Christoph Schwartz

Prediction of oligodendroglial histology and LOH 1p/19q using dynamic [18F]FET-PET imaging in intracranial WHO grade II and III gliomas

Oligodendroglial components (OC) and loss of heterozygosity on chromosomes 1p and 19q (LOH 1p/19q) are associated with better outcome in patients with glioma. We aimed to assess the fitness of [(18)F]fluoroethyltyrosine positron-emission-tomography (FET-PET) for noninvasively identifying these important prognostic/predictive factors. One hundred forty-four patients with MRI-suspected WHO grade II and III glioma underwent FET-PET scans prior to histological diagnosis. FET-PET analyses included maximal tumoral uptake (SUV(max)/BG), biological tumor volume (BTV), mean tumoral uptake (SUV(mean)/BG), total tumoral uptake (SUV(total)/BG), and kinetic analysis. Suspicion of OC was based on static and dynamic FET-uptake parameters. PET results were correlated with histology and 1p/19q status. OC tumors exhibited significantly higher uptake values, compared with astrocytomas (AC) (SUV(max)/BG 3.1 vs 2.3, BTV 15.5 mL vs 7.2 mL, SUV(total)/BG 38.5 vs 17.4, P < .01 each; SUV(mean)/BG 2.2 vs 2.1, P < .05). These differences were more pronounced in WHO grade II gliomas. Comparable results were found with respect to 1p/19q status. Kinetic analysis misclassified 18 of 34 low-grade OC tumors as high-grade glioma but misclassified only 5 of 45 of the low-grade ACs. FET-based suspicion of OC resulted in concordance rates of both 76% for the prediction of OC and LOH 1p/19q. FET-uptake was significantly higher in gliomas with OC, compared with AC, and likewise in 1p/19q codeleted, compared with noncodeleted tumors. However, FET-PET analysis did not reliably predict the presence of OC/LOH 1p/19q in the individual patient, mostly because of an overlap in PET characteristics of OC tumors and high-grade AC. Histological examination is still required for an accurate diagnosis.

Glucocorticoid (dexamethasone)-induced metabolome changes in healthy males suggest prediction of response and side effects

Glucocorticoids are indispensable anti-inflammatory and decongestant drugs with high prevalence of use at ~0.9% of the adult population. Better holistic insights into glucocorticoid-induced changes are crucial for effective use as concurrent medication and management of adverse effects. The profiles of 214 metabolites from plasma of 20 male healthy volunteers were recorded prior to and after ingestion of a single dose of 4 mg dexamethasone (+20 mg pantoprazole). Samples were drawn at three predefined time points per day: seven untreated (day 1 midday - day 3 midday) and four treated (day 3 evening - day 4 evening) per volunteer. Statistical analysis revealed tremendous impact of dexamethasone on the metabolome with 150 of 214 metabolites being significantly deregulated on at least one time point after treatment (ANOVA, Benjamini-Hochberg corrected, q < 0.05). Inter-person variability was high and remained uninfluenced by treatment. The clearly visible circadian rhythm prior to treatment was almost completely suppressed and deregulated by dexamethasone. The results draw a holistic picture of the severe metabolic deregulation induced by single-dose, short-term glucocorticoid application. The observed metabolic changes suggest a potential for early detection of severe side effects, raising hope for personalized early countermeasures increasing quality of life and reducing health care costs.

Extensive Leptomeningeal Intracranial and Spinal Metastases in a Patient with a Supratentorial Glioblastoma Multiforme, IDH-Wildtype

BACKGROUND Glioblastoma multiforme (GBM) is usually characterized by diffuse, infiltrative growth and local tumor progression. Extensive leptomeningeal metastases are rarely observed. It is unclear which GBMs are prone to this specific growth pattern and progression, and standardized salvage treatment protocols are unavailable. CASE DESCRIPTION In a 45-year-old man without focal neurologic deficit, a right temporal GBM, IDH-wildtype (biomarkers MGMT promoter methylation negative, Ki-67 proliferation rate 70%) was diagnosed. Gross tumor resection followed by concomitant and adjuvant radiotherapy and chemotherapy with temozolomide was performed. Routine follow-up imaging 8 months later showed a right parietal meningeal tumor. Resection confirmed a distant GBM, and next-generation sequencing revealed high tumor mutational burden, high-frequency microsatellite instability, and a pharmacologically targetable KIT mutation. Complete neuraxis imaging revealed multiple contrast-enhancing tumors in the craniocervical junction and levels C7, Th8-Th11, and S1. The craniocervical tumors and the cervical spine from C1-C2 were irradiated as palliative care, and second-line combined chemotherapy and antiangiogenic therapy with irinotecan and bevacizumab was initiated, which was later changed to an immune-checkpoint blockade with pembrolizumab in combination with bevacizumab owing to tumor progression. Tumor growth was slowed, but the patient eventually developed a progressive paraparesis. Subsequent KIT-targeting tyrosine kinase inhibitor therapy with imatinib was administered for a short time. The patient died 13.8 months after initial diagnosis. CONCLUSIONS High-risk genetic profiles for GBMs prone to develop extensive leptomeningeal metastases need to be identified. Guidelines on preemptive, complete neuraxis imaging in certain patients with GBM as well as treatment guidelines need to be developed.

