To detect PHOX2B pMHC on the cell surface, we generated a tetramerized 10LH scFv and stained on-target and off-target cell lines, which showed significant surface PHOX2B pMHC in neuroblastoma cells and not in HLA-matched controls (Fig. 4f, Extended Data Fig. 15a), suggesting that these reagents have the potential to be used to assess the presence of antigen in biopsied tissue samples. This evidence concerns the gene PHOX2B and neuroblastoma.