoma (GBM) using NCDB.

METHODS

A total of 74245 GBM patients were derived from the NCDB from 2004 to 2014. Analyses include short-term outcomes (at least 6-month, 1-year, or 2-year after diagnosis) and long-term survivorship (at least 3-year). The Kaplan-Meier method and accelerated failure time (AFT) models were performed for survival analysis. The multivariable binary logistic regressions were applied to identify predictors of immunotherapy receipt. Random survival forest was conducted to validate the variable importance and decision tree as well.

RESULTS

A total of 766 (1.0%) GBM patients received immunotherapy as the first-line treatment. The multivariable binary logistic regressions identified the significant predictors related to immunotherapy receipt, including the recent years of diagnosis (especially 2013 and 2014), age < 65 years, higher income, private insurance, residence-hospital distance >50 miles, care transition, treatment at the facility located in South regions or academic facilities, and adjuvant therapy. After adjusting socio-demographics, facility characteristics, and clinical treatments (surgery and adjuvant therapy), patients received immunotherapy experienced the significantly prolonged OS compared to those who didn’t [OS (months): 16.0 vs. 9.8, log-rank test p-value: < 0.001; Time Ratio (TR): 1.26 vs. 1.00 (Ref.), multivariable AFT p-value: < 0.001]. In multivariable logistic regressions, compared to patients without immunotherapy, the likelihoods of 6-month (OR: 3.89, p< 0.001), 1-year (OR: 2.38, p< 0.001), and 2-year (OR: 1.58, p=0.001) survival rates were significantly increased for those received immunotherapy. Regarding the long-term survivorship, immunotherapy was significantly associated with a 68% higher likelihood of 3-year survival rate (p=0.004).

CONCLUSIONS

Our findings demonstrated that immunotherapy in GBM patients, albeit small sample size, was significantly associated with improved short-term outcomes and 3-year survivorship after adjusting traditional clinical treatments and other covariates.
IMMU-04. UNVEILING THE TUMOR-METABOLOME-IMMUNITY AXIS OF GLIOMA
Authors: Friedrich Mirco , Bunse Lukas , Sankowski Roman , Wick Wolfgang , Prinz Marco , Platten Michael
Published: November 2021

The glioma microenvironment orchestrates tumor evolution, progression, and resistance to therapy. In high-grade gliomas, microglia and monocyte-derived macrophages constitute up to 70% of the tumor mass. However, the dynamics and phenotypes of intratumoral myeloid cells during tumor progression are poorly understood. Here we define myeloid cellular states in gliomas by longitudinal single-cell profiling and demonstrate their strict control by the tumor genotype. We report the unexpected and clinically highly relevant finding that human as well as murine gliomas with Isocitrate Dehydrogenase (IDH)1-R132H, a key oncogenic driver mutation of glioma, subdue their innate immune microenvironment by prompting a multifaceted reprogramming of myeloid and T cell metabolism. We employed integrated single-cell transcriptomic, time-of-flight mass cytometry and proteomic analyses of human healthy cortex control and glioma samples to identify myeloid cell subsets with distinct fates in IDH-mutated glioma that diverge from canonical trajectories of antigen-presenting cells as a result of a monocyte-to-macrophage differentiation block. Moving beyond single time point assessments, we now longitudinally describe differential immune cell infiltration and phenotype dynamics during glioma progression that are orchestrated by a fluctuating network of resident microglial cells and educated recruited immune cells. IDH mutations in glioma induce a tolerogenic alignment of their immune microenvironment through increased tryptophan uptake via large neutral amino acid transporter (LAT1)-CD98 and subsequent activation of the aryl hydrocarbon receptor (AHR) in educated blood-borne macrophages. In experimental tumor models, this immunosuppressive phenotype was reverted by LAT1-CD98 and AHR inhibitors. Taken together with direct effects on T cell activation, our findings not only link this oncogenic metabolic pathway to distinct immunosuppressive pathways but also provide the rationale and novel molecular targets for the development of immunotherapeutic concepts addressing the disease-defining microenvironmental effects of IDH mutations.
IMMU-07. REPROGRAMMING OF MICROGLIA/MACROPHAGES IN GLIOBLASTOMA IMPROVES ANTI-TUMOR T CELL RESPONSES
Authors: Fermi Valentina , Warta Rolf , Jungk Christine , Trong Philip Dao , Unterberg Andreas , Herold-Mende Christel
Published: November 2021

