New anti-HER2 agents: from second-generation tyrosine kinases inhibitors to bifunctional antibodies

Purpose of review: HER2-positive breast cancers have benefited since the end of the twentieth century, not only from the improvement of biological knowledge, but also from major technological advances. The latter allowed the synthesis of the first generation of enzymatic inhibitors of the HER receptor family such as lapatinib, but above all, monoclonal antibodies such as trastuzumab or pertuzumab having profoundly modified the management of these cancers. However, despite outstanding progresses, there are still patients who are not cured with these first-generation treatments, and they will need new approaches to improve disease control and impact patients' survival. Recent findings: Understanding the mechanisms of escape to these treatments, more than real resistance, has profoundly changed our pharmacological approaches. They have enabled the development of molecules blocking the signaling pathway downstream of receptors such as mTOR, PI3K inhibitors or molecules interacting with the cellular traffic of the receptor in combination with the first-generation treatments. In addition, new second-generation tyrosine kinase inhibitors have demonstrated increased in-vitro efficacy, but still need to show clinical relevance because of new toxicity profiles. The antibody engineering had also permitted a paradigm evolution of the role of the antibody treatments, particularly with the synthesis of bispecific and trifunctional antibodies, promoting the link between the tumor and the immune system, with the goal to amplify the immune anticancer response. Summary: Among the new anti-HER2 agents, second-generation tyrosine kinase inhibitors and bifunctional antibodies are promising approaches that will help to improve disease control and curability of HER2-positive breast cancers.

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