bluuebunny/crossref_metadata_2025 huggingface dataset:
P10.17.A GLUTAMINE METABOLISM AS A PROGNOSTIC FACTOR IN GBM AND OLIGODENDROGLIOMA
Authors: Trybula M , Lysiak M , Malmstrom A , Soderkvist P
Published: September 2023

BACKGROUND

Increased uptake of principal nutrients is one of the attributes of cancer cells. A recent study has shown that glutamine, but not glucose, consumption differed markedly between gliomas and adjacent healthy tissue. However, the prognostic role of glutaminolysis or glutaminolysis-related genes (GRGs) in gliomas remains unclear. Here we sought to determine if the GRG signature correlates with glioma patient survival and if it could identify patients with different outcomes.

MATERIAL AND METHODS

The RNA-seq and clinical data for The Cancer Genome Atlas (TCGA) was obtained from the GlioVis webpage. We compared the expression of the GRGs (GLUD1, GLUL, GLS1, GLS2, GOT1, GOT2, GPT, GPT2, SLC1A5, and SLC7A5) between 4 non-tumor, 220 IDH wild-type (IDHwt) and 389 IDH mutant (IDHmut) gliomas, of which 154 harbored 1p/19q codeletion. We further performed unsupervised hierarchical clustering for all glioma patients and compared survival between clusters.

RESULTS

Our results revealed that most GRGs were differentially expressed between non-tumor, IDHwt, and IDHmut gliomas. We found that gliomas grouped into 3 clusters based on the varying GRGs expression. Eighty-eight percent of glioblastomas (GBM, IDHwt) and 19% of all IDHmut tumors were characterized by low GRGs expression. These were denoted as cluster 1, and the remaining samples belonged to clusters 2 or 3, corresponding to intermediate and high GRGs expression groups, respectively. We performed survival analysis separately for IDHwt and IDHmut gliomas and found that cluster 1 patients had the worst prognosis, regardless of IDH status. We further separated IDHmut gliomas according to 1p/19q codeletion status. Oligodendroglioma (1p/19q codeleted) patients had a median survival of 33.2 months, 134.3 months, and 169.8 months in clusters 1, 2, and 3, respectively. No cluster-dependent differences in survival were seen for astrocytoma. For IDHwt (GBM) we found that patients from clusters 1 and 2 had survival of 14 months and 25 months, respectively. Due to the small number of deceased GBM patients in cluster 3, we could not estimate the median survival. The univariate analysis confirmed that cluster membership was an independent predictor of survival in oligodendroglioma (cluster 2 and 3 vs. 1, HR 0.14; 95% CI, 0.05-0.4; p=0.0005) and GBM (cluster 1 vs. 2 and 3, HR 3.05; 95% CI, 1.5-5.9; p=0.0012).

CONCLUSION

The GRG signature could define metabolic groups with distinct survivals in oligodendroglioma and GBM and constitute a new prognostic factor. We are planning further investigations to confirm our findings.
P10.19.A COMBINED TREATMENT USING MAPK AND PI3K SIGNALING PATHWAYS INHIBITORS EFFECTIVELY REDUCES GROWTH OF MELANOMA BRAIN METASTASIS CELLS IN VITRO
Authors: Sættem M , Wang J , Sundstrøm T , Thorsen F
Published: September 2023

BACKGROUND

Brain metastasis is associated with poor prognosis, and median survival time from the time of diagnosis for cancer patients with brain metastases is only a few months. Brain metastases are estimated to occur in 20-40% of cancer patients. All solid tumors may spread to the brain, but the risk of developing brain metastases is higher in breast cancer, lung cancer and melanoma. Standard treatment of melanoma brain metastases (MBM) includes radiation therapy and surgery. In melanoma, the mitogen activated protein kinase (MAPK) and the phosphoinositide 3-kinase (PI3K) signaling pathways are often activated by genetic alterations. An activation mutation (BRAFV600E) in the MAPK pathway is commonly found in melanoma refractory to therapy. This mutation leads to increased proliferation and tumor cell survival. Previous studies show that BRAF-inhibitors block the increase in cell proliferation induced by the activated BRAF gene, however, many of the patients develop drug resistance within a few months. Objectives: In this project, we aimed to show that drugs targeting BRAF (vemurafenib) and PI3K pathways (buparlisib) used in combination effectively inhibit growth of treatment resistant MBM cells.

MATERIAL AND METHODS

Our research lab has previously developed human MBM cell lines, which have been made resistant towards vemurafenib treatment. To study the potential antitumoral effects of combined treatment we used these cells in several in vitro assays such as cell viability and proliferation, cell migration, colony forming assay, spheroid growth, apoptosis by IncuCyte and western blot to confirm effects on signaling pathways.

RESULTS

We found that combination treatment reduced the viability of resistant MBM cells, as well as their ability to proliferate. Further, the cells showed less ability to migrate after therapy. Altered cell morphology was also seen. Initial results show effects on colony formation and increased apoptosis after combined treatment.

CONCLUSION

A combination of MAPK and PI3K inhibitors effectively inhibits growth and viability of treatment resistant human MBM cells, compared to single drug treatment alone. The results support clinical use of combined therapy for melanoma patients with metastatic disease.
P10.25.A ATR INHIBITION IN EXPERIMENTAL GLIOMA: DISCOVERY AND VALIDATION OF MOLECULAR TARGETS FOR FUNCTIONALLY-INSTRUCTED COMBINATION THERAPIES
Authors: Walter B , Hirsch S , Kuhlburger L , Stahl A , Schnabel L , Haeusser L A , Tsiami F , Ploeger S , Aghaallaei N , Dick A M , Skokowa J , Schmees C , Templin M , Schenke-Layland K , Tatagiba M , Nahnsen S , Merk D , Tabatabai G
Published: September 2023

BACKGROUND

The DNA damage response (DDR) is an important physiological network for the prevention of malignant transformation, e.g. by halting the cell cycle upon DNA damage detection and promoting DNA repair. Glioblastoma are incurable primary brain tumors that display acquired treatment resistance which might also be due to DDR dysregulation. Furthermore, we had recently investigated molecular effects of disrupting the (b)HLH network, a frequently altered and tumor-promoting transcriptional network in glioma. The identified downstream anti-tumor effects included the ataxia telangiectasia and Rad3 related (ATR) pathway. In the present study, we aimed at investigating the anti-glioma effects of ATR inhibition (ATRi) in experimental glioma and exploring potential treatment regimens for forward translation.

