The association between 11C-methionine uptake, IDH gene mutation, and MGMT promoter methylation in patients with grade II and III gliomas

AIM

To evaluate the association between ¹¹C-methionine positron-emission tomography (¹¹C-methionine PET) findings, isocitrate dehydrogenase (IDH) gene mutation, and O⁶-methylguanine-DNA methyltransferase (MGMT) promoter methylation in patients with grade II and III gliomas.

MATERIALS AND METHODS

Data were collected from 40 patients with grade II and III gliomas who underwent both magnetic resonance imaging (MRI) and ¹¹C-methionine PET as part of their pre-surgical examination. IDH mutation was examined via DNA sequencing, and MGMT promoter methylation via quantitative methylation-specific polymerase chain reaction (PCR).

RESULTS

A threshold of MGMT promoter methylation of 1% was significantly associated with tumour/normal tissue (T/N) ratio. The T/N ratio in samples with MGMT promoter methylation ≥1% was higher than that in samples with MGMT promoter methylation <1%, and the difference was statistically significant (p=0.011). Reliable prediction of MGMT promoter methylation (<1% versus ≥1%) was possible using the T/N ratio under the receiver operator characteristic (ROC) curve with a sensitivity and specificity of 75% each (cut-off value=1.6: p=0.0226, area under the ROC curve [AUC]=0.76172). Conversely, the T/N ratio had no association with IDH mutation (p=0.6). The ROC curve revealed no reliable prediction of IDH mutation using the T/N ratio (p=0.606, AUC=0.60577).

CONCLUSION

¹¹C-methionine PET parameters can predict MGMT promoter methylation but not IDH mutation status. ¹¹C-methionine uptake may have limited potential to reflect DNA methylation processes in grade II and III gliomas.

A multicenter randomized phase III study for newly diagnosed maximally resected glioblastoma comparing carmustine wafer implantation followed by chemoradiotherapy with temozolomide with chemoradiotherapy alone; Japan Clinical Oncology Group Study JCOG1703 (MACS study)

A randomized phase III trial in Japan commenced in June 2019. The present standard treatment for newly diagnosed glioblastoma is maximal resection followed by chemoradiotherapy with temozolomide. The purpose of this study is to confirm the superiority of maximal resection with carmustine wafer implantation followed by chemoradiotherapy with temozolomide over the standard maximal resection followed by chemoradiotherapy with temozolomide in terms of overall survival for newly diagnosed glioblastoma. A total of 250 patients will be accrued from 35 Japanese institutions in 5.5 years. Patients with >90% surgical resection will be registered and randomly assigned to each group with 1:1 allocation. The primary endpoint is overall survival and the secondary endpoints are progression-free survival, loco-regional progression-free survival and incidence of adverse events. This trial has been registered in the Japan Registry of Clinical Trial, as jRCT1031190035 [https://jrct.niph.go.jp/en-latest-detail/jRCT1031190035].

T2-FLAIR Mismatch Sign Is Caused by Long T1 and T2 of IDH-mutant, 1p19q Non-codeleted Astrocytoma

T₂-fluid-attenuated inversion recovery images (FLAIR) mismatch sign is now known to be a specific yet insensitive image feature for IDH-mutant, 1p19q non-codeleted astrocytoma. The current study revealed that lesion presenting T₂-FLAIR mismatch exhibited extremely long T₁- and T₂-relaxation time while T₂-FLAIR matched lesions showed low to moderate values. On the other hand, IDH-wildtype tumors presented noticeably short T₁- and T₂-relaxation time. These different relaxation time characteristics seemed to render T₂-FLAIR mismatch sign of becoming such a unique and specific image feature for IDH-mutant, 1p19q non-codeleted astrocytoma.

The impact of EGFR mutation status and single brain metastasis on the survival of non-small-cell lung cancer patients with brain metastases

BACKGROUND

Molecular and genetic alterations of non-small-cell lung cancer (NSCLC) now play a vital role in patient care of this neoplasm. The authors focused on the impact of epidermal growth factor receptor mutation (EGFR-mt) status on the survival of patients after brain metastases (BMs) from NSCLC. The purpose of the study was to understand the most desirable management of BMs from NSCLC.

METHODS

This was a retrospective observational study analyzing 647 patients with NSCLC, including 266 patients with BMs, diagnosed at our institute between January 2008 and December 2015. EGFR mutation status, overall survival (OS) following diagnosis, OS following BMs, duration from diagnosis to BMs, and other factors related to OS and survival after BMs were measured.

RESULTS

Among 647 patients, 252 (38.8%) had EGFR mutations. The rate and frequency of developing BMs were higher in EGFR-mt patients compared with EGFR wildtype (EGFR-wt) patients. EGFR-mt patients showed longer median OS (22 vs 11 months, P < .001) and a higher frequency of BMs. Univariate and multivariate analyses revealed that good performance status, presence of EGFR-mt, single BM, and receiving local therapies were significantly associated with favorable prognosis following BM diagnosis. Single metastasis, compared with multiple metastases, exhibited a positive impact on patient survival after BMs in EGFR-mt patients, but not in EGFR-wt NSCLC patients.

