Given the observation that enavatuzumab inhibited the growth of breast cancer cell lines in vitro and that TweakR expression correlated with HER2 overexpression in primary breast cancers, enavatuzumab was assessed for its potential to synergize with trastuzumab, the standard of care for HER2-positive breast cancer. The gene discussed is TNFRSF12A; the disease is breast carcinoma.