Extent of Resection Thresholds in Molecular Subgroups of Newly Diagnosed Isocitrate Dehydrogenase-Wildtype Glioblastoma

BACKGROUND AND OBJECTIVES

Maximizing the extent of resection (EOR) improves outcomes in glioblastoma (GBM). However, previous GBM studies have not addressed the EOR impact in molecular subgroups beyond IDH1/IDH2 status. In the current article, we evaluate whether EOR confers a benefit in all GBM subtypes or only in particular molecular subgroups.

METHODS

A retrospective cohort of newly diagnosed GBM isocitrate dehydrogenase (IDH)-wildtype undergoing resection were prospectively included in a database (n = 138). EOR and residual tumor volume (RTV) were quantified with semiautomated software. Formalin-fixed paraffin-embedded tumor tissues were analyzed by targeted next-generation sequencing. The association between recurrent genomic alterations and EOR/RTV was evaluated using a recursive partitioning analysis to identify thresholds of EOR or RTV that may predict survival. The Kaplan-Meier methods and multivariable Cox proportional hazards regression methods were applied for survival analysis.

RESULTS

Patients with EOR ≥88% experienced 44% prolonged overall survival (OS) in multivariable analysis (hazard ratio: 0.56, P = .030). Patients with alterations in the TP53 pathway and EOR <89% showed reduced OS compared to TP53 pathway altered patients with EOR>89% (10.5 vs 18.8 months; HR: 2.78, P = .013); however, EOR/RTV was not associated with OS in patients without alterations in the TP53 pathway. Meanwhile, in all patients with EOR <88%, PTEN-altered had significantly worse OS than PTEN-wildtype (9.5 vs 15.4 months; HR: 4.53, P < .001).

CONCLUSION

Our results suggest that a subset of molecularly defined GBM IDH-wildtype may benefit more from aggressive resections. Re-resections to optimize EOR might be beneficial in a subset of molecularly defined GBMs. Molecular alterations should be taken into consideration for surgical treatment decisions in GBM IDH-wildtype.

Characteristics and therapeutic strategies of brain and cranial radiation-induced sarcoma: analysis of 165 cases from our case experience and comprehensive review

BACKGROUND

Radiation-induced sarcoma (RIS) is among the neoplasms potentially caused by radiation therapy (RT) for brain tumors. However, the clinical characteristics of and ideal treatment for RIS are unclear. We analysed our case experience and conducted a comprehensive literature review to reveal the characteristics of brain and cranial RIS.

METHODS

We analysed 165 cases of RIS from the literature together with the RIS case treated at our institution. In each case, the latency period from irradiation to the development of each RIS and the median overall survival (OS) of the patients was analysed by Kaplan-Meier analysis. Spearman's correlation test was used to determine the relationship between the latency period and radiation dose or age at irradiation.

RESULTS

The mean age at the development of RIS was 39.63 ± 17.84 years. The mean latency period was 11.79 ± 8.09 years. No factors associated with early development of RIS were detected. The median OS was 11 months, with fibrosarcoma showing significantly shorter OS compared with osteosarcoma and other sarcomas (p = 0.0021), and intracranial RIS showing a worse prognosis than extracranial RIS (p < 0.0001). Patients treated with surgery (p < 0.0001) and postoperative chemotherapy (p = 0.0157) for RIS presented significantly longer OS, whereas RT for RIS was not associated with a survival benefit.

CONCLUSIONS

Although prognosis for RIS is universally poor, pathological characteristics and locations are associated with worse prognosis. Surgery and chemotherapy may be the ideal treatment strategies for RIS.

Residual diffusion-weighted imaging hyperintense signal in primary central nervous system lymphoma can predict early recurrence

BACKGROUND

The treatment response of primary central nervous system lymphomas (PCNSLs) is mainly evaluated using postcontrast T1-weighted imaging (T1WI). Because poorly enhanced lesions may contain residual tumors, the combination of evaluation methods will potentially improve the accuracy of determining treatment effectiveness. In this study, we evaluated the usefulness of diffusion-weighted imaging (DWI) in predicting recurrence among patients with PCNSL who achieved complete response (CR)/unconfirmed CR (CRu).

METHODS

Fifty-four patients newly diagnosed with PCNSL who were treated at our institution and achieved CR/CRu at the end of treatment were included in this study. The patients were divided into two groups according to the presence or absence of residual DWI hyperintense signal at the tumor site at the end of treatment. Kaplan-Meier analysis was performed to analyze the median overall survival (OS) and progression-free survival (PFS).

RESULTS

The mean age of the 54 patients was 66.4 ± 13.3 years. The induction therapies were HD-MTX in 20 patients, R-MPV in 29 patients, and other chemotherapies in five patients. Radiotherapy was performed in 35 patients, high-dose cytarabine therapy in 14 patients, and autologous hematopoietic stem cell transplantation in one patient, and of the 54 patients, 10 had no consolidation therapy. The residual DWI hyperintense signal sign was observed in 18 patients. The R-MPV regimen was statistically associated with a lower rate of residual DWI hyperintense signal (p = 0.0453). The median PFS was statistically shorter in the residual DWI hyperintense signal group than in the non-residual DWI hyperintense signal group (14.0 months vs. 85.1 months) (p < 0.0001, log-rank test).

CONCLUSION

A residual DWI hyperintense signal at the end of treatment was statistically associated with shorter PFS. Among patients who achieved CR/CRu evaluated based on postcontrast T1WI, DWI could be a valuable additional sequence to predict the early recurrence of PCNSL.

Secondary meningioma after cranial irradiation: case series and comprehensive literature review

BACKGROUND

Secondary meningioma after cranial irradiation, so-called radiation-induced meningioma, is one of the important late effects after cranial radiation therapy. In this report, we analyzed our case series of secondary meningioma after cranial irradiation and conducted a critical review of literature to reveal the characteristics of secondary meningioma.

MATERIALS AND METHODS

We performed a comprehensive literature review by using Pubmed, MEDLINE and Google scholar databases and investigated pathologically confirmed individual cases. In our institute, we found pathologically diagnosed seven cases with secondary meningioma between 2000 and 2018. Totally, 364 cases were analyzed based on gender, WHO grade, radiation dose, chemotherapy. The latency years from irradiation to development of secondary meningioma were analyzed with Kaplan-Meier analysis. Spearman's correlation test was used to determine the relationship between age at irradiation and the latency years.

RESULTS

The mean age at secondary meningioma development was 35.6 ± 15.7 years and the mean latency periods were 22.6 ± 12.1 years. The latency periods from irradiation to the development of secondary meningioma are significantly shorter in higher WHO grade group (P = 0.0026, generalized Wilcoxon test), higher radiation dose group (P < 0.0001) and concomitant systemic chemotherapy group (P = 0.0003). Age at irradiation was negatively associated with the latency periods (r = -0.23231, P < 0.0001, Spearman's correlation test).

CONCLUSION

Cranial irradiation at older ages, at higher doses and concomitant chemotherapy was associated with a shorter latency period to develop secondary meningiomas. However, even low-dose irradiation can cause secondary meningiomas after a long latency period. Long-term follow-up is necessary to minimize the morbidity and mortality caused by secondary meningioma after cranial irradiation.

Diagnostic and therapeutic challenges of glioblastoma as an initial malignancy of constitutional mismatch repair deficiency (CMMRD): two case reports and a literature review

BACKGROUND

Constitutional mismatch repair deficiency (CMMRD) results from a biallelic germline pathogenic variant in a mismatch repair (MMR) gene. The most common CMMRD-associated malignancies are brain tumors; an accurate diagnosis is challenging when a malignant brain tumor is the only tumor at presentation. We describe two cases of glioblastoma as the initial CMMRD malignancy and discuss current diagnostic and therapeutic challenges.

CASE PRESENTATION

Two children with brain tumors without remarkable family history had biallelic pathogenic germline variants in PMS2. Patient 1: A 6-year-old girl presented biallelic PMS2 germline pathogenic variants. Glioblastomas at the left frontal lobe and right temporal lobe were resistant to immune-checkpoint inhibitor, temozolomide, and bevacizumab. Patient 2: A 10-year-old boy presented biallelic PMS2 germline variants. His glioblastoma with primitive neuroectodermal tumor-like features responded to chemoradiotherapy, but he developed advanced colon cancer and acute lymphocytic leukemia. In both patients, only a monoallelic PMS2 germline variant was detected by conventional gene tests. PMS2 immunohistochemistry showed lack of staining at both the tumors and normal tissue as vascular endothelial cells. Further gene tests revealed large genomic deletion including the entire PMS2 gene, confirming biallelic PMS2 germline variants.

CONCLUSION

Conventional multi-gene panel tests are insufficient for detecting large deletions of MMR genes, resulting in misdiagnoses of CMMRD as Lynch syndrome. PMS2 variants have low cancer penetrance; family histories may thus be absent. Long-range gene analyses or immunohistochemical staining of MMR proteins in normal tissue should be considered for pediatric brain tumors with a single allele MMR variant when CMMRD is suspected.

