Independently, a new model was constructed, trained on all 41 instances to determine the importance of descirptors (and not to assess the predictive accuracy). There is a distinct divide between heavy molecules containing relatively large amount of PEG that performed well in shielding APRs and thus improving stability, and both smaller ethoxylated molecules and larger ones without any PEG (Figure ). The PLS results show a clear demarcation between strongly interacting molecules and weak or non-interacting molecules, and reveals physicochemical and structural dierences between the two groups. Broadly, highly branched molecules and those with a high PEG content are within the well-performing cluster (cluster 13 1), while linear molecules and compounds with little to no PEG content are found within the other, broader cluster of poorly performing anti-aggregation agents, with small ethoxylated compounds forming their own grouping along with fatty acids and arginine (cluster 2).