RESULTS : We found four papers from three equivalence randomized clinical trials and one non-inferiority trial comparing four trastuzumab biosimilars (SB3, ABP 980, CT-P6 and R-TPR-016) with the reference biological drug. CONCLUSIONS : The evidence was inconclusive regarding the statistical equivalence of efficacy between trastuzumab biosimilars and their reference. On the other hand, safety proved comparable.