Hydroxychloroquine was first established as an anti-malarial agent, but is now being used in a variety of applications, including the inhibition of autopagy.  Hydroxychloroquine is a lysosomotropic agent and therefore inhibits autophagy by obstructing the final step of autophagy, the fusion of autophagosomes with lysosomes, thereby preventing the acidification of the lysosomal compartment.  In the context of cancer, autophagy is thought to be adopted by tumor cells to survive in the nutrient-deficient and hypoxic tumor environment. Hydroxychloroquine has therefore been studied extensively within the context of certain cancers.