Characteristics of deceased subjects transported to a postmortem imaging center due to unusual death related to epilepsy

OBJECTIVE

Patients with epilepsy have high risk of experiencing uncommon causes of death. This study aimed to evaluate patients who underwent unusual deaths related to epilepsy and identify factors that may contribute to these deaths and may also include sudden unexpected death in epilepsy (SUDEP).

METHODS

We analyzed 5291 cases in which a postmortem imaging (PMI) study was performed using plane CT, because of an unexplained death. A rapid troponin T assay was performed using peripheral blood samples. Clinical information including the cause of death suspected by the attending physician, body position, place of death, medical history, and antiseizure medications was evaluated.

RESULTS

A total of 132 (2.6%) patients had an obvious history of epilepsy, while 5159 individuals had no history of epilepsy (97.4%). Cerebrovascular disease was the cause of death in 1.6% of patients in the group with epilepsy, and this was significantly lower than that in the non-epilepsy group. However, drowning was significantly higher (9.1% vs. 4.4%). Unspecified cause of death was significantly more frequent in the epilepsy group (78.0% vs. 57.8%). Furthermore, the proportion of patients who demonstrated elevation of troponin T levels without prior cardiac disease was significantly higher in the epilepsy group (37.9% vs. 31.1%). At discovery of death, prone position was dominant (30.3%), with deaths occurring most commonly in the bedroom (49.2%). No antiseizure medication had been prescribed in 12% of cases, while 29.5% of patients were taking multiple antiseizure medications.

SIGNIFICANCE

The prevalence of epilepsy in individuals experiencing unusual death was higher than in the general population. Despite PMI studies, no definitive cause of death was identified in a significant proportion of cases. The high troponin T levels may be explained by long intervals between death and examination or by higher incidence of myocardial damage at the time of death.

PLAIN LANGUAGE SUMMARY

This study investigated unusual deaths in epilepsy patients, analyzing 5291 postmortem imaging cases. The results showed that 132 cases (2.6%) had a clear history of epilepsy. In these cases, only 22% cases were explained after postmortem examination, which is less than in non-epilepsy group (42.2%). Cerebrovascular disease was less common in the epilepsy group, while drowning was more common. Elevated troponin T levels, which suggest possibility of myocardial damage or long intervals between death and examination, were also more frequent in the epilepsy group compared to non-epilepsy group.

In-house molecular diagnosis of diffuse glioma updating the revised WHO classification by a platform of the advanced medical care system, Senshin-Iryo

Since the World Health Organization (WHO) 2016 revision, the number of molecular markers required for diffuse gliomas has increased, placing a burden on clinical practice. We have established an in-house, molecular diagnostic platform using Senshin-Iryo, a feature of Japan's unique healthcare system, and partially modified the analysis method in accordance with the WHO 2021 revision. Herein, we review over a total 5 years of achievements using this platform. Analyses of IDH, BRAF, and H3 point mutations, loss of heterozygosity (LOH) on 1p/19q and chromosomes 10 and 17, and MGMT methylation were combined into a set that was submitted to Senshin-Iryo as "Drug resistance gene testing for anticancer chemotherapy" and was approved in August 2018. Subsequently, in October 2021, Sanger sequencing for the TERT promoter mutation was added to the set, and LOH analysis was replaced with multiplex ligation-dependent probe amplification (MLPA) to analyze 1p/19q codeletion and newly required genetic markers, such as EGFR, PTEN, and CDKN2A from WHO 2021. Among the over 200 cases included, 54 were analyzed after the WHO 2021 revision. The laboratory has maintained a diagnostic platform where molecular diagnoses are confirmed within 2 weeks. Initial expenditures exceeded the income from patient copayments; however, it has gradually been reduced to running costs alone and is approaching profitability. After the WHO 2021 revision, diagnoses were confirmed using molecular markers obtained from Senshin-Iryo in 38 of 54 cases (70.1%). Among the remaining 16 patients, only four (7.4%) were diagnosed with diffuse glioma, not elsewhere classified, which was excluded in 12 cases where glioblastoma was confirmed by histopathological diagnosis. Our Senshin-Iryo trial functioned as a salvage system to overcome the transition period between continued revisions of WHO classification that has caused a clinical dilemma in the Japanese healthcare system.

Liquid Biopsy for Glioma Using Cell-Free DNA in Cerebrospinal Fluid

Glioma is one of the most common primary central nervous system (CNS) tumors, and its molecular diagnosis is crucial. However, surgical resection or biopsy is risky when the tumor is located deep in the brain or brainstem. In such cases, a minimally invasive approach to liquid biopsy is beneficial. Cell-free DNA (cfDNA), which directly reflects tumor-specific genetic changes, has attracted attention as a target for liquid biopsy, and blood-based cfDNA monitoring has been demonstrated for other extra-cranial cancers. However, it is still challenging to fully detect CNS tumors derived from cfDNA in the blood, including gliomas, because of the unique structure of the blood-brain barrier. Alternatively, cerebrospinal fluid (CSF) is an ideal source of cfDNA and is expected to contribute significantly to the liquid biopsy of gliomas. Several successful studies have been conducted to detect tumor-specific genetic alterations in cfDNA from CSF using digital PCR and/or next-generation sequencing. This review summarizes the current status of CSF-based cfDNA-targeted liquid biopsy for gliomas. It highlights how the approaches differ from liquid biopsies of other extra-cranial cancers and discusses the current issues and prospects.

O6 -methylguanine methyltransferase promoter methylation status of glioblastoma cell line clonal population

Glioblastoma (GBM) remains a treatment-resistant malignant brain tumor in large part because of its genetic heterogeneity and epigenetic plasticity. In this study, we investigated the epigenetic heterogeneity of GBM by evaluating the methylation status of the O6 -methylguanine methyltransferase (MGMT) promoter in individual clones of a single cell derived from GBM cell lines. The U251 and U373 GBM cell lines, from the Brain Tumour Research Centre of the Montreal Neurological Institute, were used for the experiments. To evaluate the methylation status of the MGMT promoter, pyrosequencing and methylation-specific PCR (MSP) were used. Moreover, mRNA and protein expression levels of MGMT in the individual GBM clones were evaluated. The HeLa cell line, which hyper-expresses MGMT, was used as control. A total of 12 U251 and 12 U373 clones were isolated. The methylation status of 83 of 97 CpG sites in the MGMT promoter were evaluated by pyrosequencing, and 11 methylated CpG sites and 13 unmethylated CpG sites were evaluated by MSP. The methylation status by pyrosequencing was relatively high at CpG sites 3-8, 20-35, and 7-83, in both the U251 and U373 clones. Neither MGMT mRNA nor protein was detected in any clone. These findings demonstrate tumor heterogeneity among individual clones derived from a single GBM cell. MGMT expression may be regulated, not only by methylation of the MGMT promoter but by other factors as well. Further studies are needed to clarify the mechanisms underlying the epigenetic heterogeneity and plasticity of GBM.

Lateral Lumbar Interbody Fusion within Three-level for Patients with Neurological Symptoms due to Vertebral Fragility Fractures in the Lumbar Spine

There is a lack of agreement on whether minimally invasive lateral lumbar intervertebral fusion (LLIF) is a suitable treatment option for vertebral fragility fractures (VFFs). Hence, we sought to evaluate the efficacy and safety of LLIF in the management of VFF with neurological deficits in the lumbar spine. Between April 2015 and March 2020, we conducted a retrospective observational study of patients with VFF treated with three-level or less LLIF. The participants had previously received conservative treatment but had not been able to control their neurological symptoms. To assess the outcomes of the LLIF procedures, the patients were followed up for a minimum of 1 year. Clinical and radiological results, which include the timing and location of the bony fusion, were analyzed. The study involved 19 patients with 23 vertebral fracture levels. The residual height of the fractured vertebra was found to be 57.0 ± 12.3% of the height of the adjacent level. The mean Japanese Orthopedic Association score significantly improved postoperatively. Postoperative radiological parameters were significantly maintained at 1 year, and lumbar lordosis was maintained at the last follow-up (45.0 ± 26.7). In total 31 LLIF levels, bone fusion was observed in four levels at 6 months postoperatively, in 16 levels at 1 year, and in 23 levels at the last follow-up. The facet joint had the highest bony fusion location. LLIF within three levels can be safely performed in certain VFF cases with sufficient residual vertebral height.

Quantitative GABA magnetic resonance spectroscopy as a measure of motor learning function in the motor cortex after subarachnoid hemorrhage

The neural mechanisms underlying gross and fine motor dysfunction after subarachnoid hemorrhage (SAH) remain unknown. The γ-aminobutyric acid (GABA) deficit hypothesis proposes that reduced neuronal GABA concentrations and the subsequent lack of GABA-mediated inhibition cause motor impairment after SAH. This study aimed to explore the correlation between GABA levels and a behavioral measure of motor performance in patients with SAH. Motor cortical GABA levels were assessed in 40 patients with SAH and 10 age-matched healthy controls using proton magnetic resonance spectroscopy. The GABA and N-acetylasparate (NAA) ratio was measured in the normal gray matter within the primary motor cortex. The relationship between GABA concentration and hand-motor performance was also evaluated. Results showed significantly lower GABA levels in patients with SAH's left motor cortex than in controls (GABA/NAA ratio: 0.282 ± 0.085 vs. 0.341 ± 0.031, respectively; p = 0.041). Reaction times (RTs), a behavioral measure of motor performance potentially dependent on GABAergic synaptic transmission, were significantly longer in patients than in controls (936.8 ± 303.8 vs. 440.2 ± 67.3 ms, respectively; p < 0.001). Moreover, motor cortical GABA levels and RTs exhibited a significant positive linear correlation among patients (r = 0.572, rs = 0.327, p = 0.0001). Therefore, a decrease in GABA levels in the primary motor cortex after SAH may lead to impaired cortical inhibition of neuronal function and indicates that GABA-mediated synaptic transmission in the motor cortex is critical for RT.

