Frequencies of 4 tumor-infiltrating lymphocytes potently predict survival in glioblastoma, an immune desert

BACKGROUND

GBM is an aggressive grade 4 primary brain tumor (BT), with a 5%-13% 5-year survival. Most human GBMs manifest as immunologically "cold" tumors or "immune deserts," yet the promoting or suppressive roles of specific lymphocytes within the GBM tumor microenvironment (TME) is of considerable debate.

METHODS

We used meticulous multiparametric flow cytometry (FC) to determine the lymphocytic frequencies in 102 GBMs, lower-grade gliomas, brain metastases, and nontumorous brain specimen. FC-attained frequencies were compared with frequencies estimated by "digital cytometry." The FC-derived data were combined with the patients' demographic, clinical, molecular, histopathological, radiological, and survival data.

RESULTS

Comparison of FC-derived data to CIBERSORT-estimated data revealed the poor capacity of digital cytometry to estimate cell frequencies below 0.2%, the frequency range of most immune cells in BTs. Isocitrate dehydrogenase (IDH) mutation status was found to affect TME composition more than the gliomas' pathological grade. Combining FC and survival data disclosed that unlike other cancer types, the frequency of helper T cells (Th) and cytotoxic T lymphocytes (CTL) correlated negatively with glioma survival. In contrast, the frequencies of γδ-T cells and CD56bright natural killer cells correlated positively with survival. A composite parameter combining the frequencies of these 4 tumoral lymphocytes separated the survival curves of GBM patients with a median difference of 10 months (FC-derived data; P < .0001, discovery cohort), or 4.1 months (CIBERSORT-estimated data; P = .01, validation cohort).

CONCLUSIONS

The frequencies of 4 TME lymphocytes strongly correlate with the survival of patients with GBM, a tumor considered an immune desert.

[EXTENDED ENDONASAL ENDOSCOPIC APPROACH IN TREATING PITUITARY ADENOMAS AND SKULL BASE TUMORS]

INTRODUCTION

The endoscopic endonasal approach (EEA) is a rapidly growing, minimally invasive discipline applied to a broad set of skull base tumors. The introduction of the endoscopic endonasal approach for the management of lesions of the skull base has produced a paradigm shift in the way these complicated lesions are managed. The extended endonasal approach provides the most direct route to the anterior cranial base including sella, cribriform plate, planum sphenoidale, suprasellar cistern, clivus and foramen magnum. Transsphenoidal microscopic pituitary surgery has long been considered the gold standard in surgical treatment of pituitary tumors. Extended endonasal endoscopic pituitary surgery has come into prominence over the last two decades as a superior alternative to microscopic surgery. Gaining experience in this approach has allowed the use of EEA for the surgical treatment of more complex pathologies such as meningiomas, craniopharyngiomas and more.

Toward a theranostic device for gliomas

BACKGROUND

In the surgical management of glioblastoma, a highly aggressive and incurable type of brain cancer, identification and treatment of residual tissue is the most common site of disease recurrence. Monitoring and localized treatment are achieved with engineered microbubbles (MBs) by combining ultrasound and fluorescence imaging with actively targeted temozolomide (TMZ) delivery.

METHODS

The MBs were conjugated with a near-infrared fluorescence probe CF790, cyclic pentapeptide bearing the RGD sequence and a carboxyl-temozolomide, TMZA. The efficiency of adhesion to HUVEC cells was assessed in vitro in realistic physiological conditions of shear rate and vascular dimensions. Cytotoxicity of TMZA-loaded MBs on U87 MG cells and IC50 were assessed by MTT tests.

RESULTS

We report on the design of injectable poly(vinyl alcohol) echogenic MBs designed as a platform with active targeting ability to tumor tissues, by tethering on the surface a ligand having the tripeptide sequence, RGD. The biorecognition of RGD-MBs onto HUVEC cells is quantitatively proved. Efficient NIR emission from the CF790-decorated MBs was successfully detected. The conjugation on the MBs surface of a specific drug as TMZ is achieved. The pharmacological activity of the coupled-to-surface drug is preserved by controlling the reaction conditions.

CONCLUSIONS

We present an improved formulation of PVA-MBs to achieve a multifunctional device with adhesion ability, cytotoxicity on glioblastoma cells and supporting imaging.

Deoxyhypusine hydroxylase: A novel therapeutic target differentially expressed in short-term vs long-term survivors of glioblastoma

Glioblastoma (GB) is the most aggressive neoplasm of the brain. Poor prognosis is mainly attributed to tumor heterogeneity, invasiveness and drug resistance. Only a small fraction of GB patients survives longer than 24 months from the time of diagnosis (ie, long-term survivors [LTS]). In our study, we aimed to identify molecular markers associated with favorable GB prognosis as a basis to develop therapeutic applications to improve patients' outcome. We have recently assembled a proteogenomic dataset of 87 GB clinical samples of varying survival rates. Following RNA-seq and mass spectrometry (MS)-based proteomics analysis, we identified several differentially expressed genes and proteins, including some known cancer-related pathways and some less established that showed higher expression in short-term (<6 months) survivors (STS) compared to LTS. One such target found was deoxyhypusine hydroxylase (DOHH), which is known to be involved in the biosynthesis of hypusine, an unusual amino acid essential for the function of the eukaryotic translation initiation factor 5A (eIF5A), which promotes tumor growth. We consequently validated DOHH overexpression in STS samples by quantitative polymerase chain reaction (qPCR) and immunohistochemistry. We further showed robust inhibition of proliferation, migration and invasion of GB cells following silencing of DOHH with short hairpin RNA (shRNA) or inhibition of its activity with small molecules, ciclopirox and deferiprone. Moreover, DOHH silencing led to significant inhibition of tumor progression and prolonged survival in GB mouse models. Searching for a potential mechanism by which DOHH promotes tumor aggressiveness, we found that it supports the transition of GB cells to a more invasive phenotype via epithelial-mesenchymal transition (EMT)-related pathways.

[LASER INTERSTITIAL THERMAL THERAPY (LITT) IN NEUROSURGERY]

INTRODUCTION

Laser interstitial thermal therapy (LITT) has emerged as a new treatment option for various conditions within the neurosurgery world, not only due to its minimal invasiveness but also because it has been shown to be safe and effective. Combined with magnetic resonance thermography, LITT gives surgeons the ability to estimate damage in real time and precisely ablate the target tissue while minimizing thermal damage to adjacent structures. In recent years, LITT has become a reality in epilepsy surgery and in neuro-oncology and is emerging as an option in other fields in neurosurgery.

The clinical significance of radiological changes associated with gliadel implantation in patients with recurrent high grade glioma

Gliadel occasionally induces edema following its implantation. We aimed to correlate such post-surgical radiological changes to its efficacy and subsequent survival. Fifty-six patients with recurrent high grade glioma were treated between 2005 and 2016 with Gliadel implantation. Volumetric measurements of MRI features, including FLAIR abnormalities, tumor bulk (volume of gadolinium enhancement on T1) and resection cavity volumes over time were conducted. To assess dynamics over time, linear regression trendlines for each of these were calculated and examined to correlate with survival. Median follow-up after resection was 21.5 months. Median survival post-Gliadel implantation and overall survival since diagnosis were 12 months and 22 months, respectively. A subgroup of patients (n = 6) with a transient increase in FLAIR changes volume over time survived significantly longer post-Gliadel compared to those who did not demonstrate such change (36 vs 12 months, p = .03). Positive trends, representing overall growth in volume over time, of tumor bulk and resection cavity predicted survival in multivariate analyses (hazard ratios 7.9 and 84, p = .003 and .002, respectively). Increase in tumor bulk and resection cavity over time were associated with decreased survival, while transient FLAIR increase was a favorable prognostic factor. This may represent a transient inflammatory process in the tumor, possibly stemming from a presumed immune-mediated anti-tumor response.

P11.33.B Tumour Treating Fields (TTFields; 200 kHz) with chemo-radiation and maintenance TTFields/temozolomide as first-line treatment for newly-diagnosed glioblastoma: The phase 3 TRIDENT Trial (EF-32)

Background

Tumour Treating Fields therapy (TTFields; 200 kHz) is a noninvasive, loco-regional, antimitotic treatment approved for newly diagnosed glioblastoma (ndGBM) and mesothelioma. In the phase 3 EF-14 trial, TTFields/temozolomide (TMZ) significantly increased overall survival (OS) and progression-free survival (PFS) vs TMZ alone in patients with ndGBM. TTFields-related adverse events (AEs) were mainly dermatological with no increases in systemic toxicity. In preclinical models, the addition of TTFields to radiotherapy (RT) increased the therapeutic effect. In 2 clinical pilot phase 2 studies, TTFields added to RT/TMZ was reported as feasible and well-tolerated.

Material and Methods

TRIDENT (EF-32; NCT04471844) is an international, phase 3 randomised trial comparing TTFields (200 KHz, ≥ 18 h/day)/RT/TMZ vs RT/TMZ alone. Eligibility criteria include histologically confirmed ndGBM, ≥ 18 years of age (≥ 22 years of age; US), Karnofsky Performance Status ≥ 70, life expectancy ≥ 3 months, adequate organ function and eligible for RT/TMZ - participants will be stratified by extent-of-resection and O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status. During the initial 6-week investigational period, patients in the experimental arm will receive continuous TTFields and concomitant RT/TMZ whilst patients in the control arm will receive only RT/TMZ. Subsequently, all patients will receive TTFields and 6 cycles of maintenance TTFields/TMZ. TTFields will continue for 24 months or until second disease progression per Response Assessment in Neuro-Oncology (RANO), whichever occurs first. The primary endpoint is median OS. Secondary endpoints include median PFS (RANO), 1- and 2-year survival rates, overall radiological response (RANO), PFS6, PFS12, severity and frequency of AEs (Common Terminology Criteria for Adverse Events v5.0), post-treatment pathological changes in resected GBM tumours, quality-of-life per EORTC QLQ-C30, OS correlation to TTFields duration-of-usage, and neurological assessment per NANO (Neurological Assessment in Neuro-Oncology) and RANO criteria. Survival will be measured from time-of-randomisation. Sample size (N = 950; randomised 1:1) was powered for a hazard ratio &lt; 0.8 with a 5% type I error. The hypothesis, that first-line TTFields/RT/TMZ can significantly improve OS vs RT/TMZ, will be tested using a stratified log-rank test.

The study is currently open to enrollment in locations in Austria, Belgium, Czech Republic, France, Germany, Israel, Switzerland, and across the US.

CLRM-09 FIRST-LINE Tumor TREATING FIELDS (200 KHZ) THERAPY FOR NEWLY-DIAGNOSED GLIOBLASTOMA: THE PHASE 3 TRIDENT TRIAL (EF-32)

BACKGROUND

Tumor Treating Fields therapy (TTFields; 200 kHz) comprise alternating electric fields that disrupt cancer cell division, and is approved for newly diagnosed glioblastoma (ndGBM), recurrent GBM and mesothelioma. In the phase 3 EF-14 trial, TTFields/temozolomide (TMZ) significantly increased overall survival (OS) and progression-free survival (PFS) vs TMZ alone in patients with ndGBM. TTFields-related adverse events (AEs) were mainly dermatological with no increases in systemic toxicity. In preclinical models, the addition of TTFields to radiotherapy (RT) increased the therapeutic effect. Additionally, TTFields added to RT/TMZ was reported as feasible and well-tolerated in 2 clinical pilot phase 2 studies.

