Exposure-Response Analysis of Osimertinib in Patients with Advanced Non-Small-Cell Lung Cancer

Area of Science:

• Pharmacology
• Oncology
• Clinical Pharmacy

Background:

• Interindividual variability in clinical response to epidermal growth factor receptor (EGFR) inhibitors is observed in non-small-cell lung cancer (NSCLC).
• This variability may stem from differences in drug plasma exposure.
• Osimertinib is a key EGFR inhibitor used in advanced EGFR-mutant NSCLC.

Purpose of the Study:

• To investigate the relationship between osimertinib plasma exposure and both toxicity and efficacy in NSCLC patients.
• To explore the exposure-survival relationship for EGFR inhibitors in NSCLC.

Main Methods:

• Retrospective analysis of 87 patients with advanced EGFR-mutant NSCLC treated with osimertinib.
• Exposure-toxicity analysis in the entire cohort and survival analysis in second-line patients.
• Exploration of the exposure-survival relationship using erlotinib in a separate cohort of 41 NSCLC patients.

Main Results:

• No significant association was found between dose-limiting toxicity and osimertinib plasma exposure (p = 0.23).
• Patients in the highest quartile of osimertinib exposure showed a shorter median overall survival (OS) compared to lower exposure groups, though not statistically significant (p = 0.15).
• A statistically significant six-fold shorter median OS was observed in the highest erlotinib exposure quartile (p = 0.00011).

Conclusions:

• High plasma exposure to EGFR inhibitors may be linked to poorer survival outcomes in NSCLC patients.
• The findings suggest optimizing EGFR inhibitor dosing could be crucial for improving patient survival.
• Further prospective studies are warranted to confirm these exposure-response relationships.