P17.15.A ASSOCIATION OF PROTON PUMP INHIBITOR USE WITH OUTCOME OF PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

Abstract BACKGROUND Proton pump inhibitors (PPI) are often prescribed to prevent steroid-induced gastritis and peptic ulcer disease in patients with glioblastoma. Yet, these drugs may enhance the activity of aldehyde dehydrogenase 1 A1 (ALDH1A1) which has been linked to protection from oxidative stress, radiotherapy and chemotherapy. MATERIAL AND METHODS We analyzed data from 2981 patients enrolled into 5 randomized clinical trials for newly diagnosed glioblastoma to explore an association of the use of potent ALDH1A1-activating PPI (PA-PPI) and other anti-acid drugs with outcome. We assessed drug use at baseline and at defined landmarks: start of temozolomide maintenance cycles 1 (landmark 1) and 4 (landmark 2), and end of cycle 6 (landmark 3). RESULTS On univariate analysis, we noted inferior progression-free and overall survival for patients treated with PA-PPI at all 4 time points. The multivariate analysis accounting for age, sex, performance status, steroid use, extent of resection, and O6-methylguanine DNA methyltransferase promoter methylation (MGMT) status confirmed a difference for progression-free survival at landmarks 1, 2 and 3, and for overall survival at landmarks 1 and 2. No such effect was seen for the use of other anti-acid drugs. The negative association of PA-PPI use with outcome was observed independently of MGMT promoter methylation and of steroid use. CONCLUSION We conclude that PA-PPI use should be discouraged in patients with glioblastoma since alternative agents are available and since a detrimental effect cannot be excluded. Translational research studies should explore whether PPI-induced activity of ALDH mediates the potential adverse effects of PPI in glioblastoma.