AstraZeneca and Daiichi Sankyo Move into Earlier Treatment Space with Enhertu

Breast Cancer Exam

AstraZeneca and Daiichi Sankyo’s breast cancer therapeutic Enhertu received supplemental approval Thursday from the U.S. Food and Drug Administration. The therapeutic is now approved to treat adult patients with unresectable or metastatic HER2-positive breast cancer who have received a prior anti-HER2-based regimen either in the metastatic setting or in the neoadjuvant or adjuvant setting and have developed disease recurrence during or within six months of completing therapy.

Enhertu was originally approved by the FDA in 2019 for adult patients with unresectable or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting. Because the therapy was only approved for patients who had gone through two or more treatment regimens already, it was only available at the later stages of the treatment journey. The supplemental approval allows Enhertu to be used as a second-line treatment. 

“Enhertu has demonstrated significant progression-free survival in the earlier metastatic setting, potentially establishing it as a new standard of care in previously treated patients with HER2 positive metastatic breast cancer,” said Erika Hamilton, M.D., director, breast cancer and gynecological cancer research program, Sarah Cannon Research Institute, Nashville, Tennessee. “Today’s approval is an important milestone for the clinical community as we will now be able to offer Enhertu to these patients earlier in their treatment.”

In Phase III trials, the objective response rate was more than doubled in patients dosed with Enhertu in comparison to those dosed with T-DM1 (trastuzumab emtansine), an early use therapy for breast cancer. Of the patients who received Enhertu, 39 achieved a complete response and 166 achieved a partial response to the therapeutic. Additionally, 94% of patients who received Enhertu were alive after one year of treatment compared to 85.9% of those who received T-DM1.

Enhertu is a HER2-directed antibody-drug conjugate that is designed to target HER2-positive cancer cells and destroy them. HER2 is a protein that directs cancer cells to grow and in those with HER2-positive breast cancer, the protein is overexpressed in malignant cells making it an important target to eliminate tumors.

Enhertu is also approved in approximately 40 countries as a late-stage therapeutic. Enhertu is additionally approved in the U.S. and some other countries for its use in adults previously treated for HER2-positive advanced stomach cancer. Clinical trials evaluating its efficacy in stomach cancers found that treatment of Enhertu produced a confirmed response of tumor shrinkage in 40.5% of patients.

Both companies participate in a comprehensive global development program for evaluating Enhertu as a monotherapy for several cancer indications including breast, gastric, lung and colorectal. In April 2022, the partners submitted a supplemental Biologics License Application for Enhertu in the treatment of adult patients in the U.S. with unresectable or metastatic non-small cell lung cancer whose tumors have a HER2 mutation. The FDA granted the application Priority Review.

Enhertu is being studied in a number of clinical trials, including those focused on placing Enhertu as a primary and first-in-line treatment for breast cancer. The companies are also evaluating Enhertu in a variety of other solid tumors and how efficacious the therapy is in combination with other immunotherapies.

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