3D whole-brain metabolite imaging to improve characterization of low-to-intermediate grade gliomas.

PURPOSE: MRI is the standard imaging modality used for diagnosis, treatment planning, and post-treatment management of gliomas. Contrast-enhanced T1-weighted (CE-T1w) MRI is used to plan biopsy and radiation for grade IV gliomas but is less effective for grade II and III gliomas (i.e., low-to-intermediate grade gliomas) which may have minimal or no enhancement. Magnetic resonance spectroscopic imaging (MRSI) is an advanced MRI technique that has been shown, to improve diagnostic yield of biopsy and target delineation for grade IV glioma. The purpose of this study is to determine if MRSI can improve characterization and tissue sampling of low-to-intermediate grade gliomas. METHODS: Prospective grade II and grade III glioma patients were enrolled to undergo whole brain high-resolution MRSI prior to tissue sampling. Choline/N-acetyl-aspartate (Cho/NAA) maps were overlaid on anatomic imaging and imported into stereotactic biopsy software. Patients were treated with standard-of-care surgery and radiation. Volumes of spectroscopically abnormal tissue were generated and compared with anatomic imaging and areas of enhancing recurrence on follow-up imaging. RESULTS: Ten patients had pathologic diagnosis of grade II (n = 4) or grade III (n = 6) with a median follow-up of 27.3 months. Five patients had recurrence, and regions of recurrence were found to overlap with metabolically abnormal regions on MRSI at the time of diagnosis. CONCLUSION: MRSI in low-to-intermediate grade glioma patients is predictive of areas of subsequent recurrence. Larger studies are needed to determine if MRSI can be used to guide surgical and radiation treatment planning in these patients.

Optimal timing of chemoradiotherapy after surgical resection of glioblastoma: Stratification by validated prognostic classification.

BACKGROUND: Previous studies examining the time to initiate chemoradiation (CRT) after surgical resection of glioblastoma have been conflicting. To better define the effect that the timing of adjuvant treatment may have on outcomes, the authors examined patients within the National Cancer Database (NCDB) stratified by a validated prognostic classification system. METHODS: Patients with glioblastoma in the NCDB who underwent surgery and CRT from 2004 through 2013 were analyzed. Radiation Therapy Oncology Group recursive partitioning analysis (RPA) class (III, IV, V) was extrapolated for the cohort. Time intervals were grouped weekly, with weeks 4 to 5 serving as the reference category for analyses. Kaplan-Meier analysis, log-rank testing, and multivariate (MVA) Cox proportional hazards regression were performed. RESULTS: In total, 30,414 patients were included. RPA classes III, IV, and V contained 5250, 20,855, and 4309 patients, respectively. On MVA, no time point after week 5 was associated with a change in overall survival for the entire cohort or for any RPA class subgroup. The periods of weeks 0 to 1 (hazard ratio [HR], 1.18; 95% CI, 1.02-1.36), >1 to 2 (HR, 1.23; 95% CI, 1.16-1.31), and >2 to 3 (HR, 1.11; 95% CI, 1.07-1.15) demonstrated slightly worse overall survival (all P < .03). The detriment to early initiation was consistent across each RPA class subgroup. CONCLUSIONS: The current data provide insight into the optimal timing of CRT in patients with glioblastoma and describe RPA class-specific outcomes. In general, short delays beyond 5 weeks did not negatively affect outcomes, whereas early initiation before 3 weeks may be detrimental.

Outcomes of whole-brain radiation with simultaneous in-field boost (SIB) for the treatment of brain metastases.

