Validation of the Media Fill method for Cytokine-Induced Killer cells manufacturing process

Abstract Background. Media fills are used to demonstrate the adequacy of the aseptic conditions of a pharmaceutical production process, according to good manufacturing practice (GMP), using a growth medium place of the product solution. For advanced therapy medicinal product (ATMP), where the final product consists of viable cells, the media fill is still a challenge, but represents the starting point for process validation. Methods. The aim of this paper is to describe the media fill test procedure in the context of ATMP manufacturing, in particular of Cytokine-Induced Killer (CIK) cell expansion process under GMP conditions, including quality control tests and environmental monitoring. The media fill test has been designed to cover all the critical steps of the process, including worst cases and deviations. Results. From July 2019 to August 2022, we performed 16 media fill tests. During these years, the media fill protocol has been gradually improved and the worst cases were designed to be closer to reality and occurring cases. Although some deviations occurred, all the media fills performed were compliant. Conclusions. A good media fill design combined with a robust environmental monitoring program provides a high degree of assurance of the microbial safety of ATMPs.