Angiogenic and inflammatory responses in human induced microglia-like (iMG) cells from patients with Moyamoya disease

Angiogenic factors associated with Moyamoya disease (MMD) are overexpressed in M2 polarized microglia in ischemic stroke, suggesting that microglia may be involved in the pathophysiology of MMD; however, existing approaches are not applicable to explore this hypothesis. Herein we applied blood induced microglial-like (iMG) cells. We recruited 25 adult patients with MMD and 24 healthy volunteers. Patients with MMD were subdivided into progressive (N = 7) or stable (N = 18) group whether novel symptoms or radiographic advancement of Suzuki stage within 1 year was observed or not. We produced 3 types of iMG cells; resting, M1-, and M2-induced cells from monocytes, then RNA sequencing followed by GO and KEGG pathway enrichment analysis and qPCR assay were performed. RNA sequencing of M2-induced iMG cells revealed that 600 genes were significantly upregulated (338) or downregulated (262) in patients with MMD. Inflammation and immune-related factors and angiogenesis-related factors were specifically associated with MMD in GO analysis. qPCR for MMP9, VEGFA, and TGFB1 expression validated these findings. This study is the first to demonstrate that M2 microglia may be involved in the angiogenic process of MMD. The iMG technique provides a promising approach to explore the bioactivity of microglia in cerebrovascular diseases.

Supramaximal Resection Can Prolong the Survival of Patients with Cortical Glioblastoma: A Volumetric Study

We aimed to retrospectively determine the resection rate of fluid-attenuated inversion recovery (FLAIR) lesions to evaluate the clinical effects of supramaximal resection (SMR) on the survival of patients with glioblastoma (GBM). Thirty-three adults with newly diagnosed GBM who underwent gross total tumor resection were enrolled. The tumors were classified into cortical and deep-seated groups according to their contact with the cortical gray matter. Pre- and postoperative FLAIR and gadolinium-enhanced T1-weighted imaging tumor volumes were measured using a three-dimensional imaging volume analyzer, and the resection rate was calculated. To evaluate the association between SMR rate and outcome, we subdivided patients whose tumors were totally resected into the SMR and non-SMR groups by moving the threshold value of SMR in 10% increments from 0% and compared their overall survival (OS) change. An improvement in OS was observed when the threshold value of SMR was 30% or more. In the cortical group (n = 23), SMR (n = 8) tended to prolong OS compared with gross total resection (GTR) (n = 15), with the median OS of 69.6 and 22.1 months, respectively (p = 0.0945). Contrastingly, in the deep-seated group (n = 10), SMR (n = 4) significantly shortened OS compared with GTR (n = 6), with median OS of 10.2 and 27.9 months, respectively (p = 0.0221). SMR could help prolong OS in patients with cortical GBM when 30% or more volume reduction is achieved in FLAIR lesions, although the impact of SMR for deep-seated GBM must be validated in larger cohorts.

Predicting TERT promoter mutation status using 1H-MR spectroscopy and stretched-exponential model of diffusion-weighted imaging in IDH-wildtype diffuse astrocytic glioma without intense enhancement

PURPOSE

Isocitrate dehydrogenase (IDH)-wildtype diffuse astrocytic glioma with telomerase reverse transcriptase (TERT) promoter mutation is defined as glioblastoma by the WHO 2021 criteria, revealing that TERT promotor mutation is highly associated with tumor aggressiveness. The aim of this study was to identify features from MR spectroscopy (MRS) and multi-exponential models of DWI distinguishing wild-type TERT (TERTw) from TERT promoter mutation (TERTm) in IDH-wildtype diffuse astrocytic glioma.

METHODS

Participants comprised 25 adult patients with IDH-wildtype diffuse astrocytic glioma. Participants were classified into TERTw and TERTm groups. Point-resolved spectroscopy sequences were used for MRS data acquisition. DWI was performed with 13 different b-factors. Peak height ratios of NAA/Cr and Cho/Cr were calculated from MRS data. Mean apparent diffusion coefficient (ADC), perfusion fraction (f), diffusion coefficient (D), pseudo-diffusion coefficient (D*), distributed diffusion coefficient (DDC), and heterogeneity index (α) were obtained using multi-exponential models from DWI data. Each parameter was compared between TERTw and TERTm using the Mann-Whitney U test. Correlations between parameters derived from MRS and DWI were also evaluated.

RESULTS

NAA/Cr and Cho/Cr were both higher for TERTw than for TERTm. The α of TERTw was smaller than that of TERTm, while the f of TERTw was higher than that of TERTm. NAA/Cr correlated negatively with α, but not with other DWI parameters. Cho/Cr did not show significant correlations with any DWI parameters.

CONCLUSION

The combination of NAA/Cr and α may have merit in clinical situation to predict the TERT mutation status of IDH-wildtype diffuse astrocytic glioma without intense enhancement.

Monophasic-quadri-burst stimulation robustly activates bilateral swallowing motor cortices

A stable, reliable, non-invasive, quantitative assessment of swallowing function remains to be established. Transcranial magnetic stimulation (TMS) is commonly used to aid in the diagnosis of dysphagia. Most diagnostic applications involve single-pulse TMS and motor evoked potential (MEP) recordings, the use of which is not clinically suitable in patients with severe dysphagia given the large variability in MEPs measured from the muscles involved in swallowing. Previously, we developed a TMS device that can deliver quadripulse theta-burst stimulation in 16 monophasic magnetic pulses through a single coil, enabling the measurement of MEPs related to hand function. We applied a system for MEP conditioning that relies on a 5 ms interval-monophasic quadripulse magnetic stimulation (QPS5) paradigm to produce 5 ms interval-four sets of four burst trains; quadri-burst stimulation (QBS5), which is expected to induce long-term potentiation (LTP) in the stroke patient motor cortex. Our analysis indicated that QBS5 conditioned left motor cortex induced robust facilitation in the bilateral mylohyoid MEPs. Swallowing dysfunction scores after intracerebral hemorrhage were significantly correlated with QBS5 conditioned-MEP parameters, including resting motor threshold and amplitude. The degree of bilateral mylohyoid MEP facilitation after left side motor cortical QBS5 conditioning and the grade of severity of swallowing dysfunction exhibited a significant linear correlation (r = -0.48/-0.46 and 0.83/0.83; R² = 0.23/0.21 and 0.68/0.68, P < 0.001; Rt./Lt. side MEP-RMT and amplitudes, respectively). The present results indicate that RMT and amplitude of bilateral mylohyoid-MEPs after left motor cortical QBS5 conditioning as surrogate quantitative biomarkers for swallowing dysfunction after ICH. Thus, the safety and limitations of QBS5 conditioned-MEPs in this population should be further explored.

Radiographic Prediction of the Occipito-C2 Angle Variation with Changes in Distance between the Mandible and Cervical Vertebrae: A Preliminary Study

The Occipito (O) -C2 angle reflects the correct craniocervical spine alignment; however, the poor image quality of standard intraoperative fluoroscopy at times lead to inaccurate measurements. Herein, we preliminarily investigated the relationship between the O-C2 angle and the Gonion-C2 distance, which is based on the positioning of the mandible and the cervical spine. We enrolled patients who underwent cervical spine radiography in neutral, flexion, and extension positions from January 2020 to October 2020. The difference by posture changes for each parameter was defined as the Δ value, and the Spearman's rank correlation coefficient was determined. Furthermore, we determined the cutoff value of the ΔGonion-C2 distance to predict a decrease of > 10° in the ΔO-C2 angle, which is reported to be related to dysphagia and dyspnea. Seventy-four patients were included. Spearman's rank correlations for the neutral, flexion, and extension positions were 0.630 (P < 0.001), 0.471 (P < 0.001), and 0.625 (P < 0.001), respectively, while the cutoff values of the ΔGonion-C2 distance for predicting > 10° in the ΔO-C2 angle were 9.3 mm for the neutral flexion change (sensitivity: 0.435, specificity: 0.882) and 8.3 mm for the extension-neutral change (sensitivity: 0.712, specificity: 0.909). The O-C2 angle and Gonion-C2 distances correlated; however, this correlation was weaker in the flexed position. Nevertheless, the ΔGonion-C2 distance can be used as a warning sign for postoperative complications after posterior occipital bone fusion surgery, because a decrease of > 10° in the ΔO-C2 angle can be predicted with high specificity.

Clinicopathologic analysis of pineal parenchymal tumors of intermediate differentiation: a multi-institutional cohort study by the Kyushu Neuro-Oncology Study Group

PURPOSE

Pineal parenchymal tumors of intermediate differentiation (PPTIDs), which were recognized in the 2007 World Health Organization (WHO) classification, are rare, accounting for less than 1% of all central nervous system tumors. This rarity and novelty complicate the diagnosis and treatments of PPTID. We therefore aimed to evaluate the clinicopathological significance of this tumor.

METHODS

At 11 institutions participating in the Kyushu Neuro-Oncology Study Group, data for patients diagnosed with PPTID were collected. Central pathology review and KBTBD4 mutation analysis were applied to attain the diagnostically accurate cohort.

RESULTS

PPTID was officially diagnosed in 28 patients: 11 (39%) with WHO grade 2 and 17 (61%) with WHO grade 3 tumors. Median age was 49 years, and the male:female ratio was 1:2.1. Surgery was attempted in all 28 patients, and gross total resection (GTR) was achieved in 46% (13/28). Adjuvant radiotherapy and chemotherapy were administered to, respectively, 82% (23/28) and 46% (13/28). The 5-year progression-free survival (PFS) and overall survival rates were 64.9% and 70.4% respectively. Female sex (p = 0.018) and GTR (p < 0.01) were found to be independent prognostic factors for PFS and female sex (p = 0.019) was that for OS. Initial and second recurrences were most often leptomeningeal (67% and 100% respectively). 80% (20/25) of patients harbored a KBTBD4 mutation.