PURPOSE: Prospective studies have demonstrated increased local control with the addition of a radiosurgery (SRS) boost to whole-brain irradiation (WBRT) in patients with brain metastases. However, the clinical application of SRS boost can be limited by several factors, including tumor size, numbers of lesions, and high cost of care. Here, we investigate the use of WBRT with a simultaneous integrated boost (SIB) to visible lesions in patients with brain metastases. MATERIALS: From 2011 to 2016, patients were prospectively enrolled and prescribed a dose of 25 or 37.5 Gray (Gy) WBRT with a SIB dose of 45 or 52.5 Gy to the gross lesions in 10 or 15 fractions, respectively. All plans were optimized for dose coverage of the whole brain and lesions using volumetric arc therapy (VMAT). Comprehensive neurocognitive and quality of life assessments were conducted at baseline and at follow-up. RESULTS: Thirteen patients were treated on this protocol. The 1-year local control rates were 92% at the patient level, and 98.6% at the lesion level. The overall 1-year intracranial control was 46%. Patients had no significant declines in Mini-Mental State Examination (MMSE), Hopkins Verbal Learning Test-Revised (HVLT-R), and Medical Outcomes Study (MOS) Cognitive Functional status scores pre- and post-treatment. CONCLUSION: WBRT with SIB to gross lesions using VMAT planning appears to be safe and effective in the treatment of brain metastases without significant cognitive decline. This treatment strategy should be considered in those patients with a high number of metastases or ones not amenable for radiosurgery. CLINICAL TRIAL REGISTRATION CODE: NCT01218542.

Reduced-volume tumor-bed boost is not associated with inferior local control and survival outcomes in high-risk medulloblastoma.

BACKGROUND: Radiotherapy boost to the entire posterior fossa (PF) is standard of care for high-risk (H-R) medulloblastoma patients; the utility of tumor bed (TB)-only boost is unclear. The purpose of this study was to examine the impact of PF versus TB boost volume on tumor control and survival in the H-R medulloblastoma population. METHODS: Single-institution records for patients with H-R medulloblastoma were reviewed. The median craniospinal irradiation dose was 36 Gy (range, 23.4-45 Gy), and boost doses to either PF or TB were 54 to 55.8 Gy. PF (local) failures were scored as in-field, marginal (between 80% and 95% isodose lines), or distant. Kaplan-Meier methods and Cox proportional hazards were used to assess the impact of radiation boost technique on local control (LC) and survival endpoints. RESULTS: Thirty-two patients with H-R medulloblastoma were treated between 1990 and 2015, with a median follow-up length of 5.12 years. Twenty-two patients received PF boost, and 10 received TB boost. Patient and disease characteristic were comparable between groups. A total of 11 PF failures occurred, including 3 isolated LFs (2 in the PF and 1 in the TB group). Most PF failures were in-field: three of four in the TB group and six of seven in the PF group; the remainder were marginal failures. TB boost was not associated with inferior LC (hazard ratio [HR] 0.86, log-rank P = 0.81) or overall survival (HR 1.40, P = 0.56) compared with PF boost. CONCLUSION: Reduced-volume radiotherapy boost to the TB does not appear to compromise LC or survival in patients with H-R medulloblastoma; it may reduce the risk of ototoxicity.

Is less more? Comparing chemotherapy alone with chemotherapy and radiation for high-risk grade 2 glioma: An analysis of the National Cancer Data Base.

BACKGROUND: The addition of chemotherapy to adjuvant radiotherapy (chemotherapy and radiation therapy [CRT]) improves overall survival (OS) for patients with high-risk grade 2 gliomas; however, the impact of chemotherapy alone (CA) is unknown. This study compares the OS of patients with high-risk grade 2 gliomas treated with CA versus CRT. METHODS: Patients with high-risk grade 2 gliomas (subtotal resection or age ≥ 40 years) with oligodendrogliomas, astrocytomas, or mixed tumors were identified with the National Cancer Data Base. Patients were grouped into CA and CRT cohorts. Univariate analyses and multivariate analyses (MVAs) were performed. Propensity score (PS) matching was also implemented. The Kaplan-Meier method was used to analyze OS. RESULTS: A total of 1054 patients with high-risk grade 2 gliomas were identified: 496 (47.1%) received CA, and 558 (52.9%) received CRT. Patients treated with CA were more likely (all P values < .05) to have oligodendroglioma histology (65.5% vs 34.2%), exhibit a 1p/19q codeletion (22.8% vs 7.5%), be younger (median age, 47.0 vs 48.0 years), and receive treatment at an academic facility (65.2% vs 50.3%). The treatment type was not a significant predictor for OS (P = .125) according to the MVA; a tumor size > 6 cm, astrocytoma histology, and older age were predictors for worse OS (all P values < .05). After 1:1 PS matching (n = 331 for each cohort), no OS difference was seen (P = .696) between the CA and CRT cohorts at 5 (69.3% vs 67.4%) and 8 years (52.8% vs 56.7%). CONCLUSIONS: No long-term OS difference was seen in patients with high-risk grade 2 gliomas treated with CA versus CRT. These findings are hypothesis-generating, and prospective clinical trials comparing these treatment paradigms are warranted. Cancer 2018;124:1169-78. © 2017 American Cancer Society.

