Embryonic malignant transformation is concomitant to organogenesis, often affecting multipotent and migratory progenitors. Neuroblastoma (NB) is an emblematic example, arising from neural crest progenitors and characterized by a high heterogeneity and a widely disseminated clinical presentation. Metastatic triggers from the embryonic environment are suspected but yet unknown due to limited investigation access in patients and current models. Using combinations of ex vivo and in vivo models mimicking the embryonic context coupled to proteomic and transcriptomic analyses, we identify Olfactomedin1 (OLFM1) released by sympathetic derivatives at the core of a gene program promoting NB cells decohesion, primary tumor escape and dissemination.