npj Breast Cancer (Sep 2022)

Adjuvant trastuzumab emtansine in HER2-positive breast cancer patients with HER2-negative residual invasive disease in KATHERINE

  • Sibylle Loibl,
  • Chiun-Sheng Huang,
  • Max S. Mano,
  • Eleftherios P. Mamounas,
  • Charles E. Geyer,
  • Michael Untch,
  • Jean-Christophe Thery,
  • Ingo Schwaner,
  • Steven Limentani,
  • Niklas Loman,
  • Kristina Lübbe,
  • Jenny C. Chang,
  • Thomas Hatschek,
  • David Tesarowski,
  • Chunyan Song,
  • Sanne Lysbet de Haas,
  • Thomas Boulet,
  • Chiara Lambertini,
  • Norman Wolmark

DOI
https://doi.org/10.1038/s41523-022-00477-z
Journal volume & issue
Vol. 8, no. 1
pp. 1 – 6

Abstract

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Abstract Following chemotherapy and human epidermal growth factor 2 (HER2)-targeted neoadjuvant therapy for HER2-positive early breast cancer, residual invasive breast cancer at surgery may be HER2-negative on retesting in some patients. We evaluated outcomes with T-DM1 and trastuzumab in patients randomized in the phase III KATHERINE trial based on HER2-positive central testing of the pre-treatment core biopsy with HER2-negative central testing on their corresponding surgical specimen after neoadjuvant treatment. In the 70/845 (8.3%) patients with HER2-negative residual disease on retesting at surgery, there were 11 IDFS events in the 42 trastuzumab-treated patients (26.2%) and none in the 28 T-DM1-treated patients, suggesting that T-DM1 should not be withheld in this patient population.