CONCLUSIONS

Single BM with EGFR-mt performed better than other groups. Furthermore, effective local therapies were recommended to achieve better outcomes.

Prediction of IDH and TERT promoter mutations in low-grade glioma from magnetic resonance images using a convolutional neural network

Identification of genotypes is crucial for treatment of glioma. Here, we developed a method to predict tumor genotypes using a pretrained convolutional neural network (CNN) from magnetic resonance (MR) images and compared the accuracy to that of a diagnosis based on conventional radiomic features and patient age. Multisite preoperative MR images of 164 patients with grade II/III glioma were grouped by IDH and TERT promoter (pTERT) mutations as follows: (1) IDH wild type, (2) IDH and pTERT co-mutations, (3) IDH mutant and pTERT wild type. We applied a CNN (AlexNet) to four types of MR sequence and obtained the CNN texture features to classify the groups with a linear support vector machine. The classification was also performed using conventional radiomic features and/or patient age. Using all features, we succeeded in classifying patients with an accuracy of 63.1%, which was significantly higher than the accuracy obtained from using either the radiomic features or patient age alone. In particular, prediction of the pTERT mutation was significantly improved by the CNN texture features. In conclusion, the pretrained CNN texture features capture the information of IDH and TERT genotypes in grade II/III gliomas better than the conventional radiomic features.

Proteomic analysis of protein changes in plasma by balloon test occlusion

Transient ischemia provides the tolerance against prolonged ischemia in the brain. In mouse experimental model, transient ischemia changes the composition ratio of circulating proteins, which associate with neuroprotection; however, the human evidence is lacking. Here we mimicked balloon test occlusion (BTO) of carotid artery as a transient ischemia and investigated the change of composition ratio of the circulating protein in the human plasma. We collected blood samples from nine patients (5 men and 4 women; mean age 64.2 years; range 45 to 77 years) before and 48 h after BTO and investigated the changes of circulating molecules level in the proteome using LC-MS/MS analysis. Leucine-rich alpha-2-glycoprotein and serum amyloid A-1 increased and protein AMBP decreased in the blood samples after BTO. Transient change of blood flow in the brain alters molecular expression in the plasma. Because the alteration of plasma protein composition is involved in ischemic tolerance in animal models, the proteins whose level was changed by BTO may be also involved in neuroprotection against ischemia in human.

ACT-10 TREATMENT FOR GLIOBLASTOMA RECURRED AFTER CONCOMITANT CHEMORADIATION THERAPY WITH TEMOZOLOMIDE AND THEIR PROGNOSIS

There are few data about treatment for glioblastoma recurred after concomitant chemoradiation therapy with temozolomide (TMZ). We retrospectively examined treatment and prognosis of recurred glioblastoma patients who registered Kansai molecular diagnosis network for central nervous system tumors, and whose clinical information were available. One hundred and fifty-seven patients that were clinically diagnosed as recurrence between November 2007 and April 2019 were included. Their median age at primary diagnosis was 52 years old and median KPS was 80%. Proportion of methylated MGMT promoter was 43.3% (65 patients), and mutated IDH was 5.4% (8 patients). Median overall survival after recurrence (mSAR) was 8.2 months. One hundred and sixteen patients (73.9%) were received any anticancer treatment and their mSAR was 10.5m. Combination of TMZ and bevacizumab (Bev) were most frequently used for 33 patients, followed by Bev monotherapy for 17 patients, surgery + TMZ + Bev for 15 patients, surgery + TMZ for 12 patients, and TMZ monotherapy for ten. Their mSAR were 8.0m, 7.5m, 10.5m, 13.0m, and 8.0m, respectively. Using univariate analysis, MGMT promoter methylation (p=0.0007), TMZ (p=0.00933), surgery (p=0.0126), re-radiation (p=0.0367), and surgery+TMZ+Bev (p=0.0493) significantly affected prognosis. By multivariate analysis, MGMT promoter methylation, TMZ, and re-radiation were statistically significant (p=0.000138, 0.00161, 0.00403, respectively). These data showed that relatively young patients with good performance status would receive anti-cancer treatment beyond progression and MGMT promoter methylation might be one of prognostic factor for longer survival. In this cohort, re-radiation was performed for few patients and nitrosourea such as nimustine was almost not used. Further study would be needed whether these treatments have any positive effect or not.

STMO-10 SURGICAL RESECTION FOR PRIMARY MOTOR CORTEX GLIOMA, TWO CASE REPORTS

Primary motor cortex glioma is usually considered unresectable because of its high risk for motor deficit. However recent reports suggest that surgical resections for primary motor cortex brain tumor is feasible for selected patients. In this case report, we report two cases we can successfully resected primary motor cortex glioma by awake surgery without neurological worsening.

