Modeling interpatient pharmacodynamic variability of etoposide

Area of Science:

• Pharmacology
• Mathematical modeling
• Oncology

Background:

• Etoposide therapy can cause severe myelosuppression, necessitating personalized dosing strategies.
• Pharmacodynamic variability among patients complicates etoposide dose optimization.
• Adaptive control dosing aims to individualize etoposide administration to mitigate toxicity.

Purpose of the Study:

• To develop and validate precise pharmacodynamic models for etoposide effect on white blood cell count nadir.
• To investigate linear and nonlinear models for interpatient variability in etoposide response.
• To identify key factors influencing etoposide-induced myelosuppression for improved dosing.

Main Methods:

• Modeling interpatient pharmacodynamic variability of etoposide effect using white blood cell count nadir.
• Investigating new linear and nonlinear pharmacodynamic models with patient data.
• Cross-validation of developed models on an independent patient cohort.
• Utilizing a 72-hour continuous infusion etoposide dosing regimen.

Main Results:

• An unbiased nonlinear Hill model demonstrated high precision in predicting white blood cell count nadir.
• The optimal model incorporated 24-hour etoposide concentration, pretreatment white blood cell count, and serum albumin level.
• Lower pretreatment albumin levels were identified as a risk factor for severe myelosuppression.

Conclusions:

• A validated nonlinear pharmacodynamic model enables adaptive control dosing of etoposide.
• Individualized dosing based on this model can reduce the risk of severe myelosuppression.
• Serum albumin level is a critical predictor of etoposide toxicity, reflecting both kinetic and dynamic factors.