We confirmed ALK cell surface expression via flow cytometry using CDX0239 across four neuroblastoma xenograft models representative of high-risk patients seen in the clinic, an ALK-expressing neuroblastoma cell line with corresponding genetic ALK knockout (KO), a fusion-positive rhabdomyosarcoma xenograft model, and two colorectal carcinoma xenograft models. The gene discussed is ALK; the disease is rhabdomyosarcoma.