Furthermore, a case report by Gunduz et al. described complete remission after only two cycles of trastuzumab combined with chemotherapy in a patient with HER2-positive gastric adenocarcinoma showing choriocarcinomatous differentiation, with a marked decrease in β-hCG levels, illustrating the clinical feasibility of targeting HER2 in tumors with trophoblastic features.33 Here, ERBB2 is linked to gastric adenocarcinoma.