How are you requesting testing for HER2-ultralow status, in light of DB-06 trial demonstrating benefit of T-DXd for these patients?

I have asked our breast pathologists to routinely report it on all new samples and if I have a metastatic patient that might be a candidate, I have had pathology go back and stain all their prior samples for it. I’ve now used T’ Dxd in many ultralow patients and it works beautifully.

The DESTINY-Breast06 clinical trial enrolled patients with hormone receptor positive (HR+), HER2-low, and HER2-ultralow metastatic breast cancer. Ultralow is defined as IHC greater than 0 but <1. The current ASCO CAP guidelines incorporate both HER2 null (no staining) and HER2 ultralow as IHC 0. At ...

Our pathologists now automatically read out HER2 IHC 0 as either "IHC 0; ultralow" or "IHC 0; null." However, this is not yet in the ASCO/CAP guidelines and this may not be the case at many institutions.