FDA Gives Thumbs-Up to Enhertu for Hard-to-Treat HER2+ Breast Cancer
The U.S. Food and Drug Administration (FDA) approved AstraZeneca and Daiichi Sankyo Company’s Enhertu (fam-trastuzumab deruxtecan-nxki) for breast cancer. Specifically, it was approved for adults with unresectable or metastatic HER2-positive breast cancer who have had two or more previous anti-HER2-based treatments in the metastatic setting.
Enhertu is an antibody-drug conjugate (ADC) directed at HER2. The approval was based on data from the registrational Phase II DESTINY-Breast01 trial. The trial showed a confirmed objective response rate of 60.3%, including a 4.3% complete response rate and a 56% partial response rate. A median duration of response of 14.8 months was seen as of August 1, 2019.
“Enhertu has shown impressive results in women with HER2-positive metastatic breast cancer, with the majority of women benefiting from treatment and the median duration of the response exceeding 14 months,” said Jose Baselga, AstraZeneca’s executive vice president of Oncology R&D. “With this first approval, we are proud to bring Enhertu to patients with high unmet need and we look forward to further exploring its potential in additional settings.”
The approval was part of the FDA’s Accelerated Approval program. Continued approval for the indication is contingent upon verify the clinical benefit in a confirmatory trial.
The companies have also submitted the drug to Japan’s Ministry of Health, Labour and Welfare based on the DESTINY-Breast01 and Phase I trials. There are three additional ongoing Phase III trials. It is being evaluated in HER2-expressing metastatic breast and gastric cancers, advanced colorectal cancer, and non-small cell lung cancer. It is also being evaluated in combination with other cancer treatments, including immunotherapy.
The approval triggers a milestone payment from AstraZeneca to Daiichi Sankyo of $125 million. Future sales of the drug in the U.S. will be recognized by Daiichi Sankyo.
About 20% of breast cancers are HER2-positive. This is an area of significant unmet need. HER2 is a tyrosine kinase receptor growth-promoting protein found on the surface of some cancer cells, linked to aggressive disease and poor prognosis in patients with breast cancer.
The approval comes with a Boxed Warnings for the risk of interstitial lung disease and embryo-fetal toxicity. Interstitial lung disease and pneumonitis is inflammation of lung tissue, which can cause death.
“There have been many advances in the development of drugs for HER2-positive breast cancer since the introduction of Herceptin (trastuzumab) in 1998,” said Richard Pazdur, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Oncologic Diseases in the FDA’s Center for Drug Evaluation and Research.
He went on to say, “The approval of Enhertu represents the newest treatment option for patients who have progressed on available HER2-directed therapies. Drug development in the area of targeted therapies builds on our scientific understanding of malignant diseases not only in breast cancer, but in multiple other diseases.”
The DESTINY-Breast01 Phase II trial’s primary endpoint was objective response rate determined by independent central review. Secondary objectives included duration of response, disease control rate, clinical benefit rate, progression-free survival and overall survival. The trial evaluated 184 patients at more than 100 sites around the world.