Cognitive disabilities in individuals with Down syndrome (DS), also known as Trisomy 21, have no approved pharmacological treatment and represent a significant burden on DS individuals, their families and the healthcare system. The ICOD project will deliver a clinical proof of concept for a new therapy of cognitive deficits in DS by performing first in humans (phase I) and clinical efficacy (Phase II) studies with AEF0217. AEF0217 is a new chemical entity which offers a unique opportunity to treat cognitive deficits in DS. AEF0217 targets the CB1 receptor, a hyperactivity of which has been recently linked to cognitive deficit in DS. AEF0217 belongs to a new pharmacological class, named signalling specific inhibitors of the CB1 receptor (CB1-SSi), which allows to reverse cognitive deficit in animal models of DS. Because of its innovative MOA, AEF0217 is able to reduce selectively a hyperactivity of the CB1 without modifying the basal activity of this receptor and consequently without inducing behavioural side effects. The overarching goal of the ICOD project is to make this innovative first-in-class drug available for DS individuals 7 years after clinical development initiation.