Background:
Lung cancer is the most prevalent malignancy worldwide. Osimertinib has established itself as the standard of care for advanced non-small cell lung cancer harboring EGFR mutations, including both uncommon and compound mutations. This study aims to evaluate the efficacy and safety of Osimertinib in advanced non-small cell lung cancer with uncommon or compound EGFR mutations in Vietnam.
Methods:
This retrospective analysis was conducted on 52 patients with advanced non-small cell lung cancer with uncommon or compound EGFR mutations treated with Osimertinib from January 2021 to March 2026 at Vietnam National Cancer Hospital.
Result:
Of the enrolled patients, 53.8% were ≥60 years old. Multivisceral involvement (≥3 metastatic sites) was reported in 40.4% of the population, and 30.8% had brain metastases. Within the EGFR mutation spectrum identified, uncommon and compound mutations accounted for 30.8% and 69.2% of the cohort, respectively. The objective response rate was 72.8%, and clinical benefit rate was 81.5%. The overall response rate was significantly higher in the smoking group compared to the non-smoking group (p < 0.05). The median progression-free survival (PFS) was 26.04 months. The median PFS was 26.8 months in the compound mutations arm and 10.3 months in the uncommon mutations arm with statistically significant difference (p < 0.05). Multivariate Cox regression analysis revealed that patients with concomitant common mutations had a significantly improved prognosis, with a 71% reduced hazard of progression or death (HR = 0.29; p < 0.05) relative to the group without these mutations. Adverse events were predominantly grade 1–2, most commonly rash (60.2%) and diarrhea (48.6%). One patient discontinued treatment following a diagnosis of interstitial pneumonia.
Conclusion:
Osimertinib is an effective and well-tolerated treatment for advanced NSCLC patients with uncommon or compound EGFR mutations, supporting its clinical utility in this molecular subset.