PEDT-10 PHASE II TRIAL OF PATHOLOGY-BASED THREE-GROUP TREATMENT STRATIFICATION FOR PATIENTS WITH CNS GERM CELL TUMORS: A LONG-TERM FOLLOW-UP STUDY

Background

Phase II clinical trial funded by Ministry of Health, Labour and Welfare from 1995 to 2003 evaluated efficacy of pathology-based three-group treatment stratification for CNS germ cell tumors (GCTs). We here present long-term follow-up results.

Methods

Total 228 cases were registered. Germinoma was treated with carboplatin+etoposide (CARE) and extended-local irradiation, local irradiation was added for intermediate-prognosis-group, and poor-prognosis-group was treated with ifosfamide+cisplatin+etoposide (ICE) and whole-brain or craniospinal irradiation.

Results

Mean/median ages at diagnosis were 16.8/16 years and female-to-male ratio was 40-188. Registry included 123 germinomas, 76 intermediate-prognosis-group cases (including 38 germinoma with STGC), 28 poor-prognosis-group cases and 1 mature teratoma. Median 222-months follow-up was conducted, and 56 recurrences and 39 deaths were recorded. 10 and 20-year recurrence-free survival (RFS) for germinoma, intermediate and poor-prognosis-groups were 84/79%, 83/76% and 59/59%, respectively, and overall survival (OS) for each were 97/91%, 92/85% and 57/53%, respectively. Prognosis for germinoma with or without STGC was the same. Basal ganglia germinoma showed significantly shorter RFS but OS was not different from other locations. Median age at death was 24 years, and ages were significantly different depending on causes, such as disease-related (14 years on average) and complications (29 years). OS after recurrence at 5/10/20 years were 64/62/48%.Hormonal supplementation was seen in 82% for neurohypophyseal cases and antidiuretic hormone supplementation was most frequent (82%). Among available cases, 20-out-of-155 cases showed neoplastic/vascular complications, among which cavernous malformation was the most (n=9). Median period until complication presentation was 235 months, and the rate at 20 years was 11%.

Conclusions

Germinoma and intermediate-prognosis-group cases showed long-term survival for approximately 90%, while more intensive treatment would be necessitated for poor-prognosis-group. Long-term survivors often required hormonal supplementation, and increasing frequency of treatment-related complications was observed. There is no end of outpatient follow-up for CNS GCT patients.

MET-8 EFFECT OF VEGF-TARGETED THERAPY FOR SYMPTOMATIC/REFRACTORY BRAIN EDEMA CAUSED BY METASTATIC BRAIN TUMORS

Background

Molecular target therapy with EGFR and ALK inhibitors greatly improved the prognosis of lung cancer patients with driver mutation-positive metastatic brain tumors. Inhibitors of VEGF are also useful for treating brain edema induced by brain metastases. In this study, we examined the impact of VEGF inhibitors on symptomatic/refractory edema in metastatic brain tumors.

Materials and Methods

This retrospective study included the patients with metastatic brain tumors who received VEGF-targeted therapy for symptomatic/refractory brain edema. The primary cancer site, radiation therapy for metastatic brain tumors, corticosteroid administration, symptoms, Karnofsky performance status, and MR imagings before and after VEGF-targeted therapy were all gathered from the patient's medical records.

Results

19 patients with symptomatic/refractory cerebral edema [NSCLC(15), LCNEC(1), SCLC(1), breast cancer(2), colorectal cancer (2)] were treated with anti-VEGF medication. Nine patients were treated with bevacizumab as a monotherapy, and 12 patients were treated with bevacizumab or ramucirumab in combination as a multi-drug therapy. Prior brain irradiation was administered to 17 patients. Corticosteroids were used to treat brain edema in 8 patients. VEGF inhibitors were effective in all patients, improving symptoms by reducing brain edema.

Conclusion

We recommend VEGF inhibitor for symptomatic/refractory edema of metastatic brain tumors. This treatment may be successful independent of the primary cancer site.

Influence of growth hormone therapy on germinoma survivors

PURPOSE

Due to the effectiveness of growth hormone therapy (GHT), the number of cancer survivors receiving GHT has increased. Previous studies had indicated that GHT was not associated with the increasing risks of tumor recurrence and development with second neoplasm (SN) in cancer survivors. However, to date, research on those risks in germinoma survivors is still limited. The aim of this study is to evaluate the impact of GHT in relation to tumor recurrence and development with SN in pure germinoma survivors.

METHODS

This retrospective cohort study was approved by the Ethical Committee for Epidemiology of our institution. Seventy-three consecutive patients who underwent a biopsy of the lesion and were diagnosed with pure germinoma were retrospectively studied. They (median age, 15.0 years) were followed up more than 1 year after biopsy (median follow-up period, 14.3 years). The following data was obtained from the medical records of the patients: age, sex, preoperative magnetic resonance imaging findings, hormonal replacement, and events including tumor recurrence and/or SN.

RESULTS

In our patient series, 16 patients (21.9%) who were more likely to have neurohypophysial lesion and receive multiple hormonal therapies had received GHT. No significant differences in the rates of tumor recurrence and development with SN were observed between the patients who had and had not received GHT. Moreover, the recurrence-free survival and overall survival rates were not different between the patients who had and had not received GHT.

CONCLUSIONS

GHT did not increase the risks of tumor recurrence and development with SN in pure germinoma survivors.

Characteristics and therapeutic strategies of radiation-induced glioma: case series and comprehensive literature review

INTRODUCTION

The so-called radiation-induced glioma (RIG, a secondary glioma after cranial irradiation), is a serious late effect after cranial radiation therapy. The clinical characteristics of and ideal treatment for these tumors are unclear. We analyzed our case series and conducted a comprehensive literature review to reveal the precise characteristics of RIGs.

METHODS

We analyzed the cases of six patients with RIGs treated at our institution and 354 patients with RIGs from the literature. The latency period from irradiation to the development of each RIG and the median overall survival of the patients were subjected to Kaplan-Meier analyses. Spearman's correlation test was used to determine the relationship between age at irradiation and the latency period.

RESULTS

The mean age of the 360 patients at the development of RIG was 27.42 ± 17.87 years. The mean latency period was 11.35 ± 8.58 years. Multiple gliomas were observed in 28.4%. WHO grade 3 and 4 RIGs accounted for 93.3%. The latency periods were significant shorter in the higher WHO grade group (p = 0.0366) and the concomitant systemic chemotherapy group (p < 0.0001). Age at irradiation was negatively associated with the latency period (r =- 0.2287, p = 0.0219). The patients treated with radiotherapy achieved significantly longer survival compared to those treated without radiotherapy (p = 0.0011).

CONCLUSIONS

Development in younger age, multiplicity, and high incidence of grade 3 and 4 are the clinical characteristics of RIGs. Cranial irradiation at older ages and concomitant chemotherapy were associated with shorter latency for the development of RIG. Radiation therapy may be the feasible treatment option despite radiation-induced gliomas.

Molecular, Histological, and Clinical Characteristics of Oligodendrogliomas: A Multi-Institutional Retrospective Study

BACKGROUND

Reports suggest that phosphatidylinositol 3-kinase pathway alterations confer increased risk of progression and poor prognosis in oligodendroglioma, IDH-mutant, and 1p/19q-codeleted molecular oligodendrogliomas (mODG). However, factors that affect prognosis in mODG have not been thoroughly studied. In addition, the benefits of adjuvant radiation and temozolomide (TMZ) in mODGs remain to be determined.

OBJECTIVE

To evaluate the role of PIK3CA mutations in mODGs.

METHODS

One hundred seven mODGs (2008-2019) diagnosed at 2 institutions were included. A retrospective review of clinical characteristics, molecular alterations, treatments, and outcomes was performed.

RESULTS

The median age was 37 years, and 61 patients (57%) were male. There were 64 (60%) World Health Organization (WHO) grade 2 and 43 (40%) WHO grade 3 tumors. Eighty-two patients (77%) were stratified as high risk (age 40 years or older and/or subtotal resection per Radiation Treatment Oncology Group-9802). Gross-total resection was achieved in 47 patients (45%). Treatment strategies included observation (n = 15), TMZ (n = 11), radiation (n = 13), radiation/TMZ (n = 62), and others (n = 6). Our results show a benefit of TMZ vs observation in progression-free survival (PFS). No difference in PFS or overall survival (OS) was observed between radiation and radiation/TMZ. PIK3CA mutations were detected in 15 (14%) mODG, and shorter OS was observed in PIK3CA-mutant compared with PIK3CA wild-type mODGs (10.7 years vs 15.1 years, P = .009). WHO grade 3 tumors showed a shorter PFS, but no significant difference in OS was observed between WHO grades.

CONCLUSION

Our findings suggest that mODGs harboring PIK3CA mutations have worse OS. Except for an advantage in PFS with TMZ treatment, adjuvant TMZ, radiation, or a combination of the two showed no significant improvement in OS.

