AstraZeneca and Daiichi Sankyo’s star antibody-drug conjugate (ADC) Enhertu has chalked up another win in an early breast cancer setting, this time besting Roche’s Kadcyla in a phase 3 study.
Enhertu proved its prowess across patients with HER2-positive early breast cancer who are at high risk of recurrence and have residual invasive disease in the breast or axillary lymph nodes following neoadjuvant treatment in the 1,635-patient wide Destiny-Breast05 trial.
At an interim analysis of the randomized study, the drug demonstrated a “highly statistically significant and clinically meaningful improvement” in invasive disease-free survival (IDFS) compared to Roche’s older ADC Kadcyla, also known as T-DM1, AZ and Daiichi said in a Monday release.
“This landmark trial is the first to directly compare Enhertu and T-DM1 in early breast cancer and the results clearly show that Enhertu delivers superior outcomes, indicating that it may be a better option for patients with high-risk HER2-positive early breast cancer in the post-neoadjuvant setting,” AZ’s Head of Oncology Hematology R&D, Susan Galbraith, explained.
While overall survival results were not yet mature at the time of the analysis, the topline results, coupled with a win in a previous study, opens the door to Enhertu’s potential to become a “foundational treatment option” in the curative-intent setting for early breast cancer patients, according to the companies.
Earlier this year, AZ and Daiichi said Destiny-Breast11 trial saw Enhertu, used as a presurgical treatment, beat the standard of care treatment in helping patients with high-risk, locally advanced HER2-positive early breast cancer achieve a statistically significant and clinically meaningful improvement in pathologic complete response (pCR).
Taken together, the results “underscore our commitment to moving Enhertu into early-stage HER2-positive breast cancer,” Galbraith added.
The companies will present data from both studies at the upcoming 2025 European Society for Medical Oncology (ESMO) Congress and will share results from Destiny-Breast05 with global regulatory authorities.
About half of patients with HER2-positive early breast cancer have residual disease following pre-surgery (neoadjuvant) treatment, increasing the risk of disease recurrence and underscoring a need for new therapy options in the early setting to prevent a progression to metastatic disease. Breast cancer is the second most common cancer worldwide, AZ and Daiichi point out.
Enhertu entered the scene with a splash in 2019 as a third-line treatment for HER2-positive breast cancer and has since tacked on six additional indications, pulling sales of $3.75 billion in 2024.
The current Destiny-Breast05 trial is also not the first time that Enhertu has outperformed Kadcyla in a head-to-head trial. In the Destiny-Breast03 study, Enhertu mounted a 36% reduction in the risk of death over Kadcyla in second-line HER2-positive breast cancer.
Now, AZ and Daiichi are positioning the blockbuster drug to tackle the first-line breast cancer landscape. In April, a win in newly diagnosed HER2-positive metastatic breast cancer prompted the companies to prepare regulatory filings for another label expansion.