Toxicology and Biodistribution: The Clinical Value of Animal Biodistribution Studies

Since the human genome decoding, understanding and identification of genetic disturbances behind many diseases, including cancer, are intensively increasing. Scientific and technological advances in this area trigger the search for therapeutic (curative) approaches targeting the correction of gene disturbances. Gene therapy medicinal products (GTMPs) emerge in this context, bringing new challenges for their characterization. Compared to small molecules, biodistribution is fundamental to identifying target organs and anticipating safety and efficacy, may be integrated into safety and pharmacology studies, and may eventually be anticipated based on specificities of vectors and constructs. This review describes and discusses the requirements for nonclinical development and evaluation of GTMPs versus conventional ones and the needs and challenges of constructing nonclinical packages that assure GTMPs' human safety from early development, taking into consideration usefulness and/or limitations of many conventional, preclinical models. The experience gained in the European context is referenced.