Radiation Necrosis

This prospective observational study will investigate the relationship between the gut microbiome and adverse effects following stereotactic radiosurgery (SRS). Patients undergoing SRS as part of their standard clinical care will provide blood and stool samples before treatment and during follow-up. Samples will be analyzed to characterize fecal and blood metabolomic profiles and changes in the gut microbiome over time. The study has two primary objectives: to determine how stereotactic radiosurgery affects the gut microbiome and associated metabolomic profiles, and to evaluate whether microbiome- and metabolite-associated features are related to the development of adverse effects following SRS. Clinical data and standard-of-care neuroimaging will be collected longitudinally to identify outcomes including radiation necrosis and other adverse radiation effects. Biological profiles from patients who develop these outcomes will be compared with those from patients who do not, as well as within individual patients over time. The study aims to identify microbiome and metabolic signatures associated with susceptibility to adverse effects of stereotactic radiosurgery, with the long-term goal of improving risk stratification and informing future approaches to monitoring and treatment.

Cerebral radiation necrosis (CRN) is a severe complication of high-dose radiation for brain metastases (BM) or glioma, which can potentially cause significant neurologic symptoms leading to serious morbidity and impaired quality of life (QoL). The first-line therapy for symptomatic CRN (sCRN) is corticosteroids, primarily dexamethasone, which often leads to complications, refractory symptoms, and interference with anti-cancer treatment. Since 2017, bevacizumab, an antibody against Vascular Endothelial Growth Factor (VEGF), has been used in a second-line treatment setting for refractory sCRN. A small randomized clinical trial (RCT) has shown that bevacizumab significantly diminishes cerebral edema on MRI and decreases clinical symptoms of sCRN in irradiated glioma patients. Several non-randomized clinical studies demonstrated a beneficial radiological and clinical effect of bevacizumab in patients with sCRN after irradiation for BM. The optimal first-line treatment for sCRN is currently unknown. Effective and safe first-line treatment of sCRN will optimize the patient's well-being and health-related QoL. Furthermore, minimizing corticosteroid use will benefit the clinical treatment options and outcomes of concomitant or future anti-cancer treatment. This phase III multicenter, open-label, randomized clinical trial compares the clinical efficacy of first-line bevacizumab versus standard-of-care dexamethasone for sCRN in patients with high-grade glioma (HGG) or BM.

This is a multi-center, randomized, blinded trial evaluating the effect of transcutaneous auricular vagal nerve stimulator (taVNS) on radiation necrosis-related cerebral edema. In this study, consenting and eligible patients will be assigned to one of two arms: treatment (Arm 1) or sham (Arm 2). Patients in both arms will have imaging performed and tissue and blood collected for assessment of changes in area of contrast enhancement and cerebral edema, inflammatory markers, and markers of blood-brain barrier permeability.

Randomized, post-market multi-center study investigating the efficacy of two sets of treatment algorithms in brain metastases (BM) patients at the time of first intervention for radiographic progression after stereotactic radiosurgery (SRS), with or without surgery.

Various treatment options are available for brain metastases, depending on factors such as lesion site or number lesions. Radiotherapy is a commonly used treatment. Following stereotactic radiotherapy for brain metastases, a potential complication, namely brain radionecrosis, can occur subsequently. It is essential to differentiate between this radionecrosis and lesion recurrence in order to determine the appropriate treatment approach. Contrast-enhanced magnetic resonance imaging (MRI) is the most widely used technique for monitoring brain metastases. Therefore, patients undergo routine MRI at 3 months and during subsequent follow-ups, but if the lesion evolve and if distinguishing between recurrence and radionecrosis is challenging, an \[18F\]-FDG PET scan is then prescribed by oncologists or radiotherapists during follow-up consultations. As part of the standard patient management protocol, a 10-minute image acquisition begins after a 45-60 minutes wait following the radiotracer injection. A second image acquisition is then conducted 3-4 hours later. For both acquisitions, a low-dose X-ray scanner is synchronously coupled to allow attenuation correction of the PET images. Patient for whom a \[18F\]-FDG PET cerebral examination has been prescribed as part of the usual management of brain metastases will be eligible to the protocol. If the patient agrees to participate, an early imaging session is initiated immediately upon radiotracer injection, lasting 15 minutes in addition to the standard acquisition protocol.