ERBB2 and breast cancer: NCT02657343, titled “An Open-Label, Phase Ib/II Clinical Trial Of CDK 4/6 Inhibitor, Ribociclib (Lee011), In Combination With Trastuzumab Or T-Dm1 For Advanced/Metastatic HER2-Positive Breast Cancer,” overall, the safety profile of this combination therapy is favorable, but its efficacy requires further investigation (Goel et al., 2019).