Comment on: the role of biopsy in the management of patients with presumed diffuse low grade glioma: a systematic review and evidence-based clinical practice guideline

To the Editor, We have read with interest the review article by Ragel et al. on ‘‘The role of biopsy in the management of patients with presumed low grade glioma’’ recently published in the ‘‘TOPIC REVIEW & CLINICAL GUIDELINES’’ section of the journal [1]. The authors have analyzed and compared diagnostic yield and accuracy of distinct biopsy techniques within the framework of conventional histologic classification schemes. This approach, however, falls short and cannot be longer used to weigh the pros and cons of different biopsy techniques: It has increasingly become clear that the prognosis of suspected grade II gliomas is not accurately reflected by conventional histological classification [2]. Accordingly, the provided measurements of accuracy are of little help and cannot be linked to valid prognostic evaluation and tailored treatment. Failing to determine the molecular status of the individual tumors might leave patients and their neuro-oncologists with uncertainties regarding prognosis and personalized treatment options. Moreover, conventionally biopsied patients cannot be included in prospective trials demanding stratification for molecular markers. Thus, one of the most important tasks of modern stereotactic neuro-oncology is to provide timely and validly both a molecular and tissue diagnosis enabling a comprehensive characterization of the individual tumor. The paradigm shift towards molecular stereotactic biopsy techniques has already been acknowledged in the literature [3]. It has been shown, for example, that the status of biomarker profiles currently in use is the same throughout the entire viable tumor bulk and therefore can be validly determined from small sized kryo-preserved specimens [3]. Training in stereotactic neurosurgery and molecular stereotactic neuropathology, however, seems to be mandatory to achieve excellent results [3]. We strongly agree that we are currently just at the beginning of new and exciting developments. Tumors will be increasingly screened for their molecular and immunological status initially and over time when they recur after treatment. Molecular biopsy techniques represent a fast, safe, and minimal invasive tool to collect tissue specimens for these important analyses [4].

Endotracheal Tube Electrodes to Assess Vocal Cord Motor Function During Surgery in the Cerebellopontine Angle

BACKGROUND The 10th cranial nerve (CN X) is at risk during surgery in the lower cerebellopontine angle (CPA). OBJECTIVE To evaluate endotracheal surface electrodes for assessment of CN X motor function during CPA surgery. METHODS Twenty patients were enrolled. Electrophysiological recordings were analyzed and retrospectively correlated with clinical, imaging, and intraoperative data. RESULTS Recordings from endotracheal surface electrodes were reliable and eligible for analyses in 17 patients; in 3 patients, no surface electrode compound motor action potentials (CMAPs) could be obtained. Those patients with sufficient recordings underwent surgery in the CPA for tumors in 14 patients and for nontumor pathologies in 3 patients. In 12 patients, bipolar stimulation of motor rootlets in the CPA resulted in simultaneous CMAPs recorded from both surface electrodes and needle electrodes placed in the soft palate. Coactivation was particularly seen in patients with an intricate relationship between lower cranial nerves and tumor formations (n = 9/10). Amplitudes and latencies of vocal cord CMAPs showed high interindividual but low intraindividual variability. Parameters were not well correlated with the type of surgery (tumor vs nontumor surgery) and lower CN anatomy (displaced vs undisplaced). In 2 patients, vocal cord CMAPs were lost during tumor surgery, which was associated with postoperative dysphagia and hoarseness in 1 patient. CONCLUSION Endotracheal surface electrodes allow identification of vocal cord motor rootlets in the CPA. Worsening of CMAP parameters might indicate functional impairment. These aspects support the use of endotracheal surface electrodes in selected patients in whom the vagus nerve might be at risk during CPA surgery.