MATERIAL AND METHODS

We assessed ATRi monotherapy in the syngeneic SMA560/VM/Dk mouse model, performed acute cytotoxicity, clonogenic survival assays, cell cycle analyses by flow cytometry and apoptosis induction in vitro. Furthermore, we used RNA sequencing, DigiWest protein profiling analyses and genome-wide CRISPR/Cas9 loss-of function and activation screens. We evaluated synergistic or additive anti-glioma effects of functionally-instructed combination therapies by the Bliss and ZIP synergy models. We xenotransplanted zebrafish embryos with glioma cells to validate most promising combination approaches in vivo.

RESULTS

ATRi monotherapy induced prolonged latency until the onset of neurological symptoms in the SMA560/VM/Dk mouse model. ATRi reduced viability and clonogenic survival in vitro and ex vivo. Molecular analyses revealed differential patterns of gene expression, e.g. p53 signaling, differing modes of cell cycle and apoptosis regulation, arguing for a profound context specificity of the treatment. Similarly, CRISPR/Cas-9 genome-wide knockout and activation screens revealed distinct genetic vulnerabilities. Based on these

RESULTS

, we designed a drug library for investigating potential functionally-instructed modifiers of response to ATRi in experimental glioma in vitro, ex vivo and in vivo.

CONCLUSION

In summary, we present a workflow in experimental glioma for target discovery and validation leading to the design of novel combination therapies. We identify potential combination therapies involving ATRi in experimental glioma that could inform future early phase clinical trials and preclinical studies.
P10.35.A CDK12/CDK13 INHIBITION DISRUPTS A TRANSCRIPTIONAL PROGRAM CRITICAL FOR GLIOBLASTOMA SURVIVAL
Authors: Pandey D P
Published: September 2023

BACKGROUND

Glioblastoma is the most prevalent and aggressive malignant tumor of the central nervous system. Aberrant transcriptional programs are key to development and maintenance of cancer cells, and these can be exploited to target a specific cancer. Thus, targeting the transcriptional addiction specific for gliomas could offer a large therapeutic potential.

METHODS

A panel of patient-derived primary glioma stem cell (GSC) lines and glioblastoma organoids (GBO) were used to investigate the effect of transcriptional cyclin-dependent kinase (tCDK) inhibitors using a range of survival assays. A CRISPR/CAS9-based competition assay was applied to study the effect of genetic ablation of individual tCDKs. CUT&RUN was utilized to generate the genome-wide maps of the total RNA polymerase II (RNAPII) and phosphorylated species, and SLAM-seq was used to identify changes in steady-state and nascent transcriptome. Cell cycle analyses were done using EdU incorporation to mark S-phase cells.

RESULTS

We show that pharmacological inhibition or genetic ablation of the tCDKs, CDK12 and CDK13, markedly reduces the in vitro proliferation of GSCs and of ex vivo glioblastoma organoids as well as migratory capacity of GSCs. Using a xenograft mouse model, we demonstrate that CDK12/13 inhibition reduces tumor growth in vivo, which compares favorably with the existing chemotherapeutic treatments. Mechanistically, inhibition of CDK12/CDK13 leads to a genome-wide abrogation of RNAPII C-terminal Domain (CTD) phosphorylation, which in turn disrupts transcription and cell cycle progression in glioblastoma cells.

CONCLUSION

s CDK12/CDK13 inhibition may have a large therapeutic potential for glioblastoma treatment, both alone and in combination.
P11.08.B R-MPV THERAPY FOR PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA; SINGLE CENTER RETROSPECTIVE ANALYSIS
Authors: Nagashima H , Tanaka K , Yamanishi S , Sasayama T
Published: September 2023

BACKGROUND

Whole brain radiation therapy (WBRT) to primary central nervous system lymphoma (PCNSL) correlate with brain atrophy and leukoencephalopathy, negatively impacting cognitive function and quality of life. R-MPV with reduced WBRT or without WBRT has recently been reported to improve the outcomes of PCNSL. Here we retrospectively analyzed newly diagnosed PCNSL patients to compare the outcome and toxicity of R-MPV therapy with these of WBRT following R-MTX therapy in a real-life setting.

MATERIAL AND METHODS

Sixty newly histological diagnosed PCNSL patients were retrospectively evaluated. Clinical data from the database included patient characteristics, response rate, adverse effects, overall survival and radiological brain atrophy at 1 year; whole brain volume (mm2) calculated from BainLab automatically. Thirty-one patients were received WBRT (30Gy) following R-MTX therapy (R-MTX-RT group) and 29 patients were received R-MPV therapy (R-MPV group).

RESULTS

The mean age at symptom onset was significantly younger in R-MTX-RT group than in R-MPV group (64 vs 74 years, p=0.014). Complete response rate after chemotherapy was higher in R-MPV group (58% in R-MTX-RT group and 88% in R-MPV group). However, overall survival was not significant difference (53.5 month in R-MTX-RT group, 52.7 month in R-MPV group). Three patients of 31 (9.6%) in R-MTX-RT group and 6 patients (20%) in R-MPV group were not able to complete the chemotherapy regimen. Notably, patients >75 years of age sometimes had severe adverse effect with R-MPV therapy. Treatment rerated death was not significant difference in both group (3% in R-MTX-RT vs 13% in R-MPV group, Fisher’s exact test p=0.19). Brain atrophy at 1 year was significantly lesser in R-MPV group than in R-MTX-RT group (R-MTX group, n=17; 4.03%, R-MPV group, n=15; 0.95%, p=0.005).

