Affiliation:
1. Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy University of North Carolina at Chapel Hill Chapel Hill North Carolina USA
2. Department of Medical Oncology Erasmus MC Cancer Institute Rotterdam The Netherlands
3. Department of Clinical Chemistry Erasmus MC University Medical Center Rotterdam The Netherlands
4. Department of Pharmaceutical Sciences, University at Buffalo School of Pharmacy and Pharmaceutical Sciences State University of New York at Buffalo Buffalo New York USA
5. Institute for Artificial Intelligence and Data Sciences, University at Buffalo State University of New York at Buffalo Buffalo New York USA
Abstract
Neutropenia is the major dose‐limiting toxicity of irinotecan‐based therapy. The objective of this study was to assess whether inclusion of germline genetic variants into a population pharmacokinetic/pharmacodynamic model can improve prediction of irinotecan‐induced grade 4 neutropenia and identify novel variants of clinical value. A semimechanistic population pharmacokinetic/pharmacodynamic model was used to predict neutrophil response over time in 197 patients receiving irinotecan. Covariate analysis was performed for demographic/clinical factors and 4,781 genetic variants in 84 drug response‐ and toxicity‐related genes to identify covariates associated with neutrophil response. We evaluated the predictive value of the model for grade 4 neutropenia reflecting different clinical scenarios of available data on identified demographic/clinical covariates, baseline and post‐treatment absolute neutrophil counts (ANCs), individual pharmacokinetics, and germline genetic variation. Adding 8 genetic identified covariates (rs10929302 (UGT1A1), rs1042482 (DPYD), rs2859101 (HLA‐DQB3), rs61754806 (NR3C1), rs9266271 (HLA‐B), rs7294 (VKORC1), rs1051713 (ALOX5), and ABCB1 rare variant burden) to a model using only baseline ANCs improved prediction of irinotecan‐induced grade 4 neutropenia from area under the receiver operating characteristic curve (AUC‐ROC) of 50–64% (95% confidence interval (CI), 54–74%). Individual pharmacokinetics further improved the prediction to 74% (95% CI, 64–84%). When weekly ANC was available, the identified covariates and individual pharmacokinetics yielded no additional contribution to the prediction. The model including only ANCs at baseline and at week 1 achieved an AUC‐ROC of 78% (95% CI, 69–88%). Germline DNA genetic variants may contribute to the prediction of irinotecan‐induced grade 4 neutropenia when incorporated into a population pharmacokinetic/pharmacodynamic model. This approach is generalizable to drugs that induce neutropenia and ultimately allows for personalized intervention to enhance patient safety.