MATERIALS AND METHODS

TRIDENT (EF-32; NCT04471844) is an international, phase 3 randomized trial comparing TTFields (200 KHz, ≥18 h/day)/RT/TMZ vs RT/TMZ alone. Adult patients (N=950; ≥18 years of age [≥22 years of age; US]) with histologically confirmed ndGBM, Karnofsky Performance Status ≥70, life expectancy ≥3 months, adequate organ function and eligible for RT/TMZ will be enrolled. Patients will be stratified by extent-of-resection and MGMT promoter methylation status and randomized 1:1 to receive continuous TTFields/RT/TMZ or RT/TMZ during the investigational period. Subsequently, all patients will receive TTFields/6 cycles of maintenance TTFields/TMZ; TTFields will continue for 24 months or until second disease progression per Response Assessment in Neuro-Oncology (RANO). The primary endpoint is median OS. Secondary endpoints include median PFS (RANO), 1- and 2-year survival rates, overall radiological response (RANO), PFS6, PFS12, severity and frequency of AEs and quality-of-life, OS per TTFields duration-of-usage. The study is powered at 80% to detect a hazard ratio of &lt;0.8 (5% type I error). The study is currently open to enrolment in Austria, Belgium, Czech Republic, France, Germany, Israel, Switzerland, and across the US.

Clinical and prognostic implications of rim restriction following glioma surgery

Rim restriction surrounding the resection cavity of glioma is often seen on immediate post-op diffusion-weighted imaging (DWI). The etiology and clinical impact of rim restriction are unknown. We evaluated the incidence, risk factors and clinical consequences of this finding. We evaluated patients that underwent surgery for low-grade glioma (LGG) and glioblastoma (GBM) without stroke on post-operative imaging. Analyses encompassed pre- and postoperative clinical, radiological, intraoperative monitoring, survival, functional and neurocognitive outcomes. Between 2013 and 2017, 63 LGG and 209 GBM patients (272 in total) underwent surgical resection and were included in our cohort. Post-op rim restriction was demonstrated in 68 patients, 32% (n = 20) of LGG and 23% (n = 48) of GBM patients. Risk factors for restriction included temporal tumors in GBM (p = 0.025) and insular tumors in LGG (p = 0.09), including longer surgery duration in LGG (p = 0.008). After a 1-year follow-up, LGG patients operated on their dominant with post-op restriction had a higher rate of speech deficits (46 vs 9%, p = 0.004). Rim restriction on postoperative imaging is associated with longer duration of glioma surgery and potentially linked to brain retraction. It apparently has no direct clinical consequences, but is linked to higher rates of speech deficits in LGG dominant-side surgeries.

Nocardia cyriacigeorgica brain abscess in a patient on low dose steroids: a case report and review of the literature

Background

Nocardia cyriacigeorgica was first described in 2001. It is an emerging pathogen that mainly affects immunocompromised patients. A brain abscess caused by N. cyriacigeorgica has been reported only in immunocompromised hosts. We present a rare case of brain abscess caused by N. cyriacigeorgica in an adult male receiving low dose steroids.

Case presentation

A 75-year-old male weekend gardener without an immunocompromising condition presented with neurological complaints that were initially attributed to an ischemic stroke. Due to the unusual presentation and rapid progression, his condition was thought to be caused by a cerebral space-occupying lesion. He underwent an emergent right-sided parietal craniotomy and the histopathological report of the specimen was an abscess caused by N. cyriacigeorgica. The patient received appropriate antibiotic treatment and completely recovered without sequelae.

Conclusions

Nocardia species are a rare cause of brain abscess in immunocompetent patients. Their clinical presentation can mimic other more common cerebral diseases, such as brain tumors (primary and secondary) and stroke. The possibility of an abscess caused by N. cyriacigeorgica should also be considered in the differential diagnosis in an immunocompetent patient.

Abstract 266: Adaptation of colorectal cancer cells to the brain microenvironment: The role of IRS2

Colorectal cancer (CRC) reflects the fourth most frequent etiology of brain metastasis (BM), with rising incidence. Yet, molecular mechanisms supporting the formation of these lesions from CRC are unknown. We aimed to explore drivers enabling tropism and adaptation of CRC cells to the brain environment and decipher mechanisms facilitating the process. We analyzed the FoundationOne database, which contains genomic alterations data of cancer-related genes in over 16,000 human CRC primary and metastasis samples. Increased prevalence of IRS2 gene amplification was observed in 13% of BM, compared to only 3% of primary tumors or other metastatic sites. IRS2 is a cytoplasmic adaptor mediating effects of insulin and IGF-1 receptors and is involved in more aggressive behavior of different cancer types. In agreement with the genomic data, immunohistochemistry of human clinical samples showed increased expression of IRS2 protein in BM. We constructed an in vitro system mimicking the brain microenvironment using cultured human astrocytes or their conditioned media. Under these conditions, IRS2-overexpressed CRC cells survived better and formed larger 3D spheres. IRS2-silenced CRC cells showed a mirror image. Moreover, in an intracranial CRC BM mouse model, IRS2-overexpressed cells generated larger brain lesions, while silencing IRS2 dramatically decreased tumor outgrowth and extended survival. Interestingly, transcriptomic analysis revealed enrichment of oxidative phosphorylation (OXPHOS) and Wnt/β-catenin pathways by IRS2. Indeed, IRS2-expressing cells showed increased mitochondrial activity and glycolysis-independent viability. Furthermore, IRS2-expressing cells had increased β-catenin transcriptional activity. Interestingly, β-catenin inhibition (using ICG-001) or IRS2 inhibition (using NT219) in IRS2-expressing cells decreased their viability, β-catenin transcriptional activity, and mitochondrial activity, suggesting involvement of IRS2 in modulating OXPHOS through β-catenin. β-catenin is known to confer 5-FU resistance; consequently, we showed that combination of 5-FU and NT219 worked in synergy, inhibited the formation of BM, and extended animal survival. These data reveal, for the first time, the unique genomic profile of CRC BM and imply the IRS2 role in promoting CRC BM. These effects may be mediated, at least in part, by modulation of the β-catenin and OXPHOS pathway. Given the molecular signature described, the approach to patients with BM may be significantly impacted by agents such as NT219.

Citation Format: Inbal Greenberg, Anat Klein, Rachel Grossman, Ethan Sokol, Eilam Yeini, Paula Ofek, Ronit Satchi-Fainaro, Bertrand Liang, Hadas Reuveni, Tami Rubinek, Ido Wolf. Adaptation of colorectal cancer cells to the brain microenvironment: The role of IRS2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 266.

A Prospective Evaluation of Quality of Life in Patients Undergoing Extended Endoscopic Endonasal Surgery for Benign Pituitary Gland Lesion

Introduction Endoscopic endonasal surgery (EES) has become the preferred approach for pituitary tumor resection. Nevertheless, research on quality of life related to pituitary adenoma surgery is scarce.

Objective The aim of the study is to evaluate short-term quality of life in patients after endoscopic endonasal resection of pituitary tumors and to find predictors for poor quality of life (QOL) outcome.

Materials and Methods A prospective cohort study was conducted, including all patients who underwent EES for pituitary tumors in a tertiary medical referral center. Recruited patients completed the Anterior Skull Base Disease-Specific QOL (ASBS-Q) questionnaire and the Sinonasal Outcome Test 22 (SNOT-22) questionnaire before surgery, 2 and 4 to 6 months after surgery. Demographic and clinical data was collected.

Results Our study included 49 patients. The overall ASBS-Q scores significantly improved 4 to 6 months after surgery (4.46 vs. 4.2, p < 0.05). We found a significant improvement in QOL related to emotional state 2 months post surgery (4.41 vs. 3.87, p < 0.05), which became borderline significant 4 to 6 months post surgery. There was a significant improvement in pain (4.5 vs. 4.08, p < 0.05) and vitality (4.43 vs. 4.16, p < 0.05) domains 4 to 6 months post surgery. SNOT-22 scores did not change significantly postoperatively. Factors such as secreting and non-secreting tumors, tumor size, intraoperative cerebrospinal fluid leak, gross tumor resection, endocrine remission, and the use of nasoseptal flap reconstruction did not have a significant effect on QOL.

Conclusion We found that patients after EES reported improved QOL 4 to 6 months post surgery. Specific improvement was noted in the QOL related to pain and vitality.

Potential Protective Effect of Puncture Vine (Tribulus terrestris, L.) Against Xylene Toxicity on Bovine Ovarian Cell Functions

The action of the medicinal plant Tribulus terrestris (TT) on bovine ovarian cell functions, as well as the protective potential of TT against xylene (X) action, remain unknown. The aim of the present in vitro study was to elucidate the influence of TT, X and their combination on basic bovine ovarian cell functions. For this purpose, we examined the effect of TT (at doses of 0, 1, 10, and 100 ng/ml), X (at 20 μg/ml) and the combination of TT + X (at these doses) on proliferation, apoptosis and hormone release by cultured bovine ovarian granulosa cells. Markers of proliferation (accumulation of PCNA), apoptosis (accumulation of Bax) and the release of hormones (progesterone, testosterone and insulin-like growth factor I, IGF-I) were analyzed by quantitative immunocytochemistry and RIA, respectively. TT addition was able to stimulate proliferation and testosterone release and inhibit apoptosis and progesterone output. The addition of X alone stimulated proliferation, apoptosis and IGF-I release and inhibited progesterone and testosterone release by ovarian cells. TT was able to modify X effects: it prevented the antiproliferative effect of X, induced the proapoptotic action of X, and promoted X action on progesterone but not testosterone or IGF-I release. Taken together, our observations represent the first demonstration that TT can be a promoter of ovarian cell functions (a stimulator of proliferation and a suppressor of apoptosis) and a regulator of ovarian steroidogenesis. X can increase ovarian cell proliferation and IGF-I release and inhibit ovarian steroidogenesis. These effects could explain its anti-reproductive and cancer actions. The ability of TT to modify X action on proliferation and apoptosis indicates that TT might be a natural protector against some ovarian cell disorders associated with X action on proliferation and apoptosis, but it can also promote its adverse effects on progesterone release.

CTNI-09. TRIDENT PHASE 3 TRIAL (EF-32): FIRST-LINE TUMOR TREATING FIELDS (TTFields; 200 KHZ) CONCOMITANT WITH CHEMO-RADIATION, FOLLOWED BY MAINTENANCE TTFIELDS/TEMOZOLOMIDE IN NEWLY-DIAGNOSED GLIOBLASTOMA

INTRODUCTION

Tumor Treating Fields (TTFields; 200 kHz; non-invasive, loco-regional antimitotic treatment) is approved for newly-diagnosed glioblastoma (ndGBM). In the Phase 3 EF-14 trial, post-surgical radiotherapy/temozolomide, followed by maintenance TTFields/temozolomide significantly increased overall survival (OS) and progression-free survival (PFS) in patients with ndGBM versus TMZ alone. Addition of maintenance TTFields did not increase systemic toxicity; and related adverse events (AEs) were mainly dermatological. In preclinical models, addition of TTFields increased the benefit of radiotherapy. Two pilot studies showed that TTFields concomitant with radiotherapy/temozolomide is feasible and well-tolerated. The benefit of TTFields concomitant with radiotherapy/temozolomide will be investigated in the TRIDENT trial.

