Efficacy of 3rd generation TKI in patients with EGFR mutation lung adenocarcinoma with bone metastases: A review of 3 case reports and literature

RATIONALE: With the advancement of targeted therapies, epidermal growth factor receptor tyrosine kinase inhibitors have become the preferred initial treatment for patients with advanced epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer. Osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, is effective against exon 19 and 21 mutations as well as the T790M mutation. It has been approved by both the food and drug administration and European Medicines Agency for the treatment of non-small cell lung cancer patients with locally advanced or metastatic EGFR-mutated tumors, including those who have acquired T790M mutations. PATIENT CONCERNS: To evaluate the effectiveness of osimertinib in treating patients with EGFR-mutated advanced lung adenocarcinoma and bone metastases, we present the treatment outcomes of 3 patients with EGFR 19 deletion-mutated advanced lung adenocarcinoma and bone metastases who received osimertinib treatment in recent years. All 3 cases involved elderly female patients, aged 62, 62, and 54, respectively. DIAGNOSES: All 3 cases exhibited a diagnosis of pulmonary adenocarcinoma accompanied by osseous metastases, with genetic testing revealing the presence of an EGFR 19del mutation. INTERVENTIONS: In the first case, following 17 months of gefitinib therapy, disease progression prompted a switch to osimertinib treatment. In the second case, bone metastases were detected after 20 months of pemetrexed-carboplatin chemotherapy, leading to a transition to osimertinib therapy. In the third case, after 11 months of erlotinib treatment, bone metastases were identified. Subsequent interventions, including radiation therapy, pemetrexed-carboplatin chemotherapy, pemetrexed-bevacizumab maintenance therapy, and docetaxel chemotherapy, failed to arrest the progression of bone metastases. As a result, a combination of osimertinib and anlotinib targeted therapy was administered. OUTCOMES: All 3 patients experienced relatively good and favorable survival outcomes, with a progression-free survival of 22.7 months, 12 months, and 17.7 months, respectively. LESSONS: These cases suggest that osimertinib is a promising treatment option for patients with EGFR 19 deletion-mutated lung adenocarcinoma and bone metastases, although further clinical studies are needed to confirm its efficacy.