Targeted sequencing and intracranial outcomes of patients with lung adenocarcinoma brain metastases treated with radiotherapy.

BACKGROUND: Treatment for advanced lung adenocarcinoma (AC) has become increasingly personalized based on molecular results. However, for patients with AC brain metastases (BMs), intracranial outcomes based on molecular subtype and the frequency of molecular aberrations are less well defined. This study sought to report targeted next-generation sequencing results and investigate molecularly based outcomes for patients with AC-BMs treated with radiotherapy. METHODS: The records of 132 patients with AC-BMs treated at Emory University from September 2008 to August 2016 with successful next-generation sequencing were reviewed. Rates of local disease recurrence, distant brain failure (DBF), and salvage whole-brain radiotherapy (WBRT) were estimated using cumulative incidence with competing risk analysis. Univariate and multivariate analyses were performed. RESULTS: The most common aberrations included tumor protein 53 (TP53) (60%), KRAS (29%), epidermal growth factor receptor (EGFR) (20.5%), phosphatase and tensin homolog (PTEN) loss (15.5%), and MET amplification (13%). The majority of patients (62%) were treated with stereotactic radiosurgery alone. In these patients, KRAS mutation, anaplastic lymphoma kinase (ALK) rearrangement, and having ≥ 6 BMs were associated with an increased risk of salvage WBRT (P < .05). KRAS mutation remained significant for an increased risk of salvage WBRT when compared with EGFR/ALK/KRAS-negative patients (hazard ratio, 5.17; P < .05), despite a similar risk of DBF. PTEN loss was associated with increased risk of DBF (P < .05), whereas EGFR and ALK aberrations were associated with a decreased risk of local disease recurrence (P < .05). CONCLUSIONS: The results of the current study quantified the frequency of genetic aberrations in patients with AC-BMs and demonstrated their association with intracranial outcomes. In particular, a cohort of patients with KRAS mutations and ≥6 BMs were identified to be at high risk of requiring salvage WBRT after undergoing upfront stereotactic radiosurgery.

External validity of two nomograms for predicting distant brain failure after radiosurgery for brain metastases in a bi-institutional independent patient cohort.

Patients treated with stereotactic radiosurgery (SRS) for brain metastases (BM) are at increased risk of distant brain failure (DBF). Two nomograms have been recently published to predict individualized risk of DBF after SRS. The goal of this study was to assess the external validity of these nomograms in an independent patient cohort. The records of consecutive patients with BM treated with SRS at Levine Cancer Institute and Emory University between 2005 and 2013 were reviewed. Three validation cohorts were generated based on the specific nomogram or recursive partitioning analysis (RPA) entry criteria: Wake Forest nomogram (n = 281), Canadian nomogram (n = 282), and Canadian RPA (n = 303) validation cohorts. Freedom from DBF at 1-year in the Wake Forest study was 30% compared with 50% in the validation cohort. The validation c-index for both the 6-month and 9-month freedom from DBF Wake Forest nomograms was 0.55, indicating poor discrimination ability, and the goodness-of-fit test for both nomograms was highly significant (p < 0.001), indicating poor calibration. The 1-year actuarial DBF in the Canadian nomogram study was 43.9% compared with 50.9% in the validation cohort. The validation c-index for the Canadian 1-year DBF nomogram was 0.56, and the goodness-of-fit test was also highly significant (p < 0.001). The validation accuracy and c-index of the Canadian RPA classification was 53% and 0.61, respectively. The Wake Forest and Canadian nomograms for predicting risk of DBF after SRS were found to have limited predictive ability in an independent bi-institutional validation cohort. These results reinforce the importance of validating predictive models in independent patient cohorts.

