Global regulatory considerations and practices for tumorigenicity evaluation of cell-based therapy

Cell-based therapy, as a "living drug", possesses inherent complexity and heterogeneity. Tumorigenicity evaluation is a crucial aspect of safety assessment for cell-based therapies. Stem cell-based therapies such as hESCs and hiPSCs, may contain residual undifferentiated cells in final product, which have a high potential for proliferation and differentiation, posing a risk of tumor formation in vivo. Additionally, the source, phenotype, differentiation status, proliferative capacity, ex vivo culture conditions, ex vivo processing methods, injection site, and route of administration also influence the tumorigenicity risk of the cells. Tumorigenicity evaluation needs to consider the complexity of design and multifactorial influences. Through the analysis and summary of partial existing marketed and under-development products, combined with practical experience, it is found that there are many differences in requirements and practices related to cell tumorigenicity globally. Regulatory requirements also vary, and guidance and support for applicants' declaration requirements in different regions need to be considered in conjunction with product characteristics and regulatory considerations. This article comprehensively summarizes the requirements of tumorigenicity from main regulatory agencies. Currently, there is no unified global regulatory consensus on technical implementation guide, measures for quantitation or standardization have not been established for evaluation systems. However, based on regulatory requirements and industry practice summaries, through literature research and analysis of tumorigenicity strategy of representative marketed products, the basic focus, and evaluation strategies for tumorigenicity assessment have been preliminarily clarified, providing a reference for the tumorigenicity design of variety of cell-based therapy products.