Optimizing Maintenance Therapy After First-Line Treatment in HER2+ Metastatic Breast Cancer

EP: 1.Current Treatment Approaches in HER2+ Metastatic Breast Cancer

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EP: 2.Optimizing Maintenance Therapy After First-Line Treatment in HER2+ Metastatic Breast Cancer

Following initial chemotherapy, maintenance therapy becomes a critical component in managing HER2-positive metastatic breast cancer. Clinicians typically transition patients after 6 to 8 cycles of induction chemotherapy, ideally once imaging shows a plateau in response—what is often referred to as “best response.” At this stage, the standard approach has been maintenance with dual antibody therapy, commonly trastuzumab and pertuzumab, often combined with endocrine therapy in patients with hormone receptor–positive disease. This strategy is well tolerated and, in many cases, leads to durable disease control, with some patients remaining stable for years.

Response evaluation largely relies on imaging, with tumor markers providing supplementary insight. While circulating tumor DNA (ctDNA) is being explored as a potential monitoring tool, most clinicians still view it as investigational and use it more like a tumor marker than a definitive guide. PET imaging offers greater clarity in certain scenarios but is often limited by insurance constraints. Ultimately, clinicians depend on a combination of radiographic findings, clinical assessment, and patient-reported outcomes to guide the shift from induction to maintenance.

Looking ahead, studies such as HER2CLIMB-05 and ongoing results from the PATINA trial may reshape the maintenance landscape. HER2CLIMB-05 is evaluating tucatinib—a HER2-targeted tyrosine kinase inhibitor—in combination with trastuzumab, potentially offering a chemotherapy-free maintenance option. This could be particularly valuable for patients with HER2-positive, hormone receptor–negative disease where current data are more limited. There's also growing interest in whether newer maintenance approaches can prevent or delay brain metastases, a common progression site in this population. While some oncologists remain skeptical about the preventive potential of systemic agents in the central nervous system, emerging evidence may soon support more proactive strategies. These evolving insights underscore the importance of tailoring maintenance plans not only to disease biology but also to patterns of disease spread and long-term tolerability.