The αFAP-scFv TM showed a maximum tumor uptake already after 1 h p.i., whereas the αFAP-IgG4 TM seems to start accumulating at the FAP-positive tumor site at around 6 h p.i., reaching its maximum tumor accumulation at around 48 h p.i. Besides its increased tumor uptake and persistence, the αFAP-IgG4 TM demonstrated prolonged blood circulation and delayed clearance due to its extended molecular size. This evidence concerns the gene FAP and neoplasm.