Similar tumor sizes at day five between mice injected with 89Zr-CD25 IgG and those injected with 89Zr-isotype control Ab (789 ± 118 mg vs. 791 ± 262 mg) in our study further supports the lack of any therapeutic efficacy of 89Zr-CD25 IgG that might limit its applicability in the clinics. Here, IL2RA is linked to neoplasm.