In order to establish 'project progress' with respect to potency, we next defined intervals α, β and γ (as shown in Fig. for the DRD2 dataset) in bioactivity space as follows. The region α is compounds with over middle activity in the early stage, while the region β is compounds with low and middle activity in the middle and late stage and region γ is compounds with high and ultra-high activity in the middle and late stage. We then analyzed progression in the bioactivity domain across different project stages (i.e., to which extent potency could be optimized by the model) by calculating the average similarity of generated molecules to the single nearest neighbour (aSNN) present in a given part of the dataset, based on the Tanimoto similarity of Morgan fingerprints using RDKit and with the aSNN calculations performed as implemented in MolScore .