Glioblastoma (GBM) still remains incurable. In search for new treatment modalities immunotherapy might be attractive but highly depends on a sufficient infiltration and function of effector T cells in an immunosuppressive microenvironment. In this study, we analyzed if blocking or reprogramming M2polarized glioma-associated microglia/macrophages (GAMs) could improve spontaneous effector T cell responses and thus enhance the effectiveness of immunotherapy. This was tested by sorting patient-derived CD11b+ cells from GBM tissues and treating these GAMs with small molecule inhibitors (SMI) targeting the colony stimulating factor1 receptor (CSF1R). Especially CD11b+ cells treated with the SMI GW2580 presented with a reduced expression of the M2 marker CD163 (p < 0.01) and an increased expression of HLA-DR (p < 0.05). Conditioned media of SMI-treated GAMs also contained significantly higher levels of nitrite (p < 0.001) and a reduced concentration of the immunosuppressive cytokine IL-6 (p < 0.05). Moreover, gene expression profiles of GW2580-treated GAMs showed a shift from an immunosuppressive towards a pro-inflammatory phenotype. Most importantly, the addition of conditioned media of GW2580-treated GAMs to a co-culture of autologous tumor and T cells significantly reduced the number of live tumor cells as compared to the use of conditioned media of untreated GAMs (p < 0.05). Interestingly, in some cases the ability of T cells to transmigrate through a dense barrier of autologous tumor-derived endothelial cells could also be increased. In summary, we showed that CSF-1R blockade with the SMI GW2580 can reprogram GAM phenotype and thereby improve T cell activation. This strongly suggests further studies on the use of GW2580 in combination with immunotherapeutic approaches for the treatment of GBM.
IMMU-12. TUMOR CELL IDO ENHANCES IMMUNE SUPPRESSION AND DECREASES SURVIVAL INDEPENDENT OF TRYPTOPHAN METABOLISM IN GLIOBLASTOMA
Authors: Zhai Lijie , Bell April , Ladomersky Erik , Lauing Kristen , Bollu Lakshmi , Nuygen Brenda , Genet Matthew , Kim Miri , Mi Xinlei , Kocherginski Masha , Wu Jennifer , Schipma Matthew , Wray Brian , Griffiths John , Unwin Richard , Clark Simon , Acharya Rajesh , bao Riyue , Horbinski Craig , Lukas Rimas , Schiltz Gary , Wainwright Derek
Published: November 2021

OBJECTIVE

Indoleamine 2,3-dioxygenase 1 (IDO; IDO1) is an immune checkpoint that’s characterized as a potent immunosuppressive mediator through its ability to metabolize tryptophan and wild-type IDH patient-resected glioblastoma (GBM) expresses IDO in ≥ 95% of cases. Recent findings from our group led us to investigate the alternative hypothesis that IDO possesses immunosuppressive effects that are independent of its associated metabolic activity.

METHODS

Murine GBM cell lines that overexpress either wild-type or enzyme-null IDO were created for in vivo characterization of IDO enzyme-independent immunosuppressive function. Microarray was conducted to identify human IDO expression-correlated genes, which were further investigated in human GBM cell lines, patient GBM tissues and plasma, as well as the TCGA database. Ex vivo cell co-culture assays and syngeneic mouse orthotopic GBM models were employed to study immunosuppressive mechanisms.

RESULTS

Here, we demonstrate that non-enzymic IDO activity decreases survival in experimental animals and increases the expression of immunosuppressive complement factor H (CFH) in human GBM. CFH mRNA levels positively correlate with those of IDO and many other immunosuppressive genes in patient resected GBM and can be applied as a prognostic marker in both lower grade gliomas and GBM. Similar to IDO, the increased expression of CFH in patient-resected glioma was positively correlated with an increased signature for regulatory T cells (Tregs) and myeloid-derived suppressive cells (MDSCs). High expression of CFH in tumor cells increases intratumoral Tregs levels and decreases overall survival in mice with GBM, while inducing tumor associated macrophage cell differentiation.