[Astroblastoma with Rapid Cyst Expansion and Hemorrhage in an Adult: A Case Report]

Astroblastoma is an extremely rare primary brain tumor accounting for 0.45 to 2.8% of all neuroglial tumors and usually occurs in pediatrics and young adults. The natural history of astroblastoma still remains unknown. In the World Health Organization (WHO) classification of tumors of the central nervous system, astroblastoma is classified as other neuroepithelial tumors and standard treatment other than surgery has not been established. As molecular and genetic diagnosis becomes more important in the latest WHO classification of brain tumors, the development of therapeutic options based on the information of molecular genetics are expected. Here we report a case of astroblastoma in a 49-year-old male. Small tumor was discovered by coincidence during his check-up following traffic accident, but three months later, tumor bleeding with cystic enlargement resulted in disturbance of consciousness. Initial diagnosis of low grade astroblastoma with BRAF^V600E mutation was made. After 1 year, local tumor recurrence was observed. The histological diagnosis at recurrence was high grade astroblastoma. We here, discuss about diagnosis, treatment and the possibility of usefulness of molecular genetic analysis for astroblastoma with some literature review. (Received 10 August, 2021; Accepted 15 December, 2021; Published 1 April, 2022).

[Craniopharyngioma Mimicking Chordoid Glioma]

Entirely intrinsic third ventricular craniopharyngiomas showed characteristics of a round/oval shaped tumor, with rare calcification and cyst formation, and pathologically squamous-papillary type with a positive BRAF^V600E mutation. We report an extremely rare case of entirely intrinsic third ventricular craniopharyngioma, pathologically adamantiomatous but with BRAF^V600E mutation genetically, developed in a 35-year-old female. It was oval-shaped, with no calcification or cyst, and showed homogeneous enhancement. As shown in this case, it was difficult to differentiate this pathology from chordoid glioma of third ventricle, and the difficulty of this differential diagnosis has not been well documented in previous studies. Our case further implied the importance of molecular diagnosis for subclassification of craniopharyngioma. The BRAF^V600E-mutated craniopharyngioma could be the target for the development of treatment with preoperative BRAF-inhibitors. Therefore, differentiation between entirely intrinsic third ventricular craniopharyngiomas and chordoid glioma could be new issue. In this report, we discuss about the preoperative differential diagnosis from chordoid glioma and the literature review. (Received 12 August, 2021; Accepted 21 September, 2021; Published 1 February, 2022).

Impacts of genotypic variants on survival following reoperation for recurrent glioblastoma

INTRODUCTION

Recurrent glioblastoma (rGBM) prognosis is dismal. In the absence of effective adjuvant treatments for rGBM, re-resections remain prominent in our arsenal. This study evaluates the impact of reoperation on post-progression survival (PPS) considering rGBM genetic makeup.

METHODS

To assess the genetic heterogeneity and treatment-related changes (TRC) roles in re-operated or medically managed rGBMs, we compiled demographic, clinical, histopathological, and next-generation genetic sequencing (NGS) characteristics of these tumors from 01/2005 to 10/2019. Survival data and reoperation were analyzed using conventional and random survival forest analysis (RSF).

RESULTS

Patients harboring CDKN2A/B loss (p = 0.017) and KDR mutations (p = 0.031) had notably shorter survival. Reoperation or bevacizumab were associated with longer PPS (11.2 vs. 7.4-months, p = 0.006; 13.1 vs 6.2, p < 0.001). Reoperated patients were younger, had better performance status and greater initial resection. In 136/273 (49%) rGBMs undergoing re-operation, CDKN2A/B loss (p = 0.03) and KDR mutations (p = 0.02) were associated with shorter survival. In IDH-WT rGBMs with NGS data (n = 166), reoperation resulted in 7.0-month longer survival (p = 0.004) than those managed medically. This reoperation benefit was independently identified by RSF analysis. Stratification analysis revealed that EGFR-mutant, CDKN2A/B-mutant, NF1-WT, and TP53-WT rGBM IDH-WT subgroups benefit most from reoperation (p = 0.03). Lastly, whether or not TRC was prominent at re-operation does not have any significant impact on PPS (10.5 vs. 11.5-months, p = 0.77).

CONCLUSIONS

Maximal safe re-resection significantly lengthens PPS regardless of genetic makeup, but reoperations are especially beneficial for IDH-WT rGBMs with EGFR and CDKN2A/B mutations with TP53-WT, and NF1-WT. Histopathology at recurrence may be an imperfect gauge of disease severity at progression and the imaging progression may be more reflective of the prognosis.

COT-11 Relationship between preoperative liquid biopsy and prognosis of glioblastoma -Next Generation Sequencing of small noncoding RNA-

Background

Non-invasive biomarkers are required in clinical practice of glioblastoma (GBM). We have previously reported the liquid biopsy for differentiating glioblastoma, central nervous system primary lymphoma and healthy control. In this study, we analyzed the relationship between the preoperative serum expression of circulating small non-coding RNAs and the prognosis of GBM patients.

Methods

Preoperative blood samples of GBM, IDH-wildtype patients (N=26) were centrifuged and collected all small RNAs in serum. The expression of small non-coding RNAs were analyzed using a next-generation sequencing system. The small non-coding RNAs that could predict short-term survivals in GBM patients were selected by the stepwise analysis. A diagnostic model was created using the combination of these RNAs and evaluated with ROC curve.

Results

GBM patients treated with adjuvant therapy of temozolomide and radiotherapy were divided into two groups: (1) a short-term survival group (N=11) with a survival time less than 15 months and (2) a long-term survival group (N=15) with a survival time more than 15 months. In the short-term survival group, the preoperative serum expression levels of small RNA-X and small RNA-Y were high, and the expression levels of small RNA-Z and small RNA-W were low. Using these four small non-coding RNAs, a prognostic model was created. The model was able to predict the short-term survival group of GBM patients with a sensitivity of 90.9% and specificity of 93.3% (AUC: 0.969).

Conclusion

The prognostic model developed with preoperative small non-coding RNA in GBM patients may be useful for estimating the survival of GBM patients treated with adjuvant therapy of temozolomide and radiotherapy.

Intratumoral Hemorrhage After Endoscopic Third Ventriculostomy for Obstructive Hydrocephalus Caused by Brain Tumors

BACKGROUND

Endoscopic third ventriculostomy (ETV) for obstructive hydrocephalus and endoscopic biopsy (EB) for intraventricular and paraventricular tumors are standard therapies because they are minimally invasive procedures. Although EB-associated hemorrhagic risk has been well documented, there have been only a few reports on hemorrhagic risk associated with ETV. We conducted a single-institution retrospective study on the incidence of hemorrhage secondary to EB and/or ETV.

METHODS

We retrospectively reviewed patient characteristics, procedure, pathological findings, and complications including hemorrhage of 100 patients with intraventricular and paraventricular tumors who underwent EB and/or ETV at our institution from 2000 to 2020.

RESULTS

EB/ETV combined surgery (combined group), EB-alone surgery (EB-alone group), and ETV-alone surgery (ETV-alone group) were performed in 44 (44%), 24 (24%), and 32 (32%) patients, respectively, and all procedures were successful. The rates of definitive and suggestive diagnoses in EB were 76.5% and 23.5%, respectively. Adverse events were observed in 6 patients. In the combined group, acute obstruction of the ETV stoma was observed in 1 patient and transient double vision was observed in 1 patient. Transient aqueductal stenosis/obstruction was observed in 2 patients in the EB-alone group. In the ETV-alone group, hemorrhage was observed in 2 patients; these patients developed intratumoral hemorrhage despite ETV-alone surgery. Subsequently, these 2 patients underwent tumor removal, and the histopathological diagnosis was atypical teratoid/rhabdoid tumor in both.

CONCLUSIONS

For obstructive hydrocephalus with atypical teratoid/rhabdoid tumor, physicians must be aware of the risk of postoperative intratumoral hemorrhage after performing ETV.

[Elderly Glioma]

Treatment of elderly glioma patients is a challenge in neurosurgery/neuro-oncology. The International Society of Geriatric Oncology(SIOG)recommends that elderly cancer patients undergo comprehensive geriatric assessment(CGA). The CGA score proved to be a significant predictor of mortality in this cohort, and it could be a useful treatment decision tool. Because of the rapid aging of Japan's population, clinical research focusing on elderly patients with cancer is urgently needed. The Japan Clinical Oncology Group(JCOG)has established a formal policy for research in geriatric cancers. Currently, the JCOG recommends that researchers perform CGA, including G8, to assess the tolerability of treatment for clinical trials in elderly cancer patients, including glioma. Under this policy, elderly cancer patients are categorized into three groups: fit, vulnerable, and frail. For "unfit" glioma/glioblastoma patients, physicians will need to conduct appropriately reduced treatment. Hypofractionated radiotherapy(40.05 Gy/15 fractions)has been an established treatment for elderly patients with glioblastoma. The concurrent and adjuvant temozolomide have reported to have a survival benefit for "fit" elderly patients. Subsequently, alternative hypofractionated radiotherapy, including 34 Gy/10 fractions and monotherapy with temozolomide against MGMT methylated glioblastomas, have been reported as non-inferior alternative treatments. Physicians also need to consider the adverse events associated with anticonvulsants.