CONCLUSION

R-MPV therapy has benefit of avoiding WBRT in PCNSL patients. However, elderly patients exhibit increased risk for adverse events of R-MPV.
P11.09.A SIGNIFICANCE OF MOLECULAR DIAGNOSTICS FOR THERAPEUTIC DECISION MAKING IN RECURRENT GLIOMA
Authors: Blobner J , Dengler L , Blobner S , Eberle C , Weller J , Teske N , Karschnia P , Rühlmann K , Heinrich K , Ziemann F , Greif P A , Jeremias I , Wuerstlein R , Hasselmann K , Dorostkar M , Harter P N , Quach S , Stoecklein V , Albert N L , Niyazi M , Tonn J , Thon N , Westphalen B C , Baumgarten L
Published: September 2023

BACKGROUND

Targeted therapies have substantially improved survival in cancer patients with malignancies outside the brain. Whether in-depth analysis for molecular alterations may also offer therapeutic avenues in primary brain tumors remains unclear. We herein present our institutional experience for glioma patients discussed in our interdisciplinary Molecular Tumor Board (MTB) implemented at the Comprehensive Cancer Center Munich (LMU).

MATERIAL AND METHODS

We retrospectively searched the database of the MTB for all recurrent glioma patients after previous therapy. Recommendations were based uponnext-generation sequencing results of individual patient’s tumor tissue. Clinical and molecular information, previous therapy regimens and outcome parameters were collected.

RESULTS

Overall, 73 consecutive recurrent glioma patients were identified. In the median, advanced molecular testing was initiated with the third tumor recurrence. The median turnaround time between initiation of molecular profiling and MTB case discussion was 48 ± 75 days (range: 32 - 536 days). Targetable mutations were found for 50 recurrent glioma patients (68.5%). IDH1 mutation (27/73; 37%), EGFR amplification (19/73; 26%) and NF1 mutation (8/73; 11%) were the most detected alterations and a molecular-based treatment recommendation could be made for all of them. Therapeutic recommendations were implemented in 12 cases (24%) and one third of these heavily pretreated patients experienced clinical benefit with at least partial response or disease stabilization.

CONCLUSION

In-depth molecular analysis of tumor tissue may guide targeted therapy also in brain tumor patients and considerable anti-tumor effects might be observed in selected cases. However, future studies to corroborate our results are needed.
P11.22.B ANALYSIS OF FACTORS RELATED TO POSTOPERATIVE RECURRENCE AND PROGNOSIS ABOUT HIGH GRADE SPINAL CORD GLIOMAS
Authors: Guihuai W , Chuntian G , Linkai J , Beibei Y
Published: September 2023

BACKGROUND

High grade spinal glioma (HGSG), an extremely rare tumor, accounts for about 7-30% of spinal glioma. Its incidence is only 0.22/100000. The tumor has a rapid clinical progression and a poor prognosis, with a median survival time of 12-24 months. In previous studies on the prognosis of HGSG, the factors related to the prognosis are quite different due to inconsistent tumor classification and diagnosis criteria. It is rarer in the study of postoperative recurrence. Therefore, various factors limit the clinician’s judgment on the factors related to the recurrence and prognosis of HGSG after surgery.

MATERIAL AND METHODS

In this study, the clinical data of 44 patients who were pathologically diagnosed with HGSG and admitted to the Department of Neurosurgery of Beijing Tsinghua Changgung Memorial Hospital from January 1, 2015 to January 1, 2020 were retrospectively analyzed. The postoperative recurrence and death were considered as the research end time, the individual characteristics, imaging characteristics, pathological characteristics, age in treatment, gender, McCormick score, tumor location, WHO grade, tumor volume, degree of resection, radiotherapy, chemotherapy, and H3K27M expression, Ki-67 index, and P53 expression were included in the COX regression model for the univariate and multivariate analysis. The factors related to the recurrence and prognosis of HGSG after surgery were further explored.

RESULTS

The median recurrence-free duration of 44 patients with HGSG was 13.0 months, and the recurrence-free rates of 6 months and 1 year after surgery were 75.0% and 51.9%; the median survival time of the enrolled patients was 21.0 months. The multivariate COX regression analysis on the recurrence of HGSG after surgery showed that the risk of the recurrence was higher in the III-IV group than that the I-II group for the McCormick score ( p=0.001). For WHO grade, the risk of the recurrence was higher in the IV group than that in the III group (p=0.029). The multivariate COX regression analysis on that survival after HGSG surgery showed that the risk of the death was higher in the III-IV group than that in the I-II group for the McCormick score (p=0.006), and the risk of the death was higher for the tumor in the cervical segment than that in the cervical thoracic segment ( p=0.005), thoracic segment ( p=0.003), thoracolumbar segment ( p=0.011). The risk of the death was higher in the H3K27M positive group ( p=0.014) than that in the H3K27M negative group. 0.049).

CONCLUSION

HGSG, as a highly malignant tumour, exhibits rapid progression even after surgical treatment. For future post-operative recurrence and prognosis determination of HGSG, there is a need to focus on assessing the preoperative spinal cord functional status, tumour location, WHO classification and H3K27M mutation status to assist clinicians in giving the best treatment plan.
P11.36.A TUMOR CONTROL AND FUNCTIONAL OUTCOME IN VESTIBULAR SCHWANNOMA - RESULTS FROM A DUAL-CENTER STUDY COMPARING MICROSURGERY AND GAMMA KNIFE RADIOSURGERY
Authors: Wang S , Rick A , Ebner F , van Eck A , Naros G , Horstmann G , Tatagiba M
Published: September 2023

BACKGROUND

The level of evidence to provide treatment recommendations for vestibular schwannoma (VS) is low. Both Stereotactic Radiosurgery (SRS) and microsurgical resection (SURG) are available as treatment options for VS. There are very few direct comparative studies comparing both treatment modalities in large cohorts allowing detailed subgroup analysis.

