Detailed positive results from the pivotal DESTINY-Breast04 Phase III trial showed that Enhertu (trastuzumab deruxtecan) demonstrated superior and clinically meaningful progression-free survival (PFS) and overall survival (OS) in previously treated patients with HER2-low (immunohistochemistry (IHC) 1+ or IHC 2+/in-situ hybridisation (ISH)-negative) unresectable and/or metastatic breast cancer with hormone receptor (HR) positive or HR-negative disease versus standard of care physician’s choice of chemotherapy. Results will be presented during the Plenary Session today at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting, and have been simultaneously published in The New England Journal of Medicine.
Enhertu is a specifically engineered HER2-directed antibody drug conjugate (ADC) being jointly developed and commercialised by AstraZeneca and Daiichi Sankyo.
In the primary endpoint analysis for DESTINY-Breast04, Enhertu demonstrated a 49% reduction in the risk of disease progression or death versus physician’s choice of chemotherapy in patients with HER2-low metastatic breast cancer with HR-positive disease (PFS hazard ratio [HR] 0.51; 95% confidence interval [CI]: 0.40-0.64; pEnhertu compared to 5.4 months with chemotherapy, as assessed by blinded independent central review (BICR).
Results also showed a 36% reduction in the risk of death with Enhertu compared to chemotherapy in patients with HR-positive disease (OS HR 0.64; 95% CI: 0.48-0.86; p=0.003) with a median OS of 23.9 months with Enhertu versus 17.5 months with chemotherapy, meeting a key secondary endpoint of the trial.
Additionally, data showed consistent efficacy for Enhertu in the overall trial population of patients with HER2-low metastatic breast cancer with HR-positive or HR-negative disease and across levels of HER2 expression (IHC 1+ and IHC 2+/ISH-). In the key secondary endpoint analysis of PFS by BICR in all patients, a similar 50% reduction in the risk of disease progression or death was observed between Enhertu and chemotherapy (PFS HR 0.50; 95% CI: 0.40-0.63; pEnhertu compared to chemotherapy (OS HR 0.64; 95% CI: 0.49-0.84; p=0.001) with a median OS of 23.4 months for Enhertu versus 16.8 months with chemotherapy.
Shanu Modi, MD, Medical Oncologist, Memorial Sloan Kettering Cancer Center, US and Principal Investigator for the trial, said: “The results of DESTINY-Breast04 show for the first time that a HER2-directed therapy can provide a survival benefit to patients with low HER2 expression, indicating we must reconsider the way we categorise patients with metastatic breast cancer. The efficacy seen with Enhertu also reinforces the potential to establish a new standard of care for more than half of all patients with breast cancer currently categorised as having HER2-negative disease, but who actually have tumours with low HER2 expression.”
Susan Galbraith, Executive Vice President, Oncology R&D, AstraZeneca said: “Today’s results represent a pivotal moment demonstrating the potential for Enhertu to redefine the treatment of HER2-targetable cancers. DESTINY-Breast04 validates targeting the lower end of the spectrum of HER2 expression, since Enhertu reduced the risk of disease progression or death across all types of patients in the trial by half, and reduced the risk of death by over a third. We must now evolve the way we classify and treat metastatic breast cancer to ensure these patients are effectively diagnosed and treated.”
Ken Takeshita, Global Head, R&D, Daiichi Sankyo said: “As innovative research organisations, extending the survival for patients is one of our primary goals as we seek to identify potentially new treatment options for patients with metastatic breast cancer. These potentially practice-changing data show that DESTINY-Breast04 takes us one step closer to achieving this goal, as Enhertu is the first HER2-directed medicine to demonstrate a survival benefit in patients with HER2-low metastatic breast cancer. We are honoured by the recognition these important findings are receiving at one of the world’s most prominent oncology meetings as well as in one of the leading medical journals.”
Summary of results: DESTINY-Breast04