Differences in Genomic Alterations Between Brain Metastases and Primary Tumors

BACKGROUND

Brain metastases (BMs) occur in ∼1/3 of cancer patients and are associated with poor prognosis. Genomic alterations contribute to BM development; however, mutations that predispose and promote BM development are poorly understood.

OBJECTIVE

To identify differences in genomic alterations between BM and primary tumors.

METHODS

A retrospective cohort of 144 BM patients were tested for genomic alterations (85 lung, 21 breast, 14 melanoma, 4 renal, 4 colon, 3 prostate, 4 others, and 9 unknown carcinomas) by a next-generation sequencing assay interrogating 315 genes. The differences in genomic alterations between BM and primary tumors from COSMIC and TCGA were evaluated by chi-square or Fisher's exact test. Overall survival curves were plotted using the Kaplan-Meier method.

RESULTS

The comparison of BM and primary tumors revealed genes that were mutated in BM with increased frequency: TP53, ATR, and APC (lung adenocarcinoma); ARID1A and FGF10 (lung small-cell); PIK3CG, NOTCH3, and TET2 (lung squamous); ERBB2, BRCA2, and AXL1 (breast carcinoma); CDKN2A/B, PTEN, RUNX1T1, AXL, and FLT4 (melanoma); and ATM, AR, CDKN2A/B, TERT, and TSC1 (renal clear-cell carcinoma). Moreover, our results indicate that lung adenocarcinoma BM patients with CREBBP, GPR124, or SPTA1 mutations have a worse prognosis. Similarly, ERBB2, CDK12, or TP53 mutations are associated with worse prognosis in breast cancer BM patients.

CONCLUSION

The present study demonstrates significant differences in the frequency of mutations between primary tumors and BM and identifies targetable alterations and genes that correlate with prognosis. Identifying the genomic alterations that are enriched in metastatic central nervous system tumors could help our understanding of BM development and improve patient management.

PTEN mutations predict benefit from tumor treating fields (TTFields) therapy in patients with recurrent glioblastoma

INTRODUCTION

Optimal treatment for recurrent glioblastoma isocitrate dehydrogenase 1 and 2 wild-type (rGBM IDH-WT) is not standardized, resulting in multiple therapeutic approaches. A phase III clinical trial showed that tumor treating fields (TTFields) monotherapy provided comparable survival benefits to physician's chemotherapy choice in rGBM. However, patients did not equally benefit from TTFields, highlighting the importance of identifying predictive biomarkers of TTFields efficacy.

METHODS

A retrospective review of an institutional database with 530 patients with infiltrating gliomas was performed. Patients with IDH-WT rGBM receiving TTFields at first recurrence were included. Tumors were evaluated by next-generation sequencing for mutations in 205 cancer-related genes. Post-progression survival (PPS) was examined using the log-rank test and multivariate Cox-regression analysis.

RESULTS

149 rGBM patients were identified of which 29 (19%) were treated with TTFields. No significant difference in median PPS was observed between rGBM patients who received versus did not receive TTFields (13.9 versus 10.9 months, p = 0.068). However, within the TTFields-treated group (n = 29), PPS was improved in PTEN-mutant (n = 14) versus PTEN-WT (n = 15) rGBM, (22.2 versus 11.6 months, p = 0.017). Within the PTEN-mutant group (n = 70, 47%), patients treated with TTFields (n = 14) had longer median PPS (22.2 versus 9.3 months, p = 0.005). No PPS benefit was observed in PTEN-WT patients receiving TTFields (n = 79, 53%).

CONCLUSIONS

TTFields therapy conferred a significant PPS benefit in PTEN-mutant rGBM. Understanding the molecular mechanisms underpinning the differences in response to TTFields therapy could help elucidate the mechanism of action of TTFields and identify the rGBM patients most likely to benefit from this therapeutic option.

Evaluation of the Oncomine Pan-Cancer Cell-Free Assay for Analyzing Circulating Tumor DNA in the Cerebrospinal Fluid in Patients with Central Nervous System Malignancies

Available tools to evaluate patients with central nervous system (CNS) tumors such as magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) cytology, and brain biopsies, have significant limitations. MRI and CSF cytology have poor specificity and sensitivity, respectively, and brain biopsies are invasive. Circulating tumor DNA in CSF (CSF-ctDNA) could be used as a biomarker in patients with CNS tumors, but studies in this area are limited. We evaluated four CSF-ctDNA extraction methods and analyzed mutations in CSF-ctDNA with the Oncomine Pan-Cancer cell-free assay. CSF-ctDNA was extracted from 38 patients with primary or metastatic CNS tumors and 10 patients without CNS malignancy. Commercial ctDNA controls were used for assay evaluation. CSF-ctDNA yields ranged from 3.65 to 3120 ng. Mutations were detected in 39.5% of samples. TP53 was the most commonly mutated gene and copy number alterations were detected in CCND1, MYC, and ERBB2/HER2. Twenty-five percent of CSF-cytology-negative samples showed mutations in CSF-ctDNA. There was good concordance between mutations in CSF-ctDNA and matching tumors. The QIAamp Circulating Nucleic Acid Kit was the optimal method for extraction of CSF-ctDNA and the Oncomine cell-free DNA assay is suitable for detection of mutations in CSF-ctDNA. Analysis of CSF-ctDNA is more sensitive than CSF-cytology and has the potential to improve the diagnosis and monitoring of patients with CNS tumors.

Detecting non-germinomatous germ cell tumor component by arterial spin labeling perfusion-weighted MR imaging in central nervous system germ cell tumor

PURPOSE

Differentiating between germinoma and non-germinomatous germ cell tumor (NGGCT) is important because sensitivity to chemotherapy and/or radiotherapy is quite different between these two subgroups. In this study, we evaluated whether the arterial spin labeling (ASL) based perfusion-weighted imaging (PWI) could provide additional information for the differential diagnosis between germinoma and NGGCT.

METHOD

Between 2011 and 2018, 20 patients with central nervous system (CNS) germ cell tumor (GCT) who underwent preoperative MR imaging including ASL-PWI were enrolled in this study. Relative tumor blood flow (rTBF) was evaluated on ASL-PWI by manually placing regions of interest at gadolinium enhanced part of the tumors and normal subcortical white matter. Presence of intratumoral T1 hyperintense foci and apparent diffusion coefficient (ADC) were also evaluated. The final diagnosis was made by the combination of tumor markers and the histological diagnosis.

RESULTS

Among 20 patients of CNS-GCT, 11 were diagnosed as germinoma and 9 were diagnosed as NGGCT. In the germinoma subgroup, the rTBF ranged from 0.90 to 1.71 (mean 1.21, median 1.09), while it ranged from 1.14 to 5.75 (mean 3.91, median 3.31) in NGGCT subgroup. The receiver operating characteristic (ROC) curve showed that calculating rTBF is useful for differentiating between germinoma and NGGCT (area under the curve (AUC) 0.929, P = 0.0012) compared to intratumoral T1 hyperintense foci (AUC 0.788, P = 0.0304) and ADC (AUC 0.919, P = 0.0016).

CONCLUSIONS

High rTBF obtained by ASL-PWI implied the presence of NGGCT component. This information might help in deciding the chemotherapy/radiotherapy intensity.

Glioma and temozolomide induced alterations in gut microbiome

The gut microbiome is fundamental in neurogenesis processes. Alterations in microbial constituents promote inflammation and immunosuppression. Recently, in immune-oncology, specific microbial taxa have been described to enhance the effects of therapeutic modalities. However, the effects of microbial dysbiosis on glioma are still unknown. The aim of this study was to explore the effects of glioma development and Temozolomide (TMZ) on fecal microbiome in mice and humans. C57BL/6 mice were implanted with GL261/Sham and given TMZ/Saline. Fecal samples were collected longitudinally and analyzed by 16S rRNA sequencing. Fecal samples were collected from healthy controls as well as glioma patients at diagnosis, before and after chemoradiation. Compared to healthy controls, mice and glioma patients demonstrated significant differences in beta diversity, Firmicutes/Bacteroides (F/B) ratio, and increase of Verrucomicrobia phylum and Akkermansia genus. These changes were not observed following TMZ in mice. TMZ treatment in the non-tumor bearing mouse-model diminished the F/B ratio, increase Muribaculaceae family and decrease Ruminococcaceae family. Nevertheless, there were no changes in Verrucomicrobia/Akkermansia. Glioma development leads to gut dysbiosis in a mouse-model, which was not observed in the setting of TMZ. These findings seem translational to humans and warrant further study.

