The present invention relates to Proton Pump Inhibitors (PPI) for use as immunomodulators which allow to overcome immune escape in antineoplastic therapy, chronic inflammatory diseases associated with an acidic microenvironment and in chronic infection thereto associated.The therapeutic efficacy of PPIs is guaranteed by their ability of inhibiting the activity of the hydrogen/potassium adenosine triphosphatase enzyme system (H+/K+- ATPase or proton pump).The PPI according to the present invention is advantageously selected from the group consisting of omeprazole, lansoprazole, pantoprazole, esomeprazole, dexlansoprazole, rabeprazole, tenatoprazole or a mixture thereof.Additionally, the disclosure describes a vaccine composition comprising at least one Proton Pump Inhibitor and pharmaceutically acceptable excipients.
