CTLA4 and telomere syndrome: Petitprez et al. divided 608 patients with STS into 5 groups based on the different components of their immune microenvironment and found that patients with high immune cell infiltration had higher expression levels of various immune checkpoints, including PD-L1, PD-L2, CTLA-4, and TIM-3, and had a better clinical prognosis (Petitprez et al., 2020).