A study examining the tumor microenvironment of metastatic vs. non-metastatic TGCTs reported increased levels of tumor-associated MΦ expressing Programmed death ligand 1 (PD-L1) in seminoma in comparison to non-metastatic TGCTs, proposing that PD-L1+ MΦ influenced the aggressive behavior of the tumors (Sadigh et al., 2020). Here, CD274 is linked to seminoma.