A clinical perspective on escalating or de-escalating adjuvant therapy in HER2+ breast cancer

The Link Between the Microbiota and HER2+ Breast Cancer: The New Challenge of Precision Medicine

The microbiota is emerging as a key player in cancer due to its involvement in several host physiological functions, including digestion, development of the immune system, and modulation of endocrine function. Moreover, its participation in the efficacy of anticancer treatments has been well described. For instance, the involvement of the breast microbiota in breast cancer (BC) development and progression has gained ground in the past several years. In this review, we report and discuss new findings on the impact of the gut and breast microbiota on BC, focusing on the HER2+ BC subtype, and the possibility of defining microbial signatures that are associated with disease aggressiveness, treatment response, and therapy toxicity. We also discuss novel insights into the mechanisms through which microorganism-host interactions occur and the possibility of microbiota editing in the prevention and treatment optimization of BC.

Current Treatment Approaches for Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer in Adjuvant and Neoadjuvant Settings

Breast cancer (BC) is the second most common cancer and the second leading cause of mortality among women globally. Approximately 20 to 25% of BC patients have amplification of the human epidermal growth factor receptor 2 (HER2) genes, a marker of poor prognosis. However, the introduction of anti-HER2-therapies (trastuzumab, followed closely by lapatinib, pertuzumab, trastuzumab emtansine, and neratinib) has changed the natural history of HER2-positive BC and improved the outcome in HER2-positive BC patients. The preeminence of anti-HER2 combination therapy in achieving complete inhibition of the various HER receptor dimers has been demonstrated in clinical studies. However, despite these therapeutic advances, tumors expressing estrogen receptor have poorer responses to targeted therapy and are more likely to relapse. A better understanding of resistance to existing anti-HER2 agents, along with the role played by the microenvironment and of interconnected signaling pathways, can permit tailor-made therapeutic options for each patient. This review aimed to evaluate treatment approaches for BC patients with HER2-positive disease in the adjuvant and neoadjuvant settings, also exploring the possibilities of extended duration of anti-HER2 maintenance therapy.

What therapies are on the horizon for HER2 positive breast cancer?

Introduction: Despite dramatic improvements in survival achieved with currently available anti-HER2 agents, HER2-positive metastatic breast cancer remains an almost invariably deadly disease, with primary or acquired resistance to HER2-directed agents developing during treatment. Many efforts are focused on identifying new agents that may more effectively inhibit HER2 signaling and on possible combination strategies. Areas covered: This review summarizes the landscape of drugs under development for HER2-positive metastatic breast cancer, as antibody-drug conjugates, monoclonal anti-HER2 antibodies, bispecific antibodies, or novel tyrosine kinase inhibitors. Moreover, available data for possible combination of anti-HER2 drugs and different agents, as immunotherapy, PI3K/mTOR inhibitors, CDK4/6 inhibitors currently under evaluation are reviewed. These strategies may overcome mechanisms of resistance and further improve patient outcomes. Expert opinion: Identification of valuable predictive biomarkers is needed to better inform choice of treatment sequence for the individual patient and limit the financial toxicity of these agents.