The NP results by target class were benchmarked by comparison with corresponding physical property trends. The results recapitulate the main conclusions of our earlier study using fewer Clinical compounds. The most statistically significant and consistent differences between Fsp3 and stereocenter count are known to be greater in NP and naturally-inspired drugs, and aromatic ring count lower, versus synthetic drugs. However, the [Clinical-Reference] differences for the NP properties of all clinical compounds (n=1091) are not significantly correlated with the corresponding values for these three properties, or for a range of other physicochemical properties (Table .1). Similarly weak correlations are also seen using the target class data (n=17, not shown).