Expert Perspectives: Standardizing HER2 Testing in Gynecological Cancer

In the next segment of the discussion, the experts delve into parallels between gynecologic and breast cancers, particularly in how HER2 expression evolves over time. Referencing data from a recent study in triple-negative breast cancer, they highlight that repeat biopsies revealed a 30% emergence of HER2-low status in initially HER2-negative tumors. This finding is significant because it opens up new treatment options in later lines of therapy. Although such patterns in breast cancer are well studied, uncertainty remains about whether similar strategies should be routinely applied in gynecologic cancers, where HER2 biology and its implications may differ.

The conversation transitions into the current challenges of HER2 testing in gynecologic oncology. Without a formal, gynecologic-specific HER2 scoring system, many institutions are relying on testing guidelines established for gastric cancers, particularly those used in the DESTINY-PanTumor02 trial. The use of immunohistochemistry, HER2 amplification assessments, and HER2 mutation data from third-party assays is becoming more common, often integrated with broader tumor profiling. This approach helps collect consistent data and increases familiarity among pathologists, particularly at academic centers, though variability can still occur in community practices.

A key takeaway is the complexity of interpreting HER2 results in gynecologic tumors, especially as interest grows in identifying HER2-low and potentially even ultra-low expressors. The speakers acknowledge that HER2 status may become less central if more effective ADCs targeting other common markers emerge. However, for now, any HER2 expression can be clinically significant. They stress the importance of standardizing HER2 testing in gynecologic cancers through future clinical trials, which will be essential for ensuring consistent treatment decisions and advancing the precision medicine landscape in this field.