Enzalutamide Mechanism of Action: How Enzalutamide Works | Elicit
Enzalutamide Mechanism of Action
How Enzalutamide (Xtandi) Works: Androgen receptor (AR) signaling inhibition in prostate cancer.
Last updated: March 2026
Quick Summary
Enzalutamide (Xtandi) is an oral androgen receptor (AR) signaling inhibitor used in prostate cancer, including castration-resistant and castration-sensitive disease settings. It is classified as an androgen receptor inhibitor and was engineered for castration-resistant prostate cancer with AR amplification/overexpression.
Properties
| Details | |
|---|---|
| Generic Name | Enzalutamide |
| Brand Names | Xtandi |
| Drug Class | Androgen receptor inhibitor (antiandrogen) |
| Primary Target | Androgen receptor (AR) |
| Approved Indications | Castration-resistant prostate cancer (CRPC, both metastatic and non-metastatic), metastatic castration-sensitive prostate cancer (mCSPC) |
| Key Effect | Inhibits androgen receptor signaling to treat AR-driven prostate cancer |
Development History
Enzalutamide (MDV3100) was developed by Charles Sawyers and Michael Jung at UCLA and the Memorial Sloan Kettering Cancer Center, arising from a high-throughput screen of thiohydantoin scaffolds conducted in the mid-2000s and first described in Tran et al., Science 2009. The pivotal approval program centered on AFFIRM, a phase III, randomized, placebo-controlled trial in 1,199 men with metastatic CRPC who had progressed on docetaxel. The primary endpoint was overall survival; enzalutamide produced a median OS of 18.4 months versus 13.6 months for placebo, a 37% reduction in the risk of death (HR 0.63).
Xtandi's label has expanded three times since initial approval. In September 2014, the FDA approved enzalutamide for chemotherapy-naïve metastatic CRPC based on PREVAIL, a phase III trial. In July 2018, a supplemental NDA based on PROSPER extended the indication to non-metastatic CRPC. Most recently, in December 2019, enzalutamide received approval for metastatic hormone-sensitive prostate cancer (mHSPC) based on ARCHES.
Detailed Mechanism of Action
Enzalutamide is an orally bioavailable diarylthiohydantoin compound that is rapidly absorbed after oral dosing. The central pharmacological event is high-affinity, competitive binding of enzalutamide to the ligand-binding domain (LBD) of the androgen receptor (AR).
Blockade of AR nuclear translocation
Enzalutamide impairs the nuclear translocation of the AR, preventing it from accessing target gene chromatin entirely.
Inhibition of AR–DNA interaction and coactivator recruitment
Enzalutamide reduces productive chromatin occupancy and inhibits coactivator recruitment, shutting down the transcription of AR-regulated genes, including PSA (KLK3) and TMPRSS2.
Downstream transcriptional and antiproliferative consequences
Microarray profiling reveals a reversal of androgen-stimulated gene expression patterns, leading to G1 cell-cycle arrest followed by apoptosis in AR-dependent cells.
Autophagy as a parallel adaptive survival response
AR blockade triggers a parallel cytoprotective response in CRPC cells, activating the AMPK pathway and suppressing mTOR through Raptor phosphorylation.
Clinical Relevance
Approved Indications
- Metastatic CRPC (post-docetaxel): FDA-approved for men with mCRPC previously treated with docetaxel.
- Metastatic CRPC (chemo-naïve): FDA-approved for chemotherapy-naïve mCRPC based on improved overall survival.
- Non-metastatic CRPC (nmCRPC): FDA-approved for high-risk nmCRPC.
- Metastatic CSPC (mCSPC): FDA-approved in combination with androgen deprivation therapy.
Key Drug Interactions
- Strong CYP3A4 induction: Enzalutamide reduces midazolam AUC by ~86%.
- Moderate CYP2C9/CYP2C19 induction: Reduce S-warfarin AUC by 56%.
- CYP2C8 inhibition increases enzalutamide exposure: Co-administration with gemfibrozil increased composite enzalutamide plus active metabolite AUC 2.2-fold.
Special Populations
- Seizure risk: Seizures occurred in 0.9% of enzalutamide-treated patients.
- Fatigue: Fatigue is among the most commonly reported adverse events.
Emerging Indications
Oncology
- AR+ triple-negative breast cancer: Clinical trials are evaluating the use of enzalutamide in this setting.
- Metastatic urothelial carcinoma: AR expression has been implicated in bladder carcinogenesis.
Clinical Trials of Enzalutamide
Trial data synthesized from peer-reviewed publications and ClinicalTrials.gov filings.
| Trial Name | Phase | Design | N Enrolled | Indication | Primary Endpoint | Key Result | Status |
|---|---|---|---|---|---|---|---|
| EMBARK | 3 | RCT | 1068 | Nonmetastatic castration-sensitive prostate cancer | Metastasis-free survival | MFS favored enzalutamide + leuprolide | Ongoing |
| ARCHES | 3 | RCT | 1150 | mHSPC | Radiographic progression-free survival | Enzalutamide + ADT reduced risk 61% | Completed |
| ENZAMET | 3 | RCT | 1125 | mHSPC | Overall survival | Overall survival favored enzalutamide | Completed |
| PROSPER | 3 | RCT | 1401 | nmCRPC | Metastasis-free survival | Enzalutamide improved MFS vs placebo | Completed |
| AFFIRM | 3 | RCT | 1199 | mCRPC (post-docetaxel) | Overall survival | Enzalutamide improved overall survival vs placebo | Completed |
Open Research Questions
How does enzalutamide drive lineage plasticity and treatment-emergent neuroendocrine differentiation?
What is the mechanism behind enzalutamide-associated cognitive impairment and fatigue?
To what extent is cross-resistance between enzalutamide and abiraterone clinically meaningful?
Does adding a PARP inhibitor to enzalutamide benefit patients without homologous recombination repair (HRR) deficiency?
How does enzalutamide's cardiovascular risk profile compare with other AR-axis inhibitors?
This mechanism of action page was generated using Elicit's AI research agent, which synthesizes explanations from peer-reviewed pharmacology literature.