Peptides, derived from quorum-sensing compounds with potential antitumor structural characteristics, are being investigated towards their selective tumor interactions. Their structures are deduced from chemo-/bio-informatics, as well as from own experimental results. After the chemical-pharmaceutical (bio-)analytical characterization of the original and radiotracer-modified molecules, the functionality is being verified in different in-vitro cell-based and in-vivo rodent-based tumor models.