VEGFA and peritoneal mesothelioma: The Mesothelioma Stratified Therapy 4 clinical trial (MIST4, clinicaltrials.gov identifier NCT03654833) was designed to examine the efficacy and correlates of response to dual inhibition of programmed death-ligand 1 (PD-L1)-vascular endothelial growth factor (VEGF) inhibition with atezolizumab and bevacizumab (AtzBev) in patients with pleural or peritoneal mesothelioma who had progressed following first-line chemotherapy.