AstraZeneca Announces Positive Phase III DESTINY-Breast05 Trial Results for Trastuzumab Deruxtecan as Adjuvant Therapy in High-Risk HER2-Positive Early Breast Cancer

(Source: Qiu Shi Pharmacy)

On September 29, AstraZeneca announced that the Phase III DESTINY-Breast05 study of Enhertu (trastuzumab deruxtecan) as adjuvant treatment for high-risk HER2-positive early breast cancer achieved positive high-positive results in the interim analysis. Notably, earlier this year, the Phase III DESTINY-Breast11 study of trastuzumab deruxtecan as neoadjuvant treatment for HER2-positive breast cancer also yielded positive results.

DESTINY-Breast05 is a global, multicenter, randomized, open-label Phase III clinical trial (n=1635) designed to evaluate the efficacy and safety of trastuzumab deruxtecan (5.4mg/kg) compared with trastuzumab emtansine (3.6mg/kg) as adjuvant therapy in patients with HER2-positive primary breast cancer who have a high risk of recurrence and residual invasive disease in the breast or axillary lymph nodes after neoadjuvant therapy. High risk of recurrence is defined as inoperable cancer following neoadjuvant therapy (before neoadjuvant therapy) or pathologically positive axillary lymph nodes. The primary endpoint of the study is investigator-assessed invasive disease-free survival (IDFS).

The results showed that, compared with the trastuzumab emtansine group, patients in the trastuzumab deruxtecan group achieved a statistically significant and clinically meaningful improvement in invasive disease-free survival (IDFS). Overall survival (OS) was not yet mature at the interim analysis and will be assessed in subsequent analyses.

Moreover, in the DESTINY-Breast05 study, the safety profile of trastuzumab deruxtecan was consistent with its known characteristics, and no new safety concerns were identified.

Currently, about half of HER2-positive early breast cancer patients still have residual lesions after neoadjuvant therapy, which increases their risk of disease recurrence. Although patients can receive additional treatment according to the current standard of care after neoadjuvant therapy, some patients still eventually progress to metastatic disease. New treatment options are needed for early breast cancer to reduce the likelihood of disease progression and improve long-term outcomes for more patients.

Susan Galbraith, Executive Vice President of Oncology and Hematology R&D at AstraZeneca, stated: "This is a landmark study, being the first clinical trial to directly compare trastuzumab deruxtecan with trastuzumab emtansine in the early breast cancer population. The results clearly demonstrate that trastuzumab deruxtecan offers superior efficacy, suggesting it may be a better option for patients with high-risk HER2-positive disease after neoadjuvant therapy. The findings from the DESTINY-Breast05 study, along with those from the DESTINY-Breast11 study, underscore our commitment to advancing trastuzumab deruxtecan in early HER2-positive breast cancer, where patients can achieve sustained long-term outcomes and increase their chances of cure."

Ken Takeshita, Global Head of R&D at Daiichi Sankyo, stated: "Optimizing treatment is crucial for patients with early-stage breast cancer who have residual disease after neoadjuvant therapy, as this represents the last opportunity to prevent the progression to metastatic disease. The results of the DESTINY-Breast05 study demonstrate that treatment with trastuzumab deruxtecan post-surgery extends the time patients can live without invasive disease, potentially offering a new curative-intent therapy option for patients with HER2-positive early-stage breast cancer compared to the current standard of care."

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