Structural analysis of several ML hits revealed that they share an identical cyano-containing substructure (Figure ). Based on the crystal structure, this substructure appears to be a key contributor to the binding adinity of this chemical series. In the OpenDEL library, only 0.0035% (104,465 compounds) of the library contained fingerprints corresponding to this substructure, compared to 6.74% (1,939) in the PTEs within the training datasets. Additionally, only 0.9% (3,101) of the NTEs in the training dataset contained these fingerprints. This analysis suggests that DEL screening likely identified this substructure as important for target bioactivity, and the ML model seems to have learned the significance of this structural pattern from the training data.