In brief, besides in ALK-rearranged NSCLC the highest efficacy for HSP90 inhibition so far has been reported for Her2-positive breast cancer: for example, HSP90 inhibition resulted in a dose-dependent and complete degradation of active (phosphorylated) HER2 and EGFR in Her2 overexpressing cell lines [30]. Here, ERBB2 is linked to breast carcinoma.