Post-treatment neutrophil-to-lymphocyte ratio predicts for overall survival in brain metastases treated with stereotactic radiosurgery.

INTRODUCTION: Neutrophil-to-lymphocyte ratio (NLR) is a surrogate for systemic inflammatory response and its elevation has been shown to be a poor prognostic factor in various malignancies. Stereotactic radiosurgery (SRS) can induce a leukocyte-predominant inflammatory response. This study investigates the prognostic impact of post-SRS NLR in patients with brain metastases (BM). METHODS: BM patients treated with SRS from 2003 to 2015 were retrospectively identified. NLR was calculated from the most recent full blood counts post-SRS. Overall survival (OS) and intracranial outcomes were calculated using the Kaplan-Meier method and cumulative incidence with competing risk for death, respectively. RESULTS: 188 patients with 328 BM treated with SRS had calculable post-treatment NLR values. Of these, 51 (27.1%) had a NLR > 6. The overall median imaging follow-up was 13.2 (14.0 vs. 8.7 for NLR ≤ 6.0 vs. > 6.0) months. Baseline patient and treatment characteristics were well balanced, except for lower rate of ECOG performance status 0 in the NLR > 6 cohort (33.3 vs. 44.2%, p = 0.026). NLR > 6 was associated with worse 1- and 2-year OS: 59.9 vs. 72.9% and 24.6 vs. 43.8%, (p = 0.028). On multivariable analysis, NLR > 6 (HR: 1.53; 95% CI 1.03-2.26, p = 0.036) and presence of extracranial metastases (HR: 1.90; 95% CI 1.30-2.78; p < 0.001) were significant predictors for worse OS. No association was seen with NLR and intracranial outcomes. CONCLUSION: Post-treatment NLR, a potential marker for post-SRS inflammatory response, is inversely associated with OS in patients with BM. If prospectively validated, NLR is a simple, systemic marker that can be easily used to guide subsequent management.

Angiotensin receptor blockade: a novel approach for symptomatic radiation necrosis after stereotactic radiosurgery.

Preclinical evidence suggests angiotensin blockade therapy (ABT) decreases late radiation toxicities. This study aims to investigate the association between ABT and symptomatic radiation necrosis (SRN) following stereotactic radiosurgery (SRS). Resected brain metastases (rBM) and arteriovenous malformation (AVM) patients treated with SRS from 2002 to 2015 were identified. Patients in the ABT cohort were on therapy during SRS and at 1-month follow up. Kaplan Meier method and cumulative incidence model were used to analyze overall survival (OS) and intracranial outcomes. 228 consecutive patients were treated with SRS: 111 with rBM and 117 with AVM. Overall, 51 (22.4%) patients were in the ABT group: 32 (28.8%) in the rBM and 19 (16.2%) in AVM cohorts. Baseline characteristics were similar, except for higher Graded Prognostic Analysis (3-4) in the rBM (ABT: 25.0% vs. non-ABT: 49.0%, p = 0.033) and median age in the AVM (ABT: 51.4 vs. non-ABT: 35.4, p < 0.001) cohorts. In both populations, OS and intracranial efficacy (rBM-local control; AVM-obliteration rates) were statistically similar between the cohorts. ABT was associated with lower 1-year SRN rates in both populations: rBM, 3.1 versus 25.3% (p = 0.003); AVM, 6.7 vs. 14.6% (p = 0.063). On multivariate analysis, ABT was a significant predictive factor for rBM (HR: 0.17; 95% CI 0.03-0.88, p = 0.035), but did not reach statistical significance for AVM (HR: 0.36; 95% CI 0.09-1.52, p = 0.165). ABT use appears to be associated with a reduced risk of SRN following SRS, without detriment to OS or intracranial efficacy. A prospective trial to validate these findings is warranted.

