Purpose: Combining olaparib with carboplatin was recently shown to be active in both BRCA and non-BRCA mutant cancers in a recent phase I/Ib combination trial. The optimal drug sequence recommended was carboplatin 1-day before olaparib. However, carboplatin pre-treatment induced a ~50% faster olaparib clearance.Methods: To further explore this drug interaction, a population pharmacokinetic (PK) model was designed that included a lag time parameter, a second absorption compartment from tablet formulation, a single distribution/elimination compartment, and covariance among the clearance and volume parameters.Results: Clearance (6.8 L/h) and volume (33 L) estimates were comparable with literature. The only significant covariate was the presence of carboplatin on olaparib clearance, consistent with published noncompartmental PK and in vitro data.Conclusions: Simulations predicted lower steady-state peak/trough olaparib exposure through 24-36 h post carboplatin pre-treatment, but this effect was lost by day 2 and thus no dose adjustment is recommended. [ABSTRACT FROM AUTHOR]