CONCLUSIONS

Female sex and GTR were independent prognostic factors in our patients with PPTID. Leptomeningeal recurrence was observed to be particularly characteristic of this tumor. The rate of KBTBD4 mutation observed in our cohort was acceptable and this could prove the accuracy of our PPTID cohort.

Liquid biopsy with multiplex ligation-dependent probe amplification targeting cell-free tumor DNA in cerebrospinal fluid from patients with adult diffuse glioma

Background

Copy number alterations (CNAs) are common in diffuse gliomas and have been shown to have diagnostic significance. While liquid biopsy for diffuse glioma has been widely investigated, techniques for detecting CNAs are currently limited to methods such as next-generation sequencing. Multiplex ligation-dependent probe amplification (MLPA) is an established method for copy number analysis in pre-specified loci. In this study, we investigated whether CNAs could be detected by MLPA using patients' cerebrospinal fluid (CSF).

Methods

Twenty-five cases of adult diffuse glioma with CNAs were selected. Cell-free DNA (cfDNA) was extracted from the CSF, and DNA sizes and concentrations were recorded. Twelve samples, which had appropriate DNA sizes and concentrations, were subsequently used for analysis.

Results

MLPA could be successfully performed in all 12 cases, and the detected CNAs were concordant with those detected using tumor tissues. Cases with epidermal growth factor receptor (EGFR) amplification, combination of gain of chromosome 7 and loss of chromosome 10, platelet-derived growth factor receptor alpha amplification, cyclin-dependent kinase 4 amplification, and cyclin-dependent kinase inhibitor 2A (CDKN2A) homozygous deletion were clearly distinguished from those with normal copy numbers. Moreover, EGFR variant III was accurately detected based on CNA.

Conclusions

Thus, our results demonstrate that copy number analysis can be successfully performed by MLPA of cfDNA extracted from the CSF of patients with diffuse glioma.

Molecular Genetic Profile of 300 Japanese Patients with Diffuse Gliomas Using a Glioma-tailored Gene Panel

Rapid technological advances in molecular biology, including next-generation sequencing, have identified key genetic alterations in central nervous system (CNS) tumors. Accordingly, the fifth edition of the World Health Organization (WHO) CNS tumor classification was published in 2021. We analyzed 303 patients with diffuse glioma using an amplicon-based glioma-tailored gene panel for detecting 1p/19q codeletion and driver gene mutations such as IDH1/2, TERTp, EGFR, and CDKN2A/B on a single platform. Within glioblastomas (GBMs), the most commonly mutated genes were TERTp, TP53, PTEN, NF1, and PDGFRA, which was the most frequently mutated tyrosine kinase receptor in GBM, followed by EGFR. The genes that most commonly showed evidence of loss were PTEN, CDKN2A/B, and RB1, whereas the genes that most commonly showed evidence of gain/amplification were EGFR, PDGFRA, and CDK4. In 22 grade III oligodendroglial tumors, 3 (14%) patients had CDKN2A/B homozygous deletion, and 4 (18%) patients had ARID1A mutation. In grade III oligodendroglial tumors, an ARID1A mutation was associated with worse progression-free survival. Reclassification based on the WHO 2021 classification resulted in 62.5% of grade II/III isocitrate dehydrogenase (IDH)-wildtype astrocytomas being classified as IDH-wildtype GBM and 37.5% as not elsewhere classified. In summary, our glioma-tailored gene panel was applicable for molecular diagnosis in the WHO 2021 classification. In addition, we successfully reclassified the 303 diffuse glioma cases based on the WHO 2021 classification and clarified the genetic profile of diffuse gliomas in the Japanese population.

The first-in-human phase I study of a brain-penetrant mutant IDH1 inhibitor DS-1001 in patients with recurrent or progressive IDH1-mutant gliomas

BACKGROUND

Approximately 70% of lower-grade gliomas harbor isocitrate dehydrogenase 1 (IDH1) mutations, resulting in the accumulation of oncometabolite D-2-hydroxyglutarate (D-2-HG); this leads to epigenetic dysregulation, oncogenesis, and subsequent clonal expansion. DS-1001 is an oral brain-penetrant mutant IDH1 selective inhibitor. This first-in-human study investigated the safety, pharmacokinetics, pharmacodynamics, and efficacy of DS-1001.

METHODS

This was a multicenter, open-label, dose-escalation, phase I study of DS-1001 for recurrent/progressive IDH1-mutant (R132) glioma (N = 47) (NCT03030066). DS-1001 was administered orally at 125-1400 mg twice daily. Dose-escalation used a modified continual reassessment method.

RESULTS

The maximum tolerated dose was not reached. Eight patients were continuing treatment at the data cutoff. Most adverse events (AEs) were grade 1-2. Twenty patients (42.6%) experienced at least 1 grade 3 AE. No grade 4 or 5 AEs or serious drug-related AEs were reported. Common AEs (>20%) were skin hyperpigmentation, diarrhea, pruritus, alopecia, arthralgia, nausea, headache, rash, and dry skin. The objective response rates were 17.1% for enhancing tumors and 33.3% for non-enhancing tumors. Median progression-free survival was 10.4 months (95% confidence interval [CI], 6.1 to 17.7 months) and not reached (95% CI, 24.1 to not reached) for the enhancing and non-enhancing glioma cohorts, respectively. Seven on-treatment brain tumor samples showed a significantly lower amount of D-2-HG compared with pre-study archived samples.

CONCLUSIONS

DS-1001 was well tolerated with a favorable brain distribution. Recurrent/progressive IDH1-mutant glioma patients responded to treatment. A study of DS-1001 in patients with chemotherapy- and radiotherapy-naïve IDH1-mutated WHO grade 2 glioma is ongoing (NCT04458272).

Quantitative relaxometry using synthetic MRI could be better than T2-FLAIR mismatch sign for differentiation of IDH-mutant gliomas: a pilot study

This study aimed to determine whether quantitative relaxometry using synthetic magnetic resonance imaging (SyMRI) could differentiate between two diffuse glioma groups with isocitrate dehydrogenase (IDH)-mutant tumors, achieving an increased sensitivity compared to the qualitative T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign. Between May 2019 and May 2020, thirteen patients with IDH-mutant diffuse gliomas, including seven with astrocytomas and six with oligodendrogliomas, were evaluated. Five neuroradiologists independently evaluated the presence of the qualitative T2-FLAIR mismatch sign. Interrater agreement on the presence of the T2-FLAIR mismatch sign was calculated using the Fleiss kappa coefficient. SyMRI parameters (T1 and T2 relaxation times and proton density) were measured in the gliomas and compared by the Mann-Whitney U test. Receiver operating characteristic curve analysis was used to evaluate the diagnostic performance. The sensitivity, specificity, and kappa coefficient were 57.1%, 100%, and 0.60, respectively, for the qualitative T2-FLAIR mismatch sign. The two types of diffuse gliomas could be differentiated using a cutoff value of 178 ms for the T2 relaxation time parameter with 100% sensitivity, specificity, accuracy, and positive and negative predictive values, with an area under the curve (AUC) of 1.00. Quantitative relaxometry using SyMRI could differentiate astrocytomas from oligodendrogliomas, achieving an increased sensitivity and objectivity compared to the qualitative T2-FLAIR mismatch sign.

Gamma distribution model of diffusion MRI for evaluating the isocitrate dehydrogenase mutation status of glioblastomas

OBJECTIVE

To determine whether the γ distribution (GD) model of diffusion MRI is useful in the evaluation of the isocitrate dehydrogenase (IDH) mutation status of glioblastomas.

METHODS

12 patients with IDH-mutant glioblastomas and 54 patients with IDH-wildtype glioblastomas were imaged with diffusion-weighted imaging using 13 b-values from 0 to 1000 s/mm2. The shape parameter (κ) and scale parameter (θ) were obtained with the GD model. Fractions of three different areas under the probability density function curve (f1, f2, f3) were defined as follows: f1, diffusion coefficient (D) < 1.0×10-3 mm2/s; f2, D > 1.0×10-3 and <3.0×10-3 mm2/s; f3, D > 3.0 × 10-3 mm2/s. The GD model-derived parameters measured in gadolinium-enhancing lesions were compared between the IDH-mutant and IDH-wildtype groups. Receiver operating curve analyses were performed to assess the parameters' diagnostic performances.

RESULTS

The IDH-mutant group's f1 (0.474  ±  0.143) was significantly larger than the IDH-wildtype group's (0.347  ±  0.122, p = 0.0024). The IDH-mutant group's f2 (0.417  ±  0.131) was significantly smaller than the IDH-wildtype group's (0.504  ±  0.126, p = 0.036). The IDH-mutant group's f3 (0.109  ±  0.060) was significantly smaller than the IDH-wildtype group's (0.149  ±  0.063, p = 0.0466). The f1 showed the best diagnostic performance among the GD model-derived parameters with the area under the curve value of 0.753.

CONCLUSION

The GD model could well describe the pathological features of IDH-mutant and IDH-wildtype glioblastomas, and was useful in the differentiation of these tumors.

ADVANCES IN KNOWLEDGE

Diffusion MRI based on the γ distribution model could well describe the pathological features of IDH-mutant and IDH-wildtype glioblastomas, and its use enabled the significant differentiation of these tumors. The γ distribution model may contribute to the non-invasive identification of the IDH mutation status based on histological viewpoint.

Prognostic impact of PDGFRA gain/amplification and MGMT promoter methylation status in patients with IDH wild-type glioblastoma

Background

Platelet-derived growth factor receptor alpha (PDGFRA) is the second most frequently mutated tyrosine kinase receptor in glioblastoma (GBM). However, the prognostic impact of PDGFRA amplification on GBM patients remains unclear. Herein, we evaluated this impact by retrospectively analyzing outcomes of patients with IDH wild-type GBM.

