Trial: NCT06242522 evaluates fertility and pregnancy after avelumab in women treated for gestational trophoblastic tumors. Drug/intervention: Avelumab—an immune checkpoint inhibitor, human IgG1 monoclonal antibody against PD-L1. Mechanism: Blocks PD-L1 interaction with PD-1 and CD80 (B7.1), restoring T-cell activation and antitumor immunity, its IgG1 Fc can engage FcγRIIIa on NK cells to promote antibody-dependent cellular cytotoxicity (ADCC). Study intervention is data collection via telephone interviews (no new drug given). Targets (cells/pathways): PD-1/PD-L1 immune checkpoint pathway, PD-L1 on tumor/trophoblastic cells and antigen-presenting cells, effector CD8+ T cells (reinvigorated), NK cells (via ADCC). The study monitors implications for maternal–fetal tolerance pathways relevant to pregnancy outcomes.