Cyclooxygenase-2 Induction by Amino Acid Deprivation Requires p38 Mitogen-Activated Protein Kinase in Human Glioma Cells.

Glioblastomas (GBMs) are malignant brain tumors that can outstrip nutrient supplies due to rapid growth. Cyclooxygenase-2 (COX-2) has been linked to GBMs and may contribute to their aggressive phenotypes. Amino acid starvation results in COX-2 mRNA and protein induction in multiple human glioma cell lines in a process requiring p38 mitogen-activated protein kinase (p38-MAPK) and the Sp1 transcription factor. Increased vascular endothelial growth factor expression results from starvation-dependent COX-2 induction. These data suggest that COX-2 induction with amino acid deprivation may be a part of the adaptation of glioma cells to these conditions, and potentially alter cellular response to anti-neoplastic therapy.

Comparing pre-operative stereotactic radiosurgery (SRS) to post-operative whole brain radiation therapy (WBRT) for resectable brain metastases: a multi-institutional analysis.

Pre-operative stereotactic radiosurgery (pre-SRS) has been shown as a viable treatment option for resectable brain metastases (BM). The aim of this study is to compare oncologic outcomes and toxicities for pre-SRS and post-operative WBRT (post-WBRT) for resectable BM. We reviewed records of consecutive patients who underwent resection of BM and either pre-SRS or post-WBRT between 2005 and 2013 at two institutions. Overall survival (OS) was calculated using the Kaplan-Meier method. Cumulative incidence was used for intracranial outcomes. Multivariate analysis (MVA) was performed using the Cox and Fine and Gray models, respectively. Overall, 102 patients underwent surgical resection of BM; 66 patients with 71 lesions received pre-SRS while 36 patients with 42 cavities received post-WBRT. Baseline characteristics were similar except for the pre-SRS cohort having more single lesions (65.2% vs. 38.9%, p = 0.001) and smaller median lesion volume (8.3 cc vs. 15.3 cc, p = 0.006). 1-year OS was similar between cohorts (58% vs. 56%, respectively) (p = 0.43). Intracranial outcomes were also similar (2-year outcomes, pre-SRS vs. post-WBRT): local recurrence: 24.5% vs. 25% (p = 0.81), distant brain failure (DBF): 53.2% vs. 45% (p = 0.66), and leptomeningeal disease (LMD) recurrence: 3.5% vs. 9.0% (p = 0.66). On MVA, radiation cohort was not independently associated with OS or any intracranial outcome. Crude rates of symptomatic radiation necrosis were 5.6 and 0%, respectively. OS and intracranial outcomes were similar for patients treated with pre-SRS or post-WBRT for resected BM. Pre-SRS is a viable alternative to post-WBRT for resected BM. Further confirmatory studies with neuro-cognitive outcomes comparing these two treatment paradigms are needed.

Bevacizumab-induced hypertension is a predictive marker for improved outcomes in patients with recurrent glioblastoma treated with bevacizumab.