MATERIAL AND METHODS

This is a retrospective dual-center cohort study. Data was retrospectively collected from two large centers involved in the treatment of solitary vestibular schwannomas for patients between 2005 und 2011 to enable follow-up of up to 10 years. Tumor size was classified by Koos Classification. Clinical state was reported by House and Brackmann (H&B) and Gardner-Robertson (G&R) scale (with H&B and G&R 1-2 considered as good outcome), and Recurrence-free-survival (RFS) was assessed radiographically by contrast-enhanced MR imaging. VS-associated symptoms like trigeminal affection, tinnitus, and vertigo/imbalance were also collected.

RESULTS

The study population included N=901 patients, who were treated in both centers. N=559 patients were treated by SRS, and 342 patients by SURG.Treatment-related functional deterioration (e.g. hearing and facial deterioration) was significantly more common in patients treated by SURG. The incidence of complications was similar in both groups (14% and 13%). Secondary VS-related symptoms like tinnitus, vertigo, imbalance and trigeminal symptoms were significantly improved by microsurgery, but not by SRS. This study reported an overall incidence of recurrence in SURG of only 4%, and 11% in SRS respectively. Tumor control was comparable in small tumors (Koos I and II) in both SRS and SURG. Patients treated by SRS had significantly smaller tumors (p<0.001). In large VS (Koos III and IV), SURG is superior to SRS considering tumor control with a risk reduction for incidence of recurrence.

CONCLUSION

SRS can achieve similar tumor control compared to SURG in smaller VS (Koos I-II) - with less severe postinterventional morbidities (hearing and facial function loss). In large VS (Koos III-IV), tumor control by SRS is inferior to SURG. Therefore, while SURG is increasing the risk for facial palsy, it reduces the risk for recurrence. Moreover, SURG may improve secondary VS symptoms (e.g. tinnitus, vertigo/imbalance and trigeminal symptoms), even in small VS. Our data on tumor control and tumor size in SRS and SURG suggest that if combination therapy is chosen, the residual tumor for adjuvant SRS should not exceed the size of Koos II.These figures should be considered when deciding on treatment modality.
P11.47.B DNA METHYLATION-BASED SUBCLASS PREDICTS THE EFFECT OF THE EXTENT OF RESECTION ON SURVIVAL IN IDH-WILDTYPE GLIOBLASTOMA
Authors: Dankmeijer L G , Westerink L G , de Witt Hamer P C , Wesseling P , Kouwenhoven M C M , Kooi E , Verburg N
Published: September 2023

BACKGROUND

DNA methylation-based classification of diffuse glioma is increasingly used in daily practice. Yet, little is known regarding the prognostic and predictive value of DNA methylation-based subclasses of IDH-wildtype glioblastoma. A recent study found a predictive value for the effect of extent or resection (EOR) on survival for DNA methylation-based subclasses using the v11.4 classifier. We set out to validate these findings in an independent cohort and to test if these results are similar using the newest v12.5 classifier.

MATERIAL AND METHODS

A single-center retrospective cohort study of all patients with a glioblastoma, IDH-wildtype of whom DNA methylation was obtained. Patient and tumor characteristics, pre-operative Karnofsky performance status, and EOR (complete, subtotal, partial, biopsy) were retrieved. DNA methylation-based classification and MGMT promotor status were obtained using version 11.4 and 12.5 of the Heidelberg classifier. Progression-free survival (PFS) and overall survival (OS) were collected and validated using the national brain tumor registry.

RESULTS

Of 149 patients, the subtype was Mesenchymal in 57 (38.27%), RTK1 in 41 (27.52%), and RTK2 in 51 patients (34.23%). PFS and OS did not differ between the three subclasses, also not after pooling RTK1 and RTK2 into one Classical subclass. Complete or subtotal resection resulted in a longer OS than partial resection or biopsy in the entire cohort. This was similar for the pooled Classical subclass. In the Mesenchymal subclass, however, there was no survival advantage for complete or subtotal resection over partial resection or biopsy. These results were similar with the 11.4 and 12.5 classifier version.

CONCLUSION

In IDH-wildtype glioblastoma of the Mesenchymal subclass complete or subtotal resection does not result in a survival benefit. A less aggressive surgical strategy should be considered in these patients. Also, there is need for pre- or intraoperative assessment of the DNA methylation-based subclass of IDH-wildtype glioblastoma.
P11.48.A STEREOTACTIC RADIOSURGERY FOR EPENDYMOMA IN PEDIATRIC AND ADULT PATIENTS: A SINGLE-INSTITUTION EXPERIENCE
Authors: Yoo K H , Marianayagam N J , Park D J , Zamarud A , Gu X , Pollom E L , Soltys S G , Chang S D , Meola A
Published: September 2023

BACKGROUND

Ependymoma is typically classified as WHO grade 2 and its anaplastic variant as grade 3. Despite standard treatment approaches, incomplete resection or anaplastic features can lead to poor prognosis. Stereotactic radiosurgery (SRS) is a promising minimally invasive option for recurrent ependymomas after surgery and radiation therapy. This study aims to evaluate the efficacy and safety of CyberKnife radiosurgery in treatment of WHO grade II versus III ependymomas in both pediatric and adult populations.

MATERIAL AND METHODS

In our study, we evaluated the clinical and radiological records of patients who underwent CyberKnife SRS for ependymoma at our institution between 1998 and 2023. The follow-up data were available for a total of 75 ependymomas in 34 patients. The study population consisted of 14 pediatric patients (ages 3-18) and 20 adult patients (ages 19-75). The median age was 21 years and the median tumor volume accounted for 0.64 cc. The median biologically equivalent dose (BED) and single-fraction equivalent dose (SFED) were 108 Gy and 16.6 Gy, respectively. The SRS was administered at the 77% of the median isodose line.

