FDA Grants Designation For Daiichi Sankyo’s Breast Cancer Treatment

FDA recently granted Daiichi Sankyo’s Enhertu breakthrough therapy designation in the US to treat adult patients with unresectable or metastatic HER2-positive breast cancer. 

Enhertu is an HER2-directed antibody drug conjugate jointly developed by Daiichi Sankyo, Limited, and AstraZeneca. FDA specifically granted the designation for breast cancer patients who received one or more prior anti-HER2-based regimens.

FDA granted the breakthrough designation based on data from the DESTINY-Breast03 trial. In the trial, Enhertu demonstrated a 72 percent reduction in the risk of disease progression or death compared to T-DM1 in HER2-positive breast cancer patients. 

Notably, researchers identified no safety concerns.

“With the unprecedented data recently reported from the DESTINYBreast03 trial, we look forward to working closely with the FDA to bring ENHERTU to patients who have been previously treated for HER2 positive metastatic breast cancer as soon as possible,” Ken Takeshita, MD, global head of research & development at Daiichi Sankyo, said in the announcement.

Previously, FDA granted breakthrough therapy designation for Enhertu for HER2 positive metastatic breast cancer in 2017 and HER2 mutant metastatic non-small cell lung cancer and HER2 positive metastatic gastric cancer in 2020. 

Susan Galbraith, MBBChir, PhD, executive vice president of oncology research & development at AstraZeneca highlighted that this breakthrough designation brings a potential new option in earlier lines of treatment for HER2 positive metastatic breast cancer. 

“This recognition by the FDA underscores the transformative possibility of ENHERTU seen with the remarkable DESTINY-Breast03 results presented at ESMO just two weeks ago,” Galbraith continued. 

Breast cancer is the most prevalent cancer globally, with over two million cases diagnosed in 2020. Nearly one in five cases of breast cancer are considered HER2 positive.

HER2 is a tyrosine kinase receptor growth-promoting protein expressed on the surface of various tumors, including breast, gastric, lung, and colorectal cancers. Often, this type of protein is associated with aggressive disease and poor prognosis in breast cancer. 

At the end of July, Pfizer and Arvinas collaborated to develop and commercialize an investigation oral PROteolysis Targeting Chimera (PROTAC) estrogen receptor (ER) protein degrader for breast cancer.

The PROTAC protein degrader, ARV-471, is currently in Phase 2 dose expansion clinical trial to treat patients with ER-positive/HER2-negative locally advanced or metastatic breast cancer. 

Pfizer and Arvinas are looking to develop ARV-471 as the potential endocrine therapy of choice for patients and their physicians.