With encouraging activity in clinical trials that involve the lysosomal inhibitor hydroxychloroquine (HCQ) (1), the identification of palmitoyl-protein thioesterase 1 (PPT1) as the molecular target of chloroquine derivatives (2), and the launch of novel PPT1 inhibitors into clinical trials (3, 4), there is a need to understand the mechanism by which lysosomal inhibitors induce cell death and the effect of lysosomal inhibition on tumor immunity. Here, PPT1 is linked to neoplasm.