Neuroblastoma (NB) is an aggressive childhood tumor, with high-risk cases having a 5-year overall survival probability of about 50%. The multimodal therapeutic scheme of NB includes isotretinoin (13cRA), used in the post-consolidation phase as an anti-proliferative and pro-differentiative agent to minimize residual disease and prevent relapse. Through a small molecule screening, we identified isorhamnetin (ISR) as a synergistic compound with 13cRA in inhibiting up to 80% of NB cell viability. To unveil the molecular mechanisms underlying this synergism, microarray analysis was performed in CHP134 control cells, and cells treated with 13cRA (5uM), ISR (15uM), and their combination. This analysis revealed that 13cRA ISR synergism is accompanied by a marked increase in the expression of the adrenergic receptor α1B (ADRA1B) gene. Administration of doxazosin, a safe α1-antagonist used in pediatric patients, with 13cRA in NB xenografted mice exerted a marked control of tumor growth, while each of the two drugs alone was ineffective. We, therefore, preclinically identify the α1B adrenergic receptor as a novel pharmacological target in NB. We propose evaluating the addition of α1-antagonists in the post-consolidation therapy of NB to more efficiently control residual disease. Keywords: isotretinoin, 13cRA, 13-cis retinoic acid, isorhamnetin, ISR, neuroblastoma, polysome profiling, translatome, adrenergic receptors, α-blockers, combinatorial therapy, synergy Overall design: Microarray analysis was performed to enable a comprehensive view of the changes in the translational status of CHP134 cells in response to the treatment with isotretinoin (13cRA), isorhamnetin (ISR), and their combination, to identify synergistic effects. Polysomal RNA was isolated from vehicle-treated CHP134 cells and CHP134 cells treated with 5 µM 13cRA, 15 uM ISR, and both. Each condition is represented by three biological replicates, i.e. the experiment was repeated starting each time from cells seeding yielding an independent RNA sample. In total, 12 samples corresponding to 4 conditions were subjected to microarray analysis.