T-DM1 as Monotherapy for Early HER2-Positive Breast Cancer
Posted: Tuesday, January 28, 2020
A regimen of ado-trastuzumab emtansine (T-DM1) as monotherapy for stage I HER2-positive breast cancer was associated with few recurrences and significantly fewer clinically relevant toxicities compared with treatment with trastuzumab and paclitaxel. This work was presented at the 2019 San Antonio Breast Cancer Symposium (SABCS) by Sara M. Tolaney, MD, MPH, of the Dana-Farber Cancer Institute, Boston, on behalf of her colleagues (Abstract GS1-05).
The ATEMPT trial is a multicenter phase II adjuvant study that focused on 497 patients with HER2-positive stage I breast cancer. Patients were randomly assigned 3:1 to receive either T-DM1 or trastuzumab plus paclitaxel. Of the patients receiving treatment, 73% had hormone receptor–positive tumors, and 11% of tumors were T1a, 31% were T1b, and 57% were T1c.
After a median follow-up of 3 years, there were a total of 11 disease free–survival events in the T-DM1 arm consisting of 1 distant recurrence, 3 local recurrences, 3 contralateral breast recurrences, 3 deaths from other causes, and 1 death due to breast cancer recurrence. There were six disease free–survival events in the trastuzumab/paclitaxel arm as well. The 3-year disease free–survival rate for patients in the monotherapy and combination arms was 97.5% and 93.2%, respectively.
Clinically relevant toxicities were experienced by approximately 25% of patients receiving T-DM1 monotherapy compared with 36% of patients receiving trastuzumab/paclitaxel. Although this reduction was clinically significant, it was a less than a 40% relative reduction. Patients receiving the monotherapy experienced less grade 3 or 4 toxicities than did those receiving combination therapy as well (1% vs. 7%, respectively). Adverse events lead to discontinuation of therapy in 17% of patients treated with T-DM1.
Disclosure: For full disclosures of the study authors, visit abstractsonline.com.