Case1 was 32 year-old woman with right primary motor cortex oligodendroglioma. We could only perform biopsy at initial surgery, however the patient got worsening of left hemiparesis which were gradually improved by rehabilitation. The patient underwent 50 Gy of radiation therapy and 6 courses of PCV chemotherapy. 60 months after the initial surgery, the tumor recurred and the she underwent 12 courses of temozolomide chemotherapy, but tumor continued to grow. She underwent second surgery 13 years after the initial biopsy. We resected primary motor cortex tumor by awake surgery without neurological complication.

Case2 was 31 year-old woman with left primary motor cortex oligodendroglioma. We could only perform biopsy at initial surgery, however the patient got mild right hemiparesis which were improved by rehabilitation. The patient underwent 4 courses of PAV chemotherapy and 54 Gy of Intensity Modulated Radiation Therapy (IMRT). 21 months after IMRT, the tumor recurred and the she underwent second surgery. We resected primary motor cortex tumor by awake motor mapping without severe neurological complication.

In conclusion, surgical resections for primary motor cortex glioma is feasible in selected patients without severe neurological complication. Neural plasticity is the reason for this, but careful intraoperative awake mapping is necessary to achieve maximum resections.

NI-07 VALIDATION OF MACHINE LEARNING BASED HIGH GRADE GLIOMA MR SEGMENTATION VIA METHIONINE PET

Treatment planning and lesion-follow up are generally conducted by contrast-enhanced MRI in glioma patient care. On the other hand, there are, however, substantial concerns whether MRI actually reflects the extension or activity of this neoplasm, which information should be fundamentally important at every step when treating this disease. As a matter of fact, the authors of this investigation have already shown that there is no difference in tumor cell density within areas with and without contrast enhancement (J Neurosurg. 2016,125(5):1136–1142.) and furthermore that the geometry of MRI based-radiation treatment planning is significantly altered when methionine PET is integrated for this purpose (J Neurosurg. 2018 published on-line). Regardless of these concerns, there is great interest in the research community to construct a machine learning based fully automated brain tumor segmentation tool specific for gliomas using MRI. The authors attempted to validate this method by comparing MRI-based automated brain tumor segmentation and methionine PET. Consecutively collected 45 high-grade gliomas (GBM-26, grade3-19) were analyzed. BraTumIA, an automated brain tumor segmentation tool, was used for machine learning based lesion segmentation. At the same time, lesions were segmented using various thresholds on methionine PET. The authors observed 40% of pseudo-positive and 90% of pseudo-negative error on BraTumIA based lesion segmentation when methionine PET was considered as ground truth with a cut-off of 1.3 in T/N ratio. Pseudo-negative error was as high as 60% even if the threshold was elevated to 2.0. Although machine learning based glioma segmentation is expected to expand in both research and clinical use, the observed results caution the use of MRI as ground truth of spatial extension of glioma and researchers should be reminded that this imaging modality may obscure the true behavior of the disease within the patient in some cases.

NI-02 THE ASSOCIATION BETWEEN 11C-METHIONINE UPTAKE, IDH GENE MUTATION, AND MGMT PROMOTER METHYLATION IN PATIENTS WITH GRADE II AND III GLIOMAS

AIM

We evaluated the association between ¹¹C-methionine positron emission tomography (¹¹C-methionine PET) findings, isocitrate dehydrogenase (IDH) gene mutation, and O⁶-methylguanine-DNA methyltransferase (MGMT) promoter methylation in patients with grade II and III gliomas.

MATERIALS AND METHODS

Data were collected from 40 patients with grade II and III gliomas who underwent both magnetic resonance imaging (MRI) and ¹¹C-methionine positron emission tomography (PET) as part of their pre-surgical examination. We examined IDH mutation through DNA sequencing, and MGMT promoter methylation through quantitative methylation-specific polymerase chain reaction (PCR).

RESULTS

A threshold of MGMT promoter methylation of 1.0% was significantly associated with tumor/normal tissue (T/N) ratio. The T/N ratio in samples with MGMT promoter methylation ≥1.0% was higher than that in samples with MGMT promoter methylation <1.0%, and the difference was statistically significant (p = 0.011). Reliable prediction of MGMT promoter methylation (<1.0% vs ≥1.0%) was possible using the T/N ratio under the receiver operator characteristic (ROC) curve with a sensitivity and specificity of 75% each (cut-off value = 1.6) (p = 0.0226, AUC = 0.76172). Conversely, the T/N ratio had no association with IDH mutation (p = 0.6). The ROC curve revealed no reliable prediction of IDH mutation using the T/N ratio (p = 0.606, AUC = 0.60577).

CONCLUSION

¹¹C-methionine PET parameters can predict MGMT promoter methylation but not IDH mutation status. ¹¹C-methionine uptake may have limited potential to reflect DNA methylation processes in grade II and III gliomas.

MNG-08 VOLUMETRIC STUDIES IN ASYMPTOMATIC MENINGIOMAS: SLOWDOWN CASES AND GROWTH ARREST CASES

BACKGROUND

The opportunity to follow up for asymptomatic meningiomas has increased. We have reported the risk of volume increase by individual continuous volume measurement of asymptomatic meningiomas. However, We have not reached fully understanding about natural history of meningiomas. Among cases are followed up over time, there are some cases that the volume increase rates slows down or almost stops are observed.

