2603.00120 How Well Does the Clinical Pipeline Cover Approved Drug Space? A Reproducible Chemical Diversity Audit of ChEMBL Phase 1–4 Small Molecules
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.