As a PROTAC (Proteolysis-Targeting Chimera), vepdegestrant represents a novel class of heterobifunctional degraders, and its non-clinical package focused heavily on its unique mechanism and potential for off-target effects.
Based on the FDA approval documentation for VEPPANU (vepdegestrant) (NDA 219835,https://www.arvinas.com/wp-content/uploads/2026/05/NDA-219835_Approval-Rx-ONLY.pdf), which was approved on May 1, 2026, here are the key non-clinical studies and profiles conducted to support its safety and efficacy.
1. Pharmacodynamics (PD)
Vepdegestrant is a first-in-class PROTAC designed to harness the body’s ubiquitin-proteasome system to degrade the estrogen receptor (ER).
Mechanism of Action: Studies confirmed that vepdegestrant binds simultaneously to the E3 ubiquitin ligase (VHL) and the Estrogen Receptor (ER). This induces ubiquitination and subsequent proteasomal degradation of the receptor.
Target Engagement: In vitro and in vivo models demonstrated potent degradation of both wild-type ER and common ESR1 mutations (e.g., Y537S and D538G) that drive resistance to standard endocrine therapies.
Secondary PD: Selectivity profiling was conducted against broad panels (50–100+ targets) to identify unintended interactions.
2. ADME & DMPK
Pharmacokinetic (PK) studies evaluated the drug’s journey through the body and its interaction with metabolic enzymes.
Absorption: Vepdegestrant is orally bioavailable. Studies showed that taking the drug with food increases exposure, leading to the clinical recommendation to dose with food.
Metabolism:
CYP Enzymes: The drug is a substrate of CYP3A4.
Induction/Inhibition: In vitro studies assessed its potential to induce or inhibit major CYP enzymes (CYP3A4, CYP2C9, etc.) and transporters (P-gp, BCRP).
Excretion: Primary routes of elimination were characterized to understand the drug’s half-life and potential for accumulation.
3. Non-Clinical Toxicology
These studies established the safety margins and identified potential risks for human trials.
General Toxicology:
Repeat-Dose Studies: Conducted in rodents (rats) and non-rodents (monkeys) to identify target organ toxicity.
Key Findings: Notable laboratory changes in animal models included effects on white blood cells, liver enzymes (ALT/AST), and musculoskeletal findings, which mirrored the adverse reactions later seen in clinical trials.
Genetic Toxicology (Mutagenesis):
A standard battery of tests (e.g., Ames test, in vitro chromosomal aberration, in vivo micronucleus) was conducted to ensure the molecule does not damage DNA.
Reproductive & Developmental Toxicology:
Embryo-Fetal Toxicity: Studies demonstrated that vepdegestrant can cause fetal harm. Consequently, the label includes warnings for embryo-fetal toxicity and requirements for effective contraception.
Impairment of Fertility: Evaluated the drug’s impact on both male and female reproductive organs.
Safety Pharmacology:
Cardiovascular: Specialized studies (including hERG assays) evaluated the risk of QTc interval prolongation, which is a significant warning on the final approved label.
4. Summary Table of Non-Clinical Highlights
| Study Category | Study Type / Model | Conducted? | Brief Results Summary |
| Pharmacodynamics | In vitro Binding & Degradation | Yes | Confirmed ternary complex formation (Vepdegestrant + VHL + ER). Potent degradation of wild-type and mutated (Y537S, D538G) ER. |
| Pharmacodynamics | In vivo Xenograft Models | Yes | Demonstrated significant tumor growth inhibition in ESR1-mutated breast cancer models. |
| Safety Pharmacology | In vitro hERG Assay | Yes | Evaluated potential for QTc prolongation. Findings supported clinical warnings for heart rhythm changes. |
| ADME / DMPK | In vitro CYP Inhibition/Induction | Yes | Identified vepdegestrant as a substrate of CYP3A4. Assessed potential for drug-drug interactions. |
| ADME / DMPK | In vitro Transporter Assays | Yes | Evaluated interactions with P-gp and BCRP transporters. |
| Toxicology | Repeat-Dose Toxicity (Rodent) | Yes | Conducted in rats. Identified target organ effects (WBC decreases, liver enzyme increases, musculoskeletal changes). |
| Toxicology | Repeat-Dose Toxicity (Non-rodent) | Yes | Conducted in monkeys. Established safety margins and identified potential for transaminase elevations. |
| Genetic Tox | Ames / Micronucleus Battery | Yes | Standard battery conducted. No evidence of mutagenic or clastogenic potential reported. |
| Reproductive Tox | Embryo-Fetal Development (Rat) | Yes | Positive Findings: Oral administration resulted in embryo-fetal mortality and structural abnormalities at exposures below human doses. |
| Reproductive Tox | Fertility & Early Embryonic Dev | Yes | Findings suggested potential for impaired fertility in both males and females based on reproductive organ effects. |
| Carcinogenicity | 2-Year Bioassay | No | Typically deferred for advanced cancer indications or not yet completed at the time of initial accelerated approval. |
This summary is based on the prescribing information and regulatory summaries for VEPPANU. For specific study numbers and detailed histopathology results, please refer to Section 13 (Nonclinical Toxicology) and Section 12 (Clinical Pharmacology) of the full prescribing information.