METHODS

We enrolled consecutive adult patients of asymptomatic meningiomas who follow-up for 2 years or more and 3 or more MRI scans. We performed sequential volumetric measurements on 95 patients (105 lesions) who met the criteria. We classified these transient volume curve of each lesion into three groups “Growing”, “Slowdown”, and “Growth arrest” for analysis.

RESULTS

The average age at the first visit was 62.8 years, the average follow-up period was 61.8 months, and the male-female ratio was 20:75 (male: female). There were 67 cases (73 lesions: 70.9%) that were in increasing trend, and 19 cases of those were received resection. Eleven cases (12 lesions: 11.7%) showed a tendency of “slow down” the increase rate, and one patient who became symptomatic led to surgical excision. In 18 cases (18 lesions: 17.4%) in which almost no volume change was observed during the observation period, no cases resulted in surgical treatment.

CONCLUSIONS

Among the meningiomas cases that have been followed for a long time, there are not a few those increase rate of tumor volume slows or does not change. Furthermore, most of these cases did not result in surgical treatment. The presence of these “Slowdown” and “Growth arrest” cases at a certain rate may have suggested the possibility of a Gompertz curve model as the natural course of meningiomas.

NI-13 PREDICTION OF PROGNOSIS IN NEWLY DIAGNOSED GLIOBLASTOMA USING MACHINE LEARNING-BASED TEXTURE ANALYSIS OF PREOPERATIVE MRI

INTRODUCTION

Preoperative magnetic resonance imaging (MRI) is a critical modality for the determination of glioblastoma (GBM) treatment strategy, as it is thought to reflect the biology of the tumor to some extent. The authors attempted to predict prognosis of newly diagnosed GBM (nGBM) using machine learning-based texture analysis of preoperative MRI in this study.

METHOD

A total of 160 nGBMs with determined overall survival were collected from Kansai Molecular Diagnosis Network for CNS tumors. Preoperative MRI scans (T1WI, T2WI, and Gd-T1WI) from all cases were semi-quantitatively analyzed leading to acquisition of 489 texture features as explanatory variables using Matlab-based in-house software. Dichotomous overall survival (OS) with a cutoff of 15 months was regarded as the response variable (short or long OS). Lasso regression was employed for feature selection to ensure robustness of the prediction model. One hundred patients were randomly assigned as training dataset (TR), followed by predictive model construction via 5-fold cross-validation. Subsequently, the constructed model was transferred to the remaining 60 patients, which was assigned as test dataset (TD). The survival distribution between populations with predicted short and long OS was compared using log-rank test.

RESULTS

Distributions of the analyzed data were as follows; 53 short OS cases in the TR (53.0%) and 27 cases in the TD (45.0%). As for the result of transfer analysis in TD, 38 cases out of 60 (63.3%) were predicted to be short OS (76.3 % of recall, 54.3% of precision, and 63.5% of F-measure). The population of predicted short OS significantly showed poorer prognosis (median OS 14.0 vs 19.1 months) (p=0.02, log-rank test).

CONCLUSION

Short OS was successfully identified from preoperative MRI with high recall rates with our algorithm. The presented result ensures the potential of machine learning-based texture analysis for prognostic stratification of nGBM.

IMT-07 CLINICAL TRIAL OF A COCKTAIL WILMS’ TUMOR 1 (WT1) VACCINATION USING TWO HLA CLASS I PEPTIDES AND ONE CLASS II PEPTIDE FOR RECURRENT MALIGNANT GLIOMAS

PURPOSE

Our clinical trials shows the safety and clinical efficacy of Wilms’ tumor 1 (WT1) human leukocyte antigen (HLA) class I (Izumoto S et al. J Neurosurg. 2008) and class II (Tsuboi A et al. Cancer Immunol Immunother. 2019) peptide vaccination for recurrent malignant gliomas have been established. We have developed a cocktail vaccine (WT1 trio) containing two class I peptides (HLA-A*24:02 and HLA-A*02:01) and one II class peptide to improve more effective immunological response and improve patient’s prognosis. Clinical trial of a cocktail vaccination using WT1 HLA class I and II peptides for recurrent malignant gliomas is planned to verify its safety, clinical efficacy and usefulness of surrogate markers.

PATIENTS AND METHODS

Twenty-three patients with recurrent malignant gliomas, which showed WT1-positive in tumor samples and HLA-A*24:02 or HLA-A*02:01-positive in blood sample, were enrolled. These patients (age: 26–72 years old, average: 49.4) included 15 cases of glioblastomas and 8 of anaplastic astrocytomas. Patients received a WT1 trio vaccine intradermally, 7 times at 2-week intervals during 3 months.WT1-DTH and WT1-IgG antibody were regularly measured. Vaccine-related adverse events, best clinical response and the transfer rate of long-term administration of WT1 trio vaccination were estimated.

