Compliance with good manufacturing practice (GMP) is mandatory before human transplantation of cell therapies. Once cells are safely delivered, ideally patients should be monitored for the development of potential tumors and activation of the immune system158. One approach for tumor monitoring may be to assess the enhanced angiogenesis that often accompanies teratoma formation, which can be detected using 64Cu-labeled cyclic arginine-glycine-aspartic acid tetramer (64Cu-DOTA-RGD4) radiotracer with positron emission tomography (PET) imaging159. Another approach may be to use a combination of serum biomarkers (e.g., carcinoembryonic antigen, α-fetoprotein, or human chorionic gonadotropin) and magnetic resonance imaging (MRI) screening as described recently160. However, it is worth noting that these approaches would be mostly useful at the preclinical stage, especially if they are already part of the imaging procedure required for evaluating an endpoint. Their feasibility and necessity for future human trials remain to be determined.