METHODS

TRIDENT (EF-32; NCT04471844) is an international, pivotal, phase 3 randomized trial comparing triple-combination of TTFields/radiotherapy/temozolomide versus standard radiotherapy/temozolomide. Patients in both arms will receive maintenance TTFields/TMZ. Arrays of the Optune® System will be used to deliver TTFields (200 KHz) for ≥18 hours/day concomitant with radiotherapy. TTFields treatment will be continued until second disease progression (RANO) or 24 months, whichever occurs first. Patients with pathologically-confirmed ndGBM, ≥ 18 years of age (≥ 22 years of age; US), KPS ≥ 70, post-surgery/biopsy, and amenable for radiotherapy/temozolomide will be stratified by extent-of-resection and MGMT promoter methylation status. The primary endpoint is median OS. Secondary endpoints include median PFS (RANO), 1-year and 2-year survival rates, overall radiological response (ORR; RANO), PFS (PFS-6M, PFS-12M, PFS-2Y), severity and frequency of AEs (CTCAE V5.0), pathological post-treatment changes in resected GBM tumors, quality-of-life (EORTC QLQ-C30), and OS correlation to TTFields duration-of-usage. The hypothesis is that first-line TTFields/RT/TMZ triple-combination will significantly improve OS compared to radiotherapy/temozolomide; each followed by maintenance TTFields/temozolomide. Sample size (N=950; 475/arm) was powered for a HR &lt; 0.8 with 5% type I error. Survival will be measured from time-of-randomization. The TRIDENT trial is currently enrolling patients.

RESULTS/CONCLUSIONS

N/A TiP.

429 Preoperative Risk Assessment In Elective Colorectal Patients

Introduction

Cardiopulmonary Exercise Testing (CPET) and the Colorectal Physiology and Operative Severity Score (CR-POSSUM) are increasingly used in colorectal surgical practice to risk-stratify patients preoperatively and for planning level 2 HDU or ITU admission. This study aims to generate a simple, objective pre-operative risk assessment model to complement clinical judgement, and to determine objectively for whom CPET is necessary in colorectal pre-assessment.

Method

A retrospective cohort study was conducted. Demographic and perioperative data were gathered, and CR-POSSUM score was determined retrospectively. Mortality at 12 months was considered the primary outcome with readmissions up to 12 months as secondary outcomes. Statistical analysis used Binary Logistic Regression, and odds ratios were reported with confidence intervals. A new combined pre-operative risk assessment model with the most significant individual predictors was constructed.

Results

Some 167 elective patients were included in the final analysis. Half of patients had planned HDU admissions. The all-cause mortality at 90 days was 3.5% and at 12 months was 11%. Readmission rate at 30 days was 10%, with a further 11.3% at 90 days postoperatively. The ASA, Physiology Score and Operative Severity Scores correlated with mortality rates (p &lt; 0.05). Current diagnostic performance using CPET vs. the combined model identified 48% and 35% ‘high risk’ patients with 83.3% and 56.5% vs 94.4% and 76.1% sensitivity and specificity, respectively. The model draws its predictive power mainly from the CR-POSSUM.

Conclusions

Current practice at the study centre produces outcomes above the national average. The process can be improved whilst focusing resources further using the combined model.

BSCI-03. Adaptation of colorectal cancer cells to the brain microenvironment: The role of IRS2

Colorectal cancer (CRC) reflects the fourth most frequent etiology of brain metastasis (BM). Yet, molecular mechanisms supporting it are unknown. We aimed to explore drivers enabling adaptation of CRC cells to the brain and decipher mechanisms facilitating the process.

We analyzed the FoundationOne database, which contains genomic alterations data of cancer-related genes in over 16,000 human CRC primary and metastasis samples. Increased prevalence of IRS2 gene amplification was observed in 13% of BM, compared to only 3% of primary tumors or other metastatic sites. IRS2 is a cytoplasmic adaptor mediating effects of insulin and IGF-1 receptors and is involved in more aggressive behavior of different cancer types. In agreement with the genomic data, immunohistochemistry of human clinical samples showed increased expression of IRS2 protein in BM. We constructed an in-vitro system mimicking the brain microenvironment using cultured human astrocytes or their conditioned media. Under these conditions, IRS2-overexpressed CRC cells survived better and formed larger 3D spheres. IRS2-silenced CRC cells showed a mirror image. Moreover, in an intracranial CRC BM mouse model, IRS2-overexpressed cells generated larger brain lesions, while silencing IRS2 dramatically decreased tumor outgrowth and extended survival. Interestingly, transcriptomic analysis revealed enrichment of oxidative phosphorylation (OXPHOS) and Wnt/β-catenin pathways by IRS2. Indeed, IRS2-expressing cells showed increased mitochondrial activity and glycolysis-independent viability. Furthermore, IRS2-expressing cells had increased β-catenin transcriptional activity. Interestingly, β-catenin or IRS2 inhibition (using NT219) in IRS2-expressing cells decreased their viability, β-catenin transcriptional activity, and OXPHOS gene expression, suggesting involvement of IRS2 in modulating OXPHOS through β-catenin. β-catenin is known to confer 5-FU resistance; consequently, we showed that combination of 5-FU and NT219 worked in synergy, inhibited the formation of BM, and extended animal survival.

These data reveal the unique genomic profile of CRC BM and suggest IRS2 inhibition as a novel target for treatment of these patients.

Microengineered perfusable 3D-bioprinted glioblastoma model for in vivo mimicry of tumor microenvironment

Many drugs show promising results in laboratory research but eventually fail clinical trials. We hypothesize that one main reason for this translational gap is that current cancer models are inadequate. Most models lack the tumor-stroma interactions, which are essential for proper representation of cancer complexed biology. Therefore, we recapitulated the tumor heterogenic microenvironment by creating fibrin glioblastoma bioink consisting of patient-derived glioblastoma cells, astrocytes, and microglia. In addition, perfusable blood vessels were created using a sacrificial bioink coated with brain pericytes and endothelial cells. We observed similar growth curves, drug response, and genetic signature of glioblastoma cells grown in our 3D-bioink platform and in orthotopic cancer mouse models as opposed to 2D culture on rigid plastic plates. Our 3D-bioprinted model could be the basis for potentially replacing cell cultures and animal models as a powerful platform for rapid, reproducible, and robust target discovery; personalized therapy screening; and drug development.

T Cells Retain Pivotal Antitumoral Functions under Tumor-Treating Electric Fields

Tumor-treating fields (TTFields) are a localized, antitumoral therapy using alternating electric fields, which impair cell proliferation. Combining TTFields with tumor immunotherapy constitutes a rational approach; however, it is currently unknown whether TTFields' locoregional effects are compatible with T cell functionality. Healthy donor PBMCs and viably dissociated human glioblastoma samples were cultured under either standard or TTFields conditions. Select pivotal T cell functions were measured by multiparametric flow cytometry. Cytotoxicity was evaluated using a chimeric Ag receptor (CAR)-T-based assay. Glioblastoma patient samples were acquired before and after standard chemoradiation or standard chemoradiation + TTFields treatment and examined by immunohistochemistry and by RNA sequencing. TTFields reduced the viability of proliferating T cells, but had little or no effect on the viability of nonproliferating T cells. The functionality of T cells cultured under TTFields was retained: they exhibited similar IFN-γ secretion, cytotoxic degranulation, and PD1 upregulation as controls with similar polyfunctional patterns. Glioblastoma Ag-specific T cells exhibited unaltered viability and functionality under TTFields. CAR-T cells cultured under TTFields exhibited similar cytotoxicity as controls toward their CAR target. Transcriptomic analysis of patients' glioblastoma samples revealed a significant shift in the TTFields-treated versus the standard-treated samples, from a protumoral to an antitumoral immune signature. Immunohistochemistry of samples before and after TTFields treatment showed no reduction in T cell infiltration. T cells were found to retain key antitumoral functions under TTFields settings. Our data provide a mechanistic insight and a rationale for ongoing and future clinical trials that combine TTFields with immunotherapy.

Abstract 2716: P-selectin axis plays a key role in microglia immunophenotype and glioblastoma progression

Glioblastoma (GB) is an aggressive type of brain cancer with high mortality rate. It is a highly angiogenic tumor exhibiting an extremely invasive nature. As such, its brain microenvironment plays a crucial role in its progression. Microglia are the brain resident immune cells which have been shown to facilitate GB cell invasion and immune suppression. The mechanism by which GB cells alter microglia behavior is yet to be fully understood. One proposed mechanism involves adhesion molecules such as the Selectins family of proteins which are expressed on the surface of endothelial and immune cells and are involved in immune modulation and cancer immunity. We have previously shown that P-Selectin (SELP) is expressed by GB cells. Here, we investigated the factional role of SELP in GB-microglia interactions. First, we found that microglia cells facilitate the expression and secretion of SELP by GB cells, and that GB cells facilitate the expression of P-Selectin ligand by microglia. We then showed that SELP mediates microglia-enhanced GB invasion and proliferation in 2D and 3D in vitro models and has a role in microglia activation state. These findings were validated in vivo, showing that inhibition or downregulation of SELP leads to reduced tumor growth, increased overall survival and improved immune response. Single-Cells RNA-seq analysis of the tumors revealed an increase in pro-inflammatory microglia signature, reduction in cancer cell tumorigenesis potential and improved T cell activation. Our results indicated that SELP has an important role in GB progression and microenvironment activation. This work can improve our understanding of tumor-associated microglia function and the mechanisms by which GB cells suppress the immune system and invade the brain tissue.

Citation Format: Eilam Yeini, Paula Ofek, Sabina Pozzi, Nitzan Albeck, Dikla Ben-Shushan, Galia Tiram, Sapir Golan, Ron Kleiner, Ron Sheinin, Shlomit Reich-Zeliger, Rachel Grossman, Zvi Ram, Henry Brem, Thomas Hyde, Prerna Magod, Dinorah Friedmann-Morvinski, Asaf Madi, Ronit Satchi-Fainaro. P-selectin axis plays a key role in microglia immunophenotype and glioblastoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2716.

