Astrazeneca and daiichi sankyo's Enhertu draw positive data as first-line breast cancer treatment
Clinical data on cancer drugs currently approved for second-line or later metastatic breast cancer treatments suggest that it helps patients live longer without disease worsening in frontline settings, and the results can support further expansion of the use of such targeted therapies.
Astrazeneca and Daiichi Sankyo have not disclosed specific details from the Phase 3 test in metastatic HER2-positive breasts. But the planned temporary analysis showed that the drug Enhertu resulted in “an improvement in progression-free survival in both statistically significant and clinically significant.” This measure was made compared to the triple drug combination currently used as the first-line treatment for this type of cancer. These results are important because many patients with metastatic breast cancer do not live long enough to receive a second treatment.
Enhertu is an antibody drug conjugate (ADC) discovered by Daiichi Sankyo and is further developed and commercialized in collaboration with Astrazeneca. The antibody component of the drug targets HER2, a protein that is overexpressed on breast cancer cells. ENHERTU was first approved by the FDA as a third-line treatment for HER2-positive metastatic breast cancer in 2019. The therapy expands its approved uses to second-line treatments for this type of cancer in 2022.
The interim results announced on Monday were from a global phase 3 test, which enrolled 1,157 patients. ENHERTU itself was tested and used in conjunction with Pertuzumab, a Roche drug sold under the brand name Perjeta. The study drug was compared with chemotherapy paclitaxel with Perjeta and another Roche monoclonal antibody drug, Herceptin. This three-toxic combination is the standard first-line treatment for metastatic HER2-positive breast cancer.
Astrazeneca and Daiichi sankyo said improvements in progression-free survival were observed in all pre-specified subgroups of patients who received paired with perjeta. Regarding key secondary goals for measuring overall survival, the data is not yet mature. But the two companies said temporary overall survival data showed that trends favored the ENHERTU combination compared to standard tertiary drugs. Compared to standard treatment, the second cohort for evaluating ENHERTU as a monotherapy remains blind and will continue to perform final analysis to measure progression-free survival.
“This is the first trial in more than a decade, showing excellent efficacy in a wide population of HER2-positive metastatic breast cancer patients compared to current frontline care standards,” Susan Galbraith, executive vice president of Oncology R&D, Astrazeneca, said in a prepared statement. “This is an important milestone for patients and provides the foundation for the combination of Enhertu and Pertuzumab to be a key treatment option in front-line HER2-positive settings.”
On the safety side, the companies said the results so far show that the safety of the Enhertu and Perjeta combination is consistent with the known profile of each therapy. Enhertu's label comes with a black box warning to pose a risk of interstitial lung disease. The companies said they will present more data at the upcoming medical meeting and share it with regulators.
Under the partnership between Astrazeneca and daichii sankyo, the two companies develop Enhertu globally, except that Daiichi Sankyo holds all rights to the ADC. The two companies reported that the product had a total sales of more than $3.7 billion in 2024, up more than 46% from drug sales in the previous year.
Stuart S. Martin’s public domain image, through the National Cancer Institute
