Enhertu, the first antibody-drug conjugate (ADC) developed by AstraZeneca and Daiichi Sankyo, has received a seventh nod from the FDA, only 11 days after Datroway, the second ADC developed by the partners, was approved for cancer therapy.
Enhertu is the first HER2-directed medication to get regulatory approval in the U.S. for patients whose breast cancer has progressed after receiving one or more endocrine treatments and have extremely low HER2 levels.
After Enhertu made history in 2022 as the first therapy for HER2-low metastatic breast cancer, the medical world wondered how low Enhertu could actually go.
The green light not only makes Enhertu the first therapy for patients whose tumors exhibit a lower level of the HER2 protein biomarker, but it also elevates Enhertu up another level in the treatment queue for those suffering from HER2-low metastatic breast cancer. It may now be utilized after one or more unsuccessful endocrine treatments.
The FDA breakthrough is based on the findings of the DESTINY-Breast06 study, in which Enhertu demonstrated a 36% decrease in the likelihood of illness progression or mortality compared to chemotherapy. Patients who received Enhertu had an average progression-free survival of 13.2 months, whereas those who received chemotherapy had a median progression-free lifespan of just over 8 months. Of the patients who received Enhertu, 63% showed a full or partial response to treatment, compared to just under 35% of the patients who received chemotherapy.
“Endocrine therapy is typically used in the initial treatment of HR-positive metastatic breast cancer and following progression, subsequent chemotherapy is associated with poor outcomes,” Aditya Bardia, M.D., the trial investigator, stated in a release. He added that Enhertu brings with it a potentially new standard in terms of healthcare for patients with this form of the disease after endocrine therapy.
Enhertu was originally authorized in 2019 to treat individuals with severe or metastatic HER2-positive breast cancer who had previously failed on at least two earlier therapies. In 2019, AZ announced a $6.9 billion investment in Enhertu, paying $1.35 billion upfront to study and market the therapy outside of Japan. According to the companies, AZ is required to pay Daiichi $175 million as a milestone payment after Tuesday’s approval.
In 2022, Enhertu became a massive success, and in the first three quarters of 2024, it produced $2.7 billion, an increase of almost $1 billion from the first three quarters of the previous year.
Earlier this month, the firms received FDA clearance for Datroway, which is used to treat HR-positive, HER2-negative breast cancer for people who have already had endocrine-based treatment and chemotherapy. AZ agreed to become an affiliate for the TROP-2 targeted ADC in a transaction worth $5 billion, with $1 billion paid upfront.