NI-11 Clinical significance of intracystic diffusion hyperintensity lesions remaining after treatment of intracranial germ cell tumor

Background and purpose: About 30% of intracranial germ cell tumors are mixed germ cell tumors and teratomas are often found as those components. Intense chemoradiotherapy is performed according to the malignancy of the histopathology, but high-intensity lesion inside the cystic tumor on diffusion weighted imaging (DWI) sometimes remains after completion of the chemoradiotherapy. In this study, we examined the clinical significance of the DWI high-intensity lesion remaining in the cyst. METHODS: Five patients after initial chemoradiotherapy were resected residual tumor by craniotomy at our hospital from 2009 to 2019. Preoperative gadolinium-enhanced MRI defined the non-contrast-enhanced part of the tumor as intracystic, and DWI intensity was classified by its look as low-intensity, equal-intensity, and high-intensity compared to the cortex of the same slice. DWI signals in the solid area, cyst wall, and cyst were evaluated. Results: All cases were mature teratoma in histopathology, and no other tumor components were observed. On DWI, the cyst wall and solid part were visualized with low signal. High-intensity lesions and equal-intensity lesions in the cyst cavity were found in 3 and 1 cases, respectively. In these cases, pathological findings revealed a keratin-like substance in the cyst. Discussion: The intracystic high and equal intensity lesions on DWI removed after completion of chemoradiotherapy are considered to reflect the keratin-like component of mature teratoma. If DWI- high intensity and equal intensity lesions remain in the cyst of the tumor after the completion of chemoradiotherapy, tumor shrinkage cannot be expected even if the chemotherapy is strengthened. In such cases, we should consider to removing them by surgery. Conclusion: When DWI high and equal intensity lesions are found in the cysts of tumors remaining after chemoradiotherapy for intracranial germ tumors, it is possible that mature teratoma remains.

SURG-23. REOPERATION IN MOLECULAR SUBTYPES OF RECURRENT GLIOBLASTOMA

BACKGROUND

Recurrent glioblastoma (rGBM) treatment is not well defined and multiple therapeutic approaches have been proposed, none of which has shown to prolong survival in randomized trials. The role of reoperation for rGBM is still unclear. While most studies demonstrate improve overall survival (OS) and post-progression survival (PPS), recent studies employing time-dependent analysis appear to undermine the OS benefit in reoperated patients. Moreover, the relevance of rGBM molecular subtypes that benefit from reoperation is an important question that may guide clinical decision-making.

METHODS

A retrospective review of rGBM demographics, clinical, molecular, and outcome characteristics was performed for all cases managed by us between 01/2005 to 10/2019 at our institution. IDH1/IDH2 status was determined by immunohistochemistry and/or next-generation sequencing (NGS). A genetic subanalysis was conducted for most rGBM IDH-wildtype (IDH-WT) by NGS. The primary outcome was PPS. Kaplan-Meier method, multivariable Cox proportional-hazards model, and accelerated failure time model were performed in survival analysis. Random survival forest was applied to identify variable importance.

RESULTS

284 rGBM patients fulfill inclusion criteria, 145 (51.1%) had reoperation at their 1st recurrence. Reoperated patients were significantly younger, had better performance status, and had a higher extent of resection at initial surgery; meanwhile, they were less likely to receive bevacizumab. Patients undergoing reoperation experienced superior PPS (11.5 vs. 7.4, months, log-rank test: p= 0.002), which kept consistent in multivariable Cox model (HR: 0.62, p= 0.001). Moreover, reoperated rGBM IDH-WT (N= 238) had 37% reduced risk of post-progression death compared to non-reoperated patients. A subanalysis of rGBM IDH-WT molecular subtypes identified that EGFR mutant, NF1 wildtype, and TP53 wildtype subgroups could benefit from reoperation (all p&lt; 0.008).

CONCLUSIONS

Maximal safe re-resection improved the PPS of rGBM regardless of their IDH status. Reoperation for 1st recurrence was especially beneficial for GBM IDH-WT harboring EGFR alteration, TP53 WT, and NF1-WT.

BIOM-48. PTEN MUTATIONS PREDICT BENEFIT FROM TUMOR-TREATING FIELDS THERAPY IN PATIENTS WITH RECURRENT GLIOBLASTOMA

BACKGROUND

Glioblastoma IDH-wildtype (GBM-IDH-WT) recurs despite the standard of care which includes surgical resection and concurrent chemoradiotherapy. Optimal treatment for recurrent GBM-IDH-WT (rGBM) is not standardized and multiple therapeutic approaches are utilized. Clinical trials have shown that Tumor-Treating Fields (TTF) provide equal benefits compared to physician’s chemotherapy choice for patients with rGBM. However, not all rGBM patients respond equally to TTF and understanding which patients will benefit from TTF therapy is critical.

METHODS

We reviewed clinical, molecular, and outcome characteristics of rGBM patients between 09/2009 to 2/2019 in our institution. Patients who received TTF-treatment at the time of 1st recurrence were selected for analysis. Tumors were analyzed for mutations in 315 cancer-related genes by next-generation sequencing. Post-progression survival (PPS) defined as the interval from 1st recurrence to death or the time of analysis, was examined using the Log-rank test and multivariable Cox-regression model.

RESULTS

149 rGBM patients were identified of which 29 (19%) were treated with TTF. Overall, no significant difference in survival was observed in rGBM patients who received TTF therapy (13.9-months vs 10.9-months, p= 0.06). However, among TTF-treated patients (n= 29), there was improved survival in PTEN-mutant (n= 14) patients compared to PTEN-wt (n= 15), (22.2-months vs 11.6- months, p= 0.017). No differences in TTF usage were observed between groups. Within the PTEN-mutant patients (70/149, 47%), those treated with TTF (n= 14) had longer PPS (22.2-months vs 9.3-months, p= 0.005). No survival benefit with TTF-treatment was observed in PTEN-wt patients (79/149, 53%).

CONCLUSIONS

Patients with GBM-PTEN-mutant tumors show a significant improvement in survival when treated with TTF at recurrence. Understanding the molecular mechanism underpinning the differences in response to TTF therapy could help elucidate the mechanism of action of TTF and identify patients that will benefit the most from this therapeutic option.

PATH-19. MOLECULAR, HISTOLOGIC AND CLINICAL CHARACTERISTICS OF OLIGODENDROGLIOMAS: A MULTI-INSTITUTIONAL RETROSPECTIVE STUDY

In the 2016 WHO classification of CNS tumors, oligodendrogliomas are molecularly defined by IDH1 or IDH2 mutations and 1p/19q co-deletion. Some reports suggest that PI3K pathway alterations may confer increased risk of progression and poor prognosis in oligodendroglioma. However, factors that influence prognosis in molecularly defined oligodendroglioma (mOGD) have not been thoroughly studied. Also, the benefits of adjuvant radiation and temozolomide in mOGDs remain to be determined. 107 mOGDs diagnosed between 2008-2018 at the University of Texas Health Science Center at Houston (n= 39) and MD Anderson Cancer Center (n= 68) were included. A retrospective review of the demographic, clinical, histologic, molecular, and outcomes were performed. Median age at diagnosis was 37 years and 61 (57%) patients were male. There were 64 (60%) WHO Grade 2 and 43 (40%) WHO Grade 3 tumors. Ninety-five (88.8%) tumors were IDH1-mutant and 12 (11.2%) were IDH2-mutant. Eighty-two (77%) patients were stratified as high-risk: older than 40-years and/or subtotal resection (RTOG 9802). Gross-total resection was achieved in 47 (45%) patients. Treatment strategies included observation (n= 15), temozolomide (n= 11), radiation (n= 13), radiation with temozolomide (n= 62) and other (n= 6). Our results show a benefit of temozolomide vs. observation in progression-free survival (PFS). However, no benefit in PFS or overall survival (OS) was observed when comparing radiation vs. radiation with temozolomide. PIK3CA mutations were detected in 15 (14%) cases, and patients with PIK3CA-mutant mOGDs showed worse OS (10.7-years vs 15.1-years, p= 0.009). Patients with WHO Grade 3 tumors had shorter PFS but no significant difference in OS was observed compared to grade 2. Our findings suggest that mOGDs harboring PIK3CA mutations have worse OS. Except for an advantage in PFS in temozolomide treated patients, adjuvant treatment with radiation or the combination of both, showed no significant advantage in terms of OS.

Landscape of Genomic Alterations in IDH Wild-Type Glioblastoma Identifies PI3K as a Favorable Prognostic Factor

PURPOSE

IDH wild-type (WT) glioblastoma (GBM) is an aggressive tumor with poor survival despite current therapies. The aim of this study was to characterize its genomic profile and determine whether a particular molecular signature is associated with improved survival outcomes.

PATIENTS AND METHODS

Tumor samples from 232 patients with IDH-WT GBM were sequenced, and the landscape of genomic alterations was fully delineated. Genomics data from The Cancer Genome Atlas (TCGA) cohort were analyzed for confirmation. Association of alterations with survival was evaluated in both univariable and multivariable approaches.