Abstract 2854: Adaptation of colorectal cancer cells to the brain microenvironment: the role of IRS2

Colorectal cancer (CRC) reflects the fourth most frequent etiology of brain metastasis (BM), with rising incidence. Yet, molecular mechanisms supporting the formation of these lesions from CRC are unknown. We aimed to explore drivers enabling tropism and adaptation of CRC cells to the brain environment and decipher mechanisms facilitating the process. We analyzed the FoundationOne database, which contains genomic alterations data of cancer-related genes in over 16,000 human CRC primary and metastasis samples. Increased prevalence of insulin receptor substrate 2 (IRS2) gene amplification was noted in BMs relative to primary tumors and other metastatic sites. IRS2 is a cytoplasmic adaptor mediating effects of insulin and IGF-1 receptors and is known to be involved in more aggressive behavior of different cancer types. In agreement with the genomic data, immunohistochemistry of human clinical samples showed increased expression of IRS2 protein in BMs. We subsequently constructed an in vitro system mimicking the brain microenvironment using cultured human astrocytes or their conditioned media (CM). Under these conditions using InSphero system, IRS2-overexpressed CRC cells survived better and formed larger 3D spheres. IRS2-silenced CRC cells showed a mirror image. Moreover, in an intracranial CRC surgical implantation BMs mouse model, IRS2-overexpressed CRC cells generated larger brain lesions, while silencing IRS2 in IRS2-amplified CRC cells dramatically decreased tumor outgrowth and survival. Interestingly, transcriptomic analysis revealed significant enrichment of the oxidative phosphorylation pathway by IRS2. Indeed, IRS2-expressing CRC cells showed increased mitochondrial activity using Seahorse extracellular flux analysis and glycolysis-independent viability. Furthermore, IRS2-expressing cells showed enhanced AKT phosphorylation and inhibition of PI3K or AKT using Alpelisib or iAKT, respectively, slightly decreased their proliferation in CM, suggesting that mechanisms additional to the AKT pathway may mediate IRS2 activity. The Wnt/β-catenin pathway was among the most significantly enriched pathways in the transcriptome. Indeed, IRS2-expressing cells had increased transcriptional activity of the β-catenin. In addition, iAKT or Alpelisib, and most significantly the IRS2 inhibitor (NT219), decreased the transcriptional activity of β-catenin in IRS2-expressing CRC cells, suggesting relevance of IRS2 in activating β-catenin. Moreover, NT219 demonstrated significant and dose-dependent inhibition of CRC cells viability. These data reveal, for the first time, the unique genomic profile of CRC BMs and imply the IRS2 role in promoting CRC BMs. These effects may be mediated, at least in part, by modulation of the AKT and β-catenin pathway. Given the molecular signature described, the approach to patients with BMs may be significantly impacted by agents such as NT219.

Citation Format: Inbal Greenberg, Anat Klein, Rachel Grossman, Ethan Sokol, Eilam Yeini, Paula Ofek, Ronit Satchi-Fainaro, Bertrand Liang, Hadas Reuveni, Tami Rubinek, Ido Wolf. Adaptation of colorectal cancer cells to the brain microenvironment: the role of IRS2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2854.

Abstract CT258: EF-32 (TRIDENT): A pivotal randomized trial of radiation therapy concomitant with temozolomide +/- Tumor Treating Fields (TTFields) in newly diagnosed glioblastoma

Purpose: Tumor treating fields (TTFields) is a non-invasive, loco-regional antimitotic treatment approved as a standard-of-care for newly diagnosed glioblastoma (ndGBM). In the Phase 3 EF-14 trial, TTFields (200 kHz) plus temozolomide (TMZ) post-surgery and chemoradiation significantly increased survival of ndGBM patients compared to TMZ alone. The addition of TTFields was not associated with any increases in systemic toxicity. TTFields-related adverse events (AEs) were mainly dermatological. In preclinical models, TTFields increase the therapeutic effects of radiation therapy (RT). A pilot study showed that TTFields concomitant with RT and TMZ is well tolerated. The benefit of TTFields concomitant with RT and TMZ will be investigated in the TRIDENT trial. Methodology: TRIDENT (NCT04471844) is an international, pivotal randomized trial comparing standard RT with concomitant TMZ vs the triple combination of RT with concomitant TMZ and TTFields. RT is delivered through the TTFields transducer arrays. Patients in both arms will receive maintenance TTFields and TMZ. TTFields (200 KHz) will be delivered &gt;18 hours/day using the Optune device. TTFields treatment will be continued until the second disease recurrence. Patients with pathologically confirmed ndGBM, ≥ 18 years (≥ 22 years in the US), KPS ≥ 70, either sex, post-surgery or biopsy, and candidates for RT/TMZ therapy will be stratified by extent of resection and MGMT promoter methylation status. The primary endpoint is overall survival (OS). Secondary end points include progression free survival (PFS; RANO), 1- and 2-year survival rates, overall radiological response (ORR; RANO), PFS (PFS6M, PF12M, PFS2Y); severity and frequency of AEs (CTCAE V5.0); pathological changes in resected GBM tumors post treatment; quality of life (EORTC QLQ-C30); and correlation of OS to TTFields compliance. The hypothesis is that concomitant TTFields/RT/TMZ will significantly improve OS versus RT/TMZ. Sample size (N=950; 475/arm) will detect a HR&lt; 0.8 with 5% type I error. Survival will be measured from the time of randomization until date of death. At the time of analysis, patients lost to follow-up or still on protocol follow-up will be censored at the last date known to be alive. The TRIDENT trial is currently enrolling patients.

Citation Format: Wenyin Shi, Lawrence Kleinberg, Suriya A. Jeyapalan, Samuel A. Goldlust, Seema Nagpal, Stephanie E. Combs, David Roberge, Ryo Nishigawa, Rachel Grossman, Martin Glas. EF-32 (TRIDENT): A pivotal randomized trial of radiation therapy concomitant with temozolomide +/- Tumor Treating Fields (TTFields) in newly diagnosed glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT258.

P-selectin axis plays a key role in microglia immunophenotype and glioblastoma progression

Glioblastoma (GB) is a highly invasive type of brain cancer exhibiting poor prognosis. As such, its microenvironment plays a crucial role in its progression. Among the brain stromal cells, the microglia were shown to facilitate GB invasion and immunosuppression. However, the reciprocal mechanisms by which GB cells alter microglia/macrophages behavior are not fully understood. We propose that these mechanisms involve adhesion molecules such as the Selectins family. These proteins are involved in immune modulation and cancer immunity. We show that P-selectin mediates microglia-enhanced GB proliferation and invasion by altering microglia/macrophages activation state. We demonstrate these findings by pharmacological and molecular inhibition of P-selectin which leads to reduced tumor growth and increased survival in GB mouse models. Our work sheds light on tumor-associated microglia/macrophage function and the mechanisms by which GB cells suppress the immune system and invade the brain, paving the way to exploit P-selectin as a target for GB therapy.

Beyond the hashtag: describing and understanding the full impact of the #BJSConnect tweet chat May 2019

Background

Twitter engagement between surgeons provides opportunities for international discussion of research and clinical practice. Understanding how surgical tweet chats work is important at a time when increasing reliance is being placed on virtual engagement because of the COVID-19 pandemic.

Methods

Individual tweets from the May 2019 #BJSConnect tweet chat were extracted using NodeXL, complemented by Twitter searches in an internet browser to identify responses that had not used the hashtag. Aggregate estimates of tweet views were obtained from a third-party social media tool (Twitonomy) and compared with official Twitter Analytics measurements.

Results

In total 37 Twitter accounts posted 248 tweets or replies relating to the tweet chat. A further 110 accounts disseminated the tweets via retweeting. Only 58.5 per cent of these tweets and 35 per cent of the tweeters were identified through a search for the #BJSConnect hashtag. The rest were identified by searching for replies (61), quoting tweets (20), and posts by @BJSurgery that used the hashtag but did not appear in the Twitter search (22). Studying all tweets revealed complex branching discussions that went beyond the discussed paper’s findings. Third-party estimates of potential reach of the tweet chat were greatly exaggerated.

Conclusion

Understanding the extent of the discussion generated by the #BJSConnect tweet chat required looking beyond the hashtag to identify replies and other responses, which was time-consuming. Estimates of reach using a third-party tool were unreliable.

Resection of primary central nervous system lymphoma: impact of patient selection on overall survival

OBJECTIVE

Primary central nervous system lymphoma (PCNSL) is a rare CNS tumor with a poor prognosis. It is usually diagnosed by needle biopsy and treated mainly with high-dose chemotherapy. Resection is currently not considered a standard treatment option. A possible prolonged survival after resection of PCNSL lesions in selected patients has been suggested, but selection criteria for surgery, especially for solitary lesions, have never been established.

METHODS

The authors retrospectively searched their patient database for records of adult patients (≥ 18 years) who were diagnosed and treated for a solitary PCNSL between 2005 and 2019. Patients were divided into groups according to whether they underwent resection or needle biopsy. Statistical analyses were performed in an attempt to identify variables affecting outcome and possible survival advantage and to characterize subgroups of patients who would benefit from resection of their tumor compared with undergoing biopsy only.

RESULTS

A total of 113 patients with a solitary lesion of PCNSL were identified; 36 patients underwent resection, and 77 had a diagnostic stereotactic biopsy only. The statically significant preoperative risk factors included age ≥ 70 years (adjusted HR 9.61, 95% CI 2.42-38.11; p = 0.001), deep-seated lesions (adjusted HR 3.33, 95% CI 1.13-9.84; p = 0.030), and occipital location (adjusted HR 4.26, 95% CI 1.08-16.78; p = 0.039). Having a postoperative Karnofsky Performance Scale (KPS) score < 80 (adjusted HR 3.21, 95% CI 1.05-9.77; p = 0.040) and surgical site infection (adjusted HR 4.27, 95% CI 1.18-15.47; p = 0.027) were significant postoperative risk factors after the adjustment and selection by means of other possible risk factors. In a subgroup analysis, patients younger than 70 years who underwent resection had a nonsignificant trend toward longer survival than those who underwent needle biopsy (median survival 35.0 months vs 15.2 months, p = 0.149). However, patients with a superficial tumor who underwent resection had significantly longer survival times than those who underwent needle biopsy (median survival 34.3 months vs 8.9 months, p = 0.014). Patients younger than 70 years who had a superficial tumor and underwent resection had significantly prolonged survival, with a median survival of 35.0 months compared with 8.9 months in patients from the same group who underwent needle biopsy (p = 0.007).

CONCLUSIONS

Specific subgroups of patients with a solitary PCNSL lesion might gain a survival benefit from resection compared with undergoing only a diagnostic biopsy.

Endoscopic transsphenoidal surgery reduces the need for re-operation compared to the microscopic approach in pituitary macroadenomas

INTRODUCTION

Pituitary surgery has shifted in recent years from microscopic surgery(MS) to endoscopic endonasal surgery (EES). However, the comparative long-term outcome of these surgical approaches, including the need for subsequent re-operation has never been reported. We present our experience in a high-volume referral center experienced in both endoscopic and microscopic approaches to compare the need for re-operation after initial resection of non-functioning pituitary macroadenomas using these surgical approaches.

METHODS

684 patients (398 with NF adenomas) underwent trans-sphenoidal pituitary surgery in our institution between 2006 and 2017. Complete follow-up (mean 72 months, minimum two years) was available in 87 newly diagnosed patients with non-functioning pituitary macroadenomas (NFPMA; 48-microscopic and 39-endoscopic). The EES approach has been used almost exclusively since 2012. The need for repeat operation for tumor resection during the follow-up period was assessed as the primary end-point of the study. Extracted data included various demographic and clinical parameters, radiographic findings as well as the extent of resection (EOR).

