Nine-weeks versus one-year trastuzumab for early-stage HER2+ breast cancer: 10-year update of the Short-HER phase III randomized trial.

Abstract

LBA637 Background: The ShortHER trial is a phase III non-inferiority, randomized trial comparing 9 weeks (short arm) versus 1 year (long arm) of adjuvant trastuzumab combined with chemotherapy in HER2+ eBC patients. The first primary end point of the study was the event-driven analysis of disease-free survival which was achieved in 2017, presented at ASCO 2017 and published in Annals of Oncology in 2018. The HR was 1.13 (90% CI 0.89-1.42) and the non-inferiority could not be claimed as the upper border of CI crossed the upper limit of 1.29 chosen as non-inferiority margin. According to a pre-planned Bayesian analysis, the probability that the short arm was not inferior to the standard one was 80%. Methods: 1254 HER2+ early breast cancer patients were stratified according to nodal status and randomized. Median age was 55 years (range 25-78); 672 (54%) patients were node negative, 383 (30%) with 1-3 positive nodes, 198 (16%) 4 or more positive nodes. At the time of the event-driven analysis, median follow up was 6 years, 200 DFS events and 78 deaths were reported. Here we report the overall survival,+ which was the second co-primary end point, updated DFS and outcomes according to nodal status. Results: Median follow-up is now 9 years, 248 DFS events and 116 deaths have been reported. The 10 year DFS is 77% in the long arm and 78% in the short arm (HR 1.06; 90% CI 0.86-1.31). The 10-year OS is 89% in the long arm and 88% in the short arm (HR 1.15; 90% CI 0.85-1.56). The DFS and OS data overall and by nodal status are summarized in the table below. Conclusions: At a median follow-up of 9 years, the ShortHER trial shows that 1 year trastuzumab is still the standard treatment for HER2+ eBC patients as non-inferiority cannot be claimed in terms of DFS or OS. Numerically however, the differences for the patients at low risk (N0) or intermediate risk (N 1-3) is negligible and patients with 4 or more positive lymph nodes have a clear benefit with 1 year trastuzumab. I. This long-term date can reassure clinicians if, for any reason a patient at low/intermediate risk has to stop trastuzumab and, more important, might facilitate access to a far less expensive treatment to the thousands of patients worldwide who cannot afford the cost of one year of trastuzumab. Clinical trial information: NCT00629278 . [Table: see text]