PDCD1LG2 and rhabdomyosarcoma: Of note, initial correlation between response and immune cell trafficking in the tumor microenvironment of pre and post treatment tumors of a patient with advanced rhabdomyosarcoma showed stable disease but a significant reduction in % malignant cells vs. TME (70% to 34% malignant cells vs. 30% to 66% TME) in an immune rich non-fibrotic TME and enhanced immune cell trafficking with high expression of PD-L1, PD-L2, CTLA4, CD8+ killer cells, HVEM and tumor associated M2 macrophages in the TME.