To this end, we leveraged members from our library of Sx-GTs to generate a homogenously glycosylated variant of trastuzumab (Fig. 5a), an anti-human epidermal growth factor receptor 2 (HER2) mAb used to treat HER2-positive breast, gastroesophageal, and gastric cancers. The gene discussed is ERBB2; the disease is gastric cancer.