Citations

Abstract BACKGROUND BRAF pathway alterations are frequent in glial/neuroepithelial tumors. BRAF-targeted therapy with BRAF inhibitors (BRAFi) and/or MEK inhibitors (MEKi) has proven efficacy in clinical trials, though mainly enrolling pediatric patients. We sought to investigate real-world data for adult patients with BRAF-pathway mutant glial/neuroepithelial neoplasms treated with BRAFi/MEKi. METHODS Adults with BRAF-pathway mutated glial/neuroepithelial neoplasms treated with BRAFi/MEKi were retrospectively reviewed. RESULTS Five patients (n=4 female, median age at diagnosis 36) were identified (tumor types: glioblastoma n=1, high-grade astrocytoma with epithelioid features n=1, low-grade neuroepithelial tumor n=1, pilocytic astrocytoma n=1, pleomorphic xanthoastrocytoma n=1). Four had BRAF V600E and one had NF1 p.S2687Cfs*5 mutant tumors. Prior to targeted therapy initiation, patients underwent a median 2.4 treatments including surgery (n=4), radiation therapy (n=4), chemotherapy (temozolomide n=4; carboplatin/vincristine n=1). BRAF-targeted therapies included dabrafenib/trametinib (n=4), binimetinib/encorafenib (n=2), binimetinib (n=2). One NF1-mutant glioblastoma received binimetinib followed by binimetinib/bevacizumab. Median BRAFi/MEKi treatment was 15.2 months (range: 6-36 months). Toxicities included leukopenia (n=3), peripheral edema (n=1), reduced ejection fraction (n=1), skin rash (n=5), transaminitis (n=1) with all patients requiring dose reductions and 3 cases requiring discontinuation. Among patients where BRAFi/MEKi was discontinued due to toxicity, 2 received other treatments at progression, then switched to a different BRAFi/MEKi combination, which they tolerated (duration 6-10months). Best radiographic response was partial response, noted in 3 patients treated with dabrafenib/trametinib. Four patients remain alive and continue BRAFi/MEKi. CONCLUSIONS In this cohort of heavily-pretreated patients with glial/neuroepithelial neoplasms, BRAF-targeted therapy was associated with durable responses. Interestingly, two patients who were unable to tolerate one combination of BRAFi/MEKi were able to tolerate a different combination with sustained response. Our findings support ongoing use of BRAF targeted therapy for CNS tumors. Optimal timing and duration of treatment requires further prospective evaluation in adult patients.

Abstract Von Hippel-Lindau (VHL) disease is caused by pathogenic variants in the VHL gene. Abnormal function of VHL protein leads to accumulation of HIF-α and the engagement of hypoxia-sensitive genes with oncogenic effects. VHL is associated with tumors in multiple organs. Belzutifan is an oral selective inhibitor of hypoxia-inducible factor 2 alpha. Belzutifan was approved in 2021 as a targeted therapy for VHL-associated CNS hemangioblastomas, renal cell carcinomas, and pancreatic neuroendocrine tumors. Here, we report on our institutional clinical experience with belzutifan for VHL-associated CNS hemangioblastomas. From October 2021 to May 2024, thirteen adults (9 female, 4 male, median age 40) were treated. Median duration of therapy was 24 months. Seven had a partial radiographic response after median of 3 months; one patient had a partial response; 1 patient had progressive disease on belzutifan. Four patients have been taking belzutifan for less than 3 months, and do not have follow-up imaging to assess response. The most common adverse effect was fatigue (7 patients). Four patients experienced anemia and 2 experienced hypoxia. Three patients discontinued belzutifan due to adverse effects. One patient had to take multiple medication pauses, due to seizure and kidney injury, but resumed treatment with dose reduction. Nine patients remain on therapy. Based on this data, belzutifan is often well-tolerated and associated with durable radiographic responses. Toxicity profile among our patients was similar to that encountered in the clinical trial leading to approval of the agent. These findings provide real-world data supporting continued use of belzutifan in this patient population, with an awareness of potential adverse reactions. Future studies should assess continued radiographic response, sex differences, and effects after long-term use.

