For decades, the challenge of targeting estrogen receptor alpha in hormone-driven breast cancers has centred on one stubborn problem: the receptor mutates, adapts, and survives. Selective estrogen receptor degraders attempted to address this, but fulvestrant, the gold standard, degrades ER incompletely and requires intramuscular injection. The approval of vepdegestrant on 1 May 2026 changes both the biology and the delivery.
The Food and Drug Administration’s clearance of vepdegestrant — marketed as VEPPANU by Arvinas Operations, Inc. — marks the first approval ever granted to a proteolysis-targeting chimera (PROTAC), a heterobifunctional molecule that co-opts the cell’s own ubiquitin-proteasome machinery to degrade target proteins. The indication covers adult patients with estrogen receptor-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer following at least one line of endocrine therapy.
The VERITAC-2 trial was the pivotal study. Among 270 patients with confirmed ESR1 mutations, vepdegestrant reduced the risk of disease progression or death by 43% relative to fulvestrant, with median progression-free survival of 5.0 months in the vepdegestrant arm compared to 2.1 months for fulvestrant. Those numbers represent a meaningful clinical delta in a population where options narrow quickly after first-line CDK4/6 inhibitor combinations.
What makes VEPPANU scientifically distinct is its mechanism. Rather than competitively blocking the ligand-binding domain — the approach taken by aromatase inhibitors and SERDs alike — vepdegestrant recruits an E3 ubiquitin ligase to the ER protein, tagging it for proteasomal degradation. The compound degrades both wild-type and mutant forms of ESR1, including the clinically problematic Y537S and D538G mutations that confer resistance to standard endocrine therapies.
The oral formulation is also significant. At a recommended dose of 200 mg once daily with food, vepdegestrant eliminates the intramuscular injection burden of fulvestrant, which has been a persistent barrier to patient compliance and preference in community oncology settings. Companion diagnostic testing using the Guardant360 CDx liquid biopsy platform was simultaneously approved to identify ESR1-mutation-positive patients eligible for treatment.
The approval has broader implications for the PROTAC platform. Dozens of PROTAC programmes are in active clinical development across oncology, neurology, and rare disease. The regulatory precedent set by VEPPANU clarifies that targeted protein degradation is a viable therapeutic modality, not merely a promising preclinical concept. For companies developing degraders against other historically undruggable targets — including transcription factors and scaffold proteins — this approval represents meaningful de-risking of the regulatory pathway.
Arvinas entered a global licensing agreement with Rigel Pharmaceuticals for VEPPANU’s commercialisation, extending the drug’s geographic reach. Analysts tracking the ESR1-positive breast cancer market estimate eligible patients in the United States alone at approximately 40,000 annually at the relevant line of therapy.