RESULTS

WT1-DTH positive cases were 12, WT1-IgG antibody positive were in 11. In most patients, WT1 -DTH positiveness coincided with that of WT1-IgG antibody. 9 of 11 cases showed stable disease at 3 months and transferred long-term administration of WT1 trio vaccination. Transfer rate in GBM and AA of long-term administration was 33% and 25%, respectively. Grade1 skin eruption was observed at the injection sites in 15 cases, but no significant adverse events related with vaccination were shown.

CONCLUSION

the safety and clinical efficacy of WT1 trio vaccination was verified for recurrent malignant gliomas. WT1-DTH and WT1-IgG antibody may be useful surrogate markers.

NIMG-19. T1- AND T2-RELAXOMETRY FOR TISSUE CELL DENSITY QUANTIFICATION IN GLIOMA IMAGING: EXPLORATORY STUDY VIA 11C-METHIONINE PET AND VALIDATION VIA STEREOTACTIC TISSUE SAMPLING

Visualization of non-contrast-enhancing tumor lesions in glioma is one of the most crucial yet challenging issues for patients with this pathology. This study examined the hypothesis that quantitative T1- and T2-relaxometry could reflect glioma tumor load within the brain and could further be used for visualizing non-enhancing heavily tumor-loaded areas. Participants comprised patients with low- or high-grade glioma. Correlation between T1- or T2-relaxation time and 11C-methionine uptake as measured by positron emission tomography (Cohort-1) was investigated followed by comparing T1- or T2-relaxation time with tumor cell density as measured by stereotactic image-guided tissue sampling in a different cohort (Cohort-2). T1-relaxometry was achieved by converting Magnetization Prepared Rapid Gradient Echo (MP2RAGE) images and T2-relaxometry by multi-echo T2-weighted images via Bayesian inference modeling. T1-relaxation time >2000 ms but < 3200 ms or T2-relaxation time >115 ms but < 265 ms were indicative of high 11C-methionine uptake. Stereotactic tissue sampling study confirmed that tissue cell densities obtained from locations with a T1-relaxation time of 2000–3200 ms or a T2-relaxation time of 125–225 ms were significantly higher than those obtained from other locations (p < 0.001 and p = 0.03, respectively). Synthetic tumor load images were successfully reconstructed using T1- and T2-relaxation mapping. T1- and T2-relaxation times both correlated well with tumor cell density in glioma tissues. The ideal ranges for identifying high tumor load tissues were 2000–3200 ms for T1-relaxation time and 115–220 ms for T2-relaxation both measured at 3.0 T.

11C-methionine-18F-FDG dual-PET-tracer-based target delineation of malignant glioma: evaluation of its geometrical and clinical features for planning radiation therapy

OBJECTIVE

It is important to correctly and precisely define the target volume for radiotherapy (RT) of malignant glioma. 11C-methionine (MET) positron emission tomography (PET) holds promise for detecting areas of glioma cell infiltration: the authors' previous research showed that the magnitude of disruption of MET and 18F-fluorodeoxyglucose (FDG) uptake correlation (decoupling score [DS]) precisely reflects glioma cell invasion. The purpose of the present study was to analyze volumetric and geometrical properties of RT target delineation based on DS and compare them with those based on MRI.

METHODS

Twenty-five patients with a diagnosis of malignant glioma were included in this study. Three target volumes were compared: 1) contrast-enhancing core lesions identified by contrast-enhanced T1-weighted images (T1Gd), 2) high-intensity lesions on T2-weighted images, and 3) lesions showing high DS (DS ≥ 3; hDS). The geometrical differences of these target volumes were assessed by calculating the probabilities of overlap and one encompassing the other. The correlation of geometrical features of RT planning and recurrence patterns was further analyzed.

RESULTS

The analysis revealed that T1Gd with a 2.0-cm margin was able to cover the entire high DS area only in 6 (24%) patients, which indicates that microscopic invasion of glioma cells often extended more than 2.0 cm beyond a Gd-enhanced core lesion. Insufficient coverage of high DS regions with RT target volumes was suggested to be a risk for out-of-field recurrence. Higher coverage of hDS by T1Gd with a 2-cm margin (i.e., higher values of "[T1Gd + 2 cm]/hDS") had a trend to positively impact overall and progression-free survival. Cox regression analysis demonstrated that low coverage of hDS by T1Gd with a 2-cm margin was predictive of disease recurrence outside the Gd-enhanced core lesion, indicative of out-of-field reoccurrence.

CONCLUSIONS

The findings of this study indicate that MRI is inadequate for target delineation for RT in malignant glioma treatment. Expanding the treated margins substantially beyond the MRI-based target volume may reduce the risk of undertreatment, but it may also result in unnecessary irradiation of uninvolved regions. As MET/FDG PET-DS seems to provide more accurate information for target delineation than MRI in malignant glioma treatment, this method should be further evaluated on a larger scale.

NIMG-67. DEVELOPMENT OF VERSATILE MACHINE-LEARNING APPROACHES FOR RADIOGENOMICS OF GLIOMA IN DIFFERENT COHORTS

BACKGROUND

Radiogenomics aims to analyze clinical images and information, and to predict key molecular profiles of tumors. However, imaging protocol is usually different in facilities, and it has been rarely examined whether the performance of developed methods in a dataset is robustly sustained even in other independent datasets. We explored machine learning and matrix decomposition methods using preoperative magnetic resonance images (MRIs) of glioma patients to establish versatile platform regardless of the heterogeneity of the datasets.

