While several HER2-directed drugs are approved in breast cancer, the antibody conjugate trastuzumab-deruxtecan (Enhertu) is FDA-approved in any HER2 3+ cancer (if the patient lacks alternative therapies). Caris reports on the rate of HER2 positivity in 65,000 clinical cases.
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See Bryant et al., June 26, 2025:
https://pubmed.ncbi.nlm.nih.gov/40569617/
Rates of 3+ HER2 ranged from 14% in bladder cancer to 5% in cervical cancer to 0% in gliomas.
Enhertu is approved in both HER2-high and HER2-low (1+) breast cancer.
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AI CORNER
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Trastuzumab deruxtecan (Enhertu) is FDA-approved for two key indications. First, in breast cancer, it is approved for patients with unresectable or metastatic disease who are either HER2-positive (defined as IHC 3+ or IHC 2+ with ISH amplification) or HER2-low (defined as IHC 1+ or IHC 2+ with ISH-negative), making it the first HER2-targeted therapy approved for HER2-low tumors. Second, it holds a tumor-agnostic approval for use in unresectable or metastatic solid tumors that are HER2-positive (defined as IHC 3+ or ISH+) when no satisfactory alternative treatments are available. This tumor-agnostic indication applies to a range of cancers outside the breast, but only when they meet both the HER2 positivity and unmet-need criteria.