CONCLUSIONS

Here, we demonstrated that glioblastoma (GBM) cell IDO promotes the accumulation of intratumoral FoxP3+ regulatory T cells (Tregs) and tumor progression while decreasing overall survival - independent of IDO enzyme activity. Our study reveals a targetable non-metabolic IDO-dependent mechanism for future therapeutic intervention in patients with GBM.
IMMU-18. GLIOBLASTOMA-DERIVED EXTRACELLULAR VESICLES INDUCE DRAMATIC CHANGES IN THE TRANSCRIPTOMIC LANDSCAPE OF MONOCYTES
Authors: Himes Benjamin , Nesvick Cody , Li Helen , Jung Mi-Yeon , Parney Ian
Published: November 2021

Glioblastoma (GBM) is the most common and deadly primary brain tumor. Novel therapeutic strategies are urgently needed to improve outcomes, but a number of disease-specific barriers pose challenges to innovation. Tumor-mediated immunosuppression is one such hurdle, and a growing body of evidence suggests that GBM-derived extracellular vesicles (EVs) play an important role in host immunosuppression. GBM-derived EVs have been shown to induce the formation of immunosuppressive monocytes, including myeloid-derived suppressor cells. Work by our group and others has increasingly shown that these immunosuppressive monocytes are a heterogenous group, and that many constellations of surface markers are inadequate to capture the changes wrought by EVs. In order to better understand the effects of GBM-EVs on monocytes, we conducted RNA-seq analysis on monocytes collected from four healthy donors treated with GBM-derived EVs harvested by ultracentrifugation from the patient-derived BT116 cell line. Following 72h of EV conditioning, total RNA was harvested from treated monocytes and untreated controls. RNA-seq was performed using the Illumina HiSeq4000 platform with paired end index reads. Analysis was performed using RNA STAR and the hg19 ENCODE reference sequence. Differential expression analysis was performed using DESeq2. Genes with a false-discovery rate (FDR)-corrected P value < 0.05 and a log2 fold-change value of >|1| were considered significantly different between groups. Pathway analysis was performed using ClueGO in Cytoscape (GO term fusion on, p< 0.05). Unsupervised clustering analysis of the top 500 most differentially-expressed genes demonstrated grouping of BT116 EV-treated monocytes together versus untreated monocytes. Pathway analysis upregulated genes in pathways important for heparan sulfate proteoglycan synthesis and cholesterol synthesis, which could potentially point to positive regulation of EV uptake. Downregulated pathways included regulation of T cell differentiation and chemoattractant activity, underscoring the induction of a potentially immunosuppressive phenotype by GBM-derived EVs.
IMMU-23. NEOANTIGEN-DIRECTED CELLULAR THERAPY IN A PRECLINICAL MOUSE MODEL OF MALIGNANT GLIOMA
Authors: Schaettler Max , Dunn Gavin
Published: November 2021

