This study is a prospective, multicenter, single-arm, Phase II clinical trial evaluating the efficacy and safety of ivonescimab (AK112) combined with chemotherapy in patients with pleural mesothelioma who failed prior immunotherapy, anti-angiogenic therapy, or chemotherapy. The regimen consists of a treatment phase (ivonescimab 20mg/kg combined with pemetrexed 500mg/m²/gemcitabine 1000mg/m²/vinorelbine 25mg/m² every 21 days for 4 cycles) followed by a maintenance phase (ivonescimab monotherapy 20mg/kg every 21 days until disease progression, intolerance, or up to 2 years).The trial plans to enroll 25 patients, with the primary endpoint being objective response rate (ORR). Secondary endpoints include progression-free survival (PFS), overall survival (OS), and safety profiles. Exploratory endpoints investigate biomarkers such as tertiary lymphoid structures, tumor-infiltrating lymphocytes, and macrophage polarization within the tumor microenvironment.