Methods

Using a custom-made oncopanel, we evaluated PDGFRA gain/amplification in 107 GBM samples harboring wild-type IDH, along with MGMT promoter (MGMTp) methylation status.

Results

We detected PDGFRA gain/amplification in 31 samples (29.0%). PDGFRA gain/amplification predicted poor prognosis (P = .003). Compared to unamplified PDGFRA, PDGFRA gain/amplification in GBM was associated with higher patient age (P = .031), higher Ki-67 score (P = .019), and lower extent of surgical resection (P = .033). Unmethylated MGMTp also predicted poor prognosis (P = .005). As PDGFRA gain/amplification and unmethylated MGMTp were independent factors for poor prognosis in multivariate analyses, we grouped GBM cases based on PDGFRA and MGMTp status: poor (PDGFRA gain/amplification and unmethylated MGMTp), intermediate (PDGFRA gain/amplification or unmethylated MGMTp), and good (PDGFRA intact and methylated MGMTp) prognosis. The Kaplan-Meier survival analysis indicated that these groups significantly correlated with the OS of GBM patients (P < .001).

Conclusions

Here we report that PDGFRA gain/amplification is a predictor of poor prognosis in IDH wild-type GBM. Combining PDGFRA gain/amplification with MGMTp methylation status improves individual prognosis prediction in patients with IDH wild-type GBM.

Changes in the Relapse Pattern and Prognosis of Glioblastoma After Approval of First-Line Bevacizumab: A Single-Center Retrospective Study

BACKGROUND

Controversies exist regarding the aggressive recurrence of glioblastoma after bevacizumab treatment. We analyzed the clinical impact of bevacizumab approval in Japan by evaluating the clinical course and relapse pattern in patients with glioblastoma.

METHODS

We included 100 patients with IDH-wildtype glioblastoma from September 2006 to February 2018 in our institution. The patients were classified into pre-bevacizumab (n = 51) and post-bevacizumab (n = 49) groups. Overall, progression-free, deterioration-free, and post-progression survivals were compared. We analyzed the relapse pattern of 72 patients, whose radiographic progressions were evaluated.

RESULTS

Significant improvement in progression-free (pre-bevacizumab, 7.5 months; post-bevacizumab, 9.9 months; P = 0.0153) and deterioration-free (pre-bevacizumab, 8.5 months; post-bevacizumab, 13.8 months; P = 0.0046) survivals were seen. These survival prolongations were strongly correlated (r: 0.91, P < 0.0001). The non-enhancing tumor pattern was novel in the post-bevacizumab era (5/33). The presence of a non-enhancing tumor did not indicate poor post-progression survival (hazard ratio: 0.82 [0.26-2.62], P = 0.7377). The rate of early focal recurrence was significantly lower (P = 0.0155) in the post-bevacizumab (4/33) than in the pre-bevacizumab (18/39) era. There was a significant decrease in early focal recurrence after approval of bevacizumab in patients with unresectable tumors (P = 0.0110). The treatment era was significantly correlated with a decreased rate of early focal recurrence (P = 0.0021, univariate analysis; P = 0.0144, multivariate analysis).

CONCLUSIONS

Approval of first-line bevacizumab in Japan for unresectable tumors may prevent early progression and clinical deterioration of glioblastoma without worsening the clinical course following relapse.

Efficacy and safety of nivolumab in Japanese patients with first recurrence of glioblastoma: an open-label, non-comparative study

BACKGROUND

An open-label, non-comparative study assessed the efficacy and safety of nivolumab in Japanese patients with first recurrence glioblastoma.

METHODS

Patients with first recurrence of histologically confirmed World Health Organization Grade IV glioma, after treatment with temozolomide and radiotherapy, received nivolumab 3 mg/kg every 2 weeks until confirmed disease progression (Response Assessment in Neuro-Oncology criteria) or toxicity. Primary endpoint was 1-year overall survival rate assessed by Bayesian approach. The prespecified efficacy criterion was that the Bayesian posterior probability threshold for exceeding the 1-year overall survival of bevacizumab (34.5%) from the Japanese phase 2 study (JO22506) would be 93%.

RESULTS

Of the 50 enrolled patients, 44 (88.0%) had recurrent malignant glioma (glioblastoma, gliosarcoma), and of these, 26 (59.1%) had at least one measurable lesion at baseline. The Bayesian posterior mean 1-year overall survival (90% Bayesian credible intervals) with nivolumab was 54.4% (42.27-66.21), and the Bayesian posterior probability of exceeding the threshold of the 1-year overall survival rate of bevacizumab (34.5%) was 99.7%. Median (90% confidence interval) overall and progression-free survival was 13.1 (10.4-17.7) and 1.5 (1.4-1.5) months, respectively. One partial response was observed (objective response rate 1/26 evaluable patients [3.8%]). Treatment-related adverse event rates were 14.0% for Grade 3-4 and 2.0% for Grade 5; most adverse events resolved and were manageable.

CONCLUSIONS

The 1-year overall survival with nivolumab monotherapy in Japanese patients with glioblastoma met the prespecified efficacy criterion. The safety profile of nivolumab was consistent with that observed in other tumor types.

CLINICAL TRIAL REGISTRATION

JapicCTI-152967.

Acute-phase electroencephalography for an infantile atypical teratoid/rhabdoid tumor

BACKGROUND

Primary brain tumor is a leading cause of death in cancer-bearing children. Acutely progressive patterns of electroencephalography (EEG) remain to be investigated for children with rapidly growing brain tumors.

CASE REPORT

A 14-month-old boy was transferred to our department for prolonged seizures and unrecovered consciousness on his fifth day of illness. The EEG recording on admission showed highly disorganized background activity with high-voltage rhythmic delta waves. Serial EEG monitoring revealed a rapid transition of the background activity to the suppression-burst pattern, and then to generalized suppression of cortical activity within a few hours after admission. Magnetic resonance imaging detected a midline tumor at the pineal gland extending to the midbrain and pons. The tumor was pathologically confirmed as atypical teratoid/rhabdoid tumor (AT/RT) with absent expression of SMARCB1. He died of tumor progression on the 20th day after admission.

CONCLUSION

AT/RT is an additional category of brain tumors that cause the clinically and electro-physiologically critical condition in a few days after the onset.

Intraventricular mucin-producing glioblastoma arising in the septum pellucidum at the frontal horn of the lateral ventricle: A case report

Glioblastoma (GBM) most commonly appears to be intraparenchymal tumor, and intraventricular GBMs are rarely reported. In previous reports, the sites of origin were not identified. Here, we report a rare case of intraventricular mucin-producing GBM in a 73-year-old woman who had a strongly enhancing tumor in the right anterior horn of the lateral ventricle. The tumor had previously been identified one and a half years ago as a small asymptomatic lesion attached to the septum pellucidum. It had been documented to gradually enlarge during subsequent follow-up examinations. The patient underwent a gross total resection of the tumor, and a soft and gelatinous mass was observed. The pathological diagnosis was compatible with GBM, and numerous tumor cells having cytoplasmic mucin vacuoles were observed. Genetic analysis revealed TP53 and NFKBIA deletions. The patient received postoperative concurrent chemotherapy with temozolomide and radiotherapy, followed by maintenance administration of temozolomide. A follow-up examination seven months later detected an asymptomatic local recurrent lesion, which was treated with gamma-knife therapy, followed by bevacizumab administration for six months. The patient has remained clinically well for five years following surgery. The origin of a rare tumor entity, intraventricular GBM, and the specific spatial and pathological findings in our case are discussed in this report.

Clinical implications of molecular analysis in diffuse glioma stratification

The revised 4th edition of the 2016 World Health Organization Classification of Tumors of the Central Nervous System (2016 CNS WHO) has introduced the integrated diagnostic classification that combines molecular and histological diagnoses for diffuse gliomas. In this study, we evaluated the molecular alterations for consecutive 300 diffuse glioma cases (grade 2, 56; grade 3, 62; grade 4, 182) based on this classification. Mutations in the isocitrate dehydrogenase (IDH) genes were common in lower grade glioma (LGG: grade2-3), and when combined with 1p/19q status, LGGs could be stratified into three groups except for four cases (Astrocytoma, IDH-mutant: 44; Oligodendroglioma, IDH-mutant and 1p/19q codeleted: 37; Astrocytoma, IDH-wildtype: 33). 1p/19q-codeleted oligodendrogliomas were clinically the most favorable subgroup even with upfront chemotherapy. In contrast, IDH-wildtype astrocytomas had a relatively worse prognosis; however, this subgroup was more heterogeneous. Of this subgroup, 11 cases had TERT promoter (pTERT) mutation with shorter overall survival than 12 pTERT-wildtype cases. Additionally, a longitudinal analysis indicated pTERT mutation as early molecular event for gliomagenesis. Therefore, pTERT mutation is critical for the diagnosis of molecular glioblastoma (WHO grade 4), regardless of histological findings, and future treatment strategy should be considered based on the precise molecular analysis.

CD206 Expression in Induced Microglia-Like Cells From Peripheral Blood as a Surrogate Biomarker for the Specific Immune Microenvironment of Neurosurgical Diseases Including Glioma

Targeting the unique glioma immune microenvironment is a promising approach in developing breakthrough immunotherapy treatments. However, recent advances in immunotherapy, including the development of immune checkpoint inhibitors, have not improved the outcomes of patients with glioma. A way of monitoring biological activity of immune cells in neural tissues affected by glioma should be developed to address this lack of sensitivity to immunotherapy. Thus, in this study, we sought to examine the feasibility of non-invasive monitoring of glioma-associated microglia/macrophages (GAM) by utilizing our previously developed induced microglia-like (iMG) cells. Primary microglia (pMG) were isolated from surgically obtained brain tissues of 22 patients with neurological diseases. iMG cells were produced from monocytes extracted from the patients’ peripheral blood. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed a significant correlation of the expression levels of representative markers for M1 and M2 microglia phenotypes between pMG and the corresponding iMG cells in each patient (Spearman’s correlation coefficient = 0.5225, P <0.0001). Synchronous upregulation of CD206 expression levels was observed in most patients with glioma (6/9, 66.7%) and almost all patients with glioblastoma (4/5, 80%). Therefore, iMG cells can be used as a minimally invasive tool for monitoring the disease-related immunological state of GAM in various brain diseases, including glioma. CD206 upregulation detected in iMG cells can be used as a surrogate biomarker of glioma.