RESULTS

The genomic landscape of IDH-WT GBM revealed a high frequency of CDKN2A/B loss, TERT promoter mutations, PTEN loss, EGFR alteration, and TP53 mutations. Novel variants or gene mutations, such as ARID1B and MLL2, were identified. To better understand synergistic effects and facilitate decision making for precision medicine, we identified 11 pairs of gene alterations that tended to co-occur or were mutually exclusive, which were confirmed in the TCGA cohort. Survival analysis showed that genomic alterations in TP53 were associated with worse overall survival (OS). However, alterations in PI3K class I genes were associated with significantly better OS (univariable analysis: P = .002; multivariable analysis: hazard ratio [HR], 0.5785; P = .00162) and longer progression-free survival (univariable analysis: P = .0043; multivariable analysis: HR, 0.6228; P = .00913).

CONCLUSION

Genomic alterations in PI3K class I are a favorable prognostic factor in IDH-WT GBM. This new prognostic biomarker may facilitate risk stratification of patients, assist in clinical trial enrollment, and provide potential therapeutic targets

Adult diffuse midline gliomas: Clinical, radiological, and genetic characteristics

Diffuse midline gliomas (DMGs) are a diffuse glioma subtype arising from midline brain structures. It is predominantly a disease of childhood; however, it can also occur in adults. Adult DMG has not been previously well described. The aim of this study was to define the characteristics of adult DMG. We described and analyzed the clinical, radiological, and genetic alterations of 9 adult DMGs and compared them with those of 257 non-midline adult high-grade IDH-WT gliomas. The median age of all patients was 38-years old (23-68-years). Most common symptoms were headache, motor/sensory deficit, ataxia, cranial nerve deficit, and confusion. Tumor locations were brainstem (44.5%), thalamus (22.2%), pineal region (22.2%), spinal cord (22.2%), and cerebellum (11.1%). Six-patients (66.7%) were H3 K27M-WT and three (33.3%) were H3 K27M-mutant. In addition to H3 K27M mutations, TP53 gene (55.5%), CDKN2A/B and TERTp (33.3%), PDGFRA (33.3%), PIK3CA, PTEN, KDR, NF1, and MYC (22.2%) were the most frequently mutated genes. Neither IDH1/IDH2 nor EGFR alterations were present. Compared to non-midline high-grade glioma, adult DMG patients were younger (38 vs 61 years, p < 0.001) and lacked EGFR-alterations (0/9 vs 123/257, p = 0.004). The median survival of DMG and non-midline high-grade gliomas was 19 and 18 months respectively (p = 0.964). Our data support that adult DMGs have different oncogenic drivers compared to non-midline high-grade gliomas. Regardless of H3 K27M mutation status, neither of the nine adult DMG cases demonstrated IDH1/IDH2 or EGFR alterations. Larger multi-institutional studies are needed to further characterize the biology of this rare type of diffuse glioma in adults.

Ion Channels and Their Role in the Pathophysiology of Gliomas

Malignant gliomas are the most common primary central nervous system tumors and their prognosis is very poor. In recent years, ion channels have been demonstrated to play important roles in tumor pathophysiology such as regulation of gene expression, cell migration, and cell proliferation. In this review, we summarize the current knowledge on the role of ion channels on the development and progression of gliomas. Cell volume changes through the regulation of ion flux, accompanied by water flux, are essential for migration and invasion. Signaling pathways affected by ion channel activity play roles in cell survival and cell proliferation. Moreover, ion channels are involved in glioma-related seizures, sensitivity to chemotherapy, and tumor metabolism. Ion channels are potential targets for the treatment of these lethal tumors. Despite our increased understanding of the contributions of ion channels to glioma biology, this field remains poorly studied. This review summarizes the current literature on this important topic.

Additional genetic alterations in BRAF-mutant gliomas correlate with histologic diagnoses

INTRODUCTION

Recently, the term "Diffuse glioma, BRAF V600E-mutant" has been recommended for IDH-wildtype gliomas with BRAF p.V600E mutation and without CDKN2A/B deletion. However, additional alterations in gliomas that coexist with BRAF-mutations are poorly defined.

METHODS

We analyzed next-generation sequencing results in 315 cancer-associated genes for 372 gliomas from our institution (2010 to 2017). In addition, we reviewed IDH-WT gliomas with mutation and copy-number alterations available in cBioPortal, to further characterize BRAF-mutant gliomas.

RESULTS

Seventeen (4.6%) showed BRAF mutations. Tumor types included 8 glioblastomas, 2 epithelioid glioblastomas (E-GBM), 2 pleomorphic xanthoastrocytomas (PXA), 1 anaplastic oligodendroglioma, 1 diffuse astrocytoma, and 3 pilocytic astrocytomas. Fifty-three percent (53%) of cases exhibited BRAF-alterations other than p.V600E. The majority of the tumors were localized in the temporal lobe (52.9%). In addition to BRAF mutations, glioblastomas showed concomitant mutations in TP53 (3/8), CDKN2A/B-loss (6/8), TERT-promoter (6/8), and/or PTEN (5/8). Both E-GBMs and PXAs showed CDKN2A/B-loss and BRAF p.V600E with absence of TERTp, TP53, and PTEN mutations. Similar findings were observed in BRAF-mutant infiltrating gliomas from cBioPortal.

CONCLUSIONS

Knowledge of additional alterations that co-occur with BRAF-mutations in gliomas may improve diagnosis and help identify patients that could benefit from targeted therapies. Furthermore, we provide examples of two patients whose tumors responded to BRAF pathway inhibitors, arguing in favor of these therapies in patients with BRAF-mutant gliomas.

Cerebrospinal fluid ctDNA and metabolites are informative biomarkers for the evaluation of CNS germ cell tumors

Serum and cerebrospinal fluid (CSF) levels of α-fetoprotein and β-subunit of human chorionic gonadotropin are used as biomarkers for the management of central nervous system (CNS) germ cell tumors (GCTs). However, additional discriminating biomarkers are required. Especially, biomarkers to differentiate non-germinomatous germ cell tumors (NGGCTs) from germinomas are critical, as these have a distinct prognosis. We investigated CSF samples from 12 patients with CNS-GCT patients (8 germinomas and 4 NGGCTs). We analyzed circulating tumor DNA (ctDNA) in CSF to detect mutated genes. We also used liquid chromatography-mass spectrometry to characterize metabolites in CSF. We detected KIT and/or NRAS mutation, known as frequently mutated genes in GCTs, in 3/12 (25%) patients. We also found significant differences in the abundance of 15 metabolites between control and GCT, with unsupervised hierarchical clustering analysis. Metabolites related to the TCA cycle were increased in GCTs. Urea, ornithine, and short-chain acylcarnitines were decreased in GCTs. Moreover, we also detected several metabolites (e.g., betaine, guanidine acetic acid, and 2-aminoheptanoic acid) that displayed significant differences in abundance in patients with germinomas and NGGCTs. Our results suggest that ctDNA and metabolites in CSF can serve as novel biomarkers for CNS-GCTs and can be useful to differentiate germinomas from NGGCTs.

Radiology Profile as a Potential Instrument to Differentiate Between Posterior Fossa Ependymoma (PF-EPN) Group A and B

OBJECTIVE

Posterior fossa ependymoma (PF-EPN) was categorized into PF-EPN-A and PF-EPN-B subgroups based on the DNA methylation profiling. PF-EPN-A was reported to have poorer prognosis compared with PF-EPN-B. In this study, we particularly evaluated preoperative imaging to distinguish PF-EPN-A from PF-EPN-B.

METHODS

Sixteen cases of PF-EPN were treated in our institution from 1999 to 2018. The patients were divided into PF-EPN-A and PF-EPN-B groups based on H3K27me3 immunostaining positivity. We evaluated progression-free survival, overall survival, as well as preoperative magnetic resonance imaging and computed tomography scan images in both groups. Based on T1WI and Gd-T1WI magnetic resonance images, the tumor contrast rate was determined from dividing the volume of gadolinium enhanced tumor by the overall tumor volume.

RESULTS

Nine cases (4 male, 5 female) were grouped as PF-EPN-A, and 7 (4 male, 3 female) as PF-EPN-B. The median age of PF-EPN-A and PF-EPN-B were 4 and 43 years old, respectively. In the PF-EPN-A group, the progression-free survival median value was 32.6 months, and the overall survival median was 96.9 months. In contrast, PFS in PF-EPN-B did not reach a median value (P < 0.05) and all the patients were alive (P < 0.05) at the end of the study. With imaging, tumor contrast rate in PF-EPN-B was more than 50% and significantly different from PF-EPN-A (P = 0.0294). Calcification was mainly observed in PF-EPN-A, whereas cystic formation was only seen in PF-EPN-B.

CONCLUSIONS

Contrast rate less than 50%, based on the magnetic resonance images, was characteristic in the PF-EPN-A group. Comparatively, cystic component and absence of calcification were more characteristic in the PF-EPN-B group.

Advantage of high b value diffusion-weighted imaging for differentiation of common pediatric brain tumors in posterior fossa

PURPOSE

The pediatric posterior fossa (PF) brain tumors with higher frequencies are embryonal tumors (ET), ependymal tumors (EPN) and pilocytic astrocytomas (PA), however, it is often difficult to make a differential diagnosis among them with conventional MRI. The ADC calculated from DWI could be beneficial for diagnostic work up.