METHODS

Preoperative glioma MRIs and clinical information were obtained from public dataset of The Cancer Imaging Archive (TCIA, N=159) and National Cancer Center Hospital (NCC, N=166). More than 16,000 radiomic features were applied for the prediction of tumor grading and IDH mutation status. Accuracy of prediction was evaluated by AUROC (area under the receiver operating characteristic curves).

RESULTS

The performances were comparable between the image features regardless of dimension reduction methods (the best accuracy for tumor grading and IDH status prediction was 0.91 and 0.88, respectively), but they were drastically decreased in the transfer learning (0.70 and 0.69). On the other hand, they were successfully improved by applying matrix decomposition and brain embedding (0.86 and 0.79).

CONCLUSION

Our result and pipeline can be a global benchmark for future studies in heterogeneous datasets. Further evaluation in larger cohorts are planned.

PATH-02. A COMBINATION OF MGMT METHYLATION AND NFKBIA COPY NUMBER ALTERATION REFINES PROGNOSTICATION OF IDH-WT GLIOBLASTOMAS

INTRODUCTION

Recent studies have reported that NFKBIA deletion (dNFKBIA) was potentially associated with worse prognosis in glioblastoma (GBM) patients. However, no consensus has been reached to its universal prognostic value. Here, we investigated the survival impact of dNFKBIA using two primary IDH wild-type GBM cohorts: an original Japanese cohort and a dataset from The Cancer Genome Atlas (TCGA). Additionally, prognostic impact of a combination of NFKBIA copy number and MGMT methylation status was evaluated.

METHOD

The Japanese cohort was collected from cases registered in Kansai Molecular Diagnosis Network for CNS tumors (KNBTG). The survival impact of dNFKBIA and/or unmethylated MGMT (uMGMT) were analyzed for 212 KNBTG cases and 265 TCGA cases. The hazard ratio (HR) and p-value were computed using Cox regression analysis.

RESULTS

dNFKBIA was less frequently observed in KNBTG (47 cases, 22.2%) than in TCGA (84 cases, 31.7%). dNFKBIA was associated with unfavorable prognosis in KNBTG (HR 1.52, p = 0.031), while this was not validated in TCGA (HR 1.14, p=0.406). uMGMT was a common adverse prognostic factor in KNBGT (HR 1.72, p = 0.001) and TCGA (HR 1.50, p = 0.008) cohort. When stratified by NFKBIA status, uMGMT was also associated with shorter survival in NFKBIA deleted cases both in KNBTG (HR 1.87, p = 0.002) and TCGA (HR 1.59, p = 0.014). On the other hand, MGMT status was not significantly associated with prognosis in NFKBIA intact cases in either KNBTG (HR 1.45, p = 0.279) or TCGA (HR 1.55, p = 0.131).

DISCUSSION

Although the prognostic value of dNFKBIA in IDH wild-type GBM patients was not validated in TCGA cohort, our results indicated that the prognostication based on MGMT methylation was potentially interacted by NFKBIA status.

P2458Restricted left atrial motion as a result of atrial stiffening in patients with cardiac amyloidosis

Background

Left atrial (LA) involvement of abnormal amyloid fibrils could induce LA dysfunction and stiffening in patients with cardiac amyloidosis (CA). Thus, the assessments of LA function and stiffness might be a potential approach to diagnose CA phenotype among patients with hypertrophied hearts.

Purpose

We sought to determine whether LA reservoir strain with speckle tracking echocardiography could be used a marker of LA stiffness in a derivation cohort. Furthermore, we tested to our hypothesis that LA reservoir strain could differentiate CA patients from hypertrophic cardiomyopathy (HCM) in an independent validation cohort.

Methods

In the derivation cohort, echocardiography was performed simultaneously with measurements of pulmonary capillary wedge pressure (PCWP) in 50 patients with suspected or established heart failure and relatively preserved left ventricular (LV) ejection fraction (56±10%). LA maximum and minimum volume index, and reservoir strain were measured from apical four-chamber view. LA stiffness index was computed as a pressure rise from x-trough to v-wave divided by an increase from minimum to maximum indexed LA volume (Figure A). In an independent validation group, we studied a total of 33 biopsy-proved CA patients and 127 HCM patients (LV ejection fraction: 57±11% vs. 66±10%, P<0.01) in sinus rhythm on the date of comprehensive echocardiographic study. Among them, cardiac magnetic resonance imaging (CMR) could be evaluated in 17 CA patients and 98 HCM patients. Furthermore, right heart catheterization was performed with 12 CA patients and 12 HCM patients in the CMR group.

