HER2-ARC

**HER2-ARC** is an investigational HER2-directed targeted radiotherapy described by Actinium as an antibody radiation conjugate built from **trastuzumab** conjugated to a chelator and radiolabeled with **actinium-225** or **lutetium-177** for delivery of cytotoxic radiation to **HER2-expressing solid tumors**. In preclinical studies, the construct retained HER2 binding after radiolabeling and produced direct tumor-cell killing; Actinium also reported that HER2-ARC increased cell-surface calreticulin and showed enhanced antitumor activity when combined with **CD47 blockade**, consistent with a rationale of pairing targeted radioimmunotherapy with macrophage checkpoint inhibition. The program appears to be a **preclinical platform/program concept rather than an approved commercial product**, and public descriptions do not establish a single fixed final clinical composition beyond the trastuzumab-based HER2-targeted radioconjugate using Ac-225 or Lu-177 payloads.

Other names

anti-HER2 antibody radiation conjugateanti-HER-2 antibody radiation conjugateanti-HER 2 antibody radiation conjugateradioisotope-armed trastuzumab225Ac-HER2-ARC177Lu-HER2-ARC