Current trend in treatment of glioblastoma in Japan: a national survey using the diagnostic procedure combination database (J-ASPECT study-glioblastoma)

Background

In the treatment for glioblastoma (GBM), treatment modalities, such as bevacizumab (BEV) and carmustine wafers implants have been approved in Japan since 2013. However, it is unclear whether such a trend in treatment complexity can accelerate treatment centralization. The aim of this study was to reveal the current trend in the treatment of GBM in Japan.

Methods

We used diagnostic procedure combination (DPC) database to analyze the data of 1,774 patients from 305 institutions between April 2016 and March 2019. To analyze the situations associated with first-line BEV use during concurrent TMZ (temozolomide)-radiotherapy, we compared TMZ alone and TMZ–BEV groups.

Results

Of the 1,774 patients with GBM, tumor removal by craniotomy was performed in 1,572 (88.6%) patients, and stereotactic biopsy was performed in 156 (8.8%) patients. A total of 1,229 (69.3%) patients underwent radiotherapy, and 1,287 (72.5%) patients underwent chemotherapy. TMZ alone was administered to 878 (68.2%) and TMZ combined with BEV in 381 (29.6%) patients. In the TMZ–BEV group, as compared to the TMZ-alone group, the rate of discharge to home was significantly lower (P = 0.0044), and the rate of stereotactic biopsy was significantly higher (P < 0.0001). No significant difference was observed in the distribution of patients between the TMZ alone and TMZ–BEV groups depending on the scale of institution (P = 0.1240).

Conclusion

First-line BEV administration seems to be selected properly regardless of the institutional scale. This Japan-wide study of GBM treatment revealed that high level and newly introduced treatments have been steadily generalized in Japanese institutions.

Clinical significance of CDKN2A homozygous deletion in combination with methylated MGMT status for IDH-wildtype glioblastoma

OBJECTIVE

Accumulating evidence from recent molecular diagnostic studies has indicated the prognostic significance of various genetic markers for patients with glioblastoma (GBM). To evaluate the impact of such genetic markers on prognosis, we retrospectively analyzed the outcomes of patients with IDH-wildtype GBM in our institution. In addition, to assess the impact of bevacizumab (BEV) treatment, we compared overall survival (OS) between the pre- and post-BEV eras.

METHODS

We analyzed the data of 100 adult patients (over 18 years old) with IDH-wildtype GBM from our database between February 2006 and October 2018. Genetic markers, such as MGMT methylation status, EGFR amplification, CDKN2A homozygous deletion, and clinical factors were analyzed by evaluating the patients' OS.

RESULTS

CDKN2A homozygous deletion showed no significant impact on OS in patients with methylated MGMT status (p = 0.5268), whereas among patients with unmethylated MGMT status, there was a significant difference in OS between patients with and without CDKN2A homozygous deletion (median OS: 14.7 and 16.9 months, respectively, p = 0.0129). This difference was more evident in the pre-BEV era (median OS: 10.1 and 15.6 months, respectively, p = 0.0351) but has become nonsignificant in the post-BEV era (median OS: 16.0 and 16.9 months, respectively, p = 0.1010) due to OS improvement in patients with CDKN2A homozygous deletion. However, these findings could not be validated in The Cancer Genome Atlas cohort.

CONCLUSIONS

MGMT and CDKN2A status subdivided our cohort into three race-specific groups with different prognoses. Our findings indicate that BEV approval in Japan led to OS improvement exclusively for patients with concurrent unmethylated MGMT status and CDKN2A homozygous deletion.

Molecular diagnosis of diffuse glioma using a chip-based digital PCR system to analyze IDH, TERT, and H3 mutations in the cerebrospinal fluid

PURPOSE

Conventional genetic analyzers require surgically obtained tumor tissues to confirm the molecular diagnosis of diffuse glioma. Recent technical breakthroughs have enabled increased utilization of cell-free tumor DNA (ctDNA) in body fluids as a reliable resource for molecular diagnosis in various cancers. Here, we tested the application of a chip-based digital PCR system for the less invasive diagnosis (i.e., liquid biopsy) of diffuse glioma using the cerebrospinal fluid (CSF).

METHODS

CSF samples from 34 patients with diffuse glioma were collected from the surgical field during craniotomy. Preoperative lumbar CSF collection was also performed in 11 patients. Extracted ctDNA was used to analyze diagnostic point mutations in IDH1 R132H, TERT promoter (C228T and C250T), and H3F3A (K27M) on the QuantStudio^® 3D Digital PCR System. These results were compared with their corresponding tumor DNA samples.

RESULTS

We detected either of the diagnostic mutations in tumor DNA samples from 28 of 34 patients. Among them, we achieved precise molecular diagnoses using intracranial CSF in 20 (71%). Univariate analyses revealed that the World Health Organization (WHO) grade (p = 0.0034), radiographic enhancement (p = 0.0006), and Mib1 index (p = 0.01) were significant predictors of precise CSF-based molecular diagnosis. We precisely diagnosed WHO grade III or IV diffuse gliomas using lumbar CSF obtained from 6 (87%) of 7 patients with tumors harboring any mutation.

CONCLUSION

We established a novel, non-invasive molecular diagnostic method using a chip-based digital PCR system targeting ctDNA derived from CSF with high sensitivity and specificity, especially for high-grade gliomas.

Mesenchymal glioblastoma-induced mature de-novo vessel formation of vascular endothelial cells in a microfluidic device

High vascularization is a biological characteristic of glioblastoma (GBM); however, an in-vitro experimental model to verify the mechanism and physiological role of vasculogenesis in GBM is not well-established. Recently, we established a self-organizing vasculogenic model using human umbilical vein endothelial cells (HUVECs) co-cultivated with human lung fibroblasts (hLFs). Here, we exploited this system to establish a realistic model of vasculogenesis in GBM. We developed two polydimethylsiloxane (PDMS) devices, a doughnut-hole dish and a 5-lane microfluidic device to observe the contact-independent effects of glioblastoma cells on HUVECs. We tested five patient-derived and five widely used GBM cell lines. Confocal fluorescence microscopy was used to observe the morphological changes in Red Fluorescent Protein (RFP)-HUVECs and fluorescein isothiocyanate (FITC)-dextran perfusion. The genetic and expression properties of GBM cell lines were analyzed. The doughnut-hole dish assay revealed KNS1451 as the only cells to induce HUVEC transformation to vessel-like structures, similar to hLFs. The 5-lane device assay demonstrated that KNS1451 promoted the formation of a vascular network that was fully perfused, revealing the functioning luminal construction. Microarray analysis revealed that KNS1451 is a mesenchymal subtype of GBM. Using a patient-derived mesenchymal GBM cell line, mature de-novo vessel formation could be induced in HUVECs by contact-independent co-culture with GBM in a microfluidic device. These results support the development of a novel in vitro research model and provide novel insights in the neovasculogenic mechanism of GBM and may potentially facilitate the future detection of unknown molecular targets.

Update on Chemotherapeutic Approaches and Management of Bevacizumab Usage for Glioblastoma

Glioblastoma, the most common primary brain tumor in adults, has one of the most dismal prognoses in cancer. In 2009, bevacizumab was approved for recurrent glioblastoma in the USA. To evaluate the clinical impact of bevacizumab as a first-line drug for glioblastoma, two randomized clinical trials, AVAglio and RTOG 0825, were performed. Bevacizumab was found to improve progression-free survival (PFS) and was reported to be beneficial for maintaining patient performance status as an initial treatment. These outcomes led to bevacizumab approval in Japan in 2013 as an insurance-covered first-line drug for glioblastoma concurrently with its second-line application. However, prolongation of overall survival was not evinced in these clinical trials; hence, the clinical benefit of bevacizumab for newly diagnosed glioblastomas remains controversial. A recent meta-analysis of randomized controlled trials of bevacizumab combined with temozolomide in recurrent glioblastoma also showed an effect only on PFS, and the benefit of bevacizumab even for recurrent glioblastoma is controversial. Here, we discuss the clinical impact of bevacizumab for glioblastoma treatment by reviewing previous clinical trials and real-world evidence by focusing on Japanese experiences. Moreover, the efficacy and safety of bevacizumab are summarized, and we provide suggestions for updating the approaches and management of bevacizumab.

Gamma distribution model of diffusion MRI for the differentiation of primary central nerve system lymphomas and glioblastomas

The preoperative imaging-based differentiation of primary central nervous system lymphomas (PCNSLs) and glioblastomas (GBs) is of high importance since the therapeutic strategies differ substantially between these tumors. In this study, we investigate whether the gamma distribution (GD) model is useful in this differentiation of PNCSLs and GBs. Twenty-seven patients with PCNSLs and 57 patients with GBs were imaged with diffusion-weighted imaging using 13 b-values ranging from 0 to 1000 sec/mm2. The shape parameter (κ) and scale parameter (θ) were obtained with the GD model. Fractions of three different areas under the probability density function curve (f1, f2, f3) were defined as follows: f1, diffusion coefficient (D) <1.0×10-3 mm2/sec; f2, D >1.0×10-3 and <3.0×10-3 mm2/sec; f3, D >3.0 × 10-3 mm2/sec. The GD model-derived parameters were compared between PCNSLs and GBs. Receiver operating characteristic (ROC) curve analyses were performed to assess diagnostic performance. The correlations with intravoxel incoherent motion (IVIM)-derived parameters were evaluated. The PCNSL group's κ (2.26 ± 1.00) was significantly smaller than the GB group's (3.62 ± 2.01, p = 0.0004). The PCNSL group's f1 (0.542 ± 0.107) was significantly larger than the GB group's (0.348 ± 0.132, p<0.0001). The PCNSL group's f2 (0.372 ± 0.098) was significantly smaller than the GB group's (0.508 ± 0.127, p<0.0001). The PCNSL group's f3 (0.086 ± 0.043) was significantly smaller than the GB group's (0.144 ± 0.062, p<0.0001). The combination of κ, f1, and f3 showed excellent diagnostic performance (area under the curve, 0.909). The f1 had an almost perfect inverse correlation with D. The f2 and f3 had very strong positive correlations with D and f, respectively. The GD model is useful for the differentiation of GBs and PCNSLs.

