FDA approves Enhertu for HER2-low breast cancer

AstraZeneca/Daiichi-Sankyo

The HER2-directed antibody-drug conjugate Enhertu (trastuzumab deruxtecan) has won FDA approval for patients with unresectable or metastatic HER2-low breast cancer.

Enhertu, a HER2-directed antibody drug conjugate, is now the first approved therapy for patients with the HER2-low breast cancer subtype.

The recent approval covers patients with HER2-low breast cancer if they have had chemotherapy for metastatic cancer or if their cancer returned within 6 months of completing an adjuvant chemotherapy regimen.

Patients with low levels of the HER2 protein have traditionally had fewer treatment options than patients with HER2-positive breast cancer, according to the National Cancer Institute. Treatment options for such patients typically included endocrine therapy or chemotherapy.

[Image courtesy of Daiichi-Sankyo/AstraZeneca]

Overall, about 2 million women per year are diagnosed with breast cancer.

FDA estimated that approximately 60% of patients with HER2-negative breast cancer qualify for the HER2-low designation.

AstraZeneca (LON:AZN) and Daiichi Sankyo (OTCMKTS: DSNKY) jointly developed Enhertu.

To win the approval, the companies provided data from the Phase 3 DESTINY-Breast04 trial.

In April, Enhertu won Breakthrough Therapy designation from the FDA for HER2-low breast cancer, marking the fifth such designation for the drug.

In 2019, Enhertu first won FDA approval for some patients with HER2-positive unresectable or metastatic breast cancer. Two years later, the drug won an indication for previously treated HER2-positive advanced gastric cancer. Enhertu won approval in May 2022 for patients with HER2-positive metastatic breast cancer treated with an anti-HER2-based therapy.

On the London Stock Exchange, AstraZeneca shares were up 1.21% to £10,850.00. The company’s shares on the Nasdaq dipped 0.39% to $66.03.

Daiichi-Sankyo shares fared better, climbing 4.91% to $26.90.

Earlier this year, AstraZeneca and Daiichi-Sankyo announced that Enhertu led to a statistically significant improvement in progression-free survival compared with trastuzumab emtansine (T-DM1) (Kadcyla). The study focused on second-line HER2-positive unresectable or metastatic breast cancer.

The companies also have a variety of other studies underway focused on Enhertu in breast, gastric and lung cancers. Studies are also underway for HER2-mutant tumors and HER2-expressing solid tumors.