Results

The derivation cohort study found that there was a significant curvilinear correlation of LA reservoir strain to LA stiffness index (Figure B). In the validation cohort, LA reservoir strain was reduced in patients with CA compared with HCM in all participants (11.6±5.6% vs. 18.5±6.9%, P<0.01), although there was no significant difference of LA maximal volume index between 2 groups (37±16 ml/m2 vs. 37±12 ml/m2, p=0.89). In the CMR group, the late gadolinium enhancement was observed in the LA wall in 16 patients with CA (94.1%) as shown in Figure C. In contrast, the LA enhancement revealed only in 1 patient with HCM (1.0%). Among patients with invasive measures, LA stiffness index [median (interquartile range)] was higher in patients with CA than that in patients with HCM [1.1 (0.4–2.8) vs. 0.2 (0.1–0.6), P=0.01].

Conclusions

LA reservoir function was fairly limited in patients with CA compared with HCM. Restricted LA motion might be related to atrial amyloid deposits or fibrosis, which potentially provokes atrial chamber stiffening.

Validation of magnetic resonance imaging-based automatic high-grade glioma segmentation accuracy via 11C-methionine positron emission tomography

Brain Tumor Image Analysis (BraTumIA) is a fully automated segmentation tool dedicated to detecting brain tumors imaged by magnetic resonance imaging (MRI). BraTumIA has recently been applied to several clinical investigations; however, the validity of this novel method has not yet been fully examined. The present study was conducted to validate the quality of tumor segmentation with BraTumIA in comparison with results from ¹¹C-methionine positron emission tomography (MET-PET). A total of 45 consecutive newly diagnosed high-grade gliomas imaged by MRI and MET-PET were analyzed. Automatic tumor segmentation was conducted by BraTumIA and the resulting segmentation images were registered to MET-PET. Three-dimensional conformal association between these two modalities was calculated, considering MET-PET as the gold standard. High underestimation and overestimation errors were observed in tumor segmentation calculated by BraTumIA compared with MET-PET. Furthermore, when the tumor/normal ratio threshold was set at 1.3 from MET-PET, the BraTumIA false-positive fraction was ~0.4 and the false-negative fraction was 0.9. By tightening this threshold to 2.0, the BraTumIA false-positive fraction was 0.6 and the false-negative fraction was 0.6. Following comparison of segmentation performance with BraTumIA with regard to glioblastoma (GBM) and World Health Organization (WHO) grade III glioma, GBM exhibited better segmentation compared with WHO grade III glioma. Although BraTumIA may be able to detect enhanced tumors, non-enhancing tumors and necrosis, the spatial concordance rate with MET-PET was relatively low. Careful interpretation is therefore required when using this technique.

A novel protocol for three-dimensional rotational venography with low-dose contrast media in preoperative angiography of brain tumours

AIM

The most appropriate imaging protocol for three-dimensional rotational venography (3D RV) has not been established. The aim of this study was to optimise the protocol for 3D RV with low-dose contrast media using time-density curve analysis.

METHODS

Twenty-five consecutive patients with brain tumours who received preoperative assessment with 3D RV were retrospectively collected and included in this study. To optimise the imaging delay time of 3D RV with low-dose contrast media, time-density curve analysis was performed on two-dimensional conventional angiography. The image quality for depicting cortical veins and venous sinuses was compared to that of magnetic resonance (MR) venography in five cases.

RESULTS

A total of 27 3D RVs were performed in 25 patients. The time-density curves of cortical veins were different from those of cerebral arteries or sinuses. The mean time to peak of cortical veins was significantly longer than the time to peak of cerebral arteries (2.47 ± 0.35 seconds vs. 6.44 ± 1.14 seconds; p < 0.0001) and shorter than the time to peak of venous sinuses (6.44 ± 1.14 seconds vs. 8.18 ± 1.12 seconds; p < 0.0001). The optimal imaging delay time could be determined as the phases in which cortical arterial opacities disappeared and cortical veins started to appear. The mean dose of injected contrast media was 5.3 mL. The image quality of cortical veins in 3D RV was superior to that in MR venography in all cases.

CONCLUSIONS

Three-dimensional RV with low-dose contrast media was useful for the preoperative assessment of cortical veins in patients with brain tumours.

Development of New Biokinetic-Dosimetric Models for the Simulation of Iodine Blockade in the Case of Radioiodine Exposure in Man

In the case of nuclear incidents, radioiodine may be liberated. After incorporation it accumulates in the thyroid and by internal irradiation enhances the risk of cancer occurrence. By administering a large dose of non-radioactive iodine the uptake of radioiodine into the gland can be inhibited ("iodine blockade"). Biokinetic models using first order kinetics are not suited to simulate iodine blockade, as the uptake into the gland is mediated by a saturable active transport. Therefore, we integrated an uptake mechanism described by a Michaelis-Menten kinetic into a simple ICRP biokinetic model. We moreover added a total uptake blocking mechanism representing the Wolff-Chaikoff effect becoming active when the gland is saturated with iodine. The validity of the model was ascertained by comparison with IMBA software. The competition of radioiodine and stable iodine at the membrane carrier site was modeled according to the rate law for monomolecular reactions for competing substrates. Our simulations show that competition for the uptake at the membrane carrier site accounts for about 60% and the saturation of the gland with iodine for over 35% of the total protective efficacy that exceeds 95%. Following acute radioiodine exposure, it is preferable to administer a single large dose of stable iodine. In the case of continuous radioiodine exposure, a single dose of stable iodine is less effective than after an acute exposure and splitting the total available dose and shortening the dosage intervals enhance efficacy. Model-based simulations may be a useful tool to develop antidote dosage schemes for uncommon emergencies.

