Solid organ xenotransplantation at the interface between research and clinical development: Regulatory aspects

During the last years, progress has been made in survival and function of pig-to-non-human primate organ xenotransplantation using organs from genetically modified pigs and immunosuppression regimens that are clinically acceptable. This, together with increased insights into a low risk of pig-to-human transmission of porcine endogenous retrovirus, has opened the perspective of starting with first-in-human trials with xenogeneic organs. The regulatory path to clinical development is complex. Unlike an organ from human donors, an organ from pigs, either genetically modified or wild-type pigs, is considered a medicinal product for human use and hence is under regulatory oversight, in the United States by the Food and Drug Administration and in Europe by the national competent authorities of the member states as well as the European Medicines Agency. Related to the status of medicinal product, "(current) good practices" apply in the process of generating a xenogeneic organ through to the transplantation into a patient and life-long follow-up. In addition, guidances for xenotransplantation products and genetically modified organisms do apply as well. This commentary focuses on regulatory aspects of transplantation of organs from genetically modified pigs into humans, with the intention to facilitate the interactions between regulatory agencies and institutions (sponsors) in research and clinical development of these organs, to support the perspective of speeding up the process with a proper entry in clinical application, to fill an unmet medical need in patients with end-stage organ disease.