The manufacture of medicinal products in the European Union (EU) is subject to manufacturing authorisation. Any legal entity, generally a company, wishing to manufacture a medicinal product must hold a manufacturing authorisation issued by the national competent authority of the Member State where they carry out these activities. To obtain a manufacturing authorisation, all medicinal products for human use intended for the EU market must be produced in accordance with EU quality standards: Good Manufacturing Practice (GMP) principles and guidelines, and the European Pharmacopeia. The manufacturers are also obliged to have a qualified person responsible for ensuring that the requirements adopted for the manufacturing authorisation and the applicable legislation are respected. Ensuring the quality of medicines is a criterion to obtain marketing authorisation and corresponds to Module 3 of the Marketing Authorisation Application dossier, "Chemical, pharmaceutical, and biological documentation" (Chemistry, Manufacturing and Controls -CMC) that aims to determine the specifications capable of guaranteeing the reproducibility of the medicine’s composition. This stage is particularly challenging for Advanced Therapy Medicinal Products (ATMPs) regarding their level of complexity (especially for manufacturing processes) and their specific characteristics, especially the use of substances of human origin such as blood, tissues and cells, and the reproducibility when using live biological samples. That is why, Guidelines on GMP specific to ATMPs have been published in 2017 by the European Commission, in accordance with Article 5 of Regulation (EC) No 1394/2007.