The use of oil adjuvants in therapeutic vaccines

Water in oil emulsions represents one of the new promising generations of adjuvants for immunotherapy. Fifty years ago, incomplete freund adjuvant (IFA) has been used in clinical trials for prophylactic vaccines like poliomyelitis or flu vaccine because of its strong potency. However, even if the quality of the raw materials has been improved in order to avoid secondary reactions, the risk benefit ratio was not favorable to its use for prophylactic vaccines. Moreover, emulsions were highly viscous with a weak stability. The development of new adjuvants concepts like liposomes, oil in water emulsions, bacterial immunostimulating compounds has induced a loss of interest for such formulations. The emergence of immunotherapy treatments for cancer, AIDS or other diseases leads to the re-emergence of these adjuvants, as the risk benefit ratio is more favorable. Then, safety of these adjuvants has been improved by the use of more specific surfactants and refined oils but also by improving their manufacturing process, allowing even sometimes their use in clinical trials for prophylactic vaccines.