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Topics:
Breast Cancer • Medical Oncology • Journal Club ft. NEJM publications • Breast Cancer, Metastatic • HER2-low
If there is HER2-low discordance between primary and subsequent breast cancer biopsies, in which scenarios would you choose to use trastuzumab deruxtecan?
For example, if the primary breast tumor was HER2 IHC 1+, but a metastatic site was HER2 IHC 0, would you still recommend using T-DXd?
Will you change your practice in regards to obtaining new biopsies at recurrence and/or post-treatment metastatic progression?
Answer from: Medical Oncologist at Academic Institution
Because of the potential heterogeneity of HER2 expression, I would still offer T-DXd for these patients. In addition, HER2 IHC 0 may not exclude T-DXd activity based on the DAISY trial.
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Answer from: Medical Oncologist at Community Practice
Discordance in HER2 receptor status between primary and metastatic deposits can occur in up to 1/3 of samples. As with hormone receptor status, specimens collected via fine needle aspirate or on decalcified bone may produce inconsistent results for HER2 IHC.
I always recommend biopsy of a metastati...
Answer from: Medical Oncologist at Community Practice
In patients with Her-low disease (IHC 1+ or 2 + with negative Her 2 FISH), I would favor obtaining new tissue from recurrent or metastatic site before considering drugs like Trastuzumab deruxtecan. Repeat biopsy will not only help verify the contemporary Her 2 status, but also allow testing for othe...
Answer from: Medical Oncologist at Academic Institution
Yes, if metastatic disease is HER2 low.