RESULTS

The EOR was similar for both groups, with a trend towards better EOR in the EES group. The rate of surgical complications was also similar for both groups. There was a strong trend towards lower need for re-operation in the EES group compared to the MS group (12.8% vs. 29.2%, p = 0.056). In a multivariate analysis, only EOR and Knosp grade were independently associated with the need for re-operation surgery.

CONCLUSION

Our data indicate that EES in NFPMA tends to be associated with a lower need for re-operation compared to the MS approach, with a similar rate of EOR and complications.

European women in neurosurgery: II - Historical characters and living legends

A collaborative global working group of women neurosurgeons in multiple countries at different stages of their neurosurgical careers undertook the task of researching the history of European women in neurosurgery. While doing so, we happened upon many remarkable female neurosurgeons who overcame great adversity, made tremendous contributions to society and institutional neurosurgery, and displayed numerous talents beyond the operating room. In the first part of this paper, we recounted a chronology of female neurosurgeons in Europe, highlighting the most remarkable achievements of women in every decade, from the 1920's to 2020. In this paper, we honor fascinating women in European neurosurgery, both historical characters and living legends. These women have overcome great adversity and have also excelled in a huge variety of pursuits. While some were themselves refugees, we also have uncovered noteworthy examples of women who immersed themselves in humanitarian missions and who tried to better the world through political action. There are stories of women beating the odds, taking on biased institutions and proving their worth, in spite of the prevailing system. Most inspirational, we have discovered through our comprehensive research on the history of women in European neurosurgery that the future is increasingly female.

Differentiating Small-Cell Lung Cancer From Non-Small-Cell Lung Cancer Brain Metastases Based on MRI Using Efficientnet and Transfer Learning Approach

Differentiation between small-cell lung cancer (SCLC) from non-small-cell lung cancer (NSCLC) brain metastases is crucial due to the different clinical behaviors of the two tumor types. We propose the use of a deep learning and transfer learning approach based on conventional magnetic resonance imaging (MRI) for non-invasive classification of SCLC vs. NSCLC brain metastases. Sixty-nine patients with brain metastasis of lung cancer origin were included. Of them, 44 patients had NSCLC and 25 patients had SCLC. Classification was performed with EfficientNet architecture on crop images of lesion areas and based on post-contrast T1-weighted, T2-weighted and FLAIR imaging input data. Evaluation of the model was carried out in a 5-fold cross-validation manner, and based on accuracy, precision, recall, F1 score and area under the receiver operating characteristic curve. The best classification results were obtained with multiparametric MRI input data (T1WI+c+FLAIR+T2WI), with a mean overall accuracy of 0.90 ± 0.04, and F1 score of 0.92 ± 0.05 for NSCLC and 0.87 ± 0.08 for SCLC for the validation data and an accuracy of 0.87 ± 0.05, with an F1 score of 0.88 ± 0.05 for NSCLC and 0.85 ± 0.05 for SCLC for the test dataset. The proposed method provides an automatic noninvasive method for the classification of brain metastasis with high sensitivity and specificity for differentiation between NSCLC vs. SCLC brain metastases. It may be used as a diagnostic tool for improving decision-making in the treatment of patients with these metastases. Further studies on larger patient samples are required to validate the current results.

Abstract PO-003: Adaptation of colorectal cancer cells to the brain microenvironment: The role of IRS2

Brain metastases (BMs) from colorectal cancer (CRC) are currently the fourths leading cause of BMs, and their incidence is on the rise. Yet, mechanisms mediating the formation of BMs from CRC are unknown. We aimed to explore genomic drivers enabling tropism and adaptation of CRC cells to the brain environment and decipher mechanisms facilitating the process. We analyzed FoundationOne database, which contains genomic alterations data of cancer-related genes in over 16,000 human CRC primary and metastasis samples. Increased prevalence was noted in the insulin receptor substrate 2 (IRS2) gene, which was significantly amplified in BMs relative to primary tumors and other metastatic sites. IRS2 is a cytoplasmic adaptor mediating effects of insulin and IGF-1 receptors and is known to be involved in more aggressive behavior of different cancer types. In agreement with the genomic data, immunohistochemistry of human clinical samples showed increased expression of IRS2 protein in BMs. Next, we created an in-vitro system mimicking the brain microenvironment using human astrocytes or their conditioned media (CM). Under these conditions, IRS2-overexpressed CRC cells survived better and formed larger 3D spheres. IRS2-silenced CRC cells showed a mirror image. Furthermore, IRS2-overexpressed CRC cells generated larger brain lesions in an intracranial CRC BMs mice model. Interestingly, a transcriptomic analysis revealed significant enrichment of the AKT and β-catenin pathways by IRS2. Indeed, IRS2-amplified cells showed enhanced AKT phosphorylation and inhibition of PI3K or AKT using Alpelisib or Akt1/2 kinase inhibitor, respectively, effectively decreased their proliferation in CM. Importantly, IRS2-amplified cells had increased expression and transcriptional activity of the β-catenin, and AKT pathway inhibitors or IRS2 inhibitor (NT-219) had a more pronounced effect on the activity of β-catenin on those cells. These data indicate, for the first time, the unique genomic profile of CRC BMs and imply the IRS2 role in promoting CRC BMs. These effects may be mediated, at least in part, by modulation of the AKT and β-catenin pathway. These findings may pave the way for the development of novel therapeutic strategies to prevent BMs formation.

Citation Format: Inbal Greenberg, Anat Klein, Rachel Grossman, Ethan Sokol, Eilam Yeini, Paula Ofek, Ronit Satchi-Fainaro, Hadas Reuveni, Tami Rubinek, Ido Wolf. Adaptation of colorectal cancer cells to the brain microenvironment: The role of IRS2 [abstract]. In: Abstracts: AACR Special Virtual Conference on Epigenetics and Metabolism; October 15-16, 2020; 2020 Oct 15-16. Philadelphia (PA): AACR; Cancer Res 2020;80(23 Suppl):Abstract nr PO-003.

CTNI-74. PHASE 3 TRIDENT TRIAL: CONCOMITANT RADIATION THERAPY (RT) AND TEMOZOLOMIDE +/- TUMOR TREATING FIELDS (TTFIELDS) IN NEWLY DIAGNOSED GLIOBLASTOMA

BACKGROUND

Tumor treating fields (TTFields) is a non-invasive, regional antimitotic treatment approved as a standard-of-care for newly diagnosed glioblastoma (ndGBM). In the EF-14 Phase 3 trial, TTFields (200 kHz) plus temozolomide (TMZ) significantly increased survival of ndGBM patients without increasing systemic toxicity. TTFields-related AEs were mainly skin AEs. In preclinical models, TTFields increase the therapeutic effects of radiation therapy (RT). A pilot study showed that TTFields concomitant with RT and TMZ is well tolerated. The benefit of concomitant TTFields with RT and TMZ will be tested in the TRIDENT trial.

METHODS

TRIDENT is an international phase III randomized trial comparing standard RT with TMZ vs the triple combination of RT/TMZ with concomitant TTFields. RT is delivered through the TTFields arrays. Patients in both arms will receive maintenance TTFields/TMZ. TTFields (200 KHz) will be delivered &gt;18 hours/day using Optune. Patients will continue TTFields treatment until second recurrence. Patients with pathologically confirmed ndGBM, ≥ 18 years, KPS ≥ 70, either sex, post-surgery or biopsy, and amenable for RT/TMZ therapy will be stratified by extent of resection and MGMT promoter methylation status. The primary endpoint is overall survival (OS). Secondary end points: progression free survival (PFS; RANO), 1- and 2-year survival rates, overall radiological response (ORR; RANO), progression-free survival (PFS6M, PF12M, PFS2Y); severity and frequency of AEs (CTCAE V5.0); pathological changes in resected GBM tumors post treatment; quality of life (EORTC QLQ-C30); and correlation of OS to TTFields compliance. The hypothesis is that concomitant TTFields/RT/TMZ will significantly improve OS versus RT/TMZ. Sample size (N=950; 475/arm) will detect a HR&lt; 0.8 with 5% type I error. Survival will be measured from the time of randomization until date of death. At the time of analysis, patients lost to follow-up or still on protocol follow-up will be censored at the last date known to be alive.

RTID-12. PHASE 2 TRIAL OF TUMOR TREATING FIELDS (TTFIELDS) PLUS RADIATION THERAPY (RT) PLUS TEMOZOLAMIDE (TMZ) COMPARED TO RT PLUS TEMOZOLOMIDE IN NEWLY DIAGNOSED GLIOBLASTOMA (ndGBM)

OBJECTIVE

In the EF-14 phase 3 trial, TTFields 9200 kHz) added to maintenance TMZ increased median OS to 20.9 months versus 16.0 months with maintenance TMZ (p&lt; 0.001) in ndGBM. Preclinical investigations showed that TTFields/RT have a synergistic effect. A pilot study (N=10) in ndGBM demonstrated the feasibility and safety of TTFields combined with RT/TMZ (Grossman Front Onc 2020). The only TTFields-related adverse event was array-associated skin toxicity. Median PFS was 8.9 months. Based on these encouraging results, this prospective, randomized phase 2 study [NCT03869242] in 60 patients further investigates if the addition of TTFields TMZ/RT treatment in ndGBM patients improves treatment efficacy and delays disease progression.

METHODS

Following debulking surgery or biopsy, 60 patients (≥18 years) with histologically confirmed GBM, KPS≥70 and life expectancy &gt;3 months will be randomized 1:1 to: i) RT with concomitant TMZ/TTFields (200 kHz) for 6 weeks followed by up to 6 months of maintenance TMZ combined with TTFields (experimental arm) up to 24 months; or ii) RT with concomitant TMZ alone followed by maintenance TMZ combined with TTFields (control arm). Patients with early progressive disease, significant comorbidities precluding maintenance RT or TMZ or with implanted electronic devices will be excluded. The primary endpoint is the rate of progression free survival at 12 months (PFS12). Treatment with TTF will be continued until second progression or 24 months (the earlier of the two). All patients will be followed for survival. All adverse events will graded per CTCAE V5.0. The sample size of 60 patients provides 80% power with two-sided alpha level of 0.05 to detect a PFS12 of 46.5% with RT/TMZ/TTFields compared to 29.4% with RT/TMZ followed, respectively, by maintenance TMZ/TTFields (calculated from the RT/TMZ followed by maintenance TMZ/TTFields arm of the EF-14 trial). Follow-up will continue for &gt;12 months from recruitment of the last patient.

Abstract CT206: Concurrent Tumor Treating Fields (TTFields) and radiation therapy for newly diagnosed glioblastoma: A safety and feasibility study

Background: Tumor Treating Fields (TTFields) are a non-invasive, loco-regional, anti-mitotic treatment comprising low-intensity alternating electric fields. In the phase III EF-14 study in newly diagnosed glioblastoma (ndGBM), TTFields in combination with temozolomide (TMZ) significantly improved survival compared with TMZ alone. In preclinical studies TTFields had a radiosensitizing effect and increased the efficacy of radiation therapy (RT). This pilot study [NCT03780569] evaluated the feasibility and safety of TTFields administered concurrently with RT and TMZ in ndGBM patients.

