CD38 and neoplasm: Furthermore, we demonstrated the specificity of [68Ga]Ga‐AJ206 for CD38 by co‐administering 2 mg kg−1 nonradioactive AJ206, which significantly reduced the radioactivity uptake in MM1S tumor xenografts (P < 0.01) (Figure 4D,E), however no significant difference was observed in nonspecific tissues (Figure S6, Supporting Information).