Population Pharmacokinetics and Exposure-Response Analysis of First-Line Osimertinib Plus Chemotherapy in Patients...

Area of Science:

• Pharmacology and Oncology
• Clinical Trial Analysis

Background:

• Osimertinib is a third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) effective in EGFR-mutated non-small cell lung cancer (NSCLC).
• The FLAURA2 trial demonstrated improved progression-free survival (PFS) with first-line osimertinib plus chemotherapy compared to osimertinib monotherapy in advanced NSCLC.
• Understanding osimertinib pharmacokinetics (PK) and its relationship with efficacy and safety is crucial for optimizing treatment.

Purpose of the Study:

• To conduct a population pharmacokinetic (PopPK) analysis of osimertinib and its active metabolite, AZ5104, using data from 2,196 patients across six clinical studies.
• To assess the impact of intrinsic and extrinsic factors on osimertinib PK variability.
• To evaluate the relationship between osimertinib exposure and PFS, as well as safety outcomes in the FLAURA2 combination arm.

Main Methods:

• Population pharmacokinetic modeling was performed using pooled data from six Phase I-III studies (AURA, AURA2, AURA3, ADAURA, FLAURA, FLAURA2).
• Covariate analysis identified factors influencing osimertinib and AZ5104 pharmacokinetics.
• Cox proportional hazard models assessed the exposure-PFS relationship in FLAURA2, and exposure-safety relationships were analyzed for adverse events.

Main Results:

• No covariates were found to have a clinically meaningful impact on the pharmacokinetics of osimertinib or its active metabolite, AZ5104.
• Osimertinib exposure did not show a relationship with progression-free survival in the FLAURA2 combination arm; pemetrexed cycles were associated with PFS.
• No exposure-safety relationship was observed for osimertinib concerning adverse events, including those leading to dose modifications.

Conclusions:

• The population pharmacokinetic analysis confirms minimal impact of patient-specific factors on osimertinib exposure, supporting consistent dosing.
• The established efficacy of first-line osimertinib plus chemotherapy in FLAURA2 is further reinforced by the PK/PD and safety findings.
• Osimertinib 80 mg once daily in combination with chemotherapy represents a robust first-line treatment option for patients with EGFR-mutated advanced NSCLC.