AstraZeneca's Enhertu: A Game Changer in Breast Cancer Treatment

AstraZeneca and Daiichi Sankyo have received a significant boost with the U.S. Food and Drug Administration (FDA) approval of Enhertu (trastuzumab deruxtecan) for the treatment of adult patients with unresectable or metastatic hormone receptor (HR)-positive, HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2-ultralow (IHC 0 with membrane staining) breast cancer. This approval expands the eligible patient population for Enhertu, a HER2-directed antibody drug conjugate (ADC), and has the potential to significantly impact the breast cancer treatment landscape.



The approval is based on the results of the DESTINY-Breast06 Phase III trial, which demonstrated Enhertu's superiority over chemotherapy in terms of median progression-free survival (PFS) and objective response rate (ORR). In the trial, Enhertu showed a 36% reduction in the risk of disease progression or death versus chemotherapy (hazard ratio [HR] 0.64; 95% confidence interval [CI]: 0.54-0.76; p<0.0001) in the overall trial population. A median PFS of 13.2 months was seen in patients randomized to Enhertu compared to 8.1 months in those randomized to chemotherapy. The confirmed ORR in the overall trial population was 62.6% for Enhertu versus 34.4% for chemotherapy.



The approval brings Enhertu to an earlier HR-positive treatment setting and broadens the patient population eligible for treatment with a HER2-directed therapy to those with HER2-ultralow disease. This expansion is expected to drive increased sales of Enhertu, contributing to AstraZeneca's revenue growth. In 2023, AstraZeneca recorded $1.28 billion in Enhertu revenue, which mainly included its share of profits and royalties in key markets such as the U.S. Combined sales of the drug for the two companies amounted to $2.57 billion in 2023, more than doubling from $1.25 billion the year before.

The approval of Enhertu for earlier-stage breast cancer has the potential to shift market share in the breast cancer treatment landscape by expanding into earlier treatment settings, increasing competition in the HER2 space, and potentially expanding into new patient populations and tumor types. AstraZeneca's oncology business chief Dave Fredrickson has stated that there is still opportunity to drive continued growth beyond the current 50% market share in the HER2-low space. Additionally, the potential expansion into HER2-ultralow and earlier lines of treatment, as well as the pan-tumor nod, could further increase Enhertu's market share and solidify AstraZeneca's position in the breast cancer treatment space.

In conclusion, the FDA approval of Enhertu for earlier-stage breast cancer is a significant milestone for AstraZeneca and Daiichi Sankyo, as it expands the eligible patient population and drives increased sales of the drug. This approval has the potential to shift market share in the breast cancer treatment landscape and contribute to AstraZeneca's projected revenue growth in the coming years.