FDA Approves Enhertu for Use in Metastatic Breast Cancer

This approval of trastuzumab deruxtecan (Enhertu) follows the March release of data from the DESTINY-Breast03 trial on the anti-HER2 monoclonal antibody, also a HER2-directed antibody-drug conjugate, which indicated superior outcomes vs trastuzumab emtansine.

Adult patients living with unresectable or metastatic HER2-positive breast cancer have a new treatment option in their armamentarium following the FDA’s approval of trastuzumab deruxtecan (Enhertu; AstraZeneca/Daiichi Sankyo) in several settings, including earlier in the course of disease, based on final data from the DESTINY-Breast03 trial.

In 2021, breast cancer was the most common cancer diagnosed in the United States, at an estimated 284,200 new cases.

Now, Enhertu can be utilized as adjuvant or neoadjuvant therapy among individuals whose disease recurs within 6 months of them finishing treatment with another anti-HER2 therapy, as well as in cases of metastatic disease. The chemotherapy is already approved for use in the setting of treatment failure on 2 or more anti–HER2-based regimens among those with disease metastasis.

“Enhertu is already established in the later-line treatment of patients with HER2-positive metastatic breast cancer, and we are thrilled that with this approval, patients in the US will now be able to access the transformative potential of Enhertu earlier in their treatment,” said Dave Fredrickson, executive vice president, Oncology Business Unit, AstraZeneca, in a press release announcing the approval. “We look forward to bringing this important, potentially paradigm-shifting medicine to even more patients across the globe in an earlier setting as quickly as possible.”

The approval follows the March release of interim data from phase 3 DESTINY-Breast03, which evaluated progression-free survival (PFS) and overall survival (OS), objective response, and safety among patients with metastatic breast cancer (mBC) randomized 1:1 to trastuzumab deruxtecan or trastuzumab emtansine (T-DM1), the current standard of care in HER2-positive mBC. Those data demonstrated superior outcomes from trastuzumab deruxtecan, including PFS and an overall response rate that were more than twice as high, at 75.8% vs 34.1% and 79.7% vs 34.2%.

Enhertu first received an accelerated approval from the FDA in December 2019, which was based on data on tumor response rate and response duration from the phase 2 DESTINY-Breast01 trial. That was followed by a Breakthrough Therapy Designation in October 2021 and January’s Priority Review.

This newest approval comes via the FDA’s Real-Time Oncology Review program. The press release also noted the inclusion of Enhertu as a Category 1 recommendation in the National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology for persons who have local or regional stage IV HER2-positive breast cancer.

Among the DESTINY-Breast03 findings that the FDA based its decision on are the 72% (HR, 0.28; 95% CI, 0.22-0.37; P < .0001) reduced risk of disease progression or death vs trastuzumab emtansine, as well as the lack of grade 4/5 treatment-related interstitial lung disease events.

“Today’s FDA approval highlights the importance of the FDA’s accelerated pathway that allows for earlier approval of medicines to treat serious medical conditions such as breast cancer,” stated Ken Keller, global head, oncology business, and president and CEO, Daiichi Sankyo. “Data from DESTINY-Breast03 not only confirmed the results of DESTINY-Breast01, but also demonstrated the superiority of Enhertu in prolonging PFS compared to T-DM1 in an earlier setting of HER2-positive mBC.”