Enhertu notched another win for AstraZeneca and Daiichi Sankyo that could see uptake moved slightly earlier in a specific subset of breast cancer patients.
The Phase 3 DESTINY-Breast06 study set Enhertu against chemotherapy. The ADC hit the progression-free survival primary endpoint in the primary trial population of HR-positive breast cancer patients who are low on HER2, or the human epidermal growth factor receptor 2, and have gone through one or more lines of endocrine therapy.
Enhertu also showed an early trend toward improvement in the secondary endpoint of overall survival, but data were still immature at the time of analysis.
DESTINY-Breast06 is “the next chapter” for Enhertu, said Greg Rossi, AstraZeneca’s head of oncology Europe and Canada, in an interview with Endpoints News. “Moving earlier in breast cancer with different combinations, including into early-stage disease is … critical,” he said.
Barclays analysts said the results are “yet another win” for the “groundbreaking” ADC, adding the drug is projected to have $11.5 billion in peak sales. During the first quarter of 2024, Enhertu sales rocketed 79% from the same three months last year to $461 million.
AstraZeneca said it will present detailed results from DESTINY-Breast06 at an upcoming medical meeting and share them with global regulatory agencies. Enhertu also met the PFS primary endpoint in the overall population. The study, which enrolled more than 800 participants, also recruited HR-positive and HER2-ultralow patients with advanced or metastatic disease.
In August 2022, Enhertu won FDA approval for HER2-low metastatic breast cancer patients who had at least one prior line of chemotherapy. The new data “allows us to go earlier in the treatment sequence [in HER2-low patients] — so before chemotherapy — meaning these patients have only received typically a couple lines of endocrine therapy,” Rossi said.
There are around two million breast cancer patients globally, with HR-positive disease representing around 70% of all breast cancers, and “we’re now talking about 85%” of that subset, he added.
AstraZeneca also plans to move Enhertu beyond breast cancer and into a “substantial number of [other] tumors that have low levels of HER2 expression,” Rossi added. On April 6, Enhertu won a tumor-agnostic FDA accelerated approval for patients with unresectable or metastatic HER2-positive solid tumors who have received prior systemic treatment and have no satisfactory alternative treatment options.