METHOD

We acquired DWI at b = 1000 and 4000(s/mm²). The relationship between ADC and the three types of brain tumors was evaluated with Mann-Whitney U test. We also performed simple linear regression analysis to evaluate the relationship between ADC and cellularity, and implemented receiver operating characteristic curve (ROC curve) to test the diagnostic performance among tumors.

RESULTS

The highest ADC (b1000/b4000 × 10^-3 mm²/s) was observed in PA (1.02-1.91/0.73-1.28), followed by PF-EPN (0.83-1.28/0.60-0.79) and the lowest was ET (0.41-0.75/0.29-0.47). There was significant difference among the groups in both ADC value (b-1000/b-4000: ET vs. PF-EPN p < 0.0001/0.0001, ET vs. PA p < 0.0001/0.0001, PF-EPN vs. PA p < 0.0001/0.0001). ROC analysis revealed that ADC in both b-values showed complete separation between ET and PF-EPN. And it also revealed that ADC at b-4000 could differentiate PF-EPN and PA (96.0%) better than ADC at b-1000 (90.1%). The stronger negative correlation was observed between the ADC and cellularity at b-4000 than at b-1000 (R²  = 0.7415 vs.0.7070) CONCLUSIONS: ADC of ET was significantly lower than the other two groups, and ADC of PA was significantly higher than the other two groups in both b-1000 and b-4000. Our results showed that ADC at b-4000 was more useful than ADC at b-1000 especially for differentiation between PF-EPN and PA.

Primary and Recurrent Growing Teratoma Syndrome in Central Nervous System Nongerminomatous Germ Cell Tumors: Case Series and Review of the Literature

BACKGROUND

The term "growing teratoma syndrome (GTS)" has been used as follows: patients with germ cell tumor (GCT) who present with enlarging original/metastatic masses during or after appropriate systemic chemotherapy despite normalized serum markers. In other words, the definition of the term GTS is not fully established. We analyzed and reviewed our case series regarding GTS that developed after the treatment of central nervous system (CNS) nongerminoatous germ cell tumors (NGGCTs).

METHODS

Our institutional review board approved this retrospective study. Between 2003 and 2018, we treated 16 patients (16 males; age ranging from 5.4 to 51.9 years, median 13.8) with CNS-NGGCT at our institution. We reviewed those patients and also reviewed the literature about GTS of CNS. We defined primary GTS (p-GTS) as the enlargement of cyst size and/or solid tumor occurred during treatment in the absence of marker elevation, and recurrent GTS (r-GTS) as the enlargement of teratoma after complete response of initial tumors.

RESULTS

Among 16 patients with CNS-NGGCT, we surgically confirmed mature/immature teratoma components in 15 patients. Two patients underwent surgical removal of tumor before neoadjuvant therapy, and among the rest 14 patients, 6 developed p-GTS, and 2 patients underwent salvage surgery during chemo-/chemoradiotherapy. Those with histologic diagnosis of immature teratoma during salvage surgery had a shorter interval from the initiation of chemoradiotherapy compared with mature teratoma (P < 0.05). One patient developed r-GTS. In the literature review, most of the p-GTS consisted of enlargement with the multicystic component. Histologic diagnosis of immature teratoma during salvage surgery was observed in earlier stages of chemoradiotherapy (P < 0.05, log-rank test). Previous history of p-GTS might be a risk factor of r-GTS.

CONCLUSIONS

The incidence of p-GTS, enlargement of the cystic component during treatment, is not rare. Physicians need to be aware of this important phenomenon.

EPID-12. IMPACT OF RACE AND GEOGRAPHIC LOCATION ON IDH MUTATIONS AND GLIOBLASTOMA SURVIVAL

Glioblastoma (GBM) is the most common primary malignant brain tumor of the central nervous system with a 5-year survival of < 5%. Population studies have demonstrated that among all ethnicities, non-Hispanic whites (NHW) have the worst prognosis; however, differences within the oncogenome based on ethnicity have not been assessed. We utilized the Texas Cancer Registry (TCR) for population-based analysis including 4,134 GBM patients between the years of 1995 to 2013 with 75.6% NHW and 16.5% Hispanics. In accordance with previously published findings, within the TCR we detected a 12% relative survival improvement in Hispanics compared to NHW when controlling for known survival mediators including age, resection, chemotherapy, and radiation. In order to assess for oncogenic differences, we utilized a prospectively maintained database of 257 GBM patients within the city of Houston, TX (14.9% Hispanic) and 48 GBM patients from the National Institute of Neurology and Neurosurgery in Mexico City, Mexico (100% Hispanic) to assess for oncogenomic differences attributable to ethnicity. Next generation sequencing of GBM within the Houston cohort, for 315 tumor-related genes, identified no significant differences in genomic alterations owing to ethnicity. However, when we compared the multigenerational, mixed-heritage Hispanics present in the Houston cohort to the Mexico cohort (Sanger sequencing), a significant difference was found in the frequency of IDH1and IDH2mutations (29.8 % Mexico Hispanics, 7.9% Houston Hispanics; p=0.014). In particular, the rate of IDH2mutations is significantly enriched in the Mexico population (19%) when compared to the Houston population (0%) or to previously published rates of IDH2 mutations in GBM (~3%). Ultimately, these findings highlight the need for multiethnic trial enrollment as well as the need for improved testing of IDH2 mutations in patients of distinct ethnicities. Future studies are needed to identify the mechanisms promoting the increased frequency of IDH2 mutations in Mexican Hispanics.

PATH-24. CXCR4 IS A POTENTIAL THERAPEUTIC TARGET FOR GLIOBLASTOMA AND DIFFUSE INTRINSIC PONTINE GLIOMAS

Glioblastoma (GBM) is the most common adult malignant brain tumor with poor prognosis and Diffuse Intrinsic Pontine Glioma (DIPG) is a pediatric type of glioblastoma for which there is no effective therapy. CXCR4, a G-protein coupled receptor, has been shown to play a role in GBM invasion, cell survival, proliferation and angiogenesis. A CXCR4 inhibitor (AMD3100/Plerixafor) has been suggested as a potential therapeutic strategy for GBM with an isolated case report of a long-term survivor and an ongoing clinical trial evaluating its effects in GBM patients. However, there is a poor understanding of the expression of CXCR4 in GBM and DIPGs. In this study, we evaluated the expression of CXCR4 in 21-DIPG and 36-GBM cases. In GBMs, CXCR4 was expressed in 5.6% of cases in tumor cells and in 19.4% of cases in endothelial cells in blood vessels. In DIPGs, we observed expression of CXCR4 in 28.6% of cases in tumor cells and in 14.3% of cases in endothelial cells. We observed absence of CXCR4 expression in all IDH-mutant GBMs. There was no correlation between CXCR4 or EGFR expression, p53-mutations or H3F3A p.K27M mutations in DIPGs. There was a trend of poorer prognosis in CXCR4 positive DIPGs but the difference did not reach statistical significance. Furthermore, we evaluated the effects of Plerixafor in the survival of DIPG and U87-GBM cell lines and observed a dose-dependent reduction in cell viability. RT-PCR and immunohistochemistry of DIPG cells showed variable CXCR4 expression in the cell lines that did not correlate with sensitivity to Plerixafor. In conclusion, in vitro experiments show that the CXCR4 inhibitor Plerixafor is a potential therapeutic strategy for GBM and DIPGs. However, CXCR4 is not universally expressed in glioblastomas and its expression should be considered in clinical trials that evaluate the efficacy of CXCR4 inhibitors in GBM and DIPGs.

CBMT-40. THE RELATIONSHIP BETWEEN GLIOMA AND THE GUT-BRAIN AXIS

Recent studies demonstrate the potential role of the microbiome in immune-oncology, revealing specific microbial taxa can augment the effects of various therapeutic modalities against tumors. Gut dysbiosis, a disequilibrium in the host’s bacterial ecosystem, can potentially lead to overrepresentation of some bacteria and favor chronic inflammation and immunosuppression. However, the effects of microbial dysbiosis on non-gastrointestinal cancers in particular gliomas are unknown. Here, we explored the effects of glioma and Temozolomide (TMZ) on the fecal microbiome (FM) in mice (n=24) and FM and metabolome in humans (n=40). Aged C57/B6 mice were implanted with Gl261 tumor cells or vehicle and were assigned to one of the following treatment (oral) groups: vehicle, 5mg/kg TMZ or 25mg/kg TMZ beginning 14 days after surgery for 3-weeks following a 5 day on/2 day off treatment. Fecal samples were collected prior to surgery, at treatment initiation and weekly thereafter until sacrifice and sequenced for 16s RNA. Fecal samples were collected from humans with newly diagnosed glioma before resection, chemoradiation, and after chemoradiation (16s RNA, metabolomic, neurotransmitter analysis). In mice, FM beta diversity was significantly altered with glioma (p=0.003) while the alpha diversity remained unchanged. At a genus and family level analysis the relative abundance of Bacteroides (p=0.01) and Bacteroidaceae (p=0.02) was increased. Beta diversity of mice receiving 5mg/kg TMZ changed from baseline (p=0.02). Collectively, this suggests that glioma alters the FM, to what consequence remains to be explored. Alpha (Observed OTUs, p=0.029) and beta diversity (p=0.034) differences in mice correlated with survival (< 25 - >25 days). In humans, norepinephrine and 5-hydroxyindoleacetic acid were significantly lower in glioma patients at diagnosis compared to controls. Our findings demonstrate for the first time the relationship between glioma and the gut-brain axis. Understanding alterations in the FM in glioma patients may allow novel interventions and should be further investigated.

