Highlights
- Limertinib, a third-generation EGFR tyrosine kinase inhibitor, significantly improves progression-free survival (PFS) compared to gefitinib in locally advanced or metastatic NSCLC with EGFR-sensitising mutations.
- The median PFS was 20.7 months with limertinib versus 9.7 months with gefitinib (HR 0.44; p<0.0001), indicating a 56% reduction in risk of progression or death.
- Both treatments showed comparable rates of grade 3 or higher treatment-related adverse events (25%), with limertinib demonstrating a manageable safety profile.
Clinical Background and Disease Burden
Non-small-cell lung cancer (NSCLC) represents the majority of lung cancer cases globally, with epidermal growth factor receptor (EGFR) mutations present in approximately 10-40% of patients depending on ethnicity. EGFR-sensitising mutations, notably exon 19 deletions and exon 21 L858R point mutations, confer sensitivity to EGFR tyrosine kinase inhibitors (TKIs). First-generation TKIs such as gefitinib have been standard first-line therapies but are limited by eventual acquired resistance and modest progression-free survival. Third-generation TKIs, designed to overcome resistance mechanisms and improve efficacy, represent a critical unmet need in this population.
Research Methodology
This multicentre, randomised, double-blind, double-dummy, phase 3 trial was conducted across 56 hospitals in China, enrolling adults (≥18 years) with locally advanced or metastatic NSCLC harboring EGFR exon 19 deletion or exon 21 L858R mutations confirmed by the Cobas EGFR Mutation Test. Patients (N=337) were allocated 1:1 to oral limertinib 80 mg twice daily plus gefitinib-matching placebo or gefitinib 250 mg once daily plus limertinib-matching placebo, in 21-day cycles until disease progression or discontinuation. Randomisation was stratified by EGFR mutation subtype and presence of CNS metastases. The primary endpoint was progression-free survival (PFS) assessed by independent central review (ICR). Efficacy analyses included all treated patients, and safety analyses included those with at least one safety assessment.
Key Findings
The median age was 63 years, with 64% female participants. Limertinib significantly prolonged median PFS to 20.7 months (95% CI 15.2-22.1) versus 9.7 months (95% CI 8.3-11.1) with gefitinib (hazard ratio 0.44; 95% CI 0.34-0.58; p<0.0001), indicating a 56% reduction in risk of progression or death. The incidence of grade 3 or higher treatment-related adverse events was identical at 25% in both groups. Treatment-related serious adverse events occurred less frequently in the limertinib group (5%) compared to gefitinib (10%). Mortality due to adverse events was similar (4% each group), with fewer deaths judged related to study drug in the limertinib arm. These data establish limertinib as a more effective first-line option without increasing severe toxicity.
Mechanistic Insights
Limertinib, as a third-generation EGFR TKI, irreversibly inhibits both sensitising and resistance-conferring EGFR mutations, with enhanced blood-brain barrier penetration, potentially explaining improved efficacy and CNS metastasis control. Its selectivity spares wild-type EGFR, reducing off-target toxicity relative to first-generation TKIs like gefitinib.
Expert Commentary
Leading oncologists emphasize the clinical importance of this trial, highlighting that limertinib’s marked PFS advantage could translate into improved quality of life and delayed need for subsequent therapies. Current guidelines increasingly favor third-generation EGFR TKIs in first-line management of EGFR-mutated NSCLC, and this study supports inclusion of limertinib as a new therapeutic option.
Controversies and Limitations
Limitations include conduct exclusively in Chinese centers, which may affect generalizability to other ethnic populations. Overall survival data are pending, which are critical for assessing long-term benefit. Additionally, CNS metastasis subgroups require further analysis to confirm intracranial efficacy.
Conclusion
This phase 3 trial demonstrates that limertinib offers superior efficacy and comparable safety to gefitinib for first-line treatment of locally advanced or metastatic NSCLC with EGFR-sensitising mutations. Limertinib should be considered a valuable addition to the therapeutic armamentarium, addressing an unmet need for improved outcomes in this patient population.
References
- Soria J-C, Ohe Y, Vansteenkiste J, et al. Osimertinib in Untreated EGFR-Mutated Advanced Non-Small-Cell Lung Cancer. N Engl J Med. 2018;378(2):113-125.
- Wu YL, Zhou C, Hu CP, et al. Afatinib versus cisplatin plus gemcitabine for first-line treatment of Asian patients with advanced non-small-cell lung cancer harboring EGFR mutations (LUX-Lung 6): an open-label, randomized phase 3 trial. Lancet Oncol. 2014;15(2):213-222.
- ClinicalTrials.gov. NCT04143607. Efficacy and Safety of Limertinib in NSCLC. Accessed 2024.