Adoptive cellular therapy in the form of CAR T cells or TCR engineered T cells has emerged as a novel approach in the treatment of both solid and hematologic malignancies. Neoantigens generated by tumor somatic mutations represent potentially attractive therapeutic targets in this context owing to their tumor-specific expression and circumvention of immunological tolerance. However, existing cell therapy systems generally target self-proteins or virally overexpressed antigens that fail to recapitulate the features of endogenous tumor neoantigens. Thus, there exists a need for a model in which tumor-specific neoantigens can be targeted via adoptive cellular therapy. Prior work from our lab identified the Imp3D81N mutation (mImp3) within GL261 as a neoantigen recognized by CD8 T cells in both intracranial tumors and draining cervical lymph nodes. To generate a system for targeting this neoantigen, we isolated and cloned mImp3-specific TCRs through a single-cell sort followed by a nested multiplexed PCR reaction. The specificity and functionality of these isolated TCRs was determined through introduction into a T cell hybridoma, identifying a top candidate based upon a high degree of cytokine production and specificity for the mutant epitope. A TCR transgenic mouse was then generated in which more than 90% of all T cells were CD8 T cells bearing this mImp3-specific TCR. T cells isolated from this mouse display specificity for the mImp3 peptide and display in vitro reactivity to GL261 and other cell lines in a mImp3-dependent manner. Therefore, this model represents the first TCR transgenic targeting a brain tumor neoantigen, opening the door for further investigation into cell therapy against this class of antigens.
IMMU-33. NEOANTIGEN-SPECIFIC T CELLS CAN INFILTRATE IDH-MUTANT LOWER GRADE GLIOMAS AND PERSIST IN THE PERIPHERAL BLOOD
Authors: Zhang Michael , Wang Cliff , Pan Zheng , Yuen Benjamin , Peng Songming , Kwok Darwin , Nejo Takahide , Martin Michael , Hong Chibo , Hilz Stephanie , Phillips Joanna , Shai Anny , Oberheim-Bush Nancy Ann , Hervey-Jumper Shawn , McDermott Michael , Mandl Stefanie , Okada Hideho , Costello Joseph
Published: November 2021

The prospect of using immunotherapy for IDH-mutant LGGs has been daunting given the immune-poor microenvironment and low mutational burden. We hypothesized that LGG-targeting T cells might still be present at low frequency and with limited regional infiltration into the tumor. To improve sensitivity, we combined high-density multi-region tumor sampling with high-throughput neoantigen-T cell screening for a patient with WHO Grade II diffuse astrocytoma who eventually progressed, at second recurrence, to anaplastic astrocytoma. We performed maximal-anatomic sampling from 10 distinct regions of the tumor at the initial resection, as well as single sampling at first recurrence, for exome-based prediction of clonal and subclonal expressed neoantigens, RNAseq-based estimation of regional immune cell composition, and T cell receptor (TCR) beta deep sequencing. Based on our predictions, we then generated a barcoded library of patient-specific peptide-HLA multimers loaded with predicted neopeptides. Using this library, neoantigen-specific CD8 T cells were captured and isolated from patient peripheral blood and subjected to single cell TCR sequencing. We screened patient-derived peripheral blood drawn two years after initial resection and identified five T cell clones recognizing three LGG neoepitopes. Two neoepitopes were derived from truncal, tumor-wide mutations, including a truncating splice-site mutation in TP53 and a missense mutation in MRPL46. Each of these neoepitopes were recognized by two distinct TCRs, consistent with TCR convergence. A third neoepitope was derived from a subclonal MRPL46 mutation. Using the TCR beta sequence as a molecular barcode, TCRs specific to the 2 clonal neoepitopes, but not the subclonal neoepitope, were detectable in the glioma and blood at initial resection, as well as in the recurrent glioma. In summary, we demonstrate the existence and persistence of neoantigen-targeting T cells within the blood and tumor of an IDH-mutant LGG patient. These findings suggest a feasible methodology to develop personalized T cell-based immunotherapies for IDH-mutant LGGs.
IMMU-53. STING-ING GLIOBLASTOMA WITH SPHERICAL NUCLEIC ACIDS
Authors: Mahajan Akanksha , Hurley Lisa , Tommasini-Ghelfi Serena , Dussold Corey , Stegh Alexander , Mirkin Chad
Published: November 2021