RESULTS

At a median follow-up of 42.7 months (range: 3.8-438.3) after treatment, our analysis revealed that only 17 (22.7%) ependymomas progressed. The 5-year local tumor control (5-yrs-LTC) rate for all ependymomas was 78.1%, with a lower rate of 59.6% observed in the pediatric cohort and a higher rate of 90.2% in adult patients. For ependymomas classified as WHO grade II, the 5-yrs-LTC rate was 85.9%, whereas it was 58.5% for those classified as WHO grade III. The 5-year overall survival (5-yrs-OS) rate was 73.6% for all patients, with significantly higher rates observed in pediatric patients (94.7%) than in adult patients (41%). The 5-yrs-OS rate was 100% for patients with WHO grade II tumors, whereas it decreased significantly to 35.9% for patients with WHO grade III ependymomas. The 5-year progression-free survival (5-yrs-PFS) rate was 68.5% for all patients, with higher rates observed in pediatric patients (78.3%) than in adult patients (49.2%). The 5-yrs-PFS rate for patients with WHO grade II lesions was 88.8%, whereas it was significantly lower at 32.6% for patients with WHO grade III tumors. Stereotactic radiosurgery (SRS) was effective in improving tumor-associated symptoms in 29 (85.3%) patients with 62 (82.7%) symptomatic ependymomas. These symptoms included headache, back pain, dizziness, nausea, vomiting, cranial nerve palsy, ataxia, motor impairment, sensory deficit, seizures, and weight loss. Notably, no patients developed adverse radiation effects.

CONCLUSION

CyberKnife SRS is a safe and effective treatment for ependymoma in both adults and children, with potential for significant improvements in tumor-related symptoms. Our study supports its use as a minimally invasive alternative to surgery, warranting further investigation.
P11.50.A STEREOTACTIC RADIOSURGERY FOR RECURRENT MEDULLOBLASTOMA IN PEDIATRIC AND ADULT PATIENTS: A SINGLE-INSTITUTION EXPERIENCE
Authors: Yoo K H , Marianayagam N J , Park D J , Gu X , Pollom E L , Soltys S G , Chang S D , Meola A
Published: September 2023

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in children. In recent decades, the therapeutic landscape has undergone significant changes, with stereotactic radiosurgery (SRS) emerging as a promising modality for the treatment of recurrent medulloblastoma. Our study aims to provide a comprehensive long-term analysis of the efficacy and safety of SRS for both pediatric and adult patients with recurrent medulloblastomas at a single institution.

MATERIAL AND METHODS

In our study, we retrospectively reviewed the clinical and radiological records of patients who underwent CyberKnife SRS for medulloblastoma at our institution between 1998 and 2023. Clinical and radiographic follow-up data were available for a total of 15 medulloblastomas in 10 patients. The study population consisted of 8 pediatric patients (ages 3-18) and 2 adult patients (ages 19-75). The median age at the time of SRS was 13 years and the median tumor volume accounted for 1.88 cc. The median biologically equivalent dose (BED) and single-fraction equivalent dose (SFED) were 126 Gy and 18 Gy, respectively. The SRS was administered at the 75% of the median isodose line.

RESULTS

Following a median follow-up of 39 months (range: 6-78) post-treatment, 8 (53.3%) of the medulloblastomas progressed, 2 (13.3%) showed radiographic regression, and 5 (33.3%) remained stable in volume. The 3-year local tumor control rate for all medulloblastomas was 65.2%, with lower rates observed in the adult cohort (50%) and higher rates in pediatric patients (67.3%). The 3-year overall survival rate was 70%, with significantly higher rates in pediatric patients (75%) compared to adult patients (50%). The 3-year progression-free survival rate was 58.3%, with higher rates in pediatric patients (60%) compared to adult patients (50%). Two pediatric patients developed radiation-induced edema, while two adult patients experienced radiation necrosis at the latest follow-up, with both adult patients passing away.

CONCLUSION

SRS is a safe and effective long-term treatment option for recurrent medulloblastoma in both pediatric and adult patients, resulting in improved patient outcomes. Although rare, radiation-induced edema and necrosis were observed as adverse events but were manageable. Overall, our findings provide optimistic evidence for the use of SRS as a viable treatment modality for medulloblastoma.
P11.67.B A RETROSPECTIVE STUDY OF 222 PATIENTS WITH NEWLY DIAGNOSED PRIMARY CNS LYMPHOMA - OUTCOMES INDICATIVE OF IMPROVED SURVIVAL OVER TIME
Authors: Bairey O , Lebe E , Buxbaum C , Porges T , Taliansky A , Gurion R , Goldschmidt N , Tzuk Shina T , Zektser M , Hofstetter L , Siegal T
Published: September 2023

BACKGROUND

Primary central nervous system lymphoma (PCNSL) is a rare disease with an incidence of 0.4/per 100,000 person-years. As there is a limited number of prospective randomized trials in PCNSL, large retrospective studies on this rare disease may yield information that might prove useful for the future design of randomized clinical trials.

MATERIAL AND METHODS

We retrospectively analyzed the data of 222 newly diagnosed PCNSL patients treated in 5 referral centers in Israel between 2001-2020. During this period, combination therapy became the treatment of choice, rituximab has been added to the induction therapy, and consolidation with irradiation was largely laid off and was mostly replaced by high-dose chemotherapy with or without autologous stem cell transplantation.

RESULTS

Patients older than 60 comprised 67.5% of the study population. First-line treatment included high-dose methotrexate (HD-MTX) in 94% of patients with a median MTX dose of 3.5gr/m2 (range 1.14-6 gr/m2) and a median cycle number of 5 (range 1-16). Rituximab was given to 136 patients (61%) and consolidation treatment to 124 patients (58%). Patients treated after 2012 received significantly more treatment with HD-MTX and rituximab, more consolidation treatments, and autologous stem cell transplantation. The overall response rate was 85% and the complete response (CR)/unconfirmed CR rate was 62.1%. After a median follow-up of 24 months, the median PFS and OS were 21.9 and 43.5 months respectively with a significant improvement since 2012 (PFS:12.5 vs. 34.2 p=0.006 and OS:19.9 vs 77.3 p=0.0003). A multivariate analysis found that the most important factors related to OS were obtaining a CR followed by rituximab treatment and ECOG performance status.

