Analysts at Jefferies called the approval “highly significant,” estimating it could add $2 billion to $3 billion to peak Enhertu sales.
The FDA has greenlit the frontline use of AstraZeneca and Daiichi Sankyo’s antibody-drug conjugate Enhertu in patients with metastatic, HER2-positive breast cancer.
“First-line approval is highly significant because it expands the total addressable market to patients who typically remain on therapy much longer than those in later lines,” analysts at Jefferies said in a note Monday evening. The approval covers the use of Enhertu with Roche’s HER2 blocker Perjeta, according to a Monday news release.
Jefferies expects the earlier use of Enhertu to add $2 billion to $3 billion to its peak sales, taking into consideration “some cannibalization of second-line demand.” The firm now anticipates Enhertu’s peak sales to hit $10 billion to $12 billion.
The FDA’s decision was backed by “impressive” data from the DESTINY-Breast09 study, the firm added in its note. Results presented at the American Society of Clinical Oncology meeting in June showed that the drug combo suppressed the risk of disease progression or death by 44% compared to a regimen consisting of taxane, Herceptin and Perjeta.
Objective response rate reached 85.1% in the Enhertu arm, with 15.1% complete responses. Median duration of response in this group was 39.2 months.
Monday’s approval continues Enhertu’s regulatory rally this year. In January, the FDA approved its second-line use for patients with unresectable or metastatic breast cancer who have ultralow levels of HER2 expression. Enhertu is the first HER2-targeting therapy approved for patients with low and ultralow expression levels.
A few months later, in April, the European Union likewise gave Enhertu its blessing for the HER2 ultralow population after at least one prior line of endocrine treatment.
Designed to target HER2, Enhertu is an antibody-drug conjugate that carries a topoisomerase I inhibitor payload, allowing it to damage cancer cells’ genomes, killing the cells. Enhertu was first approved in December 2019 for the third-line treatment of HER2-positive breast cancer, after which it has continued to rack up regulatory wins, including a tumor-agnostic HER2 nod in April 2024.
AstraZeneca and Daiichi Sankyo continue to seek out areas of expansion for Enhertu beyond breast cancer. In March, the partners said the drug led to a “statistically significant and clinically meaningful improvement” in overall survival in patients with HER2-positive unresectable or metastatic gastric or gastroesophageal junction cancer. An external data monitoring board recommended stopping the study early due to “superior efficacy.”
The companies at the time said they would approach regulators with these data but did not provide a specific timeline for the filing.
