Synaptic vesicle protein 2A predicts response to levetiracetam in patients with glioma

Objectives: To correlate SV2A expression in surgically removed tumor and peritumoral tissue of glioma patients with epilepsy with the clinical response to levetiracetam in a prospective cohort. Methods: Forty glioma patients with epilepsy were recruited. All patients had undergone surgery and were on levetiracetam monotherapy. Clinical characteristics were documented. Follow-up visits were scheduled at 3 and 6 months. Patients who responded to levetiracetam were compared to those who did not respond. Expression of SV2A was determined by means of immunohistochemistry in the surgically removed tumor and peritumoral tissue. Optical density (OD) was used to measure SV2A expression. Results: In total, 34 patients were eligible for analysis. Patients with a good response to treatment had significantly stronger SV2A expression as demonstrated by OD in tumor tissue (mean 44.5, SD 17.3) as well as in peritumoral tissue (mean 67.5, SD 7.8) than patients who did not show such a response (mean 8.1, SD 7.7, p < 0.01 and 45.6, SD 11.2, p < 0.01). SV2A expression predicted efficacy of levetiracetam monotherapy with an accuracy of 91%. Conclusions: Our results suggest that expression of SV2A in tumor and peritumoral tissue is correlated to the clinical response to levetiracetam and predicts levetiracetam efficacy. Neurology (R) 2011;77:532-539