CONCLUSION

The observed improvement in outcomes may be due to multiple components such as an intention to treat all patients regardless of age with HD-MTX- based combination chemotherapy, treatment in dedicated centers, and more aggressive consolidation with the

INTRODUCTION

of HDC-ASCT.
P11.72.A INTRACRANIAL CONTROL OF BRAIN METASTASES IN PATIENTS TREATED WITH RADIOTHERAPY PLUS CHEMOTHERAPY, IMMUNOTHERAPY, TARGETED THERAPY AND IMMUNOCHEMOTHERAPY OR TARGETED THERAPY WITH CHEMOTHERAPY
Authors: Sulejmani A , Rinkel G , Etminan N , Brehmer S
Published: September 2023

BACKGROUND

Brain metastases (BM) are the most common intracranial malignancy. For many years, patients with BM were excluded from clinical trials of systemic cancer therapies based on their presumed bad prognosis, which results in a therapeutic nihilism as soon a BM is diagnosed. With the development of immunotherapies and targeted therapies as systemic cancer therapy, we questioned if there is a difference in intracranial response, regardless of the indicated radiotherapy (RT) for the BM.

MATERIAL AND METHODS

67 patients older than 18 years, with multiple BM treated between December 2016 and October 2021, with in total 237 metastases were analyzed. The volume of each metastasis on MRI was calculated at the time of appearance and every 3 months thereafter. The primary outcome was intracranial control according to RANO-BM at 6 months. Because of missing data (MRI at 6 months), 92 metastases had to be excluded, leaving 145 for the analysis. Patients were divided into groups (RT+chemotherapy - CT-group, RT+immunotherapy/targeted therapy - IT/TT-group, RT+chemo-immunotherapy/targeted therapy - CT+IT/TT-group). The second outcome measure was time to progression of metastases; for this outcome 183 metastases could be analyzed. For statistical analysis chi-square test and Tarone-Ware test were performed.

RESULTS

In the CT-group (n=40)10% (n=4) had a progressive disease (PD), 33% (n=13) had a partial response (PR), 57 % (n=23) complete response (CR), and no one stable disease (SD). In the CT+IT/TT-group (n=28) 14% (n=4) had PD, 11% (n=3) SD, 11% (n=3) PR and 64% (n=18) CR. In the IT/TT-group (n=78) 14% (n=11) had PD, 4% (n=3) SD, 26% (n=20) PR and 56% (n=44) CR. The p values for difference in intracranial control were between CT-group/IT/TT-group 0,81 and between CT-group/CT+IT/TT-group 0,58. Patients in the IT/TT-group had a better outcome if a targetable mutation was present (p=0,005). The median time to progression (days) was 474 ± 30 for the CT-group; 581 ± 50 for the IT/TT- group and 360 ± 35 for the CT+IT/TT-group. Tarone-Ware test showed a trend in the progression distributions between the 3 groups favoring the IT/TT-group p= 0,082.

CONCLUSION

Intracranial response could be achieved in all analyzed subgroups without statistically significant difference. Against the background of this data, the therapeutic nihilism due to the presumed bad prognosis is not justified. A subgroup analysis of the IT /TT group showed a significantly better outcome for patients who had a matching gene. Patients who received immunotherapy or targeted therapies showed a trend towards later progression than chemotherapy or combination therapy. Larger patient cohorts should be investigated to see if this trend could be confirmed.
P12.04.B MGMT-STATUS OF TUMOR INFILTRATING MACROPHAGES IN HUMAN GLIOBLASTOMA
Authors: Zeiler A , Liesche-Starnecker F , Delbridge C , Wagner A , Gempt J , Schlegel J
Published: September 2023

BACKGROUND

Glioblastomas are the most prevalent malignant brain tumors in adults, with a frequency ranging from 0.59 to 3.69 in the western world. They are accompanied by a fatal prognosis and a median survival of 12.2 to 18.2 months. Their significant intratumoral and intertumoral heterogeneity is the reason for this. Tumor associated macrophages including microglia can represent up to 30-40% of the cellular component of the tumor and are thought to have an impact on the tumor's behavior. The MGMT promotor methylation is the most significant clinical prognostic factor. Patients with a methylated promotor have a better prognosis and a better response to Temozolomid treatment. This experimental study should determine if the microglia or the tumor cells are responsible for the MGMT status. Moreover, it should show how the MGMT-protein is distributed intracellularly in both cell-populations.

MATERIAL AND METHODS

Therefore, the MGMT-Status of 13 samples of patients with glioblastoma from the division of neurosurgery of the TU München were analyzed. Using magnetic cell sorting and an anti-CD11b antibody, tumor cells and microglia were separated in each sample. A MGMT-assay was carried out for each cell population to demonstrate the proportion of methylated MGMT promotor regions. 25 histological sections underwent immunofluoresence double staining to get a better look at the MGMT protein's intracellular distribution. Two sections of each sample were stained with anti-MGMT antibody and anti-GFAP antibody or anti-IBA1 antibody, respectively, to determine if the MGMT protein is present either in the nucleus or in the cytoplasm of the tumor cells and microglia. A minimum of 200 cells of every section was analyzed manually. Statistical analysis was performed using Mann-Whitney-U-test and a p-value <0.05 was defined as significant.

