The potential of molecular targeted therapy to improve the clinical outcomes of patients with early-stage breast cancer (BC) as adjuvant therapy has been first demonstrated through endocrine treatment. The introduction of HER2 blockade, through the successful clinical development of trastuzumab, changed the natural history of HER2-positive BC subtype. Areas covered: There are ongoing efforts to augment further the use of targeted agents as adjuvant treatment in BC, hoping that early introduction of targeted therapy blocking key oncogenic drivers of micro-residual disease, will significantly improve clinical outcomes. In the present Review, we present data through extensive search of PubMed about the following targeted adjuvant therapeutic strategies in BC: i) HER2 blockade and ongoing efforts to further augment its efficacy for patients with HER2-positive disease, ii) angiogenesis inhibition, iii) PI3K-mTOR- AKT pathway inhibition, iv) CDK4/6 inhibition, v) PARP inhibition. Expert commentary: we provide insights about challenges and potential ways to overcome them, in terms of successful clinical development of targeted agents as adjuvant therapy for patients with BC. In particular, we emphasize the need to systematically assess minimal residual cancer burden as a way to increase the rates of successful clinical development of targeted agents in the adjuvant setting.
Keywords: Breast cancer; adjuvant treatment; minimal residual cancer; targeted therapy.