ERBB2 and neoplasm: To date preclinical and clinical studies examining STS inhibition in ER positive breast cancers have shown beneficial outcomes; reduced tumour growth and proliferation in pre-clinical models14,15,50 and reduced proliferation, steroid levels and prolonged patient survival in clinical trials.18,19,51,52 Limited tests have also been done in the preclinical setting for ER negative breast cancers (MDA-MB-231 cell line, TNBC subtype) with similar promising findings.53 To the best of our knowledge no tests have been carried out in HER2 models or patients.