Phase 1/2, multicenter, non-randomized, open-label, multiple-dose first-in-human study of U3-1402 (anti-HER3 antibody drug conjugate) in subjects with HER3-positive metastatic breast cancer.

TPS1116 Background: There is a need for effective late-line treatments in metastatic breast cancer. HER3 overexpression in breast cancer is associated with poor prognosis, but there is as yet no approved targeted treatment against HER3. U3-1402 is a novel antibody-drug conjugate (ADC) comprised of a fully humanized anti-HER3 antibody (patritumab) covalently conjugated via a cleavable peptide linker to a derivative of the topoisomerase I...