Abstract BACKGROUND Pituitary adenomas are often effectively managed with medical therapy, surgery, and radiation therapy. However, up to 15% of pituitary neoplasms exhibit rapid growth, invasive behavior, or, rarely, metastasize despite optimal standard treatments. Temozolomide is associated with a survival benefit for patients with these aggressive pituitary tumors. METHODS We present a case series of 8 patients with an aggressive pituitary tumor (APT) or pituitary carcinoma (PC) treated with temozolomide. RESULTS Eight patients (3 female, median age at diagnosis 44) with APT (n=6) or PC (n=2) were treated. A variety of pituitary tumor types were represented (1 prolactinoma, 5 corticotroph adenomas, 1 gonadotroph adenoma, 1 thyrotropinoma). Prior to temozolomide initiation, patients underwent a median 5 treatments including medical management (n=4), surgery (n=7), radiation therapy (n=7). Temozolomide was started at median 3.5 recurrence. Median treatment duration was 6 cycles (n=6, 150-200 mg/m2 days 1-5, 28-day cycles; n=1, 75 mg/m2, days 1-21, 28-day cycles). Seven patients experienced progression after temozolomide treatment, median progression-free survival (PFS) was 4 months. One patient remains on treatment, progression-free at 5 months. MGMT methylation status was assessed for 3 tumors. Among 2 patients with MGMT promoter methylated tumors, PFS was 4 months for one patient, the other remains on treatment. For one patient with MGMT promoter unmethylated corticotroph adenoma, PFS was 9 months. No ≥ grade 4 toxicities were noted. Most common toxicities were nausea (n=5), thrombocytopenia (n=3), and fatigue (n=2). CONCLUSION In this group of heavily pretreated patients, temozolomide monotherapy was well-tolerated and associated with median PFS of 4 months. Interestingly, PC patients had longer PFS at 9 months and 24 months. Our findings support use of single-agent temozolomide chemotherapy for patients with APT/PC, but further prospective analysis is needed to identify patients more likely to benefit from treatment and optimal timing of chemotherapy initiation.

Abstract INTRODUCTION Belzutifan is a selective inhibitor of hypoxia-inducible factor 2-alpha that has been FDA approved for Von Hippel–Lindau (VHL) syndrome-associated tumors. There is limited real-world evidence in CNS hemangioblastoma. Our objective was to report on our clinical experience with belzutifan. METHODS We retrospectively reviewed our institutional (Mayo Clinic Rochester) experience of belzutifan in adults (18 years or older) with VHL and craniospinal hemangioblastomas not amenable to surgery. The study period was October 2021 to March 2023. RESULTS 4 patients (all female) with a median age of 36 years at time of belzutifan initiation were included. Median duration of therapy at last follow-up was 11 months (6-17 months). All patients had radiographic response to therapy after a median of 3 months (2-5 months), with maximal response to therapy after a median of 8 months (3-17 months). Therapy was well tolerated. The most common adverse effect was anemia. No patients had treatment pauses or dose adjustments due to toxicity. No patients experienced hypoxia. DISCUSSION We showed that belzutifan is safe and well-tolerated with strong disease response for CNS hemangioblastoma in adults with VHL, supporting continued use of belzutifan in this patient population. Future studies should assess duration of treatment, effects of cessation after long-term use, and markers of therapeutic response.

Abstract BACKGROUND Dexamethasone is commonly used to manage peritumoral edema and alleviate neurologic symptoms in patients with intracranial tumors. The optimal dexamethasone dose for brain metastases is unknown and widely variable. Recent literature reports the most common regimen is 4 mg four times daily. However, the half-life of dexamethasone is 35-54 hours, suggesting that such frequent dosing may be unnecessary. We explored the dose-effect relationship of dexamethasone on brain metastases patient outcomes to improve quality of care. METHODS We retrospectively identified 100 patients (1/1/2016 – 12/31/2022) with brain metastases who were treated with dexamethasone and had adequate follow-up. All patients received standard oncologic care including chemotherapy, radiotherapy, and/or surgical intervention. We evaluated the association between dexamethasone dosing regimens (< 4 mg twice daily versus > 4 mg three times daily), clinical outcomes (performance status, clinical and radiographic response to corticosteroids, survival), and dexamethasone adverse effects during the acute presentation and at first neuro-oncologic follow-up. RESULTS Seventy-two patients received less frequent dexamethasone dosing (< 4 mg twice daily), while 28 received more frequent dexamethasone dosing (> 4 mg three times daily). Patients with higher frequency dexamethasone dosing were more likely to have radiographic evidence of midline shift (p < 0.001), compression of ventricles (p < 0.001), and herniation (p = 0.0020) at presentation. Those with more frequent dosing more often demonstrated radiographic response to dexamethasone (67.9% vs. 45.8%, p = 0.0323), but there were no differences in symptomatic improvement, Karnofsky Performance Status, seizure reduction, survival, or the frequency of adverse events (e.g., hyperglycemia, hypertension, infection, psychosis) between the two cohorts. CONCLUSIONS These results suggest that for most patients with brain metastases, less frequent dexamethasone dosing may lead to clinical outcomes that are similar to those patients who received more frequent dosing. However, higher doses of dexamethasone can be considered for those with more concerning radiologic features.