Methods: Patients with histologically confirmed ndGBM were treated with TTFields/RT/TMZ followed by adjuvant TMZ/TTFields. TTFields (200 kHz) were delivered for ≥18 hours/day with transducer arrays removed during RT delivery. RT was administered to the tumor bed in 30 fractions (total dose 60 Gy) in combination with daily TMZ (75 mg/m2). In the adjuvant phase, patients received monthly TMZ (150-200 mg/m2 for 5 days) plus TTFields. The primary outcome was safety of the combined therapies; secondary outcomes included progression-free survival (PFS) and overall survival (OS). Adverse events (AEs) were graded per CTCAE v4.0.

Results: Ten patients were enrolled at a single center between April and December 2017. Median age was 60.2 years, median Karnofsky Performance Score was 90.0, and eight (80%) patients were male. Five (50%) patients had undergone tumor resection while the remainder had biopsy only. Eight patients experienced ≥1 RT treatment delay; delays were unrelated to TTFields treatment. All patients experienced ≥1 AE. Three patients suffered from serious AEs (urinary tract infection, confusional state, and decubitus ulcer) that were considered unrelated to TTFields. The most common AE was skin toxicity, reported in eight (80%) patients; all were of low severity (CTCAE grade 1-2) and were reported as related to TTFields treatment. Median PFS from enrollment was 8.9 months; median OS was not reached at the time of study closure.

Conclusions: Eighty percent of patients experienced grade 1-2 TTFields-related skin toxicity. No other TTFields-related toxicities were observed and there was no increase in RT- or TMZ-related toxicities as a result of combining TTFields with these therapies. Based on the safety and preliminary efficacy results of this pilot study, a phase 2 randomized trial (N=60; NCT03869242) and the Phase 3 TRIDENT trial have been initiated to further investigate the efficacy of concomitant RT/TMZ/TTFields in ndGBM.

Citation Format: Felix Bokstein, Deborah Blumenthal, Dror Limon, Carmit Ben Harosh, Zvi Ram, Rachel Grossman. Concurrent Tumor Treating Fields (TTFields) and radiation therapy for newly diagnosed glioblastoma: A safety and feasibility study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT206.

Updated safety/feasibility study of concurrent tumor treating fields (TTFields) and radiation therapy for newly diagnosed glioblastoma

e14535

Background: Tumor Treating Fields (TTFields), a non-invasive, loco-regional, anti-mitotic treatment comprises low-intensity alternating electric fields. In the phase III EF-14 study in newly diagnosed glioblastoma (ndGBM), TTFields in combination with temozolomide (TMZ) significantly improved survival compared to TMZ alone. In preclinical studies TTFields had a radiosensitizing effect and increased the efficacy of radiation therapy (RT). This pilot study [NCT03780569] evaluated the feasibility and safety of TTFields administered concurrently with RT and TMZ in ndGBM patients. Methods: Patients with histologically confirmed ndGBM were treated with TTFields/RT/TMZ followed by adjuvant TMZ/TTFields. TTFields (200 kHz) were delivered for ≥18 hours/day with transducer arrays removed during RT delivery. RT was administered to the tumor bed in 30 fractions (total dose 60 Gy) in combination with daily TMZ (75 mg/m2). In the adjuvant phase, patients received monthly TMZ (150–200 mg/m2 for 5 days) plus TTFields. The primary outcome was safety of the combined therapies; secondary outcomes included progression-free survival (PFS) and overall survival (OS). Adverse events (AEs) were graded per CTCAE v4.0. Results: Ten patients were enrolled at a single center between April and December 2017. Median age was 60.2 years, median Karnofsky Performance Score was 90.0, and eight (80%) patients were male. Five (50%) patients had undergone tumor resection while the remainder had biopsy only. Eight patients experienced ≥1 RT treatment delay; delays were unrelated to TTFields treatment. All patients experienced ≥1 AE. Three patients suffered from serious AEs (urinary tract infection, confusional state, and decubitus ulcer) that were considered unrelated to TTFields. The most common AE was skin toxicity, reported in eight (80%) patients; all were of low severity (CTCAE grade 1–2) and were reported as related to TTFields treatment. Median PFS from enrollment was 8.9 months; median OS was not reached at the time of study closure. Conclusions: Eighty percent of patients experienced grade 1–2 TTFields-related skin toxicity. No other TTFields-related toxicities were observed and there was no increase in RT- or TMZ-related toxicities as a result of combining TTFields with these therapies. Based on the safety and preliminary efficacy results of this pilot study, a phase 2 randomized trial (N = 60; NCT03869242) and the Phase 3 TRIDENT trial have been initiated to further investigate the efficacy of concomitant RT/TMZ/TTFields in ndGBM. Clinical trial information: NCT03780569.

Concurrent Tumor Treating Fields (TTFields) and Radiation Therapy for Newly Diagnosed Glioblastoma: A Prospective Safety and Feasibility Study

Background: TTFields are a loco-regional, anti-mitotic treatment comprising low-intensity alternating electric fields. In the EF-14 study of newly diagnosed glioblastoma (ndGBM), TTFields in combination with temozolomide (TMZ) significantly improved survival vs. TMZ alone. In preclinical studies TTFields had a radiosensitizing effect and increased the efficacy of radiation therapy (RT). This study prospectively evaluated the feasibility and safety of TTFields administered concurrently with RT and TMZ in ndGBM patients. Methods: Patients with histologically confirmed ndGBM were treated with TTFields/RT/TMZ followed by adjuvant TMZ/TTFields. TTFields (200 kHz) were delivered for ≥18 hours/day with transducer arrays removed during RT delivery. RT was administered to the tumor bed in 30 fractions (total dose 60 Gy) combined with daily TMZ (75 mg/m²). In the adjuvant phase, patients received monthly TMZ (150-200 mg/m² for 5 days) plus TTFields. Patients were followed for 24 months or until second disease progression. The primary outcome was safety of the combined therapies; secondary outcomes included progression-free survival (PFS) and overall survival (OS). Adverse events (AEs) were graded per CTCAE v4.0. Results: Ten patients were enrolled at a single center between April and December 2017. Median age was 60.2 years, median Karnofsky Performance Score was 90.0, and 80% patients were male. Five (50%) patients had undergone tumor resection while the remainder had biopsy only. Eight patients experienced ≥1 RT treatment delay; delays were unrelated to TTFields treatment. All patients experienced ≥1 AE. Three patients suffered from serious AEs (urinary tract infection, confusional state, and decubitus ulcer) that were considered unrelated to TTFields. The most common AE was skin toxicity, reported in eight (80%) patients; all were of low severity (CTCAE grade 1-2) and were reported as related to TTFields treatment. Median PFS from enrollment was 8.9 months; median OS was not reached at the time of study closure. Conclusions: Eighty percent of patients experienced grade 1-2 TTFields-related skin toxicity. No other TTFields-related toxicities were observed without an increase in RT- or TMZ-related toxicities as a result of combining TTFields with these therapies. Preliminary efficacy results are promising and warrant further investigation of concurrent TTFields/RT/TMZ treatment in ndGBM patients.

Virtual biopsy using MRI radiomics for prediction of BRAF status in melanoma brain metastasis

Brain metastases are common in patients with advanced melanoma and constitute a major cause of morbidity and mortality. Between 40% and 60% of melanomas harbor BRAF mutations. Selective BRAF inhibitor therapy has yielded improvement in clinical outcome; however, genetic discordance between the primary lesion and the metastatic tumor has been shown to occur. Currently, the only way to characterize the genetic landscape of a brain metastasis is by tissue sampling, which carries risks and potential complications. The aim of this study was to investigate the use of radiomics analysis for non-invasive identification of BRAF mutation in patients with melanoma brain metastases, based on conventional magnetic resonance imaging (MRI) data. We applied a machine-learning method, based on MRI radiomics features for noninvasive characterization of the BRAF status of brain metastases from melanoma (BMM) and applied it to BMM patients from two tertiary neuro-oncological centers. All patients underwent surgical resection for BMM, and their BRAF mutation status was determined as part of their oncological work-up. Their routine preoperative MRI study was used for radiomics-based analysis in which 195 features were extracted and classified according to their BRAF status via a support vector machine. The BRAF status of 53 study patients, with 54 brain metastases (25 positive, 29 negative for BRAF mutation) was predicted with mean accuracy = 0.79 ± 0.13, mean precision = 0.77 ± 0.14, mean sensitivity = 0.72 ± 0.20, mean specificity = 0.83 ± 0.11 and with a 0.78 area under the receiver operating characteristic curve for positive BRAF mutation prediction. Radiomics-based noninvasive genetic characterization is feasible and should be further verified using large prospective cohorts.

Comparison of Motor Outcome in Patients Undergoing Awake vs General Anesthesia Surgery for Brain Tumors Located Within or Adjacent to the Motor Pathways

BACKGROUND

Surgical removal of intra-axial brain tumors aims at maximal tumor resection while preserving function. The potential benefit of awake craniotomy over craniotomy under general anesthesia (GA) for motor preservation is yet unknown.

OBJECTIVE

To compare the clinical outcomes of patients who underwent surgery for perirolandic tumors while either awake or under GA.

METHODS

Between 2004 and 2015, 1126 patients underwent surgical resection of newly diagnosed intra-axial tumors in a single institution. Data from 85 patients (44 awake, 41 GA) with full dataset who underwent resections for perirolandic tumors were retrospectively analyzed.

RESULTS

Identification of the motor cortex required significantly higher stimulation thresholds in anesthetized patients (9.1 ± 4 vs 6.2 ± 2.7 mA for awake patients, P = .0008). There was no group difference in the subcortical threshold for motor response used to assess the proximity of the lesion to the corticospinal (pyramidal) tract. High-grade gliomas were the most commonly treated pathology. The extent of resection and residual tumor volume were not different between groups. Postoperative motor deficits were more common in the anesthetized patients at 1 wk (P = .046), but no difference between the groups was detected at 3 mo. Patients in the GA group had a longer mean length of hospitalization (10.3 vs 6.7 d for the awake group, P = .003).

CONCLUSION

Awake craniotomy results in a better early postoperative motor outcome and shorter hospitalization compared with patients who underwent the same surgery under GA. The finding of higher cortical thresholds for the identification of the motor cortex in anesthetized patients may suggest an inhibitory effect of anesthetic agents on motor function.

Incidence and impact of stroke following surgery for low-grade gliomas

OBJECTIVE

Ischemic complications are a common cause of neurological deficits following low-grade glioma (LGG) surgeries. In this study, the authors evaluated the incidence, risk factors, and long-term implications of intraoperative ischemic events.

METHODS

The authors retrospectively evaluated patients who had undergone resection of an LGG between 2013 and 2017. Analysis included pre- and postoperative demographic, clinical, radiological, and anesthetic data, as well as intraoperative neurophysiology data, overall survival, and functional and neurocognitive outcomes.

RESULTS

Among the 82 patients included in the study, postoperative diffusion-weighted imaging showed evidence of acute ischemic strokes in 19 patients (23%), 13 of whom (68%) developed new neurological deficits. Infarcts were more common in recurrent and insular surgeries (p < 0.05). Survival was similar between the patients with and without infarcts. Immediately after surgery, 27% of the patients without infarcts and 58% of those with infarcts experienced motor deficits (p = 0.024), decreasing to 16% (p = 0.082) and 37% (p = 0.024), respectively, at 1 year. Neurocognitive functions before and 3 months after surgery were generally stable for the two groups, with the exception of a decline in verbal rhyming ability among patients with infarcts. Confusion during awake craniotomy was a strong predictor of the occurrence of an ischemic stroke. Mean arterial pressure at the beginning of surgery was significantly lower in the infarct group.

