In comparison with [89Zr]Zr-DFO-seribantumab-F(ab’)2 48 h pi, the tumor-to-blood ratio of [68Ga]Ga-ZHER3 was similar, but [68Ga]Ga-ZHER3 provided significantly better contrast in HER3-expressing organs, particularly in liver, which is a common site for metastases in many cancers. Here, ERBB3 is linked to cancer.