The novel anti-HER3 ADC (patritumab DXd; U3-1402) consisting of the anti-HER3 antibody patritumab conjugated with the topoisomerase isomerase inhibitor DXd as the toxin payload has been investigated as monotherapy in a safety study of patients with EGFR inhibitor resistant, EGFR-mutated lung cancer [151] and is currently being evaluated in patients with HR+/HER negative early breast cancer (NCT04610528) [152]. The gene discussed is ERBB3; the disease is breast cancer.