RESULTS

The separarte MGMT-assay of microglia and tumor cells showed methylated MGMT promotors in 3 samples in both cell populations. Tumor cells as well as microglia demonstrated intracellular MGMT Protein, with no significant difference (0.122 MGMT+ Microglia vs. 0.152 MGMT+ Tumor Cells; p=0.101). The intracellular distribution of the MGMT protein strengthened this result. Tumor cells demonstrated a significantly higher percentage of nuclear MGMT protein (0.602 nuclear MGMT vs. 0.203 cytoplasmic MGMT; p<0.0001), whereas microglial cells showed a significantly higher expression of cytoplasmic MGMT protein (0.608 cytoplasmic MGMT vs. 0.157 nuclear MGMT; p<0.0001).

CONCLUSION

According to the findings of this experimental study, both the microglia and the tumor cells are responsible for the clinical MGMT status. This might fit into the theory of macrophage polarization in the microenvironment of heterogenous tumors. The MGMT protein distribution pattern implies that tumor cells and microglia express their MGMT protein in different cellular compartments.
P12.05.B THE ROLE OF ONCO-METABOLITE IN THE IDH MUTANT GLIOBLASTOMA MICROENVIRONMENT
Authors: Behringer S , Joseph K , Beck J , Schnell O , Heiland H , Ravi V M
Published: September 2023

BACKGROUND

Recently, we found that the reactive astrocytes in the IDH wild type glioblastoma contribute to anti-tumor immunity and support pro-oncogenic signaling. Here, we characterized the transcriptomic signature of IDH1/2-mutant glioma associated astrocytes and determined a unique inflammatory transformation, profoundly different to astrocytes in IDH wildtype glioma patients due to an onco-metabolite R-2-hydroxyglutarate using Next generation sequencing and human ex-vivo slice model.

MATERIAL AND METHODS

We purified and transcriptionally profiled astrocytes from 9 patients with confirmed IDH1-R132H mutation, by means of RNA-sequencing and the data were analyzed using the established pipelines. We also used spatial transcriptomics to evidently show the spatial distribution of astrocytes in IDH-mutated/wildtype glioma samples. We validated our findings using human organotypic slice model inoculated with IDH-mutant cell line or treated with oncometabolite 2-hydroxy glutarate. Additionally, LC-MS was further used to give us a chart of neurotransmitters due to altered microenvironment.

RESULTS

Our results from RNA sequencing showed a transcriptional transformation of reactive astrocytes within the microenvironment of IDH-mutated tumors compared to wildtype glioma by means of RNA-sequencing of purified astrocytes. And, using our established human neocortical GBM model inoculated with IDH mutant tumor and R-2HG treatment, we showed that we were able to activate inflammatory transcriptional programs in astrocytes, mediated by the presence of microglia. Further, by spatially mapping the transcriptomic profiles of purified microglia, we were able to confirm that microglia also demonstrate inflammatory activation in IDH mutated glioma. This inflammatory astrocyte transformation is associated with a loss of neurotransmitter homeostasis (disrupted levels of glutamate) in the treated sections, as has been previously reported in IDH mutated tumors. Additionally, R-H2G increased neuronal spiking rate in, pointing to potential excitotoxicity.

CONCLUSION

Our work provides a crucial contribution towards understanding the role of R-2HG in the IDH mutant glioma microenvironment and sheds light on the significant microenvironmental differences to IDH wild-type glioma.
P12.06.A PERICYTE-LIKE CELLS EXPRESSING FIBROBLAST ACTIVATION PROTEIN ARE MAIN PRODUCERS OF FIBRILLAR EXTRACELLULAR MATRIX IN GLIOBLASTOMA
Authors: Vymola P , Garcia-Borja E , Cervenka J , Balaziova E , Vymolova B , Vodicka P , Busek P , Sedo A
Published: September 2023

BACKGROUND

Compared to the normal brain, glioblastomas (GBMs) contain higher amounts of extracellular matrix (ECM) composed of fibrillar proteins such as collagen I and fibronectin. These proteins are associated with glioma cell invasion and poor clinical outcome of GBM patients, but their origin remains unclear. The highest levels of fibrillar ECM can be found in perivascular niches, which are, among others, resided by fibroblast activation protein (FAP) expressing pericyte-like cells. The aim of this study was to determine the role of FAP+ pericyte-like cells in the production of fibrillar ECM proteins and their importance in glioma cell biology.

MATERIAL AND METHODS

FAP+ pericyte-like cells, glioma stem-like cells (GSCs) and primary endothelial cells were isolated from human GBMs. M2 macrophages were differentiated from monocytes isolated from healthy donors´ buffy coats. The expression of FAP, collagen I and fibronectin in GBM tissues and different cell types (FAP+ pericyte-like cells, glioma cell lines, GSCs, M2 macrophages) was analyzed by immunohistochemistry and ELISA. FAP+ pericyte-like cells and glioma cells were used to prepare extracellular matrices, which were analyzed using mass spectrometry. Solubilized ECM was used in a modified transwell migration assay.

RESULTS

Compared to the non-tumorous brain, high levels of collagen I and fibronectin were present in the vicinity of FAP+ pericyte-like cells in GBMs. The expression of collagen I and fibronectin was higher in GBMs with higher FAP expression. In vitro, FAP+ pericyte-like cells produced the largest amount of collagen I and fibronectin compared to other cell types and secreted these proteins extracellularly, resulting in production of 3D extracellular matrices rich in collagen I and fibronectin. Mass spectrometry revealed that the ECM produced by FAP+ pericyte-like cells strongly differs in composition compared to glioma cell ECM. The ECM produced by FAP+ pericyte-like cells enhanced migration of glioma stem-like cells.

CONCLUSION

FAP+ pericyte-like cells are the main producers of fibrillar ECM proteins such as collagen I and fibronectin in GBM tissue. By this means, their presence within the GBM microenvironment affect the migration of glioma stem-like cells.