BACKGROUND: Bevacizumab is a monoclonal antibody targeting vascular endothelial growth factor and is approved for the treatment of patients with recurrent glioblastoma (GBM). Previous authors have reported differential response to bevacizumab on an individual basis. Bevacizumab-induced hypertension is a well-documented side effect, and some reports have suggested this occurrence to be related to treatment outcome in other cancers. In the current study, the authors analyzed patients with recurrent GBM who were treated with bevacizumab based on whether the patients developed drug-induced hypertension. METHODS: All patients with GBM treated within the Emory Healthcare system from 2007 through 2012 were reviewed. A total of 82 patients were identified who received bevacizumab for the treatment of recurrent GBM and were included in the current study. Patients were classified as normotensive or hypertensive depending on whether hypertension developed that was attributable to therapy. Progression-free survival (PFS) and overall survival (OS) were graphed by the Kaplan-Meier method. Univariate and multivariate analyses were performed using the Cox proportional hazards method. RESULTS: The median follow-up was 19.7 months. Of the 82 patients with recurrent GBM who were treated with bevacizumab, 30 developed drug-induced hypertension. The median time to the development of hypertension was 21 days. The median PFS for the normotensive and hypertensive groups were 2.5 months (95% confidence interval [95% CI], 1.6-3.0 months) and 6.7 months (95% CI, 4.6-10.0 months), respectively (P<.001). The median OS times for the normotensive and hypertensive groups were 4.9 months (95% CI, 4.4-6.8 months) and 11.7 months (95% CI, 9.0-20.5 months), respectively (P<.001). CONCLUSIONS: Patients with recurrent GBM who developed bevacizumab-induced hypertension demonstrated significantly better PFS and OS compared with normotensive individuals. Bevacizumab-induced hypertension may be a physiologic marker of outcome in patients with recurrent GBM.

Novel risk stratification score for predicting early distant brain failure and salvage whole-brain radiotherapy after stereotactic radiosurgery for brain metastases.

BACKGROUND: The purpose of this study was to evaluate predictors of early distant brain failure (DBF) and salvage whole-brain radiotherapy (WBRT) after treatment with stereotactic radiosurgery (SRS) for brain metastases and create a clinically relevant risk score to stratify patients' risk for these events. METHODS: The records of 270 patients with brain metastases who were treated with SRS between 2003 and 2012 were reviewed. Pretreatment patient and tumor characteristics were analyzed with univariate and multivariate analyses. The cumulative incidences of first DBF and salvage WBRT were calculated. Significant factors were used to create a score for stratifying early (6-month) DBF risk. RESULTS: No prior WBRT, a total lesion volume < 1.3 cm(3), primary breast cancer or malignant melanoma histology, and multiple metastases (≥2) were found to be significant predictors of early DBF. Each factor was ascribed 1 point because of similar hazard ratios. Scores of 0 to 1, 2, and 3 to 4 were considered to indicate low, intermediate, and high risk, respectively. This correlated with 6-month cumulative incidences of DBF of 16.6%, 28.8%, and 54.4%, respectively (P < .001). For patients without prior WBRT, the 6-month cumulative incidence of salvage WBRT was 2%, 17.7%, and 25.7%, respectively (P < .001). CONCLUSIONS: Early DBF after SRS requiring salvage WBRT remains a significant clinical problem. Patient stratification for early DBF can better inform the decision for the initial treatment strategy for brain metastases. The provided risk score may help to predict early DBF and subsequent salvage WBRT if SRS is initially used. External validation is needed before clinical implementation.

The Utility of Spectroscopic MRI in Stereotactic Biopsy and Radiotherapy Guidance in Newly Diagnosed Glioblastoma.

Current diagnostic and therapeutic approaches for gliomas have limitations hindering survival outcomes. We propose spectroscopic magnetic resonance imaging as an adjunct to standard MRI to bridge these gaps. Spectroscopic MRI is a volumetric MRI technique capable of identifying tumor infiltration based on its elevated choline (Cho) and decreased N-acetylaspartate (NAA). We present the clinical translatability of spectroscopic imaging with a Cho/NAA ≥ 5x threshold for delineating a biopsy target in a patient diagnosed with non-enhancing glioma. Then, we describe the relationship between the undertreated tumor detected with metabolite imaging and overall survival (OS) from a pilot study of newly diagnosed GBM patients treated with belinostat and chemoradiation. Each cohort (control and belinostat) were split into subgroups using the median difference between pre-radiotherapy Cho/NAA ≥ 2x and the treated T1-weighted contrast-enhanced (T1w-CE) volume. We used the Kaplan-Meier estimator to calculate median OS for each subgroup. The median OS was 14.4 months when the difference between Cho/NAA ≥ 2x and T1w-CE volumes was higher than the median compared with 34.3 months when this difference was lower than the median. The T1w-CE volumes were similar in both subgroups. We find that patients who had lower volumes of undertreated tumors detected via spectroscopy had better survival outcomes.

