drug screening Article 50 controlled study 45 human 45 Humans 39 nonhuman 39 unclassified drug 32 Animals 31 animal 30 chemistry 30 animal experiment 24 metabolism 23 mouse 22 male 20 human cell 19 animal model 18 Male 16 Mice 16 Xenograft Model Antitumor Assays 16 drug effect 16 in vitro study 16 in vivo study 16 cell proliferation 15 pathology 15 IC50 14 antineoplastic agent 14 female 14 genetics 14 Cell Line, Tumor 13 tumor cell line 13