Abstract BACKGROUND Dexamethasone is commonly used for symptomatic management in primary central nervous lymphoma (PCNSL). The optimal dosing scheme for dexamethasone is unknown and practice patterns widely vary among clinicians. In this study, we explored the dose-effect relationship of dexamethasone on PCNSL outcomes to better influence quality care for these patients. METHODS We retrospectively identified 24 Mayo Clinic patients (1/1/2018 – 12/31/2022) with pathologically confirmed PCNSL who received dexamethasone. All patients otherwise received standard oncologic care including methotrexate-based systemic chemotherapy and/or radiotherapy. The association between dexamethasone dosing regimens and clinical outcomes (performance status, clinical and radiographic response, survival) in addition to potential adverse effects were evaluated in the acute phase of presentation and at first post-treatment oncology follow up. RESULTS Nine patients received less frequent dexamethasone dosing (4 mg twice daily or less), while 15 received more frequent dexamethasone dosing (4 mg four times daily). Fourteen patients received dexamethasone prior to biopsy, 2 of which (1 in each cohort) had a non-diagnostic biopsy and required a second procedure 3 weeks to 3 months later to confirm PCNSL diagnosis. There were no statistically significant differences in time to diagnosis from presentation or clinical and radiographic improvement including Karnofsky Performance Status, reduction in seizures, or survival between the two cohorts. Additionally, there were no differences in the frequency of adverse events (e.g., hyperglycemia, hypertension, infection, psychosis) between the two dosing regimens. CONCLUSIONS These results suggest that more frequent dexamethasone dosing is not associated with better clinical outcomes in the symptomatic management of PCNSL. Twice daily or less frequent dosing can be considered without compromising patient outcomes.

Abstract Pleomorphic xanthoastrocytomas (PXAs) are rare primary brain tumors that mainly affect children and young adults. We report a case of recurrent PXA in an adult and review the literature. To our knowledge, this is the first adult report highlighting clinical, CSF, and imaging findings of recurrent PXA with leptomeningeal spread. A 60-year-old woman presented with a 2-month history of fluctuating mental status, aphasia, low-back pain, progressive paraparesis, and urinary retention. She was previously diagnosed with a left temporal PXA 17 years prior and underwent gross total resection with no evidence of tumor recurrence for the next several years. Approximately 10 months prior to her current presentation, she was found to have radiographic recurrence of the left temporal PXA. She underwent gross total resection, with final pathology revealing anaplastic transformation, WHO grade 3, BRAF V600E mutation positive. She next underwent photon radiotherapy, and chemotherapy with temozolomide. She had good clinical and radiographic response to treatment for 8 months prior to developing her current symptomatology. MRI of the brain and spine showed local recurrence with new diffuse contrast enhancement of the spinal cord and nerve roots. Cerebrospinal fluid (CSF) analysis showed a total nucleated cell count of 10/mcL, protein >1250 mg/dL, glucose < 20 mg/dL, and xanthochromia. CSF cytology was positive for malignant cells consistent with PXA. Although PXA is often associated with a favorable prognosis, recurrence with anaplastic transformation can be associated with dissemination throughout the nervous system and worse outcomes. Despite the rarity of such cases, clinicians should remain vigilant, especially when anaplastic transformation occurs. Early detection of leptomeningeal involvement through thorough CSF analysis and appropriate imaging can facilitate prompt intervention and potentially improve patient outcomes.

Abstract Low-grade meningiomas with subtotal resection carry significantly shorter recurrence-free survival rates than those with gross total resection. We report the natural history of a case of low-grade meningioma after subtotal resection and review the literature. We aim to highlight known global health disparities in oncology treatment by describing a case of meningioma progression following subtotal resection. A 40-year-old Kenyan woman presented locally with headache, nausea, and vision loss over approximately a six month time period. A 5 cm olfactory groove meningioma was discovered, and she subsequently underwent subtotal resection that was likely limited due to hemorrhagic complications. Over the following two years, she developed progressive dizziness, nausea, gait instability, difficulty performing tasks, and visual loss prompting medical evaluation at our institution. Physical examination demonstrated blindness, bilateral proptosis with severe vertical gaze palsy, and prominent frontal bossing. MRI Brain revealed a 9 cm enhancing mass arising from the cribriform plate with elevation of an ununited overlying frontal craniotomy flap and apparent meningoceles extending through the presumed osteotomy bilaterally. She underwent successful resection with pathology demonstrating CNS WHO Grade 1 meningioma. Her postoperative neurologic exam showed subtle improvement, specifically in regards to orientation questions. In this patient, bone flap displacement from prior craniotomy allowed significant interval tumor growth while minimizing mass effect on brain parenchyma. This case highlights global health disparities in low-grade meningioma management related to appropriate healthcare access in underserved patients.