One treatment-related death occurred (6.3%) due to hypoalbuminemia.<h4>Conclusions</h4>These results demonstrate the significant efficacy and predictable toxicities of trastuzumab and docetaxel in patients with HER2-positive RM SGC, leading to the simultaneous approval of trastuzumab and HER2 companion diagnostics assay for this setting in Japan. Here, ERBB2 is linked to Hypoalbuminemia.