CONCLUSIONS

Recurrent surgeries and insular tumor locations are risk factors for intraoperative strokes. Although they do not affect survival, these strokes negatively affect patient activity and performance status, mainly during the first 3 postoperative months, with gradual functional improvement over 1 year. Several intraoperative parameters may suggest the impending development of an infarct.

NCMP-05. THE INCIDENCE AND IMPACT OF POST-OPERATIVE STROKE IN SURGERY FOR LGG

BACKGROUND

Postoperative neurological deficits may outweigh the benefit conferred by maximal resection of gliomas. We evaluated the incidence of ischemic events in patients undergoing surgery for low-grade gliomas (LGG) and the long-term neurological and cognitive sequelae.

METHODS

Between 2013–2017, 168 patients underwent surgical resection or biopsy for LGG at our center. A full dataset, including pre- and postoperative magnetic resonance imaging (MRI) and long-term clinical evaluation findings, was available for 82 patients (study group). Ischemic complications, overall and progression-free survival, and functional and neurocognitive outcomes were evaluated.

RESULTS

The immediate postoperative MRI revealed an acute ischemic stroke adjacent to the tumor resection cavity in 19 patients (23%), 13 of whom developed new neurological deficits due to the ischemic event. Infarcts were more common in patients with recurrent tumors, especially those involving the Sylvian fissure (p< 0.05). Surgery for insular gliomas had the strongest association with postoperative infarcts. Survival of patients w/wo a postoperative infarct was the same. The median Karnofsky-Performance Status was lower for the infarct group vs. the non-infarct group at 3 months post-surgery (p=0.016), with a gradual significant improvement for the former over one year (p=0.04). Immediately after surgery, 27% of the patients without infarcts and 58% of those with infarcts experienced a new motor deficit (p=0.037), decreasing to 16% (p=0.028) and 37% (p=0.001), respectively, at one year. Neurocognitive analysis findings before and 3 months after surgery were unchanged, but patients with an infarct had a significant decrease in naming (p=0.04). Confusion during awake craniotomy was a strong predictor of an ischemic stroke.

CONCLUSIONS

Intraoperative strokes are more prevalent among patients who undergo recurrent surgeries, especially in the insula. Although they do not affect survival, these strokes negatively impact the patients’ activity and performance status, especially during the first 3 postoperative months, with gradual functional improvement over one year.

ACTR-46. TUMOR TREATING FIELDS COMBINED WITH RADIOTHERAPY AND TEMOZOLOMIDE FOR THE TREATMENT OF NEWLY DIAGNOSED GLIOBLASTOMA: FINAL RESULTS FROM A PILOT STUDY

BACKGROUND

Tumor Treating Fields (TTFields) are a non-invasive, loco-regional, anti-mitotic treatment comprising low intensity alternating electric fields approved for GBM. Preclinical data show that TTFields have a radio-sensitizing effect. This pilot study evaluated the safety and feasibility of TTFields/RT/TMZ in ndGBM patients.

METHODS

Patients with histologically confirmed ndGBM were treated with TTFields/RT/TMZ followed by maintenance TTFields and TMZ for up to 24 months. TTFields (200kHz) were delivered for >18 hours/day with removal of the transducer arrays during RT delivery. TMZ was administered at 75 mg/m2/daily for 6 weeks and RT at a total dose of 60 Gy. The primary endpoint was safety of the combined TTFields/RT/TMZ; secondary endpoints included progression-free survival (PFS), overall survival (OS) and toxicity. Adverse events (AEs) were graded per CTCAE V4.0.

RESULTS

Ten patients were enrolled at a single center in Israel between April and December 2017. All patients had recovered from maximal debulking surgery or biopsy. Five patients (50%) had undergone gross total resection; rest had biopsy only. Median age was 59 and median KPS was 80. Median dose of RT was 60 Gy. Six patients (60%) reported at least one AE. The most common AE was TTFields-related skin toxicity reported in 4 patients (40%), of Grade 1–2 in severity. Two patients reported serious AEs (seizures and general deterioration) considered unrelated to TTFields. Median PFS with RT/TMZ/TTFields was 10.5 months. Median OS has not been reached.

CONCLUSIONS

The proportion of patients with TTFields-related skin toxicity was similar to that reported in EF-14 phase 3 study (52%). No other TTFields-related toxicities were reported. There was no increase in RT- or TMZ-related toxicities with TTFields/RT/TMZ combination. A phase 2 randomized study has been initiated to investigate the efficacy of concomitant RT/TMZ/TTFields in 60 ndGBM patients.

P04.06 The incidence and impact of post-operative stroke in surgery for LGG

BACKGROUND: INTRODUCTION

Postoperative neurological deficits may outweigh the benefit conferred by maximal resection of gliomas. Ischemic complications are a common cause of such deficits. In this study, we evaluated the incidence of ischemic events in patients undergoing surgery for low-grade gliomas (LGG) and the long-term neurological and cognitive implications of those events.

METHODS

Between 2013–2017, 168 patients underwent surgical resection or biopsy for LGG at our center. A full dataset, including pre- and postoperative magnetic resonance imaging (MRI) and long-term clinical evaluation findings, was available in 82 patients that underwent resection, and they comprised our study cohort. We retrospectively analyzed pre- and postoperative demographic, clinical, radiological, anesthetic, and intraoperative neurophysiology data to characterize associated ischemic complications. Overall and progression-free survival, as well as functional and neurocognitive outcomes were evaluated as well.

RESULTS

The immediate postoperative MRI showed evidence of an acute ischemic stroke adjacent to the tumor resection cavity in 19 patients (23%), 13 of whom developed new neurological deficits as a result of the ischemic event. Infarcts were more common in patients undergoing surgery for a recurrent tumor, especially those involving the Sylvian fissure (p<0.05). Surgery for insular gliomas had the strongest association with postoperative infarcts (multivariate analysis: odds ratio =12.4, 95% confidence interval 2.21–69.8). There was no difference in survival between patients with or without a postoperative infarct. The median Karnofsky Performance Status was lower for the infarct group compared to the non-infarct group at 3 months after surgery (p=0.016), with a gradual significant improvement for the former over one year of follow-up (p=0.04). Immediately after surgery, 27% of the patients without infarcts and 58% of those with infarcts experienced a new motor deficit (p=0.037), decreasing to 16% (p=0.028) and 37% (p=0.001), respectively, at one year. Neurocognitive analysis findings before and 3 months after surgery were unchanged, but there was a significant decrease in naming in patients who experienced an infarct (NeuroTrax computerized battery score of 100±9 and 83±19, p=0.04 respectively). Confusion during awake craniotomy was a strong predictor of the occurrence of an ischemic stroke.

CONCLUSIONS

Intraoperative strokes are more prevalent among patients who undergo recurrent surgeries, especially procedures in the insula. Although they do not affect survival, these strokes negatively affect the patients’ activity and performance status, especially during the first 3 postoperative months, with gradual functional improvement over one year.

P12.05 Evaluating the compatibility of tumor treating electric fields with key antitumoral immune functions

BACKGROUND

TTFields has the ability to induce immunogenic cell death (ICD). As immunotherapy and TTFields have different mechanisms of action (MOA), combining these therapies is a rational approach. Contrarily, TTFields may interfere with immune functions critical for effective T cell function.

MATERIAL AND METHODS

We cultured T cells from healthy donors’ peripheral blood or from viably dissociated glioblastoma samples under normal or TTFields conditions, with or without superantigen-stimulation. In order to assess T cell responses we used eight-color flow cytometry by monitoring select pivotal antitumoral functions: proliferation (CFSE), IFNγ secretion, cytotoxic degranulation (CD107a), activation/exhaustion (PD1) and viability. Evaluation of direct cytotoxicity was done by using chimeric antigen receptor (CAR) T cells.

RESULTS

TTFields did not change T cell activation rates for all evaluated functions with the exception of reduced proliferation - in line with TTFields’ MOA. TTFields substantially reduced the viability of activated proliferating T cells, moderately affected activated nonproliferating T cells and had almost no effect on the viability of non-activated cells. Polyfunctionality analysis of T-cells, associated with effective antitumoral responses, demonstrated that under TTFields, the activated non-proliferating T cells retained polyfunctional capabilities. PD1-expressing TILs, a subset containing most of the tumor antigen-specific TILs, exhibited unaltered viability and functionality under TTFields. CAR T-cells, which utilize the same killing machinery as unmodified T cells, exhibited unaltered cytotoxic capability under TTFields. Immunohistochemical evaluation of GBM samples before TTFields treatment and after recurrence showed that some patients had accommodated large increases in their CD8 and CD4 counts. RNA-Seq performed on GBM samples from 6 standardly-treated and 6 TTFields-treated patients before treatment and after recurrence. The data shows differential increases in TTFields-treated patients to controls, in the expression of immune genes associated with favorable prognosis (e.g. t-bet, NKG2D, ICOS-L, CD70) and concurrent decreases in genes associated with poor prognosis (e.g. IL4, TSLP, various complement genes).

CONCLUSION

The preclinical data showed that all antitumoral T cell functions examined, but proliferation, were unhindered by TTFields. The clinical data showed that TTFields may shift treated tumors to a state more conducive of antitumoral immune responses. Our findings support the further preclinical and clinical investigation into combining TTFields with immunotherapy.

P14.79 Randomized phase II trial of Tumor Treating Fields plus radiation therapy plus temozolomide compared to radiation therapy plus temozolomide in patients with newly diagnosed glioblastoma

BACKGROUND

In last decade, there were numerous attempts to improve the outcome of patients with glioblastoma (GBM), but even after maximal surgical resection, radiation therapy (RT) and temozolomide (TMZ), followed by maintenance TMZ for 6 months the median OS is 14.6 months. In the EF-14 Phase III trial, the addition of Tumor Treating Fields (TTFields) at 200 kHz to maintenance TMZ increased the median OS to 20.9 months, compared with 16.0 months with maintenance TMZ alone (HR, 0.63; 95% CI, 0.53–0.76; p<0.001). Based on these results, the currently accepted standard of care for newly diagnosed GBM (ndGBM) is surgical resection if safely feasible, followed by RT with concomitant TMZ, and then followed by maintenance TMZ in combination with TTFields. Preclinical investigations have shown a radio-sensitizing effect of TTFields on glioma cells, suggesting synergistic effects between TTFields and radiotherapy. In a pilot study of 10 patients with ndGBM, we demonstrated that there was no increased treatment-related toxicity when TTFields were given in combination with RT/TMZ. The only TTFields-related adverse event was skin toxicity below the arrays. Preliminary progression free survival (PFS) data was encouraging. Based on the results of the pilot study, we designed this prospective, randomized Phase II study to further investigate if the addition of TTFields TMZ/RT treatment in ndGBM patients improves treatment efficacy and delays disease progression.