Epidermal growth factor receptor (EGFR) amplification rates observed in screening patients for randomized trials in glioblastoma

PURPOSE

Epidermal growth factor receptor (EGFR) amplification has been reported to occur in ~ 50% of glioblastomas (GBMs). We are conducting several global studies that require central testing for EGFR amplification during screening, representing an opportunity to confirm the frequency of amplification in GBM in a large cohort and to evaluate whether EGFR amplification differs by region of the world.

METHODS

EGFR amplification was measured by fluorescence in situ hybridization during screening for therapeutic trials of an EGFR antibody-drug conjugate: two Phase 2/3 global trials (INTELLANCE-1, INTELLANCE-2), and a Japanese Phase 1/2 trial (INTELLANCE-J). We evaluated the proportion of tumor tissue samples harboring EGFR amplification among those tested and differences in amplification frequency by geography.

RESULTS

EGFR was amplified in 54% of 3150 informative cases screened for INTELLANCE-1 and -2, consistent with historic controls, but was significantly lower in patients from Asia versus the rest of the world (35% vs. 56%, P < 0.0030). The independent INTELLANCE-J trial validated this finding (33% amplified of 153 informative cases).

CONCLUSIONS

EGFR amplification occurs less frequently in patients from Asia than elsewhere. Further study is required to understand biological differences to optimize treatment in glioblastoma.

Immune Mechanisms Underlying Susceptibility to Endotoxin Shock in Aged Hosts: Implication in Age-Augmented Generalized Shwartzman Reaction

In recent decades, the elderly population has been rapidly increasing in many countries. Such patients are susceptible to Gram-negative septic shock, namely endotoxin shock. Mortality due to endotoxin shock remains high despite recent advances in medical care. The generalized Shwartzman reaction is well recognized as an experimental endotoxin shock. Aged mice are similarly susceptible to the generalized Shwartzman reaction and show an increased mortality accompanied by the enhanced production of tumor necrosis factor (TNF). Consistent with the findings in the murine model, the in vitro Shwartzman reaction-like response is also age-dependently augmented in human peripheral blood mononuclear cells, as assessed by enhanced TNF production. Interestingly, age-dependently increased innate lymphocytes with T cell receptor-that intermediate expression, such as that of CD8⁺CD122⁺T cells in mice and CD57⁺T cells in humans, may collaborate with macrophages and induce the exacerbation of the Shwartzman reaction in elderly individuals. However, endotoxin tolerance in mice, which resembles a mirror phenomenon of the generalized Shwartzman reaction, drastically reduces the TNF production of macrophages while strongly activating their bactericidal activity in infection. Importantly, this effect can be induced in aged mice. The safe induction of endotoxin tolerance may be a potential therapeutic strategy for refractory septic shock in elderly patients.

Combination therapy using fibrinogen γ-chain peptide-coated, ADP-encapsulated liposomes and hemoglobin vesicles for trauma-induced massive hemorrhage in thrombocytopenic rabbits

BACKGROUND

We previously developed substitutes for red blood cells (RBCs) and platelets (PLTs) for transfusion. These substitutes included hemoglobin vesicles (HbVs) and fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV, H12)-coated, adenosine diphosphate (ADP)-encapsulated liposomes [H12-(ADP)-liposomes]. Here, we examined the efficacy of combination therapy using these substitutes instead of RBC and PLT transfusion in a rabbit model with trauma-induced massive hemorrhage with coagulopathy.

STUDY DESIGN AND METHODS

Thrombocytopenia (PLT count approximately 40,000/μL) was induced in rabbits by repeated blood withdrawal and isovolemic transfusion with autologous RBCs. Thereafter, lethal hemorrhage was induced in rabbits by noncompressible penetrating liver injury. Subsequently, H12-(ADP)-liposomes with platelet-poor plasma (PPP), platelet-rich plasma (PRP), or PPP alone were administered to stop bleeding. Once achieving hemostasis, HbVs, allogenic RBCs, or 5% albumin were transfused into rabbits to rescue them from fatal anemia following massive hemorrhage.

RESULTS

Administration of H12-(ADP)-liposomes/PPP as well as PRP (but not PPP) effectively stopped liver bleeding (100% hemostasis). The subsequent administration with HbVs as well as RBCs after hemostasis markedly rescued rabbits from fatal anemia (75% and 70% survivals for 24 hr, respectively). In contrast, 5% albumin administration rescued none of the rabbits.

CONCLUSION

Combination therapy with H12-(ADP)-liposomes and HbVs may be effective for damage control resuscitation of trauma-induced massive hemorrhage.