This case report describes a 51-year-old male with advanced Epidermal Growth Factor Receptor (EGFR) mutant (p.T790M and p.L858R) lung adenosquamous carcinoma who achieved a rapid partial response (PR) to ivonescimab monotherapy following progression on multi-line therapies, including third-generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs), platinum-based chemotherapy, anti-angiogenic therapy, and immune checkpoint inhibitors. Here, EGFR is linked to adenosquamous carcinoma.