Clinical outcomes for a novel 6 degrees of freedom image guided localization method for frameless radiosurgery for intracranial brain metastases.

Stereotactic radiosurgery (SRS) is an accepted method of treatment for intracranial brain metastases with sub-millimeter accuracy. Frameless radiosurgery (FRS) is becoming an alternative to framed SRS due to its less invasive requirements. The purpose of this study is to describe the clinical outcomes and local patterns of failure for a novel 6 degrees of freedom CT guided method of localization for FRS of intracranial brain metastases. 42 patients underwent linear accelerator-based FRS to 94 intracranial brain metastases between 01/2009 and 07/2011. 78 and 22 % of treated sites were intact metastases and resection cavities, respectively. 55 % of patients had undergone prior brain radiotherapy (45 % SRS, 26 % whole brain radiation therapy). The 1 year actuarial local recurrence rate was 18 %, with a median imaging follow-up period of 13.2 months. Single fraction equivalent dose was the most important predictor of local recurrence. The 1 year actuarial first distant brain recurrence and total intracranial recurrence rate was 58 and 69 %, respectively. The crude radiographic radiation necrosis rate was 3 %. Of the 10 local recurrence events, 8 (80 %) were in-field only, 1 (10 %) was marginal only, and 1 (10 %) was both. The preponderance of in-field only patterns of failure suggests that geographic miss is not a major contributor to local recurrence using this novel localization method for FRS. The 1 year local control rate is comparable to other similar published series of framed and frameless radiosurgery.

Mutant Isocitrate Dehydrogenase 1 Expression Enhances Response of Gliomas to the Histone Deacetylase Inhibitor Belinostat.

Histone deacetylase inhibitors (HDACis) are drugs that target the epigenetic state of cells by modifying the compaction of chromatin through effects on histone acetylation. Gliomas often harbor a mutation of isocitrate dehydrogenase (IDH) 1 or 2 that leads to changes in their epigenetic state presenting a hypermethylator phenotype. We postulated that glioma cells with IDH mutation, due to the presence of epigenetic changes, will show increased sensitivity to HDACis. This hypothesis was tested by expressing mutant IDH1 with a point alteration-converting arginine 132 to histidine-within glioma cell lines that contain wild-type IDH1. Glioma cells engineered to express mutant IDH1 produced D-2-hydroxyglutarate as expected. When assessed for response to the pan-HDACi drug belinostat, mutant IDH1-expressing glioma cells were subjected to more potent inhibition of growth than the corresponding control cells. Increased sensitivity to belinostat correlated with the increased induction of apoptosis. Finally, a phase I trial assessing the addition of belinostat to standard-of-care therapy for newly diagnosed glioblastoma patients included one patient with a mutant IDH1 tumor. This mutant IDH1 tumor appeared to display greater sensitivity to the addition of belinostat than the other cases with wild-type IDH tumors based on both standard magnetic resonance imaging (MRI) and advanced spectroscopic MRI criteria. These data together suggest that IDH mutation status within gliomas may serve as a biomarker of response to HDACis.

Using Brain Tumor MRI Structured Reporting to Quantify the Impact of Imaging on Brain Tumor Boards.

