Patients with early HER2-positive/hormone receptor (HR)-positive breast cancer who receive neoadjuvant trastuzumab emtansine (T-DM1) with or without endocrine therapy (ET) for only 12 weeks may achieve a clinically meaningful pathologic complete response (pCR), according to a study published in the Journal of Clinical Oncology.1

Prior studies suggest that T-DM1 may be as effective as current standard therapy — chemotherapy plus anti-HER2 compounds — and has fewer toxic effects.


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For this phase 2, prospective trial (ClinicalTrials.gov Identifier: NCT01745965), researchers randomly assigned 375 patients with early HER2-positive/HR-positive breast cancer 1:1:1 to 12 weeks of T-DM1 (3.6mg/kg every 3 weeks for 4 cycles) with or without ET, or to trastuzumab (8mg/kg loading dose, then 6mg/kg every 3 weeks for 4 cycles) with ET.

pCR was confirmed by surgery within 3 weeks of experimental treatment or by histologic confirmation of non-pathologic complete response. Patients also received adjuvant therapy per treatment standards.

pCR, the primary endpoint of the study, was achieved in 41% of patients in the T-DM1 arm, 41.5% in the T-DM1 plus ET arm, and 15.1% in the trastuzumab plus ET arm (P < .001).

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The safety profile was favorable across all 3 treatment arms, but a significantly higher prevalence of grade 1 to 2 adverse events (AEs) was observed in the T-DM1 arms. The most frequently reported AEs in T-DM1 were thrombocytopenia, nausea, and elevation of liver enzymes.

The study authors concluded that “T-DM1 may be an efficient and safe alternative for patients who are not suited for systemic chemotherapy in this setting.”

Reference

  1. Harbeck N, Gluz O, Christgen M, et al. De-escalation strategies in human epidermal growth factor receptor 2 (HER2)–positive early breast cancer (BC): final analysis of the west german study group adjuvant dynamic marker-adjusted personalized therapy trial optimizing risk assessment and therapy response prediction in early BC HER2- and hormone receptor–positive phase II randomized trial—efficacy, safety, and predictive markers for 12 weeks of neoadjuvant trastuzumab emtansine with or without endocrine therapy (ET) versus trastuzumab plus ET. J Clin Oncol. 2017 Jul 6. doi: 10.1200/JCO.2016.71.9815 [Epub ahead of print]