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13-12-2018 | Breast cancer | News | Article

Trastuzumab emtansine targets residual invasive HER2-positive breast cancer

medwireNews: Adjuvant trastuzumab emtansine (T-DM1) halves the risk of invasive disease recurrence or death versus trastuzumab in patients with residual invasive human epidermal growth factor receptor (HER)2-positive early breast cancer, researchers report.

The preliminary findings of the KATHERINE trial, at around 41 months of follow-up, showed that 91 (12.2%) of 743 patients randomly assigned to receive adjuvant T-DM1 3.6 mg/kg every 3 weeks for 14 cycles had a recurrence of invasive disease or died during the study.

This was significantly lower than the 165 (22.2%) cases of recurrent invasive disease or death observed among the 743 patients randomly assigned to receive adjuvant trastuzumab 6.0 mg/kg on the same schedule , Gunter von Minckwitz (German Breast Group, Neu-Isenburg) and colleagues report in The New England Journal of Medicine.

All of the women included in the phase III study had HER2-positive early breast cancer with residual invasive disease in the breast or axilla detected at surgery after completion of neoadjuvant therapy containing a taxane (with or without anthracycline) and trastuzumab.

The estimated 3-year invasive disease-free survival rate – defined as freedom from ipsilateral invasive breast tumour recurrence, ipsilateral locoregional invasive breast cancer recurrence, contralateral invasive breast cancer, distant recurrence or death – was 88.3% in the T-DM1 group and 77.0% in the trastuzumab group.

This corresponded to a statistically significant hazard ratio of 0.50, in favour of T-DM1.

von Minckwitz and team also found that women who received T-DM1 had a lower rate of distant recurrence as the first invasive-disease event than those who received trastuzumab, at 10.5% versus 15.9%.

Furthermore, similar results were observed across a number of subgroup analyses that stratified women by baseline characteristics, hormone receptor status, extent of residual disease after surgery and whether they received single or dual HER2-targeted therapy in the neoadjuvant regimen.

The investigators say that “[t]he safety profile of T-DM1 was consistent with that in previous studies; as expected, there were more adverse events with T-DM1 than with adjuvant trastuzumab.”

Indeed, the serious adverse event rate was 12.7% with T-DM1 and 8.1% with trastuzumab, while 18.0% and 2.1% of patients receiving T-DM1 and trastuzumab, respectively, discontinued treatment as a result of adverse events.

von Minckwitz and co-authors conclude: “Additional follow-up will be necessary to determine whether there is an effect of adjuvant T-DM1 on overall survival.”

These results were simultaneously presented at the 2018 San Antonio Breast Cancer Symposium in Texas, USA.

By Laura Cowen

medwireNews is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group

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