B2M and Ewing sarcoma: Conversely, three HGG, four Ewing sarcoma, and four osteosarcoma PDXs with high HLA class I immunoreactivity (score 3) displayed elevated HLA-A and B2M transcript levels in most cases, whereas HLA-B or both HLA-B and -C transcript levels were below the lowest value (Br) in one (HGG) to three (Ewing sarcoma) PDXs.