Abstract
RATIONALE: epidermal growth factor receptor (EGFR) mutations play a pivotal role in non-small cell lung cancer (NSCLC), with the EGFR exon 20 insertion (EGFR20ins) mutation being the third most prevalent alteration in the EGFR gene. Patients harboring this mutation typically exhibit a greater tumor burden and poorer overall prognosis. This mutation is strongly associated with resistance to EGFR-TKIs, presenting significant challenges for clinical management. Furmonertinib, an innovative third-generation EGFR-TKI, has been validated in numerous trials for its effectiveness in targeting the EGFR20ins mutation. Against this background, the study aims to explore the clinical application of furmonertinib in patients with advanced EGFR20ins-mutant NSCLC. PATIENT CONCERNS: A patient with advanced EGFR20ins-mutant NSCLC initially presented with a significant tumor burden, resulting in rapid disease progression and a decline in quality of life, which subsequently led to a poor prognosis. DIAGNOSES: Next-generation sequencing of the tumor tissue identified an EGFR20ins mutation (p.p772_H773insPHP) with a mutation prevalence of 83.58%. INTERVENTIONS: The patient received high-dose furmonertinib as first-line treatment. Throughout the treatment, tumor burden, disease stability, progression-free survival (PFS), and adverse effects were closely monitored. OUTCOMES: The patient experienced prolonged advantages from high-dose furmonertinib as initial therapy and attained a PFS of 27 months. The patient demonstrated substantial reduction in tumor burden, attained extended disease stability, and noted enhancements in overall quality of life, accompanied by tolerable adverse effects. LESSONS: Furmonertinib, as a third-generation EGFR-TKI, demonstrated substantial efficacy in patients with advanced EGFR20ins-mutant NSCLC, significantly extending PFS and improving quality of life. This drug offers a promising new treatment option for patients with resistance to conventional therapies. Further studies will help validate the application of furmonertinib in a broader patient population.