[Weekly Vinblastine in Pediatric Optic Pathway/Hypothalamic Glioma:2 Cases Report]

It is reported that vinblastine monotherapy has promising activity in patients with pediatric optic pathway/hypothalamic glioma(OPHG)who experienced treatment failure after initial treatment with standard chemotherapy. However, there have been no reports on vinblastine monotherapy against OPHG in Japan. Since vinblastine is an unauthorized drug under the Ministry of Health and Welfare, we used it after completing an in-hospital institutional review board application for each case. In the first case, a 6-year-old boy with recurrent OPHG with hydrocephalus was referred to our hospital. Weekly vinblastine was started at a dose of 6mg/m² and was then reduced to 5mg/m² and 4mg/m² sequentially due to hematotoxicity. After 11 cycles of vinblastine, improvement in hydrocephalus was observed. After 22 cycles of vinblastine, the best response was observed, and we continued treatment up to 35 cycles. Progression of the disease was observed after 47 cycles and then we changed treatment to another regimen after 48 cycles of vinblastine. In the second case, a 6-year-old boy with chemotherapy-naïve recurrent OPHG underwent chemotherapy with vincristine and carboplatin. After 9 treatment cycles with carboplatin, hypersensitivity was observed. Subsequently, he was treated using weekly vinblastine as per the same protocol as that in our first case. A moderate response was observed after 18 cycles of vinblastine. After 48 cycles of vinblastine, the best response was observed, and we completed treatment. In both cases, severe adverse events were not observed and the treatment was well-tolerated. Vinblastine administered once per week is well-tolerated and maintains quality of life in children with OPHG.

Usefulness of Histogram-Profile Analysis in Ring-Enhancing Intracranial Lesions

BACKGROUND

Several intracranial pathologies present as a ring-enhancing lesion on conventional magnetic resonance imaging (MRI), creating diagnostic difficulty. We studied the characteristics of the anatomical border of gadolinium enhancement on T1-weighted imaging (WI) and hypointensity on T2WI to employ a simple technique of histogram-profile analysis of MRI for differentiation of various ring-enhancing intracranial lesions.

METHODS

After approval from the institutional review board, preoperative MRI (T2WI, postcontrast T1WI) scans were analyzed retrospectively in 18 patients with histologically confirmed brain abscess, 66 glioblastomas, 46 brain-metastases, and 16 tumefactive multiple sclerosis (MS). T2WI and postcontrast T1WI were overlapped, and histogram-profile analysis was performed with in-house image-fusion software. The pattern of differential-peaks in histogram-profile was assessed visually. Kaplan-Meier survival analysis incorporating histogram-profile patterns was performed in patients with glioblastoma.

RESULTS

The histogram-profile study revealed 4 distinct patterns. Pattern 1 showed no differential T2-hypointensity trough, pattern 2 had T2-hypointensity trough inside, whereas pattern 3 had T2-hypointensity trough overlapping the enhanced margin. Pattern 4 had T2-hypointensity trough immediately external to the enhanced margin. Pattern 1 was specific for tumefactive MS (93.3%), whereas pattern 4 was specific for glioblastoma (40.7%). Pattern 4 glioblastoma was subdivided into rim (T2-hypointensity ≥50% of circumference of contrast-enhanced tumor) and arc (T2-hypointensity <50% of circumference of contrast-enhanced tumor). Pattern 4 glioblastoma was further subdivided into group A (edema: T2-hyperintensity ≥50% of circumference of contrast-enhanced tumor) and group B (less edema: T2-hyperintensity <50% of circumference of contrast-enhanced tumor). Patients with pattern 3 glioblastoma (37.6%) had better survival compared with others (P = 0.0341) and pattern 4B had decreased survival compared with pattern 4A (P = 0.0001) and others (P = 0.0003).

CONCLUSIONS

Tumefactive MS and a subset of glioblastomas show specific patterns in histogram-profile analysis. The difference in anatomical border also determines difference in survival in glioblastoma. Histogram-profile analysis is a simple and efficient technique to differentiate these pathologies.

Abscess Formation in Metastatic Brain Tumor with History of Immune Checkpoint Inhibitor: A Case Report

We present the case of a 68-year-old man with brain metastasis from lung cancer and a history of immune checkpoint inhibitor administration, with overlapping abscess within the metastatic lesion. He initially received antibiotic treatment under a diagnosis of brain abscess because of a hyper-intense area on diffusion-weighted imaging inside the gadolinium-enhanced wall. The size of the enhanced lesion did not change much, but the extent of perifocal edema decreased after antibiotic treatment. After 2–4 months, the lesion gradually enlarged, and imaging characteristics changed from single cyst to multiple cysts. Surgical resection was performed and pathological examination revealed the lesion as metastasis from the lung tumor. Smear preparation of the tumor contents detected Gram-positive bacilli, confirming the dual pathology of metastasis and brain abscess. Discussing the pathogenesis, we speculated that therapy with durvalumab (MEDI4736), an anti-PD-L1 antibody, induced immune status modification including immunosuppressive regulation, which might have promoted abscess formation.

High Expression of Glypican-1 Predicts Dissemination and Poor Prognosis in Glioblastomas

OBJECTIVE

Glioblastoma (GBM) relapses locally or in a disseminated pattern and is highly resistant to chemoradiotherapy. Although dissemination is associated with poor prognosis for patients with GBM, the clinicopathologic factors that promote dissemination have not been elucidated. Glypican-1 (GPC-1) is a heparin sulfate proteoglycan that is attached to the extracytoplasmic surface of the cell membrane and regulates cell motility. The aim of this study was to determine whether GPC-1 expression correlated with GBM dissemination and patient prognosis.

METHODS

GPC-1 expression was examined by immunohistochemistry in 53 patients with GBM who received radiotherapy and temozolomide treatment. We assessed the relationship between dissemination and clinicopathologic factors, including GPC-1 expression. We also evaluated the relationship between GPC-1 expression and overall survival (OS) by uni- and multivariate analyses of a range of clinicopathologic factors, including age, Karnofsky Performance Status, extent of resection, and O6-methylguanine-DNA methyltransferase (MGMT) status.

RESULTS

Logistic regression analysis revealed that GPC-1 expression correlated with dissemination (P = 0.0116). Log-rank tests revealed that age, Karnofsky Performance Status, extent of resection, MGMT status, dissemination (P = 0.0008) and GPC-1 expression (P = 0.0011) were significantly correlated with OS. Multivariate analysis indicated that age, MGMT status, and GPC-1 expression were significantly correlated with OS. GPC-1 expression had the highest hazard ratio (2.392) among all regressors.

CONCLUSIONS

GPC-1 expression significantly correlated with OS in patients with GBM who received radiotherapy and temozolomide treatment. GPC-1 expression can help predict the occurrence of dissemination and shorter OS in patients with GBM.

Prognostic importance of temozolomide-induced neutropenia in glioblastoma, IDH-wildtype patients

Standard treatment for patients with primary glioblastoma (GBM) includes surgery, radiotherapy, and concomitant and adjuvant temozolomide (TMZ). Recent reports have demonstrated that TMZ-induced myelosuppression correlates with survival in patients with GBM. However, those results were evaluated before the 2016 revision of the World Health Organization classification. This study examined whether myelosuppression during concomitant TMZ phase correlates with prognosis in GBM, IDH-wildtype patients. We examined circulating blood cell counts in 50 patients with GBM, IDH-wildtype who received the standard treatment protocol between August 2005 and November 2015. We assessed relationships between rates of decrease in blood cells (white blood cells (WBC), neutrophils, lymphocytes, red blood cells, and platelets) during the concomitant TMZ phase and overall survival (OS) using univariate and multivariate analyses including other clinicopathological factors (age, sex, Karnofsky Performance Status (KPS), extent of resection, O⁶-methylguanine-DNA methyltransferase (MGMT) status). Log-rank testing revealed that age, KPS, extent of resection, MGMT status, and decrease rates of WBC, neutrophils, and platelets correlated significantly with OS. On multivariate analysis, age, MGMT status, and decrease rate of neutrophils correlated significantly with OS. Patients with a ≥ 40% decrease in neutrophils showed significantly longer OS than those with < 40% (hazard ratio = 2.815; 95% confidence interval = 1.177-7.038; P = 0.0196). A decrease of ≥ 40% in neutrophils represents a predictor of good prognosis for GBM, IDH-wildtype. Blood cell counts during the concomitant TMZ phase can help predict OS in patients with GBM, IDH-wildtype receiving the standard treatment protocol.