Katherine Peters

INTRODUCTION: It has long been established that high-dose methotrexate is an essential part of therapy for primary central nervous system lymphoma. When regimens utilizing high-dose methotrexate were first studied, a dose of 8 g/m2 was used. More recently, reduced dosing strategies have been studied and adopted in attempts to reduce rates of adverse events. Studies utilizing 3.5 g/m2 of methotrexate have shown promising outcomes and improved rates of adverse events but there have never been any randomized head-to-head studies of differing dose levels of high-dose methotrexate. The purpose of this study was to compare efficacy and safety of different dosing strategies of high-dose methotrexate (HD-MTX) for primary central nervous system lymphoma (PCNSL). METHODS: This single center retrospective review was conducted between 07/01/2013 to 6/3/2020. The patient population was separated into two arms based upon dose of methotrexate. The high intensity (HiHD) arm was defined as patients who received doses > 3.5 g/m2, while the low intensity (LiHD) arm received ≤ 3.5 g/m2. The primary endpoint was overall response rate (ORR) and secondary endpoints include efficacy via 2-year overall survival (OS), progression to transplant, and utilization of consolidation or salvage therapy. Safety was assessed through monitoring of relevant laboratory studies. RESULTS: A total of 92 patients were included in this analysis. Baseline demographics were similar between groups, with the LiHD group trending toward older age. There were 78 patients eligible for assessment for ORR; there was no significant difference between the two groups (42.0% LiHD vs. 44.4% HiHD; p = 1.0). Rates of OS, progression to transplant and progression to consolidation chemotherapy were not different between groups. There were statistically significantly higher rates of renal and/or hepatic dysfunction with the first dose in the HiHD group compared with the LiHD group (11.5% LiHD vs. 64.3% HiHD; p ≤ 0.01). CONCLUSIONS: In this PCNSL patient cohort, there is no difference in terms of efficacy between HiHD LiHD methotrexate, but patients in the HiHD group had higher rates of renal and hepatic dysfunction. Limitations include small sample size and disparity between group sizes.

Meningiomas are the most common primary intracranial tumor. They are slow growing and often incidentally found tumors that arise from the arachnoid villi. As they grow, they have a greater likelihood of becoming symptomatic with seizures being one of the most clinically significant symptoms. Seizures are more likely to present as a symptom of larger meningiomas and meningiomas that compress cortical areas particularly those in non-skull base locations. These seizures are often managed medically, utilizing the same anti-seizure medications that are used to treat other causes of epilepsy. We discuss common anti-seizure medications used including valproate, phenobarbital, carbamazepine, phenytoin, lacosamide, lamotrigine, levetiracetam and topiramate and their common adverse effects. The goal of pharmacotherapy for seizure control is to maximize seizure control while minimizing the adverse effects of the medication. The decision to provide medical management is dependent on individual seizure history and plans for surgical treatment. Patients who did not require seizure prophylaxis before surgery are commonly prescribed seizure prophylaxis postoperatively. Symptomatic meningiomas not controlled by medical management alone are commonly evaluated for surgical resection. The efficacy of surgical resection in providing seizure freedom is dependent on several features of the tumor including tumor size, the extent of the peritumoral edema, the number of tumors, sinus infiltration and the degree of resection.

Radiation necrosis, also known as treatment-induced necrosis, has emerged as an important adverse effect following stereotactic radiotherapy (SRS) for brain metastases. The improved survival of patients with brain metastases and increased use of combined systemic therapy and SRS have contributed to a growing incidence of necrosis. The cyclic GMP-AMP (cGAMP) synthase (cGAS) and stimulator of interferon genes (STING) pathway (cGAS-STING) represents a key biological mechanism linking radiation-induced DNA damage to pro-inflammatory effects and innate immunity. By recognizing cytosolic double-stranded DNA, cGAS induces a signaling cascade that results in the upregulation of type 1 interferons and dendritic cell activation. This pathway could play a key role in the pathogenesis of necrosis and provides attractive targets for therapeutic development. Immunotherapy and other novel systemic agents may potentiate activation of cGAS-STING signaling following radiotherapy and increase necrosis risk. Advancements in dosimetric strategies, novel imaging modalities, artificial intelligence, and circulating biomarkers could improve the management of necrosis. This review provides new insights into the pathophysiology of necrosis and synthesizes our current understanding regarding the diagnosis, risk factors, and management options of necrosis while highlighting novel avenues for discovery.

The standard regimen for the treatment of newly diagnosed primary CNS lymphoma (PCNSL) remains regimens that contain high-dose methotrexate (MTX). While these regimens can provide control for some patients, there is a dearth of options for the treatment of patients with PCNSL who cannot tolerate MTX-containing regimens, or whose cancers are refractory to MTX. In this article, we review a promising new option; ibrutinib, a Bruton tyrosine kinase inhibitor, for patients with relapsed and refractory PCNSL.

Low-grade gliomas/glioneuronal tumors comprise one-third of all pediatric-type CNS tumors. These tumors are generally caused by activating mutations in the mitogen-activated protein kinase (MAPK) pathway. Targeted drugs, such as trametinib, have shown promise in other cancers and are being utilized in low-grade gliomas. A retrospective chart review was conducted to evaluate radiographic response, visual outcomes, tolerability, and durability of response in progressive circumscribed low-grade gliomas treated with trametinib. Eleven patients were treated with trametinib. The best radiographic response was 2/11 partial response, 3/11 minor response, 3/11 stable disease, and 3/13 progressive disease. In the patients with partial or minor response, the best response was seen after longer durations of therapy; 4 of 5 best responses occurred after at least 9 months of therapy with a median of 21 months. Patients with optic pathway tumors showed at least stable vision throughout treatment, with 3 having improved vision on treatment. Trametinib is effective and well-tolerated in patients with progressive low-grade glioma. Best responses were seen after a longer duration of therapy in those with a positive response. Patients with optic pathway lesions showed stable to improved vision while on treatment.