The US FDA has granted BTD for Enhertu based on results from the DESTINY-Breast03 trial, in which Enhertu reduced the risk of disease progression or death

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AstraZeneca Cambridge R&D Centre aerial view. (Credit: AstraZeneca.)

AstraZeneca has received the US Food and Drug Administration (FDA) breakthrough therapy designation (BTD) for Enhertu (trastuzumab deruxtecan) to treat a type of breast cancer.

The drug has been indicated for treating unresectable or metastatic HER2-positive breast cancer in adults, who previously received one or more prior anti-HER2-based regimens.

Enhertu is a HER2-directed antibody-drug conjugate (ADC) jointly developed by AstraZeneca and Daiichi Sankyo, using the latter’s DXd ADC technology.

In March 2019, the two pharmaceutical companies reached a collaboration agreement for the joint development of Enhertu, along with datopotamab deruxtecan in July last year.

Enhertu was previously granted BTDs in late-line HER2-positive metastatic breast cancer, HER2-mutant metastatic non-small cell lung cancer (NSCLC) and HER2-positive metastatic gastric cancer.

AstraZeneca oncology R&D executive vice president Susan Galbraith said: “This is an important step in bringing Enhertu as a potential new option in earlier lines of treatment for HER2-positive metastatic breast cancer, given the urgent need to improve outcomes.

“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.”

The US FDA has granted BTD based on data from the Phase 3 DESTINY-Breast03 trial, which enrolled around 500 patients in Asia, Europe, North America, and South America.

The trial assessed the safety and efficacy of Enhertu in HER2-positive breast cancer patients, previously treated with trastuzumab and a taxane, compared to T-DM1.

Progression-free survival (PFS) based on blinded independent central review was the primary efficacy endpoint of the Phase 3 trial.

Its secondary efficacy endpoints include overall survival, objective response rate, duration of response, PFS based on investigator assessment and safety.

In the DESTINY-Breast03 trial, Enhertu showed a reduction in the risk of disease progression or death by 72%, compared to T-DM1.

Also, the drug showed a safety profile consistent with previous clinical trials, with no new safety concerns and Grade 4 or 5 treatment-related interstitial lung disease events.

Daiichi Sankyo global R&D head Ken Takeshita said: “By granting a fourth Breakthrough Therapy Designation to Enhertu, the FDA continues to recognise the significant potential of this medicine across multiple HER2-targetable tumours.

“With the unprecedented data recently reported from the DESTINY-Breast03 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.”

Enhertu was previously approved in the US, Japan, the EU and several other countries, for a similar indication, based on the results from the DESTINY-Breast01 trial.