One suppressive mechanism was recently identified in drug-resistant malignant gestational trophoblastic disease (where invasiveness of fetal tissue apparently does not shut off) [83]: As in other solid tumors [84], Pembrolizumab, a monoclonal antibody that blocks the tumor-expressed programmed cell death ligand 1 (PD-L1) signaling to the T cell inhibitory receptor (programmed death protein 1[PD-1]) pathway, was found clinically effective in inhibiting tumor growth. The gene discussed is CD274; the disease is gestational trophoblastic neoplasm.