Pertuzumab, another anti-HER2 monoclonal antibody approved in combination with trastuzumab (dual blockade) for early and advanced breast cancer, was tested as monotherapy at two different dose levels in HER2-negative breast cancer in a phase II trial (Bachelot et al., 2019; Gianni et al., 2016; Swain et al., 2020; von Minckwitz et al., 2017). The gene discussed is ERBB2; the disease is breast cancer.