- Adjuvant trastuzumab emtansine (T-DM1) failed to demonstrate a DFS or safety advantage over paclitaxel plus trastuzumab (TH) for patients with stage I human epidermal growth factor receptor 2(HER2)-positive breast cancer.
Why this matters
- The drug antibody conjugate, T-DM1 has activity against metastatic HER2-positive breast cancer and in patients with residual disease after neoadjuvant HER2-directed therapy.
- Multicenter, phase 2 ATEMPT study.
- 497 patients with HER2-positive breast cancer were randomly assigned (3:1) to either T-DM1 every 3 weeks for 17 cycles or TH weekly for 12 cycles followed by trastuzumab every 3 weeks for further 13 cycles.
- Primary endpoints were 3-year DFS or clinically relevant toxicities (CRTs).
- Funding: Genentech, Inc.
- 3-year DFS rates for the T-DM1 and TH groups were 97.5% and 93.2%, respectively.
- CRTs were observed in 46% of patients in each group.
- Grade 3 or higher nonhematologic toxicities in the T-DM1 and TH groups were 10% and 11%, respectively, and grade ≥2 neurotoxicities were 11% and 23%, respectively.
- 4 patients in the T-DM1 group had grade 4 hematologic toxicity vs none in the TH group.
- 17% of patients in the T-DM1 group had toxicities requiring early discontinuation vs 6% in the TH group.
- Study was not powered to determine efficacy differences between groups.
- Short median follow-up duration.
- Responding to an audience member's concerns regarding the financial toxicity of T-DM1, Dr. Sara. M. Tolaney, MD, MPH of Dana-Farber Cancer Institute, Boston, said “certainly we did consider this and we had our pharmacist do some calculations looking at this financial toxicity, and it is true that a year of T-DM1 does cost a little more than two times as much as TH.”