LGG-20. CLINICAL FEATURES AND TREATMENT RESULTS FOR PEDIATRIC OPTICO-HYPOTHALAMIC ASTROCYTOMA

Current consensus for the treatment of optico-hypothalamic astrocytoma (OHA) is a chemotherapy-first policy, limiting the role of surgery for histopathological diagnosis and partial decompression. However, a subgroup of OHA patients show resistance to chemotherapy and have a worse prognosis. In this study, we retrospectively analyzed our clinical experiences of the treatment of patients with OHA in two university hospitals. We have extracted and analyzed the medical charts of 15 pediatric OHA patients treated in two university hospitals since 1990. NF-1-associated OHA patients were excluded. Patient ages ranged from 10 months to 21 years (median 7 years). Out of 15 cases, 12 patients had a tumor larger than 3 cm and classified as Dodge 3. The final histopathological diagnosis was pilocytic astrocytoma in 13 cases. Three patients with tumors classified as Dodge 1 or 2 show good prognosis only by biopsy or partial resection. However, regarding Dodge 3 tumor, patient prognosis is worse regardless of chemotherapy and radiotherapy. After the initial surgery, chemotherapy was administered in 11 cases and radiotherapy in 5 cases. Multiple surgeries are needed for tumor control in 7 patients. Four patients died of tumor progression or treatment-associated complications. When the initial tumor is large enough to cause neurological deterioration, a chemotherapeutic tumor suppressive effect might be limited in a subset of large OHA cases. Therefore, it is important to consider the proper timing of safe surgical decompression in the early phase when a large tumor does not respond to chemotherapy.

IMMU-09. NIVOLUMAB THERAPY FOR A PEDIATRIC-ONSET PRIMARY INTRACRANIAL MELANOMA

Primary intracranial malignant melanoma (PIMM) is an uncommon cancer in childhood, that accounts for approximately 1% of melanoma, and 0.07% of brain tumors even in all age group. Because extracranial malignant melanoma usually occurs as a cutaneous lesion, affected patients have a chance to receive the early diagnosis and curable resection of the isolated tumor. However, unresectable metastatic cases have a poor prognosis with a median overall survival of 8 months. We report a 12-year-old girl with PIMM who received nivolumab therapy after an administration of dacarbazine. The tumor harbored no BRAF mutation. After the intravenous administration of nivolumab, cerebrospinal fluid 5-S-cysteinyldopa levels declined and circulating CD8⁺HLA-DR⁺T cells increased, indicating the initial effect of nivolumab on PIMM. However, multiple lesions progressed for two month-immunotherapy, during which cerebrospinal fluid nivolumab concentrations attained to 1.2% of serum ones. The present case demonstrated the safety and modest effect of nivolumab for CNS melanoma. Nivolumab is a tolerable first-line therapy for diffuse PIMM, but pediatric patients need a more intensified CNS-specific immunotherapy.

TBIO-08. BASE-RESOLUTION METHYLOMES OF GLIOMAS BEARING HISTONE H3.3 MUTATIONS REVEAL A G34 MUTANT-SPECIFIC SIGNATURE SHARED WITH BONE TUMORS

BACKGROUND

Two recurrent mutations, K27M and G34R/V, in H3F3A, encoding non-canonical histone H3.3, are reported in pediatric and young adult gliomas, whereas G34W mutation was prevalent in bone tumors. In contrast to K27 mutation, it remains elusive how G34 mutations affect the epigenome. Here we performed whole-genome bisulfite sequencing of four G34R-mutated gliomas and the G34V-mutated glioma cell line KNS-42. Similarly, we analyzed seven and three gliomas harboring K27M and no mutations in H3F3A, respectively. These data were compared with those on bone tumors.

RESULTS

G34R-mutated gliomas exhibited lower global methylation levels, similar CpG island (CGI) methylation levels, and compromised hypermethylation of telomere-proximal CGIs compared with those bearing K27M and no mutations. Hypermethylated regions specific to G34R-mutated gliomas were enriched for CGIs, including those of OLIG1, OLIG2, and canonical histone genes in the HIST1 cluster. These CGIs were hypermethylated in osteosarcomas with, but not without, the G34W mutation. In KNS-42 cells, CGIs with G34V-mutated histone H3.3 exhibited higher methylation levels than those with wild-type histone H3.3. This effect was also observed in the G34R-mutated glioma samples.

CONCLUSIONS

Gliomas bearing G34R/V mutations display characteristic methylomic alterations, some of which are shared by osteosarcomas with the G34W mutation. Deposition of G34 variants may lead to elevated methylation of otherwise hypomethylated, histone H3.3-bearing CGIs.

HGG-24. HIGH-GRADE GLIOMA WITH A NOVEL FUSION GENE OF VCL-ALK

A previously healthy 2-year-old boy presented with status epilepticus following intermittent vomiting. Computed tomography scan showed a 7cm mass on the left occipital lobe with midline shift, inferior cerebellar herniation, and diffuse cerebral edema. The extensive dissemination to bilateral cerebral hemispheres, brain stem, and optic nerve was also observed. He underwent brain biopsy from the lesion on his left occipital lobe. The histopathological diagnosis determined the diffuse or epithelial proliferation of astrocytic tumor cells with high mitotic rate, positive for p53 and glial fibrillary acidic protein positive staining consistent with high-grade glioma. The progressive tumor led to communicating hydrocephalus, that was favorably controlled by cerebrospinal fluid shunting. The data from the FoundationOne CDx cancer genome profile disclosed a novel VCL- anaplastic lymphoma kinase (ALK) fusion in the tumor cells of the patient. ALK rearrangement was determined to be positive for the tumor cells assessed by fluorescence in situ hybridization. Only 4 pediatric cases of glioma with ALK-rearrangement have ever been reported. All of them received subtotal or gross total resections and then survived with or without chemotherapy. This is the first case of glioma harboring VCL as a novel partner of ALK fusion gene. After the favorable response to the first-line chemotherapy, subsequent irradiation therapy has now been scheduled. The molecular classification of high-grade glioma may help to expand the targeted therapy for unresectable advanced brain tumor.

ACT-02 Changes in Recurrence Pattern and Prognosis of Glioblastoma after Approval of Bevacizumab as First-line Application

Introduction: There exist controversies on recurrence and aggressiveness after use of first-line bevacizumab (BEV) which has been approved in Japan and proven to be beneficial. Therefore, we analyzed the clinical impact of BEV approval by investigating the overall clinical course and glioblastoma (GBM) relapse pattern.

Methods: We included 100 patients with IDH-wildtype GBM between September 2006 and February 2018 from our institution. They were subdivided into pre-BEV (n=51) and post-BEV (n=49) groups. Overall, progression-free, deterioration-free, and post-progression survivals (OS, PFS, DFS, and PPS, respectively) were compared. We analyzed the relapse pattern of 72 patients, whose radiographic progressions were confirmed.

Results: Significant improvements in DFS (median DFS in the pre-BEV and post-BEV eras: 8.5 and 13.8 months, P=0.0046), and PFS (7.5 and 9.9 months, P=0.0153) after BEV approval were observed. These survival prolongations were strongly correlated (r: 0.91, P<0.0001). Non-enhancing tumor emerged as a novel recurrence pattern in the post-BEV era (five of 33; 15.2%). Changes in relapse pattern did not significantly impact OS, PFS, and DFS. No significant difference in PPS between pre-BEV and post-BEV eras was observed (6.7 and 5.5 months, P=0.2319). The rate of early (within 6 months) focal recurrence was significantly lower (P=0.0155) in the post-BEV era (four of 33; 12.1%) than in the pre-BEV era (18 of 39; 46.2%). A significant decrease in early focal recurrence after BEV approval was observed exclusively in patients with unresectable tumors (P=0.0110). Treatment era was the only parameter significantly correlated with decreased early focal recurrence rate (P=0.0021, univariate analysis; P=0.0144, multivariate analysis).

Conclusions: We found that, first-line BEV in Japan for unresectable tumors has a positive impact on the prevention of early progression and clinical deterioration of GBM without accelerating the clinical course after recurrence.

IM-03 CD206 expression in peripheral blood-derived induced-microglia-like cells as a surrogate biomarker for the specific immune microenvironment of glioma

INTRODUCTION: As recent advancement of multimodal treatments including immune-check point inhibitors have not led to massive outcome improvement of glioma. Targeting the peculiar immune microenvironment of glioma is a promising approach to innovate a breakthrough treatment, however, there remains to be technical and ethical burdens for monitoring the bioactivities of immune cells in neural tissues. Herein, we examined the feasibility of non-invasive monitoring of glioma-associated microglia/macrophages (GAM) properties through utilization of our originally developed induced-microglia-like (iMG) cells technique. METHODS: We isolated primary microglia (pMG) from surgically-obtained brain tissues of 15 patients with neurosurgical diseases. We induced iMG cells from monocyte extracted from their corresponding peripheral blood by MACS treatment. Expression profiles of representative markers for an M1 and M2 microglia phenotype were analyzed in both pMG and iMG cells by qPCR. RESULTS: q-PCR revealed that a significant correlation of expression level of microglial markers between pMG and the corresponding iMG in each patient. Synchronous upregulations of CD206 were exclusively detected in patients with glioma. CONCLUSION: The present study suggested that iMG cells can be a less-invasive monitor tool for disease-related bioactivity of microglia, thereby seem to be utilized as an intermedium for investigation of relationship between microglia and neuronal diseases including glioma. CD206 upregulation detected by iMG technique can surrogate the specific microenvironment of glioma surrounding tissues and might be utilized as a future biomarker of glioma.

