Simple Summary
HER2-positive breast cancer is an aggressive subtype in which HER2 overexpression promotes tumor growth and increases the risk of disease recurrence. Monoclonal antibodies have improved treatment outcomes, although their efficacy and safety vary across therapeutic strategies. The aim of this systematic review was to evaluate the efficacy and safety of monoclonal antibodies in adults with HER2-positive breast cancer. We identified eight reports of seven phase III randomized controlled trials evaluating four monoclonal antibodies: pertuzumab, denosumab, atezolizumab, and bevacizumab. Pertuzumab, particularly combined with trastuzumab, improved tumor response and progression-related outcomes with an acceptable safety profile. Denosumab and atezolizumab showed no significant clinical benefit, whereas bevacizumab did not improve efficacy and increased toxicity. Overall, these findings highlight the heterogeneous efficacy and safety profiles of monoclonal antibodies and support treatment selection according to the clinical setting and individual patient characteristics.
Abstract
Background/Objectives: HER2-positive breast cancer is one of the most aggressive subtypes of breast cancer, characterised by overexpression of the HER2 receptor, which promotes tumour proliferation and is associated with a poorer clinical prognosis. The introduction of targeted therapies based on monoclonal antibodies has brought about a significant change in the management of the disease, improving survival and disease control. However, the efficacy and safety of some of these treatments remain under investigation. The aim was to evaluate the efficacy and safety of monoclonal antibodies in adult patients with HER2-positive breast cancer compared with placebo or any other drug, with both treatment and control groups receiving other anticancer therapies. Methods: A systematic review of the scientific literature was conducted, based on phase III, randomized, controlled, double-blind clinical trials published between 2020 and 2026 in the PubMed, Cochrane and Scopus databases. The review was carried out following the PICO framework and the PRISMA guidelines. Results: Eight reports of seven clinical trials were included, evaluating four monoclonal antibodies: pertuzumab, denosumab, atezolizumab and bevacizumab. Treatment with pertuzumab showed a significant improvement in tumour response and progression-free survival with an acceptable safety profile. In contrast, bevacizumab, denosumab and atezolizumab did not show significant clinical benefits and, furthermore, were associated with a higher incidence of adverse effects. Conclusions: Pertuzumab is an effective therapeutic strategy for the treatment of HER2-positive breast cancer. However, individualised treatment selection and appropriate monitoring of adverse effects are necessary.