ED-03 * THE IMPACT OF VALPROIC ACID USE ON HIGH GRADE GLIOMA

Abstract

BACKGROUND: Valproic acid (VPA), other than its seizure activity, has shown potential benefit as a chemosensitizing agent due to its histone deacetylase inhibitor activity in the management of patients with high grade glioma. On the other hand, VPA could also potentially increase the toxicity of chemotherapeutic agents. We aim to study the use of VPA on the outcomes of patients with high grade gliomas. METHODS: All patients with high grade glioma seen at the Neuro-oncology clinic in National Cancer Centre Singapore between 2006 to 2008 were analyzed retrospectively. Patients with high grade glioma, defined as World Health Organization (WHO) grade III or IV astrocytic, oligodendroglial, oligoastrocytic tumors were included in the study. RESULTS: A total of 122 patients were analyzed. Median age of diagnosis for the cohort was 49.6 years. 87 patients (71.3%) underwent surgical resection, while 33 patients (27%) had a biopsy performed. In the cohort, 60 patients (49.2%) had concurrent temozolomide and radiotherapy thereafter. Median follow up time for the cohort was 1.5 years. Median overall survival (OS) was comparable for VPA users and non-users (VPA users: 25.2 months (95% CI: 18.0, 48.0) versus non-VPA users: 33.6 months (95% CI: 20.4, 67.2), p = 0.348). Among the 60 patients who underwent concurrent temozolomide and radiotherapy, the use of VPA conferred a marginal worsening of OS (VPA users: 25.2 months (95% CI: 18.0, 38.4) versus non-VPA users: 33.6 months (95% CI: 20.4, 67.2), p = 0.083). CONCLUSIONS: In our study, high grade glioma patients on VPA have similar median OS compared to those who were not on VPA. However, there is a trend towards decreased overall survival in those patients who had concurrent temozolomide and radiotherapy with VPA use. This could be related to increased treatment toxicity. The role of VPA in high grade glioma will need to be clarified in further studies.