The study was based on the hypothesis of equivalence of BCD-022 (trastuzumab by JSC BIOCAD, Russia) in combination with paclitaxel used as the therapy of inoperable or metastatic HER2(+) breast cancer in comparison with Herceptin® (F. Hoffmann-La Roche Ltd., Switzerland) in combination with paclitaxel. This evidence concerns the gene ERBB2 and breast cancer.