MPC-06 Cutting-edge of Cancer Genomic Medicine for brain tumors

Kyushu University Hospital was designated a Cancer Genome Core Hospital in April 2018, and the multi-gene panel test has been introduced since August 2019. The expert panel has been held for 21 cases of the central nervous system (11 adult glioma, 5 pediatric brain tumors, 5 extramedullary tumors). Actionable gene abnormalities were newly detected in two cases. First case is epithelioid glioblastoma with BRAF V600E mutation, and second is embryonal tumor with VCL-ALK fusion. For the first case, BRAF/MEK inhibitor can be used by the prospective trial of patient-proposed healthcare services with multiple targeted agent based on the result of gene profiling by multigene panel test (NCCH1901). For the second case, we are planning to introduce ALK inhibitor by indicator-initiated clinical trial while continuing ICE therapy. The current approved agents for tumor-agnostic treatment are immune checkpoint inhibitors for mismatch repair deficient (dMMR) cases and TRK inhibitors for NTRK fusion gene-positive cases. We selected microsatellite instability (MSI) test and immunostaining of MMR gene for the indication of immune checkpoint inhibitor for recurrent glioma and Lynch syndrome that require dMMR evaluation, but FoundationOne CDx (F1CDx) allows simultaneous evaluation of MSI and MMR gene abnormalities. Regarding the indication of TRK inhibitors, F1CDx assay is selected as a companion diagnosis for ALK, NTRK1/2/3 fusion gene analysis for pediatric cases. At present, the actionable gene abnormalities are detected by multi-gene panel tests in about 10% of brain tumors. Development of tumor-agnostic treatment will expand the molecular target therapy for brain tumor in the future. Based on the experience of different schemes for molecular targeted therapy, it became clear that it is necessary to establish a cancer genome medical system for prompt introduction of precision medicine for highly malignant brain tumors.

TERT promoter mutation confers favorable prognosis regardless of 1p/19q status in adult diffuse gliomas with IDH1/2 mutations

TERT promoter mutations are commonly associated with 1p/19q codeletion in IDH-mutated gliomas. However, whether these mutations have an impact on patient survival independent of 1p/19q codeletion is unknown. In this study, we investigated the impact of TERT promoter mutations on survival in IDH-mutated glioma cases. Detailed clinical information and molecular status data were collected for a cohort of 560 adult patients with IDH-mutated gliomas. Among these patients, 279 had both TERT promoter mutation and 1p/19q codeletion, while 30 had either TERT promoter mutation (n = 24) or 1p/19q codeletion (n = 6) alone. A univariable Cox proportional hazard analysis for survival using clinical and genetic factors indicated that a Karnofsky performance status score (KPS) of 90 or 100, WHO grade II or III, TERT promoter mutation, 1p/19q codeletion, radiation therapy, and extent of resection (90-100%) were associated with favorable prognosis (p < 0.05). A multivariable Cox regression model revealed that TERT promoter mutation had a significantly favorable prognostic impact (hazard ratio = 0.421, p = 0.049), while 1p/19q codeletion did not have a significant impact (hazard ratio = 0.648, p = 0.349). Analyses incorporating patient clinical and genetic information were further conducted to identify subgroups showing the favorable prognostic impact of TERT promoter mutation. Among the grade II-III glioma patients with a KPS score of 90 or 100, those with IDH-TERT co-mutation and intact 1p/19q (n = 17) showed significantly longer survival than those with IDH mutation, wild-type TERT, and intact 1p/19q (n = 185) (5-year overall survival, 94% and 77%, respectively; p = 0.032). Our results demonstrate that TERT promoter mutation predicts favorable prognosis independent of 1p/19q codeletion in IDH-mutated gliomas. Combined with its adverse effect on survival among IDH-wild glioma cases, the bivalent prognostic impact of TERT promoter mutation may help further refine the molecular diagnosis and prognostication of diffuse gliomas.

NIMG-29. DEVELOPING AUTOMATIC SEGMENTATION METHOD FOR BRAIN TUMOR MR IMAGES THAT CAN BE USED AT MULTIPLE FACILITIES

BACKGROUND

Manual segmentation of brain tumor images from a large volume of MR images generated in clinical routines is difficult and time-consuming. Hence, it is imperative to develop a machine learning model for automated segmentation of brain tumor images.

PURPOSE

Machine learning models for automated MR image segmentation of gliomas may be useful. However, the image differences among facilities cause performance degradation and impede successful automatic segmentation. In this study, we proposed a method to solve this issue.

METHODS

We used the data from the Multimodal Brain Tumor Image Segmentation Benchmark (BraTS) and the Japanese cohort (JC) datasets collected from 10 facilities. Three models for tumor segmentation were developed. The BraTS model was trained on the BraTS dataset, and the JC model was trained on the JC dataset; whereas, the Fine-tuning model was a fine-tuned BraTS model using the JC dataset.

RESULTS

MR images of 544 patients were obtained for the JC dataset. Half of the JC dataset was used for independent testing. The Dice coefficient score of the JC model for the JC dataset was 0.779± 0.137, whereas that of the BraTS model was remarkably lower (0.717 ± 0.207). The mean of the Fine-tuning models for the JC dataset was 0.769 ± 0.138. There was a significant difference between the BraTS and JC models (P &lt; 0.0001) and the BraTS and Fine-tuning models (P = 0.002); however, no significant difference was observed between the JC and Fine-tuning models (P = 0.673).

CONCLUSIONS

Application of the BraTS model to heterogeneous datasets can significantly reduce its performance; however, fine-tuning can solve this issue. Since our fine-tuning method only requires less than 20 cases, this methodology is particularly useful for a facility where there are a few glioma cases.

Base-resolution methylomes of gliomas bearing histone H3.3 mutations reveal a G34 mutant-specific signature shared with bone tumors

Two recurrent mutations, K27M and G34R/V, in H3F3A, encoding non-canonical histone H3.3, are reported in pediatric and young adult gliomas, whereas G34W mutation is prevalent in bone tumors. In contrast to K27M mutation, it remains elusive how G34 mutations affect the epigenome. Here we performed whole-genome bisulfite sequencing of four G34R-mutated gliomas and the G34V-mutated glioma cell line KNS-42 for comparison with gliomas harboring K27M and no mutations in H3F3A and with G34W-mutated bone tumors. G34R-mutated gliomas exhibited lower global methylation levels, similar CpG island (CGI) methylation levels, and compromised hypermethylation of telomere-proximal CGIs, compared to the other two glioma subgroups. Hypermethylated regions specific to G34R-mutated gliomas were enriched for CGIs, including those of OLIG1, OLIG2, and canonical histone genes in the HIST1 cluster. They were notably hypermethylated in osteosarcomas with, but not without, G34W mutation. Independent component analysis revealed that G34 mutation-specific components shared a significant similarity between glioma and osteosarcoma, suggesting that G34 mutations exert characteristic methylomic effects regardless of the tumor tissue-of-origin. CRISPR/Cas9-mediated disruption of G34V-allele in KNS-42 cells led to demethylation of a subset of CGIs hypermethylated in G34R-mutated gliomas. These findings will provide a basis for elucidating epigenomic roles of G34 oncohistone in tumorigenesis.

A juvenile case of epilepsy-associated, isocitrate dehydrogenase wild-type/histone 3 wild-type diffuse glioma with a rare BRAF A598T mutation

Here, we report a juvenile (18-year-old male) case of epilepsy-associated, isocitrate dehydrogenase wild-type/histone 3 wild-type diffuse glioma with a rare BRAF mutation and a focal atypical feature resembling diffuse astrocytoma. The patient presented with refractory temporal lobe epilepsy. Subsequently, magnetic resonance imaging revealed a hyperintense lesion in the right temporal lobe on fluid attenuated inversion recovery images. The patient underwent right lateral temporal lobectomy and amygdalohippocampectomy. Histopathologically, the tumor showed isomorphic, diffuse, infiltrative proliferation of glial tumor cells and intense CD34 immunoreactivity. The tumor cells were immunonegative for isocitrate dehydrogenase 1 (IDH1) R132H and BRAF V600E. Notably, the tumor cells showed the lack of nuclear staining for α-thalassemia/mental retardation syndrome, X-linked (ATRX). In addition, the Ki-67 labeling index, using a monoclonal antibody MIB-1, was elevated focally at tumor cells with p53 immunoreactivity. Molecular analyses identified a BRAF^A598T mutation, the first case reported in a glioma. BRAF^A598T is predicted to result in loss of kinase action; however, inactive mutants can stimulate mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase (ERK) signaling through CRAF activation. Thus, according to the recent update of the consortium to inform molecular and practical approaches to central nervous system tumor taxonomy (cIMPACT-NOW update 4), our case is also compatible with diffuse glioma with the mitogen-activated protein kinase (MAPK) pathway alteration. Thorough immunohistochemical and molecular studies are necessary for diagnosis of epilepsy-associated, diffuse gliomas. Partial resemblance in histopathological and molecular genetic features to diffuse astrocytoma also calls for attention.

Intraoperative Tissue Expansion Using a Foley Catheter for a Scalp Defect: Technical Note

BACKGROUND

Primary closure of the surgical wound during neurosurgical procedures is sometimes difficult because of limited ability to expand the scalp, or because the skin defect is large. Hence, our institution recently adopted the technique of intraoperative tissue expansion using a Foley catheter for these cases. We describe this easily accomplished, readily available, effective, economical technique and describe our experience performing the technique.

