According to results published on Sunday, AstraZeneca and Daiichi Sankyo’s Enhertu increased life by more than six months in patients with a kind of advanced breast cancer when compared to regular treatment.
The findings, presented at the American Society of Clinical Oncology (ASCO) meeting in Chicago, could open up a large, new multibillion-dollar patient population for the drug, which was approved in the United States in late 2019 as a third-line treatment for the 15% of patients with HER2-positive breast cancer.
Over 550 patients with so-called HER2-low breast cancer – most with hormone-sensitive tumors – whose disease had progressed and had completed at least one round of chemotherapy are currently enrolled in the ongoing phase III research.
In patients with hormone-sensitive tumors, Enhertu extended life by 6.4 months, according to an interim review. Patients in the study lived an average of 23.9 months, compared to 17.5 months for chemotherapy patients.
Patients on Enhertu lived 6.3 months longer than those on placebo in a small group of patients with hormone-insensitive tumors.
It was surprising, according to David Fredrickson, executive vice president of AstraZeneca’s oncology unit, that the benefit in overall survival was visible even at the interim analysis.
“That gives me a lot of faith in the fact that the advantage we’re seeing here is real.”
Patients with advanced HER2-positive breast cancer now have a better prognosis because to a slew of targeted medicines. However, more than half of women with breast cancer who have progressed to other organs and have little or no HER2 expression – known as HER2-low status – have few therapy options.
Enhertu-treated hormone-sensitive patients also lived an average of 10.1 months before their condition worsened, compared to 5.4 months for chemotherapy, which was statistically significant.
The PFS for hormone-insensitive patients was more than doubled with Enhertu, at 6.6 months against 2.9 months with chemotherapy.
AstraZeneca is in talks with regulators throughout the world about getting approval in the HER2-low population. Last month, Jefferies analysts predicted $2.5 billion in annual global peak Enhertu sales for these patients, and $6.6 billion overall.
The medicine, which is given as an intravenous infusion, has a number of side effects. It’s been related to interstitial lung disease, a sort of lung scarring (ILD). In the experiment, 45 Enhertu patients exhibited varied degrees of ILD compared to one chemotherapy patient.
Enhertu is an antibody drug conjugate (ADC), a type of therapy in which modified antibodies bind to tumor cells and release cell-killing chemicals.
It was approved as a second-line therapy option last month after a study found that it lowered the risk of disease progression or death by 72 percent when compared to Roche’s Kadcyla, the standard medication.
Enhertu is being researched for usage in the early stages of breast cancer, as well as lung and colorectal malignancies. It has been approved for the treatment of HER2-positive gastric cancer.
“At least in the next several years, I’m very sure Enhertu is going to finish revolutionising the therapeutic paradigm in breast cancer,” Tara Hansen, a consultant at Informa Pharma Custom Intelligence, told Dailion.
In 2021, Enhertu made $214 million in sales. In a deal worth up to $6.9 billion, AstraZeneca acquired partial rights to the Daiichi Sankyo chemical three years ago.