Enhertu Cuts Risk of Early Breast Cancer Recurrence by 53% Compared With T-DM1

Key Facts

The European Medicines Agency updated the product information for Enhertu on October 20, 2026, allowing its use after surgery to treat early-stage HER2-positive breast cancer in patients who had residual invasive disease after initial treatment. The expanded use is based on the DESTINY-Breast05 trial, which compared the drug with T-DM1, the current standard of care in the European Union for this group after surgery. The results showed a relative 53% reduction in the risk of invasive disease recurrence or death with Enhertu compared with T-DM1. The proportion of patients alive and free of invasive disease after three years was 92.4% in the Enhertu group, versus 83.7% in the comparison group. This puts the trial data at the center of the regulatory update, while overall survival remains under evaluation in later analyses.

In the primary analysis of invasive disease-free survival, the hazard ratio was 0.47, with a 95% confidence interval of 0.34 to 0.66 and a p-value of less than 0.0001. Daiichi Sankyo said Enhertu "significantly reduced the risk of invasive disease recurrence or death" compared with T-DM1. This outcome measures survival without invasive disease recurrence or death, according to the trial’s specified endpoint; the three-year figures show the proportion of patients in each group who remained alive and free of invasive disease. The difference between 92.4% and 83.7% describes the groups’ outcomes at that time point, while the 53% risk reduction expresses the relative comparison in the primary analysis. The trial included 1,635 patients from Asia, Europe, North America, Oceania and South America.

Overall survival data were immature at the planned interim analysis, with maturity of 2.9% at the data cutoff, and Daiichi Sankyo said this measure "will be assessed in future analyses." The reported results therefore focus on invasive disease-free survival, and the trial does not provide a final finding in this analysis on the treatment’s effect on overall survival. The company set July 2, 2025, as the data cutoff date. By then, median study follow-up was 29.9 months in the Enhertu group and 29.7 months in the T-DM1 group. The similar durations provide a time frame for comparing the two study arms, while the overall survival assessment remains tied to later analyses.

AstraZeneca said Enhertu’s safety profile in the trial "was consistent with its known profile, with no new safety concerns identified." The statement provides context for the reported clinical results, but does not change the trial’s primary comparison between the drug and T-DM1. T-DM1, according to AstraZeneca, was the standard of care in the European Union after surgery for patients with residual invasive disease. The regulatory update covers patients who still had this disease after initial treatment, within the early-stage HER2-positive breast cancer setting. This type accounts for about one in five breast cancer cases, according to the company.

Epidemiological figures put the target group within the broader burden of breast cancer. AstraZeneca says Europe sees about 540,000 diagnoses annually, while about 2.4 million diagnoses and more than 690,000 deaths were recorded globally in 2024. The Europe figure is an annual rate and is not attributed to 2024. The two global figures describe the number of cases and deaths that year and do not identify how many patients are eligible for Enhertu. These data provide background on the disease’s prevalence, while the trial results are limited to its participants and the treatment group covered by the update.