RESUMEN
Drug development is a complex, resource intensive and long process in any disease area, and developing medicines to treat rare diseases presents even more challenges due to the small patient populations, often limited disease knowledge, heterogeneous clinical manifestations, and disease progression. However, common to all drug development programs is the need to gather as much information as possible on both the disease and the patients' needs ahead of the development path definition. Here, we propose a checklist named START, a tool that provides an overview of the key pillars to be considered when starting an orphan drug development: STakeholder mapping, Available information on the disease, Resources, and Target patient value profile. This tool helps to build solid foundations of a successful patient-centered medicines development program and guides different types of developers through a set of questions to ask for guidance through the starting phase of a rare disease therapeutic pathway.