To compare trastuzumab/hyaluronidase-oysk and paclitaxel with trastuzumab/hyaluronidase-oysk maintenance to carboplatin, paclitaxel, and pertuzumab/trastuzumab/hyaluronidase-zzxf and pertuzumab/trastuzumab/hyaluronidase-zzxf maintenance to carboplatin and paclitaxel in patients with Human epidermal growth factor 2 (HER-2) positive serous carcinoma or carcinosarcoma. Here, ERBB2 is linked to serous adenocarcinoma.