To identify relevant pairs in each of our three drug sets (FDA, EGFR and PMB), we computed all pairwise distances in each fingerprint as either Jaccard distance dJ (ECFP4, ECFP6, MHFP6, AP, MAP4, MACCS keys) or Taxicab distance dT (MXFP, MQN). For all fingerprints, distance zero indicates highest similarity. For each molecule in each set, we then selected the NN for each of the eight fingerprints, as well as any molecule appearing in at least seven of the eight lists of top-20 nearest neighbors. In addition, we selected all drug pairs having a certain similarity in each fingerprint by applying a maximum Jaccard distance (dJ ) threshold (see Methods for details).