METHODS

With this procedure, the subcutaneous tissue (usually the subperiosteal layer) surrounding the skin defect is dissected to make a subcutaneous pocket in which to place a 20-French Foley catheter. The standard expander is a 30-mL balloon. The catheter is inserted into the subcutaneous pocket, and the balloon is inflated with 10-30 mL of saline for 5 minutes, after which the balloon is deflated for 3 minutes in a cyclic loading manner. After sufficient expansion, the primary closure of the surgical wound is achieved with minimal tension on the surrounding skin.

RESULTS

Between November 2018 and February 2020, we performed this technique in 5 patients, each with a large surgical defect in the scalp. Primary closure was achieved, and postoperative wound healing was excellent in all 5 patients.

CONCLUSIONS

Intraoperative skin expansion using a Foley catheter-which is easily performed, readily available, and economical-can be used to achieve surgical wound closure during various neurosurgical procedures.

First-line bevacizumab contributes to survival improvement in glioblastoma patients complementary to temozolomide

INTRODUCTION

First-line bevacizumab (BEV) is now available as a treatment option for glioblastoma patients with severe clinical conditions in Japan. However, the survival benefits remain controversial. To elucidate these potential survival benefits, we retrospectively analyzed survival in glioblastoma patients receiving BEV.

METHODS

We analyzed survival in 120 patients with IDH-wild type glioblastoma treated from 2002 to 2018. Overall survival (OS) was assessed in three treatment era subgroups [pre-temozolomide (TMZ), TMZ, and TMZ-BEV], and the correlations of prognostic factors with survival were evaluated.

RESULTS

An improvement in survival was observed after BEV approval (median OS in the pre-TMZ, TMZ, and TMZ-BEV eras: 14.6, 14.9, and 22.1 months, respectively). A Cox proportional hazards model identified extent of resection and MGMT methylation status as significant prognostic factors in the TMZ era; however, these factors were not significant in the TMZ-BEV era. In subgroup analyses, patients with MGMT methylation had improved OS after TMZ introduction (pre-TMZ vs. TMZ, 18.5 vs. 28.1 months; P = 0.13), and those without MGMT methylation had significantly increased OS after BEV approval (TMZ vs. TMZ-BEV, 12.2 vs. 16.7 months; P = 0.04).

CONCLUSIONS

Our findings imply that optional first-line administration of BEV can overcome the impact of conventional risk factors and prolong survival complementary to TMZ. The patient subgroups benefitting from TMZ and BEV did not seem to overlap, and stratification based on risk factors, including MGMT methylation status, might be effective for selecting patients in whom BEV should be preferentially used as a first-line therapy.

A Dorsally Located Endodermal Cyst in the Foramen Magnum Mimicking an Arachnoid Cyst: A Case Report

INTRODUCTION

Endodermal cysts are congenital benign cystic lesions in the central nervous system and cause various symptoms. Although some have been reported in the posterior fossa, endodermal cysts located dorsal to the brainstem are extremely rare.

CASE PRESENTATION

The case was of a 10-year-old girl who presented with bilateral upper limb weakness and tremor. Magnetic resonance imaging demonstrated a 4.5-cm cystic lesion with T1-weighted hypointense and T2-weighted hyperintense content in the midline of the cisterna magna dorsal to the medulla oblongata. The cyst was cerebrospinal fluid-like, causing us to suspect a symptomatic arachnoid cyst. The lucent cyst wall had no apparent attachment, and complete recovery ensued following total excision of the cyst wall. Pathology confirmed a diagnosis of endodermal cyst.

DISCUSSION/CONCLUSION

Herein, we review the past literature on this rare entity. An endodermal cyst in the cisterna magna tends to be less strongly attached and to show a cerebrospinal fluid-like component on magnetic resonance images that mimics an arachnoid cyst. The characteristics of dorsally located endodermal cysts may differ from those in other locations.

MPC-01 PROGNOSTIC ROLE OF TERT PROMOTER IMPROVES THE STRATIFICATION OF IDH-MUTATED LOWER GRADE GLIOMA

TERT promoter mutation is associated with favorable prognosis and 1p/19q codeletion in IDH-mutated gliomas. The current diagnostic system, however, did not incorporate this change as a diagnostic marker in this entity. We investigated the value of prognostication incorporating TERT using the Japanese original cohort of 560 IDH-mutated adult gliomas. We collected the information of molecular status of IDH, TERT and 1p/19q and patient clinical data including Karnofsky performance status (KPS). TERT mutation and 1p/19q codeletion were found in 303 and 285 cases, respectively. For the purpose of this study, the patient cohort was divided into four groups by a combination of 1p/19q and TERT status, and the characteristics of 1p/19q intact-TERT mutated group (Astro-TERT group) (n=24) were dissected in light of the differences comparing with 1p/19q intact-TERT wild (Astro-group, n=251) or 1p/19q codeleted-TERT mutated (Oligo-group, n=279) cases. Astro-TERT group with any grade showed intermediate overall survival between the Oligo-group and Astro-group although the survival differences were not statistically significant (median OS: not reached (NR) versus NR, and 106 months, respectively. p>0.05). In grade II-III gliomas, the survival curve of the Astro-TERT group overlapped with that of the Oligo-group while the Astro-TERT group showed short survival as well as the Astro-group. We further conducted subgroup analysis by adjusting KPS in grade II-III tumors. In the subgroup with favorable KPS (90–100) and gradeII-III (n=438), The OS of Astro-TERT group (median NR) was significantly longer survival than that of Astro-group (median NR p=0.032), and was comparable with that of the Oligo-group (median NR, p>0.05). Thus, TERT promoter status provides the additional information for prognostication at least in grade II-III gliomas in the current diagnostic system.

ACT-14 A FIRST-IN-HUMAN STUDY OF MUTANT IDH1 INHIBITOR DS-1001B IN PATIENTS WITH RECURRENT GLIOMAS

BACKGROUND

WHO grade II/III gliomas frequently harbor isocitrate dehydrogenase 1 (IDH1) mutations, resulting in intratumoral accumulation of oncometabolite D-2-hydroxyglutarate (D-2-HG) and subsequent clonal expansion. DS-1001b is an oral selective inhibitor of mutant IDH1 R132X that was designed to penetrate the blood-brain barrier.

METHODS

In this first-in-human, multicenter, phase I study (NCT03030066), eligible patients (pts) with recurrent/progressive IDH1 mutant glioma received DS-1001b twice daily (bid), continuous. A modified continual reassessment method was used for dose escalation. RANO and RANO-LGG criteria were used to assess tumor response. Pts who planned to undergo salvage surgery after developing progressive disease (PD) and who provided informed consent received DS-1001b treatment until surgery. Tumor samples were also obtained from those pts to measure the free form of DS-1001b and D-2-HG levels.

RESULTS

Between Jan 2017 and May 2019, DS-1001b (125–1400 mg bid) had administered for 47 pts, and 15 pts were continuing treatment. Maximum tolerated dose (MTD) was not reached. Most AEs were Gr 1–2. Gr 3 AEs were observed in 40% of pts. No Gr 4 or 5 AEs or serious drug-related AEs were reported. One dose limiting toxicity was Gr 3 white blood cell count decreased (1000 mg bid). Of 35 evaluable pts with contrast enhancing gliomas, one, five and 11 achieved complete response, partial response and stable disease (SD), respectively. Of evaluable 12 pts with contrast non-enhancing gliomas, four achieved minor response and eight achieved SD. Peak plasma concentration (Cmax) and area under the curve (AUC) increased dose-dependently.

CONCLUSIONS

DS-1001b was well tolerated up to 1400 mg bid with favorable brain distribution, and MTD was not reached. Recurrent/progressive IDH1 mutant glioma pts responded to treatment. Investigation is ongoing to determine the recommended Phase II dose. The latest data will be updated. Funding source: This study was funded by Daiichi Sankyo Co., Ltd.

ACT-16 THE POTENTIAL OF HYPOFRACTIONATED RADIOTHERAPY AND BEVACIZUMAB FOR GLIOBLASTOMA TREATMENT

INTRODUCTION

First-line bevacizumab (BEV) is now available as a treatment option for glioblastoma (GBM) patients with severe clinical conditions in Japan. However, the survival benefits remain controversial. As we have emphasized the combined effect of BEV and radiation therapy, the strategies; 1) first-line add-on BEV to TMZ-radiation for unresectable GBMs and 2) re-irradiation using IMRT under BEV administration for recurrent GBMs, have been positively applied. To elucidate these potential survival benefits, we retrospectively analyzed survival in GBM patients.

METHODS

We analyzed survival in 101 patients with IDH-wild type GBM treated from 2006 to 2018. PFS and OS were assessed in two subgroups (TMZ and TMZ-BEV eras), and the correlations of prognostic factors with survival were evaluated.

RESULTS

After BEV approval, OS prolongation tendency (median OS: 14.9 vs. 22.1 months; P = 0.52) was observed, and this tendency was clearer in unresectable cases (10.1 vs 16.1 m P = 0.38). Subanalysis showed a significant prolongation of prognosis in the MGMT unmethylated group (12.2 vs 16.7 m; P = 0.04). In 10 patients of recurrent GBMs receiving BEV combined re-irradiation, adverse events of Grade 3 or higher did not occur. All patients showed PR (N=5) or CR (N=5) after treatment. The mPFS and mOS from the recurrence were 4.3 and 9.4 months, however, no local relapse was observed at their second recurrences.

CONCLUSIONS

Our treatment strategy has improved the outcome of high-risk cases after BEV approval. These results implied that hypofractionated radiotherapy under BEV administration might be an efficient treatment protocol as a first-line for high-risk cases, such as after partial excision and MGMT unmethylation.