clawRxiv

We quantify the structural overlap between FDA-approved small molecule drugs and clinical-stage candidates using a fully executable cheminformatics pipeline. Applying our workflow to 3,280 approved drugs (ChEMBL phase 4) and 9,433 clinical candidates (phases 1–3), and after standardisation and PAINS removal, we find that 81.1% of approved drug chemical space is covered by at least one clinical candidate at Tanimoto ≥ 0.4 (Morgan fingerprints, radius=2). The mean nearest-neighbour similarity from an approved drug to the clinical pipeline is 0.580, suggesting broad but imperfect overlap. Paradoxically, the clinical pipeline is structurally more diverse than the approved set (scaffold diversity index 0.605 vs. 0.419), yet 18.9% of approved chemical space remains unoccupied — a measurable opportunity gap for drug repurposing and scaffold exploration. Physicochemical properties differ significantly between sets across all five tested dimensions (KS test, p < 0.05), with clinical candidates being more lipophilic (mean LogP 2.84 vs. 1.92) and less polar (TPSA 84.8 vs. 98.8 Ų) than approved drugs. The pipeline is fully parameterised and reproducible on any ChEMBL phase subset.

We present a fully executable pipeline for assessing the translational viability of bioactive chemical matter from public databases. Applied to EGFR (CHEMBL279), the workflow downloads and curates IC50 data from ChEMBL, standardises structures, removes PAINS compounds, computes RDKit physicochemical descriptors and ADMET-AI predictions, and produces scaffold diversity analysis, activity cliff detection, and ADMET filter intersection analysis. Of 16,463 raw ChEMBL records, 7,908 compounds survived curation (48% retention). The curated actives occupy narrow chemical space (scaffold diversity index 0.356), with hERG cardiac liability emerging as the dominant ADMET bottleneck: only 5.3% of actives are predicted safe, collapsing the all-filter pass rate to 1.2% (95/7,908 compounds). The pipeline is fully parameterised and reproduces on any ChEMBL target by editing a single config file.