HEXB and nasopharyngeal carcinoma: These preliminary clinical findings have been supported by in vitro studies in NPC and GM2 gangliosidoses patient cell lines, and in vivo studies in the NPC (Npc1−/−) and Sandhoff (Hexb−/−) mouse models, which corroborate the pharmacological properties of N-acetyl-l-leucine and N-acetyl-dl-leucine in relation to the observed therapeutic effects (Ecem Kaya and Frances Platt, personal communication) [19].