The Stimulator of Interferon Genes (STING) pathway represents a major innate immune sensing mechanism for tumor-derived DNA. Modified cyclic dinucleotides (CDNs) that mimic the endogenous STING ligand cGAMP are currently being explored in patients with solid tumors that are amenable to intratumoral delivery. Inadequate bioavailability and insufficient lipophilicity are limiting factors for clinical CDN development, in particular when consideration is given to systemic administration approaches. We have shown that the formulation of oligonucleotides into Spherical Nucleic Acid (SNA) nanostructures, i.e.,the presentation of oligonucleotides at high density on the surface of nanoparticle cores, lead to biochemical and biological properties that are radically different from those of linear oligonucleotides. First-generation brain-penetrant siRNA-based SNAs (NCT03020017, recurrent GBM) have recently completed early clinical trials. Here, we report the development of a STING-agonistic immunotherapy by targeting cGAS, the sensor of cytosolic dsDNA upstream of STING, with SNAs presenting dsDNA at high surface density. The strategy of using SNAs exploits the ability of cGAS to raise STING responses by delivering dsDNA and inducing the catalytic production of endogenous CDNs. SNA nanostructures carrying a 45bp IFN-simulating dsDNA oligonucleotide, the most commonly used and widely characterized cGAS activator, potently activated the cGAS-STING pathway in vitro and in vivo. In a poorly immunogenic and highly aggressive syngeneic mouse glioma model, in which tumours were well-established, only one dose of intranasal treatment with STING-SNAs decelerated tumour growth, improved survival and importantly, was well-tolerated. Our use of SNAs addresses the challenges of nucleic acid delivery to intracranial tumor sites via intranasal route, exploits the binding of dsDNA molecules on the SNA surface to enhance the formation of a dimeric cGAS:DNA complex and establishes cGAS-agonistic SNAs as a novel class of immune-stimulatory modalities for triggering innate immune responses against tumor.
INNV-02. ACCELERATING RESEARCH FOR BREAST CANCER BRAIN METASTASIS AND LEPTOMENINGEAL DISEASE THROUGH PATIENT-LED COLLABORATIONS
Authors: Hodgdon Christine
Published: November 2021

PATIENT-DRIVEN INITIATIVE OF THE METASTATIC BREAST CANCER (MBC) ALLIANCE

The Breast Cancer Brain Metastasis (BCBM) Initiative: Marina Kaplan Project launched in June 2020 as an official project of the MBC Alliance which includes 32 nonprofits, 12 industry partners, and 30 individual patient advocates. The project has grown to include 35 members with representation from industry, research institutions, and individual patients. Nearly one-third of the group is comprised of patients living with brain metastases or LMD.

DISPARITIES FOR PATIENTS LIVING WITH BCBM & LMD

In the US, approximately 200,000 new cases of brain metastases are diagnosed each year.1 Approximately 10-15% of patients with MBC will develop brain metastases, and may be as high as 30-50% for certain subtypes.2 A diagnosis of central nervous system (CNS) metastasis often accelerates an already incurable diagnosis. CNS metastasis are difficult to image and detect, tend to have poorer prognoses with lower overall survival, and are treated with invasive therapies which can have lasting side effects. Furthermore, most clinical trials exclude patients with CNS metastasis which further hinders research.

VALUES & OBJECTIVES

The overarching goal of this initiative is to accelerate the scope and breadth of evidence-based CNS metastasis research by targeting entities conducting clinical trials and collaborating with them to do the following: (1) Increase the quality and quantity of basic research; (2) increase the number of clinical trials in areas where research is lacking; (3) diversify the type of clinical trial interventions; (4) eliminate restrictive eligibility criteria in clinical trials; (5) Incorporate clinically meaningful trial endpoints.

References

Eichler, April F et al. The biology of brain metastases-translation to new therapies. Nat Rev. Clinical oncology vol. 8,6 (2011): 344-56. doi: 10.1038/nrclinonc.2011.58

Brosnan EM, Anders CK. Understanding patterns of brain metastasis in breast cancer and designing rational therapeutic strategies. Ann Transl Med. 2018;6(9):163. doi: 10.21037/atm.2018.04.35
INNV-14. PREDICTIVE UTILITY OF TEMOZOLOMIDE RESPONSE AS DETERMINED BY 3D EX-VIVO CELL CULTURE ASSAYS IN NEWLY DIAGNOSED GLIOBLASTOMA: A SINGLE INSTITUTION CASE SERIES EVALUATING PROGRESSION FREE SURVIVAL
Authors: Lipinski Lindsay J , Abad Ajay , Fenstermaker Robert A , Fabiano Andrew J , Prasad Dheerendra , Smith Ashley M , Gevaert Matthew , DesRochers Teresa M , Vibat Cecile Rose T
Published: November 2021

