AstraZeneca and Daiichi Sankyo announced that the US Food and Drug Administration (FDA) has approved their Enhertu (trastuzumab deruxtecan) to treat a type of breast cancer.

The US health agency indicated Enhertu for unresectable or metastatic HER2-low breast cancer in adult patients, who have received prior chemotherapy in the metastatic setting.

It has approved Enhertu under its Real-Time Oncology Review programme, following the Priority Review and Breakthrough Therapy Designation in this setting.

Enhertu is a specifically engineered HER2-directed antibody-drug conjugate (ADC), jointly developed and commercialised by AstraZeneca and Daiichi Sankyo.

The FDA approval was based on the results from the Phase 3 DESTINY-Breast04 trial in patients with HER2-low metastatic breast cancer.

In the trial, Enhertu reduced the risk of disease progression or death by 50%, and increased overall survival by more than six months, compared to chemotherapy.

Enhertu showed a safety profile that was consistent with previous clinical trials with no new safety concerns identified, said AstraZeneca.

AstraZeneca oncology business unit executive vice president Dave Fredrickson said: “The rapid approval of Enhertu in HER2-low metastatic breast cancer by the FDA underscores the urgency to bring this transformational medicine to patients as quickly as possible.

Daiichi Sankyo president and CEO and oncology business global head Ken Keller said: “Today’s FDA approval marks a monumental moment in breast cancer treatment as Enhertu is the first-ever HER2-directed medicine to be approved for the treatment of patients with HER2-low metastatic breast cancer.

“With the ground-breaking survival benefit seen in the DESTINY-Breast04 trial, this milestone confirms the importance of targeting lower levels of HER2 expression in the treatment of metastatic breast cancer and we are thrilled that we can now offer Enhertu to even more patients.”

In a separate development, AstraZeneca’s new tablet formulation of Calquence (acalabrutinib) has been approved in the US for all current indications.

The indications include chronic lymphocytic leukaemia (CLL), small lymphocytic lymphoma (SLL) and patients with relapsed or refractory mantle cell lymphoma (MCL), in adults.

The US FDA has granted the approval under its accelerated approval, based on overall response rate data from the results of ELEVATE-PLUS trials.

In the studies, Calquence capsule and tablet formulations showed bioequivalence, which indicates similar efficacy and safety profile with the same dosing strength and schedule.

The tablet is advised for administration together with gastric acid-reducing agents, including proton pump inhibitors (PPIs), antacids and H2-receptor antagonists (H2RAs).