As reported in BioPharmaDive, the U.S. Food and Drug Administration (FDA) has postponed its decision on camizestrant, an experimental oral therapy for breast cancer being developed by AstraZeneca, following a request for additional data. The delay comes shortly after an advisory committee raised concerns about the strength of the existing evidence supporting the drug in a novel treatment setting.
According to AstraZeneca, regulators opted to extend the review period to evaluate newly submitted analyses, including data linking camizestrant’s performance to longer-term clinical outcomes. The company plans to present these findings at the American Society of Clinical Oncology (ASCO) annual meeting in early June. While a revised decision date has not yet been announced, AstraZeneca indicated it will continue working with the agency to advance the application.
Camizestrant belongs to a newer class of endocrine therapies known as selective estrogen receptor degraders (SERDs). These medicines are designed to degrade estrogen receptors, a key driver of many hormone receptor (HR)-positive breast cancers. Unlike fulvestrant—an established injectable SERD—camizestrant is administered orally, reflecting a broader industry push to improve convenience and potentially enhance effectiveness in this therapeutic category.
Several oral SERDs have already reached the market, but their approved use is currently limited. Existing agents are indicated only for patients whose tumors harbor ESR1 mutations, which can confer resistance to earlier hormone therapies. Their clinical benefit in earlier lines of treatment remains uncertain, leaving an unmet need in this space.
AstraZeneca has positioned camizestrant as a potential next-generation option with broader utility. The company is exploring its use across multiple treatment settings, including earlier stages of disease progression. A key component of the company’s regulatory submission is data from the Phase 3 SERENA-6 study, which evaluated whether switching patients from standard hormone therapy to camizestrant could delay disease progression.
In that trial, patients already receiving a combination regimen either continued their existing therapy or replaced the hormonal component with camizestrant. Results showed a notable reduction—over 50%—in the risk of disease progression or death among those who transitioned to the investigational drug. Despite these findings, the FDA advisory committee concluded in late April that the available data were not sufficiently robust to support approval in this specific context, prompting the request for further evidence.
External experts have echoed these concerns. Analysts citing feedback from oncologists report skepticism about whether the current dataset justifies adoption in clinical practice, particularly given the unconventional treatment strategy evaluated in the study.
Despite the regulatory uncertainty in the U.S., AstraZeneca recently received a positive opinion from the European Medicines Agency, clearing a path for potential approval in Europe under the brand name Etcamah. The company continues to view camizestrant as a significant commercial opportunity, projecting peak annual sales in the multi-billion-dollar range as part of its broader oncology portfolio strategy.
The FDA’s final decision will likely hinge on whether the forthcoming data can convincingly demonstrate sustained clinical benefit and clarify the drug’s role in treatment sequencing for HR-positive breast cancer.
