The American Society of Clinical Oncology (ASCO) released updated guidelines in the Journal of Clinical Oncology for the use of adjuvant trastuzumab emtansine in patients with early HER2-positive breast cancer.

The members of the Expert Panel updating the guidelines noted that the update was prompted “largely” by the publication of the KATHERINE phase 3 trial results.

The KATHERINE trial was a randomized trial that included patients with stage I to III HER2-positive breast cancer who received neoadjuvant chemotherapy and HER2-targeted therapy but had residual invasive cancer in the breast or lymph nodes at the time of surgery.

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The trial met its primary endpoint, showing a prolonged invasive disease-free survival for patients who received trastuzumab emtansine compared with patients who received trastuzumab (hazard ratio [HR], 0.50; 95% CI, 0.39-0.64; P <.001). The trial also showed that patients who received trastuzumab emtansine had a lower risk of distant recurrence compared with trastuzumab (HR, 0.60; 95% CI, 0.45-0.79).

Grade 3 or worse adverse events were more frequent among the trastuzumab emtansine arm compared with trastuzumab (25.7% vs 15.4%), as were any-grade events of peripheral sensory neuropathy (18.6% vs 6.9%).

The updated guidelines recommend offering 14 cycles of adjuvant trastuzumab emtansine to patients with HER2-positive breast cancer with pathologic invasive residual disease at surgery after standard preoperative chemotherapy and HER2-targeted therapy, unless disease recurrence or unmanageable toxicity occurs.

The updated guidelines also recommend offering available and approved formulations of trastuzumab, including trastuzumab, trastuzumab and hyaluronidase-oysk, and available biosimilars. To date, the US Food and Drug Administration has approved 5 trastuzumab biosimilars: trastuzumab-dkst, trastuzumab-pkrb, trastuzumab-anns, trastuzumab-dttb, and trastuzumab-qyyp.

Disclosure: The process of updating the guidelines was funded fully by ASCO. Most of the members of the Expert Panel disclosed no relationships that would create a conflict of interest, which is in accordance with ASCO’s Conflict of Interest Policy Implementation for Clinical Practice Guidelines.


Denduluri N, Somerfield MR, Chavez-MacGregor M, et al. Selection of optimal adjuvant chemotherapy and targeted therapy for early breast cancer: ASCO guideline update. J Clin Oncol. Published online October 20, 2020. doi:10.1200/JCO.20.02510