Comparability: what we can learn from the review of advanced therapy medicinal products.

Publicly available summaries from Marketing Authorization Applications for gene and cell therapy products (advanced therapies) were evaluated to explore data expectations for product characteristics pre and post changes (comparability). Public assessment reports were used to analyze trends in information requests from regulators concerning comparability from current commercial advanced therapies. In the analysis, 12 products approved in the USA and EU were included. Inadequacies were highlighted for comparability data (six products); additional information requests (five products) and major objections were identified relating to comparability (two products, EU). Postapproval authorization obligations were imposed for six products. Comparability data are essential component for regulatory applications and public assessment reports provide a valuable source of insight into regulators' expectations.