To this end, in this study we exploited the availability of serum samples from an homogeneous cohort of mesothelioma patients, enrolled in the NIBIT-MESO-1 trial (NCT02588131), to investigate the presence and levels of sPD-L1, before and in the course of treatment with the anti-CTLA-4 mAb tremelimumab combined with the anti-PD-L1 mAb durvalumab. This evidence concerns the gene CTLA4 and mesothelioma.