Effect of Temozolomide Chemotherapy on Seizure Frequency in Patients with WHO grade II oligodendrogliomas.

Objective: Assess the impact of Temozolomide (TMZ) on seizure frequency in patients with WHO grade II oligodendrogliomas. Background: Assessing efficacy of antitumor treatment in low grade gliomas (LGG) remains challenging. Literature suggests that seizure reduction may serve as a surrogate marker for tumor response. TMZ has been reported to reduce seizure frequency in a subset of patients with LGG. We analyze seizure response to TMZ in patients with low grade oligodendrogliomas. Design/Methods: Retrospective analysis of patients with histopathological diagnosis of WHO grade II oligodendroglioma treated at MSKCC from 2005–2015. All had seizures within 3 months prior to treatment with TMZ despite use of antiepileptic drugs (AEDs) and had available follow up data on seizure frequency after treatment completion. None had other antitumor therapy during TMZ treatment. Results: 42 met inclusion criteria. Eight (19%) had simple partial seizures, 11 (26.2%) complex partial, 7 (16.6%) simple and complex partial, 15 (35.7%) both partial and generalized seizures, 1 had a generalized seizure. All were on AEDs prior to TMZ. Six had prior radiotherapy and 2 had prior PCV. All 42 had previous surgery; 12 (28.5%) biopsy, 20 (47.6%) gross total resection and 15 (35.7%) had a second resection after disease progression. Median time between prior treatment and starting TMZ was 3 years. TMZ was started in 30 patients (71.4%) due to disease progression. AED regimen was changed in 31 (73.8%) within 3 months prior to TMZ treatment. Seizure reduction occurred in 36 (85.7%) with a median of 12 cycles of TMZ treatment (range 4–24). Of those; 29 (80.5%) had radiographically stable disease and 7 (19.5%) had objective radiographic response. AEDs dosage was reduced or completely eliminated in 11 at the end of TMZ treatment. Conclusions: We report a high seizure reduction rate in a homogenous group with WHO grade II oligodendrogliomas which preceded radiographic response to treatment. Disclosure: Dr. Haggiagi has nothing to disclose. Dr. Avila has received royalty payments from Up-To-Date.