Glioblastoma is an aggressive tumor that is clinically and pathologically heterogeneous, and as such, remains challenging to treat. Response to initial standard treatment is widely variable and patient specific. We describe a cohort of 11 newly diagnosed patients enrolled in the 3D-PREDICT study at a single institution who underwent maximal safe surgical resection with tumor tissue collected prospectively for ex vivo cell culture assays against a panel of commonly used agents, including temozolomide. Nine of eleven patients received concurrent radiation + temozolomide followed by adjuvant temozolomide as per current standard of care. Two patients progressed immediately following concurrent chemoradiation; pseudoprogression was ruled out with short interval repeat imaging and clinical deterioration with pathology confirming recurrent tumor on re-resection in one patient. Median follow-up was 10 months (range 2-18). Outcomes were assessed retrospectively using Kaplan-Meier time-to-event curves, separating into two groups the temozolomide responders (n=4) and temozolomide nonresponders (n=7), as defined by the previously validated assay. The event was reached when radiographic tumor recurrence/progression occurred. Due to limited sample size, statistical significance was not reached, but a trend toward longer time to recurrence was noted among the temozolomide responder group. Continued experience with this tool may help clinicians predict which patients with newly diagnosed glioblastoma will respond well to initial treatment with temozolomide and those that may be more appropriate for clinical trial enrollment, independent of MGMT promoter methylation status. Longer term studies with a larger number of patients will help to determine the true significance of this drug response prediction assay.
INNV-20. RADIOGRAPHIC RESPONSE AND SEIZURE CONTROL IN IDH1 MUTANT GLIOMA PATIENTS USING IVOSIDENIB
Authors: Peters Katherine , Patel Mallika , Alford Candice , Chavez Gerardo , Kim Jung-Young , Durling Jennifer , Novack Tracy , Batich Kristen , Shoaf Madison , Hanzlik Emily , Affronti Mary , Johnson Margaret , Landi Daniel , Khasraw Mustafa , Desjardins Annick , Friedman Henry , Ashley David M
Published: November 2021

Isocitrate dehydrogenase 1 (IDH1) is commonly mutated in grade II-III gliomas, and the mutant enzyme leads to the production of the oncometabolite 2-hydroxyglutarate (2-HG). 2-HG is responsible for the gliomagenesis associated with these tumors and the promotion of seizures via glutamate receptors. Ivosidenib, a small molecule oral mIDH1 inhibitor, has shown promise in clinical trials to treat IDH1 mutant gliomas, and providers can utilize this agent in IDH1 mutant glioma patients. We evaluated our IDH1 mutant glioma patients treated off-label with ivosidenib and described the radiographic response and seizure control in this cohort when ivosidenib was initiated between October 2020 to February 2021. Radiographic response was determined using RANO criteria, and seizure control was determined by comparing seizures per month before and after initiation of ivosidenib. All patients represented received single-agent ivosidenib dosed at 500 mg orally once a day. One patient required a dose reduction to 250 mg orally once a day because of drug-induced diarrhea. In our cohort of six patients, patient age range was 31 to 74 years with four female patients and two male patients. Diagnoses represented were astrocytoma, IDH1 mutant (n=3) oligodendroglioma (WHO), IDH1 mutant, 1p19q co-deleted (n=2), and anaplastic astrocytoma IDH1 mutant (n=1). Three patients experienced a reduction of seizure frequency, two patients did not have seizures before or after therapy, and one patient remained with the same level of seizures (1 seizure/month). Radiographic responses recorded included three patients with stable disease, two patients with minor responses, and one patient with a partial response. Treatment with ivosidenib is ongoing for this cohort of mIDH1 glioma patients. Updated information on prolonged disease control and seizure control in this cohort of IDH1 mutant glioma patients will be presented. Therapeutics, such as ivosidenib, can lead to improved seizure control and radiographic outcomes in IDH1 mutant glioma patients.