FDA Approves Vepdegestrant for ESR1-Mutated Advanced Breast Cancer

The U.S. Food and Drug Administration has approved vepdegestrant for the treatment of patients with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-), ESR1-mutated advanced or metastatic breast cancer who have previously received endocrine-based therapy.

The approval targets a specific subset of advanced breast cancer patients harboring mutations in the ESR1 gene, which often lead to resistance against conventional endocrine therapies.

Mechanism of Action and the PROTAC Approach

Vepdegestrant is an orally administered proteolysis-targeting chimera, commonly known as a PROTAC. Unlike traditional estrogen receptor antagonists that block the receptor’s activity, a PROTAC degrader leverages the body’s own ubiquitin-proteasome system to eliminate the estrogen receptor protein entirely.

By inducing the degradation of the estrogen receptor, vepdegestrant aims to overcome the resistance mechanisms that allow ESR1-mutated cancer cells to continue growing even in the absence of estrogen.

Clinical Evidence from the VERITAC-2 Trial

The regulatory decision was supported by data from the pivotal Phase 3 VERITAC-2 clinical trial. This open-label, randomized study compared the efficacy of vepdegestrant against fulvestrant, a standard-of-care endocrine therapy.

According to trial data, vepdegestrant demonstrated a statistically significant improvement in median progression-free survival (PFS) compared to fulvestrant. Reports indicate a median PFS of 5.0 months for patients receiving vepdegestrant, compared to 2.1 months for those receiving fulvestrant.

the drug showed higher overall response rates (ORR) and clinical benefit rates (CBR) in the second-line ESR1-mutant setting, suggesting a more effective alternative for patients whose tumors have evolved to resist earlier treatments.

Patient Eligibility and Use

Vepdegestrant is indicated for patients who meet the following criteria:

• Diagnosis of advanced or metastatic breast cancer.
• Tumors that are ER-positive and HER2-negative.
• Presence of ESR1 mutations.
• Prior treatment with endocrine-based therapy.

The medication is designed as a second-line-plus treatment option, providing a targeted therapeutic path for patients who have progressed after initial endocrine interventions, such as those involving cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors.

Development and Partnership

The drug was co-developed by the biotechnology company Arvinas, Inc. And Pfizer Inc. The partnership focused on the development of PROTAC technology to address “undruggable” targets in oncology.

The transition from the acceptance of the New Drug Application (NDA) in August 2025 to final approval marks a significant step in the clinical application of protein degradation therapy for breast cancer.