<i>In vivo</i> tumor binding was evaluated by PET-CT imaging with <sup>89</sup>Zr-labeled MIL33B in murine xenograft (HeLa cervical) and syngeneic tumor models (4T1 breast, B16F10 melanoma, CT26 colorectal) expressing human 4Ig-B7-H3. The gene discussed is CD276; the disease is melanoma.