Multidisciplinary tumor boards (TB) are an essential part of brain tumor care, but quantifying the impact of imaging on patient management is challenging due to treatment complexity and a lack of quantitative outcome measures. This work uses a structured reporting system for classifying brain tumor MRIs, the brain tumor reporting and data system (BT-RADS), in a TB setting to prospectively assess the impact of imaging review on patient management. Published criteria were used to prospectively assign three separate BT-RADS scores (an initial radiology report, secondary TB presenter review, and TB consensus) to brain MRIs reviewed at an adult brain TB. Clinical recommendations at TB were noted and management changes within 90 days after TB were determined by chart review. In total, 212 MRIs in 130 patients (median age = 57 years) were reviewed. Agreement was 82.2% between report and presenter, 79.0% between report and consensus, and 90.1% between presenter and consensus. Rates of management change increased with increasing BT-RADS scores (0-3.1%, 1a-0%, 1b-66.7%, 2-8.3%, 3a-38.5%, 3b-55.9, 3c-92.0%, and 4-95.6%). Of 184 (86.8%) cases with clinical follow-up within 90 days after the tumor board, 155 (84.2%) of the recommendations were implemented. Structured scoring of MRIs provides a quantitative way to assess rates of agreement interpretation alongside how often management changes are recommended and implemented in a TB setting.

Applying a Radiation Therapy Volume Analysis Pipeline to Determine the Utility of Spectroscopic MRI-Guided Adaptive Radiation Therapy for Glioblastoma.

Accurate radiation therapy (RT) targeting is crucial for glioblastoma treatment but may be challenging using clinical imaging alone due to the infiltrative nature of glioblastomas. Precise targeting by whole-brain spectroscopic MRI, which maps tumor metabolites including choline (Cho) and N-acetylaspartate (NAA), can quantify early treatment-induced molecular changes that other traditional modalities cannot measure. We developed a pipeline to determine how spectroscopic MRI changes during early RT are associated with patient outcomes to provide insight into the utility of adaptive RT planning. Data were obtained from a study (NCT03137888) where glioblastoma patients received high-dose RT guided by the pre-RT Cho/NAA twice normal (Cho/NAA ≥ 2x) volume, and received spectroscopic MRI scans pre- and mid-RT. Overlap statistics between pre- and mid-RT scans were used to quantify metabolic activity changes after two weeks of RT. Log-rank tests were used to quantify the relationship between imaging metrics and patient overall and progression-free survival (OS/PFS). Patients with lower Jaccard/Dice coefficients had longer PFS (p = 0.045 for both), and patients with lower Jaccard/Dice coefficients had higher OS trending towards significance (p = 0.060 for both). Cho/NAA ≥ 2x volumes changed significantly during early RT, putting healthy tissue at risk of irradiation, and warranting further study into using adaptive RT planning.

A Fully Automated Post-Surgical Brain Tumor Segmentation Model for Radiation Treatment Planning and Longitudinal Tracking.

Glioblastoma (GBM) has a poor survival rate even with aggressive surgery, concomitant radiation therapy (RT), and adjuvant chemotherapy. Standard-of-care RT involves irradiating a lower dose to the hyperintense lesion in T2-weighted fluid-attenuated inversion recovery MRI (T2w/FLAIR) and a higher dose to the enhancing tumor on contrast-enhanced, T1-weighted MRI (CE-T1w). While there have been several attempts to segment pre-surgical brain tumors, there have been minimal efforts to segment post-surgical tumors, which are complicated by a resection cavity and postoperative blood products, and tools are needed to assist physicians in generating treatment contours and assessing treated patients on follow up. This report is one of the first to train and test multiple deep learning models for the purpose of post-surgical brain tumor segmentation for RT planning and longitudinal tracking. Post-surgical FLAIR and CE-T1w MRIs, as well as their corresponding RT targets (GTV1 and GTV2, respectively) from 225 GBM patients treated with standard RT were trained on multiple deep learning models including: Unet, ResUnet, Swin-Unet, 3D Unet, and Swin-UNETR. These models were tested on an independent dataset of 30 GBM patients with the Dice metric used to evaluate segmentation accuracy. Finally, the best-performing segmentation model was integrated into our longitudinal tracking web application to assign automated structured reporting scores using change in percent cutoffs of lesion volume. The 3D Unet was our best-performing model with mean Dice scores of 0.72 for GTV1 and 0.73 for GTV2 with a standard deviation of 0.17 for both in the test dataset. We have successfully developed a lightweight post-surgical segmentation model for RT planning and longitudinal tracking.