MATERIAL AND METHODS

Following debulking surgery or biopsy, 60 adult patients (≥18 years) with histologically confirmed GBM, KPS≥70 and life expectancy of at least 3 months will be randomized 1:1 to either a) RT with concomitant TMZ and TTFields (200 kHz) for 6 weeks followed by up to 6 months of maintenance TMZ in combination with TTFields (experimental arm) up to 24 months; or b) RT with concomitant TMZ alone followed by maintenance TMZ in combination with TTFields (control arm). Exclusion criteria: patients with early progressive disease, significant comorbidities precluding maintenance RT or TMZ or patients with an implanted electronic device. The primary endpoint is progression free survival at 12 months (PFS12). Treatment with TTFields will be continued until second progression or 24 months (the earlier of the two). All patients will be followed for survival. Grading and severity of all adverse events will be recorded using CTCAE V5.0. The sample size of 60 patients provides 80% power with a two-sided alpha level of 0.05 to detect a PFS12 of 46.5% with RT/TMZ/TTFields compared to 29.4% with RT/TMZ followed, respectively, by maintenance TMZ/TTFields (calculated from the RT/TMZ followed by maintenance TMZ/TTFields arm of the EF-14 trial). It is forecasted to take 24 months to fully recruit. Follow-up will continue for >12 months from recruitment of the last patient.

P14.71 Tumor Treating Fields combined with radiotherapy and temozolomide for newly diagnosed glioblastoma: final safety and efficacy results from a pilot study

BACKGROUND

Tumor Treating Fields (TTFields) are a non-invasive, loco-regional, anti-mitotic treatment consisting of low intensity alternating electric fields. The combination of TTFields with maintenance temozolomide significantly improved survival versus temozolomide alone in the phase 3 EF-14 study in newly diagnosed glioblastoma (ndGBM). In preclinical studies, TTFields increased the number of glioma cells undergoing cellular death following radiotherapy (RT) by inhibiting DNA damage repair, suggesting a radio-sensitizing effect of TTFields. This pilot study is the first to evaluate the safety and feasibility of administering TTFields concomitant to RT and TMZ in ndGBM patients.

MATERIAL AND METHODS

Patients diagnosed with ndGBM were treated with TTFields/RT/TMZ followed by maintenance TMZ and TTFields for up to 24 months. TTFields (200kHz) were delivered for >18 hours/day while the transducer arrays were removed during delivery of RT. TMZ was administered at a dose of 75 mg/m2/daily for 6 weeks and RT at a total dose of 60 Gy. The primary endpoint was safety of the combined TTFields/RT/TMZ; secondary endpoints included progression-free survival (PFS), overall survival (OS) and toxicity. Adverse events (AEs) were graded according to CTCAE V4.0.

RESULTS

10 ndGBM patients that recovered from maximal debulking surgery or biopsy were enrolled at a single center in Israel between April and December 2017. Five patients (50%) had undergone gross total resection while the rest had biopsy only. Eight of the patients were male, median age was 59, median KPS was 80 and median dose of RT was 60 Gy. Six patients (60%) reported at least one AE. The most common AE was TTFields-related skin toxicity, reported in four patients (40%), all of which were grade 1–2 in severity. Two patients reported serious AEs (seizures and general deterioration) that were considered unrelated to TTFields. Median PFS with RT/TMZ/TTFields was 10.5 months. Median OS has not yet been reached.

CONCLUSION

The proportion of patients with TTFields-related skin toxicity was similar to that reported in ndGBM patients in the randomized Phase III study (52%), where patients started TTFields at least 4 weeks after RT. No other TTFields-related toxicities were reported and there were no increase in RT- or TMZ-related toxicities as a result of combining TTFields with RT in addition to TMZ. Based on the safety and preliminary efficacy results of this pilot study, a phase II randomized study has been initiated to investigate the efficacy of concomitant RT/TMZ/TTFields in 60 ndGBM patients.

In Vivo Biodistribution of Engineered Lipid Microbubbles in Rodents

Maximal resection of intrinsic brain tumors is a major prognostic factor for survival. Real-time intraoperative imaging tools, including ultrasound (US), are crucial for maximal resection of such tumors. Microbubbles (MBs) are clinically used in daily practice as a contrast agent for ultrasound and can be further developed to serve combined therapeutic and diagnostic purposes. To achieve this goal, we have developed novel MBs conjugated to specific ligands to receptors which are overexpressed in brain tumors. These MBs are designed to target a tumor tissue, visualize it, and deliver therapeutic molecules into it. The objective of this study was to assess the biodistribution of the test items: We used MBs labeled with indocyanine green (MB-ICG) for visualization and MBs conjugated to a cyclic molecule containing the tripeptide Arg-Gly-Asp (RGD) labeled with ICG (MB-RGD-ICG) to target brain tumor integrins as the therapeutic tools. Male Sprague Dawley rats received a single dose of each MB preparation. The identification of the MB in various organs was monitored by fluorescence microscopy in anesthetized animals as well as real-time US for brain imaging. Equally sized control groups under identical conditions were used in this study. One control group was used to establish fluorescence background conditions (ICG), and two control groups were used to test autofluorescence from the test items (MBs and MB-RGD). ICG with or without MBs (naked or RGD-modified) was detected in the brain vasculature and also in other organs. The pattern, duration, and intensity of the fluorescence signal could not be differentiated between animals treated with ICG alone and animals treated with microbubbles MBs-ICG or MBs-RGD-ICG. Following MB injection, either naked or combined with RGD, there was a sharp rise in the Doppler signal within seconds of injection in the brain. The signal was mainly located at the choroid plexus, septum pellucidum, and the meninges of the brain. The signal subsided within a few minutes. Injection of saline or ICG alone to respective animals did not result in a similar raised signal. Following a single intravenous administration of MB-ICG and MB-RGD-ICG to rats, the MBs were found to be effectively present in the brain.

Abstract 3954: Evaluating the compatibility of tumor treating electric fields with key anti-tumoral immune functions

Background: Combining Tumor Treating electrical Fields (TTFields) with immunotherapy is a rational approach due to their different mechanisms of action (MOA) and to TTFields’ ability to induce immunogenic cell death (ICD). Conversely, TTFields may interfere with immune functions critical for effective T cell responses.

Methods: T cells from healthy donors’ peripheral blood or from viably dissociated glioblastoma samples were cultured under normal or TTFields conditions, with or without superantigen-stimulation. Eight-color flow cytometry was used to assess T cell responses by monitoring select pivotal antitumoral functions: proliferation (CFSE), IFNγ secretion, cytotoxic degranulation (CD107a), activation/exhaustion (PD1) and viability. Direct cytotoxicity was evaluated using chimeric antigen receptor (CAR) T cells.

Results: The viability of stimulated T cells that attempted to proliferate decreased under TTFields, in line with TTFields’ MOA. Small or no reductions in viability were found in activated T cells that did not attempt to proliferate and in unstimulated T cells.

The functionality of stimulated peripheral-blood T cells and tumor-infiltrating T cells (TILs) under TTFields was unhindered: T cells exhibited comparable PD1 upregulation, IFNγ secretion and CD107a expression as controls. T cell polyfunctionality, associated with effective antitumoral responses, was retained under TTFields conditions. PD1-expressing TILs, a subset containing most of the tumor antigen-specific TILs, exhibited unaltered viability and functionality under TTFields. CAR T-cells, which utilize the same killing machinery as unmodified T cells, exhibited unaltered cytotoxic capability under TTFields.

Immunohistochemical evaluation of GBM samples before TTFields treatment and after recurrence showed that some patients had accommodated large increases in their CD8 and CD4 counts. RNA-Seq performed on GBM samples from 6 standardly-treated and 6 TTFields-treated patients before treatment and after recurrence. The data shows differential increases in TTFields-treated patients to controls, in the expression of immune genes associated with favorable prognosis (e.g. t-bet, NKG2D, ICOS-L, CD70) and concurrent decreases in genes associated with poor prognosis (e.g. IL4, TSLP, various complement genes).

Conclusions: The preclinical data showed that all antitumoral T cell functions examined, but proliferation, were unhindered by TTFields. The clinical data showed that TTFields may shift treated tumors to a state more conducive of anti-tumoral immune responses. Our findings support the further preclinical and clinical investigation into combining TTFields with immunotherapy.

Citation Format: Gil Diamant, Hadar Simchony, Tamar Shiloach, Anat Globerson-levin, Lital Gasri Plotnitsky, Zelig Eshhar, Niv Pencovich, Rachel Grossman, Zvi Ram, Ilan Volovitz. Evaluating the compatibility of tumor treating electric fields with key anti-tumoral immune functions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3954.

Abstract CT008: Tumor Treating Fields combined with radiotherapy and temzolomide for newly diagnosed glioblastoma: Final results from a pilot study

Background: Tumor Treating Fields (TTFields) are a non-invasive, loco-regional, anti-mitotic treatment comprising low intensity alternating electric fields. In the Phase III EF-14 study in newly diagnosed glioblastoma (ndGBM), TTFields significantly improved survival compared to temozolomide (TMZ). Preclinical data have demonstrated that TTFields increased glioma cell death following radiation therapy (RT), suggesting a radio-sensitizing effect of TTFields. We therefore initiated a pilot study to evaluate the safety and feasibility of administering TTFields concomitant to RT and TMZ in ndGBM patients.

Methods: Patients with histologically confirmed ndGBM were treated with TTFields/RT/TMZ followed by maintenance TTFields and TMZ for up to 24 months. TTFields (200kHz) were delivered for &gt;18 hours/day with removal of the transducer arrays during delivery of RT. TMZ was administered at a dose of 75 mg/m2/daily for 6 weeks and RT at a total dose of 60 Gy. The primary endpoint was safety of the combined TTFields/RT/TMZ; secondary endpoints included progression-free survival (PFS), overall survival (OS) and toxicity. Adverse events (AEs) were graded according to CTCAE V4.0.

Results: Ten patients were enrolled at a single center in Israel between April and December 2017. All patients had recovered from maximal debulking surgery or biopsy. Five patients (50%) had undergone gross total resection while the rest had biopsy only. Median age was 59 and median KPS was 80. Median dose of RT was 60 Gy. Six patients (60%) reported at least one AE. The most common AE was TTFields-related skin toxicity, reported in 4 patients (40%), all of which were Grade 1-2 in severity. Two patients reported serious AEs (seizures and general deterioration) that were considered unrelated to TTFields. Median PFS with RT/TMZ/TTFields was 10.5 months. Median OS has not yet been reached.

Conclusions: The proportion of patients with TTFields-related skin toxicity was similar to that reported in ndGBM patients in the randomized Phase III study (52%). No other TTFields-related toxicities were reported, nor was there an increase in RT- or TMZ-related toxicities as a result of combining TTFields with RT in addition to TMZ. Based on the safety and preliminary efficacy results of this pilot study, a Phase II randomized study has been initiated to investigate the efficacy of concomitant RT/TMZ/TTFields in 60 ndGBM patients.

Citation Format: Rachel Grossman, Dror Limon, Felix Bokstein, Zvi Ram. Tumor Treating Fields combined with radiotherapy and temzolomide for newly diagnosed glioblastoma: Final results from a pilot study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT008.