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About a third of triple-negative tumours are HER2-low and so eligible for trastuzumab deruxtecan, but the difference between a HER2 score of 0 and 1+ is the one pathologists agree on least, and most triple-negative tumours were scored before the label mattered. Re-scoring archived slides with digital help when a patient relapses would find the eligible third.
Schettini's 3,689-patient study found HER2-low in 36.6 percent of triple-negative tumours, no biological difference between HER2-low and HER2 0 triple-negative disease, and suboptimal reproducibility of the HER2-low call among pathologists; DESTINY-Breast04 showed trastuzumab deruxtecan lengthens survival in HER2-low metastatic disease including the triple-negative cohort. The HER2 score was designed to find amplification, so the 0 versus 1+ distinction was never quality-assured, and the HER2-ultralow category (0 with faint staining in 10 percent or fewer cells) that DESTINY-Breast06 validated in hormone receptor-positive disease has no triple-negative evidence yet. Digital scoring algorithms for HER2 low expression are in validation.
A second publication from the DESTINY-Breast04 trial, later than the first and described in its title as an update or longer-term analysis. Read it with the primary publication linked from the trial page; the record was linked automatically and its figures have not been checked by hand.
Patients whose breast cancer was previously called HER2-negative may now be eligible for an effective HER2-directed drug if their tumour has even low-level HER2 staining, so pathology reports must now distinguish HER2-low (1+ or 2+/ISH-negative) from HER2-zero. This applies to metastatic disease after at least one line of chemotherapy; it does not mean these patients benefit from trastuzumab or other older HER2 drugs.
HER2-low is a drug eligibility label, not a biological subtype, in triple-negative disease; because a third of patients qualify for trastuzumab deruxtecan on a score pathologists disagree about, re-scoring and digital assistance for HER2 0 versus 1+ is a practical gap.
Shares DESTINY-Breast04, DESTINY-Breast04: trastuzumab deruxtecan works in HER2-low breast cancer, creating a new treatable group, HER2-low and HER2-ultralow metastatic breast cancer, HER2-low and HER2-ultralow and the tag tnbc-evidence.
Shares Immunohistochemistry (IHC), Digital pathology & AI, Biomarkers are not validated or standardised, Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem and the tag tnbc-evidence.
Shares Immunohistochemistry (IHC), Digital pathology & AI, Knowledge reaches practice too slowly, Biomarkers are not validated or standardised and the tag tnbc-evidence.
Shares Digital pathology & AI, Biomarkers are not validated or standardised, Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem, Triple-negative breast cancer (TNBC) and the tag tnbc-evidence.
Shares Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem, HER2, Triple-negative breast cancer (TNBC) and the tag tnbc-evidence.
Shares Daiichi Sankyo, Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem, AstraZeneca, Antibody-drug conjugate (ADC) and the tag tnbc-evidence.
Shares Immunohistochemistry (IHC), Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem, Triple-negative breast cancer (TNBC) and the tag tnbc-evidence.
Shares Immunohistochemistry (IHC), Biomarkers are not validated or standardised, Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem, Triple-negative breast cancer (TNBC) and the tag tnbc-evidence.