Funding: Supported by the National institute for cancer research (LX22NPO5102), Charles University Grant Agency (GAUK 1084120) and Centre for Tumour Ecology (CZ.02.1.01/0.0/0.0/16_019/0000785). EATRIS-CZ (LM2023053), Cooperatio Program, research area ,,Oncology and Haematology", and Ministry of Health of the Czech Republic (NV19 03 00501).
P12.13.B FIBROBLAST ACTIVATION PROTEIN AS A POTENTIAL THERANOSTIC TARGET IN BRAIN METASTASES OF DIVERSE SOLID TUMOURS
Authors: Vymolova B , Zubal M , Matrasova I , Vymola P , Veprkova J , Syrucek M , Tomas R , Vanickova Z , Krepela E , Konecna D , Busek P , Sedo A
Published: September 2023

BACKGROUND

Brain metastases (BM) are a common complication of oncologic disease associated with dismal prognosis and there is an urgent need for novel therapeutic approaches. Fibroblast activation protein (FAP), a transmembrane serine protease, is an emerging theranostic target in cancer due to its frequent upregulation in the tumour microenvironment. FAP protein itself and/or FAP+ cells were shown to promote cancer progression in several extracranial malignancies. However, very little is known about the expression of FAP and the role of FAP+ cells in the unique microenvironment of BM. In this study, we quantified FAP expression and characterized FAP+ cells in BM of various origin.

MATERIAL AND METHODS

FAP enzymatic activity and protein concentration were determined in samples of BM (n=58) and control non-tumorous brain tissue (n=12) by an enzymatic assay using a specific fluorogenic substrate, western blot, and ELISA. Expression of FAP and the characteristics of FAP+ cells were analysed by IHC (n=112). Expression of collagen was quantified by Masson´s trichrome staining (n=106) and collagen I concentration was measured by ELISA (n=56).

RESULTS

FAP expression was significantly higher in BM in comparison to non-tumorous brain tissue, both at the protein and enzymatic activity level. BM with higher FAP expression displayed higher levels of collagen I. FAP was predominantly confined to stromal cells expressing markers typical of cancer-associated fibroblasts and residing in collagen rich regions. FAP expression on tumour cells in a portion of BM was also noted , mainly in BM originating from lung, breast, and renal cancer, melanoma, and sarcoma. Increased FAP expression and the presence of FAP+ stromal cells were common features of BM irrespective of their origin.

CONCLUSION

We are the first to provide a detailed analysis of FAP expression in BM of diverse origin and characterise FAP+ cells in their microenvironment. The frequent upregulation of FAP and its presence on both stromal and tumour cells support the use of FAP as a promising theranostic target in BM.

Funding: This research was funded by the Charles University grant no. 342522 and Program Cooperatio, research area ,,Oncology and Haematology"; Ministry of Health of the Czech Republic - grant NU22-03-00318; Ministry of Education, Youth and Sports of the Czech Republic - LM2023053 of EATRIS-CZ and project “Center of Tumor Ecology” (CZ.02.1.01/0.0/0.0/16_019/0000785) - Operational Program Research, Development and Education; project National Institute for Cancer Research (Programme EXCELES, ID Project No. LX22NPO5102) by the European Union - Next Generation EU.
P12.14.B HIGHLY INVASIVE GLIOMA CELLS MOTILITY MEASUREMENTS ON A VARIETY OF EXTRACELLULAR MATRIX PROTEINS
Authors: Shevtsov M , Tagaeva R , Yudintceva N , Fedorov E , Kim A , Rozanov O , Garaev T , Samochernykh K , Bobkov D
Published: September 2023

BACKGROUND

Glioblastoma multiforme (GBM) is a heterogeneous highly invasive malignant brain tumor. The extracellular matrix (ECM) produced by tumor microenvironment plays an important role in the regulation of cell motility and invasion into surrounding healthy tissue. In this research we determined the effect of various ECM proteins on the motility of primary tumor cells.

MATERIAL AND METHODS

Primary tumor cells were isolated from biopsy material obtained during GBM surgical removal. Cultivation of the piece of tumor (0.5 mm3) was carried out in the form of an 3D explant model at 37°C in 5% CO2-incubator. After several months, cells migrated from the tumor spontaneously formed spheroids. To assess the rate of cell migration, spheroids were seeded on 24-well plate coated with poly-L-lysine, fibrinogen, collagen type I, and Matrigel. After 3 days, the field of view in the well (n=9) was microphotographed every 15 min for 56 hours, after which the tracks of cells outside the spheroids were manually marked (n=50) on the obtained images. The average and maximum speeds were calculated, as well as the straightness of the track (the ratio of the Euclidean distance to the track length). The Mean square displacement (MSD) was plotted against time for each protein studied in comparison with random walk simulation calculated for the equal track parameters (number of steps, mean and sd) on correspondent protein.

RESULTS

Live-cell imaging of the patient-derived cells revealed the heterogeneous population of actively moving cells outside the spheroids. The following results of measuring cell motility were obtained (mean ± sd): (1) Mean speed on poly-L-lysine 4.3 ± 2.5 μm/h; on fibrinogen 11.1 ± 5.7 μm/h; on collagen type I 8.8 ± 5.1 μm/h; on Matrigel 9.7 ± 3.6 μm/h. (2) Max speed on poly-L-lysine 63.8 ± 30.1 μm/h; on fibrinogen 90.0 ± 38.9 μm/h; on collagen type I 96.1 ± 42.1 μm/h; on Matrigel 84.1 ± 34.1 μm/h. (3) Straightness on poly-L-lysine 0.24 ± 0.14 μm/h; on fibrinogen 0.18 ± 0.11 μm/h; on collagen type I 0.14 ± 0.09 μm/h; on Matrigel 0.20 ± 0.12 μm/h. MSD analysis showed the greatest contribution of random walk in the motility of cells on collagen type I, the smallest - on Matrigel.

CONCLUSION

Proteins of ECM affect not only the speed of cell movement, but also the tortuosity of their tracks. Further studies will clarify the mechanisms of GBM invasion depending on the composition of the ECM.