The Food and Drug Administration has agreed to quickly review AstraZeneca and Daiichi Sankyo’s drug Enhertu for treating metastatic breast cancer that expresses low levels of a protein known as HER2. If approved, the therapy would become the first targeted option for this type of tumor, potentially reshaping how doctors categorize and treat advanced breast cancer.
The FDA’s review, announced by the companies Monday, comes nearly two months after researchers presented clinical trial results that showed Enhertu halved the risk of breast cancer progression versus chemotherapy for patients with this kind of tumor, and cut the risk of death by more than a third.
AstraZeneca and Daiichi Sankyo are seeking approval of their drug for HER2-low breast cancer that’s either spread or can’t be removed by surgery, and has been previously treated once before in the metastatic setting.
A decision from the regulator is expected sometime in the fourth quarter, AstraZeneca and Daiichi Sankyo said. In addition to granting Enhertu priority review, the FDA is evaluating the companies’ application under a program known as “real-time oncology review,” which allows the agency to begin its assessment before an application is fully submitted. Novartis’ breast cancer treatment Piqray was the first new medicine approved under the program in early 2019, but it’s since become more common, featuring in nine new drug approvals last year.
Enhertu is also being reviewed through Project Orbis, an initiative from the FDA and other health regulators around the world to collaborate and share information during concurrent reviews of new drugs.
Enhertu is already approved in the U.S. and dozens of other countries for patients with HER2-positive metastatic breast cancer who have previously received a HER2-targeting medicine.
Typically, breast tumors are either classified as HER2 positive or HER2 negative, with the result guiding subsequent treatment choices. While HER2-positive tumors are more aggressive, physicians can turn to a slate of drugs aimed at the protein, such as Roche’s Herceptin or newer options like Perjeta and Kadcyla.
But the results AstraZeneca and Daiichi Sankyo presented at the American Society of Clinical Oncology conference in June showed Enhertu could help patients who would previously be considered HER2-negative, but still had low levels of the protein. The significant benefit reported from the companies’ study could push doctors to rethink how they’ve approached treatment for these patients, should Enhertu win approval as expected.
Still, Enhertu comes with substantial side effects, and was associated in testing with a type of lung scarring that requires additional monitoring.