Another related shortcoming of Papyrus is its disregard for peptides and nucleic acids, even more so since one of the most abundant protein classes of level 3 are family A GPCR peptide receptors. This means that, though many drugs and compounds have been designed for these receptors, they do not have a single related data point in the dataset. In turn, related peptide derived models will only show limited performance. In a future version we would like to explore the possibility of increasing peptide representation in the Papyrus dataset, but for now this is what we settled on.