Osimertinib is an irreversible third-generation EGFR tyrosine kinase inhibitor with activity against common sensitizing EGFR alterations and the T790M resistance mutation.
Pharmacology
Osimertinib targets mutant EGFR signaling. Its design provides activity against EGFR exon 19 deletions, L858R and T790M, among other relevant EGFR alterations depending on the clinical context.
Central nervous system activity
Osimertinib has clinically meaningful CNS penetration and activity. Published reviews describe greater brain exposure and demonstrated intracranial activity compared with earlier-generation EGFR inhibitors.
Pharmacokinetics
The official U.S. prescribing information contains detailed pharmacokinetic data covering absorption, distribution, metabolism and elimination. Osimertinib has a prolonged effective half-life that supports once-daily administration.
Because pharmacokinetic values can vary according to the population and analysis method, clinicians should use the official prescribing information rather than relying on isolated internet summaries.
Resistance
Resistance to osimertinib can arise through multiple mechanisms.
These include:
- EGFR C797S alterations
- MET amplification
- Other bypass pathway changes
- Gene fusions
- Histologic transformation
- Additional molecular changes affecting tumor dependence on EGFR
Major clinical studies
AURA program
Early AURA studies established activity in previously treated EGFR T790M-positive disease and contributed to the initial regulatory development of osimertinib. The EMA reports response data from studies involving previously treated T790M-positive patients.
AURA3
AURA3 compared osimertinib with platinum-pemetrexed chemotherapy in previously treated EGFR T790M-positive advanced NSCLC and demonstrated improved progression-free survival with osimertinib.
FLAURA
FLAURA evaluated first-line osimertinib against first-generation EGFR TKIs in advanced EGFR-mutated NSCLC. The study established osimertinib as a major first-line EGFR-targeted treatment and demonstrated CNS activity.
ADAURA
ADAURA evaluated adjuvant osimertinib after surgical resection in EGFR-mutated NSCLC. The trial demonstrated a substantial reduction in recurrence risk, including reduced CNS recurrence, and later survival analyses supported a significant overall-survival benefit in the studied population.
FLAURA2
FLAURA2 evaluated osimertinib with pemetrexed and platinum chemotherapy versus osimertinib alone in previously untreated advanced EGFR-mutated NSCLC. Regulatory information reports longer progression-free survival with the combination.
LAURA
LAURA evaluated osimertinib following definitive platinum-based chemoradiation in unresectable stage III EGFR-mutated NSCLC. The study supported the subsequent U.S. approval of osimertinib in this setting.
Interpreting clinical evidence
Clinical-trial results apply to defined study populations and treatment conditions. Trial outcomes should not be interpreted as guarantees for individual patients.