title: Metrics other than potency reveal systematic variation in responses to cancer drugs.
abstract: Large-scale analysis of cellular response to anticancer drugs typically focuses on variation in potency (half-maximum inhibitory concentration, (IC50)), assuming that it is the most important difference between effective and ineffective drugs or sensitive and resistant cells. We took a multiparametric approach involving analysis of the slope of the dose-response curve, the area under the curve and the maximum effect (Emax). We found that some of these parameters vary systematically with cell line and others with drug class. For cell-cycle inhibitors, Emax often but not always correlated with cell proliferation rate. For drugs targeting the Akt/PI3K/mTOR pathway, dose-response curves were unusually shallow. Classical pharmacology has no ready explanation for this phenomenon, but single-cell analysis showed that it correlated with significant and heritable cell-to-cell variability in the extent of target inhibition. We conclude that parameters other than potency should be considered in the comparative analysis of drug response, particularly at clinically relevant concentrations near and above the IC50.
authors.affiliation: Harvard Medical School Library of Integrated Network-based Cellular Signatures Center, Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Fallahi-Sichani
authors.forename: Saman
authors.initials: S
authors.lastname: Honarnejad
authors.forename: Laura M
authors.initials: LM
authors.lastname: Heiser
authors.forename: Joe W
authors.identifier: 0000000192256756
authors.initials: JW
authors.lastname: Gray
authors.forename: Peter K
authors.initials: PK
authors.lastname: Sorger
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D013329:Structure-Activity Relationship
chemical_list: D000970:Antineoplastic Agents