South San Francisco, CA – The U.S. Food and Drug Administration (FDA) has accepted a New Drug Application (NDA) for giredestrant, an investigational oral therapy developed by Genentech, a member of the Roche Group, for a specific form of advanced breast cancer. The application seeks approval for giredestrant in combination with everolimus to treat adult patients with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2-negative (HER2-negative), ESR1-mutated locally advanced or metastatic breast cancer who have experienced disease progression following prior endocrine-based treatment. This represents a potential new avenue for patients facing resistance to standard-of-care therapies.
The FDA’s acceptance of the NDA is based on data from the Phase III evERA trial, which demonstrated a significant clinical benefit. According to Genentech, the trial showed that giredestrant plus everolimus reduced the risk of disease progression or death by 44% in the overall patient population and by 62% in patients with ESR1 mutations, compared to standard-of-care endocrine therapy plus everolimus. This data positions giredestrant as a potentially groundbreaking treatment option.
Understanding ESR1 Mutations and Treatment Resistance
Breast cancer is a complex disease, and treatment strategies often evolve as cancer cells develop resistance to initial therapies. Estrogen receptor (ER)-positive breast cancer, which accounts for a significant proportion of all breast cancer cases, relies on estrogen to fuel its growth. Endocrine therapies, such as tamoxifen and aromatase inhibitors, block estrogen’s effects or reduce estrogen production. However, many patients eventually develop resistance to these treatments.
ESR1 mutations, alterations in the gene encoding the estrogen receptor, are a common mechanism of resistance to endocrine therapy. These mutations can make the receptor constitutively active, meaning it signals for cell growth even in the absence of estrogen. Giredestrant is a selective estrogen receptor degrader (SERD) designed to target and degrade the estrogen receptor, including mutated forms. The combination with everolimus, an mTOR inhibitor, aims to further disrupt cancer cell growth pathways. Researchers believe this combination could address a critical unmet need in patients who have progressed on prior CDK4/6 inhibitor therapies.
The evERA Trial: Key Findings and Implications
The evERA trial, a pivotal study supporting the NDA, involved patients with ESR1-mutated, ER-positive, HER2-negative advanced breast cancer who had previously been treated with a CDK4/6 inhibitor. The trial’s primary endpoint was progression-free survival (PFS), the length of time patients lived without their cancer growing or spreading. The statistically significant improvements in PFS observed with giredestrant plus everolimus suggest a meaningful clinical benefit for patients. The trial as well evaluated overall survival (OS), even though those results are still maturing and will be closely watched by the medical community.
Levi Garraway, M.D., Ph.D., chief medical officer and head of Global Product Development at Genentech, emphasized the potential impact of giredestrant. “The clinically meaningful benefit seen with giredestrant could enable an important new treatment option to help delay disease progression or death in people with advanced, ER-positive breast cancer,” he stated in a company press release. If approved, giredestrant plus everolimus would be the first and only oral SERD combination approved in the post-CDK4/6 inhibitor setting, offering a convenient and potentially effective treatment option for patients.
What are SERDs and mTOR Inhibitors?
Selective Estrogen Receptor Degraders (SERDs) are a class of drugs that work by binding to the estrogen receptor and promoting its degradation, effectively reducing the amount of the receptor available to drive cancer cell growth. Unlike some earlier anti-estrogen therapies, SERDs aim to completely eliminate the receptor protein.
mTOR inhibitors, like everolimus, target the mammalian target of rapamycin (mTOR) pathway, a key regulator of cell growth, proliferation, and survival. By inhibiting mTOR, these drugs can help slow down cancer cell growth and enhance the effects of other therapies.
Regulatory Timeline and Next Steps
The FDA has assigned a Prescription Drug User Fee Act (PDUFA) date of December 18, 2026, for its decision on the giredestrant NDA. Which means the agency is expected to complete its review of the application and announce its decision by this date. The PDUFA date is a target date, and the FDA can approve or reject the application before or after this date.
The FDA’s review will involve a thorough evaluation of the data from the evERA trial, as well as information on the drug’s manufacturing process and safety profile. If approved, giredestrant will likely become a significant addition to the treatment landscape for advanced breast cancer, particularly for patients with ESR1 mutations who have exhausted other options. Genentech, founded over 40 years ago and headquartered in South San Francisco, California, is a leading biotechnology company and a member of the Roche Group. The company focuses on discovering, developing, and commercializing medicines for serious and life-threatening conditions.
Looking Ahead: Impact on Breast Cancer Care
The potential approval of giredestrant represents a significant step forward in personalized medicine for breast cancer. Identifying ESR1 mutations through genomic testing is becoming increasingly common, allowing physicians to tailor treatment strategies to the specific characteristics of each patient’s tumor. The availability of a targeted therapy like giredestrant could improve outcomes and quality of life for patients with this challenging disease.
Beyond giredestrant, Genentech also received FDA acceptance in March 2025 for a supplemental Biologics License Application (sBLA) for Gazyva (obinutuzumab) for the treatment of lupus nephritis, a debilitating autoimmune disease affecting the kidneys. This demonstrates the company’s continued commitment to developing innovative therapies for a range of serious medical conditions.
The coming months will be crucial as the FDA completes its review of giredestrant. The medical community and patients alike await the agency’s decision with anticipation, hoping for a new treatment option that can offer hope and improved outcomes for those battling advanced breast cancer.
Stay informed: For the latest updates on giredestrant and breast cancer research, please consult the FDA website and the National Cancer Institute.
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