This case report aims to explore the feasibility and efficacy of ivonescimab monotherapy in an elderly patient with EGFR-TKI-resistant advanced lung adenocarcinoma complicated by malignant pericardial effusion.<h4>Case presentation</h4>A 77-year-old female with a 19-year history of postsurgical left lung adenocarcinoma was admitted with dyspnea and edema. The gene discussed is EGFR; the disease is lung adenocarcinoma.