Although most studies refer to this dataset as an external test set, it is far from a real-world test to find new actives versus a new protein target. The PDBbind coreset is stratified from the general set. Every target present in the set is also present in the training set, so there are no new target proteins. This may explain why reports using only PDBbind as training and this external test set show modest performance when trained on protein alone. Regarding the compounds, approximately 30% are duplicates with the training set but bind to different proteins in the test set.