Enzalutamide vs. Abiraterone vs. Darolutamide: Comparing Hormonal Therapies for Advanced Prostate Cancer

Research-informed explainer — last updated April 12, 2026

For men with advanced prostate cancer, a class of drugs called androgen receptor pathway inhibitors (ARPIs) — including enzalutamide, abiraterone, darolutamide, and apalutamide — has transformed survival outcomes, but each agent has a different mechanism, side effect profile, and approved indication depending on disease stage. Choosing between them requires understanding where you are in your prostate cancer journey.

This article draws on research from three prostate cancer specialists who co-authored the defining trials. Neal Shore, DR, at Grand Strand Medical Center in Conway, South Carolina, co-led the AFFIRM enzalutamide trial (cited over 4,500 times), the PROSPER enzalutamide trial in nonmetastatic castration-resistant disease, the ARCHES trial of enzalutamide in metastatic hormone-sensitive disease, the PROfound olaparib trial, and the ARAMIS darolutamide trial — collectively representing the evidence base for nearly every stage of advanced prostate cancer. Paul Sieber, M.D., at WellSpan Health in Lancaster County, co-led the denosumab bone-metastasis-free survival trial (cited nearly 800 times) — directly addressing bone health during long-term androgen deprivation therapy. Edward Schaeffer, M.D., Ph.D., Chair of Urology at Northwestern Memorial Hospital, published on the rising incidence of metastatic prostate cancer and on genomic classifier-guided treatment selection.

Background: androgen deprivation therapy as the foundation

All of these drugs are used on top of — or as alternatives to — standard androgen deprivation therapy (ADT), which reduces testosterone to castrate levels (below 50 ng/dL) via surgical orchiectomy or GnRH agonists/antagonists (leuprolide, degarelix, relugolix). ADT alone was the cornerstone of advanced prostate cancer treatment for decades, but most metastatic tumors eventually become "castration-resistant" — growing despite low testosterone.

The next-generation ARPIs were developed to address the mechanisms of castration resistance: androgen receptor mutations that activate the receptor at low testosterone levels, AR gene amplification, intratumoral androgen synthesis, and splice variants like AR-V7 that lack the drug-binding domain.

Understanding the prostate cancer disease states

Choosing the right ARPI depends on disease stage:

• mHSPC (metastatic hormone-sensitive prostate cancer): Castrate-naive metastatic disease; responds to testosterone suppression
• nmCRPC (nonmetastatic castration-resistant): PSA rising despite castrate testosterone, no visible metastases on conventional imaging
• mCRPC (metastatic castration-resistant): Metastatic disease that progresses despite ADT

Comparison of approved ARPIs

Enzalutamide: the most extensively studied ARPI

The AFFIRM trial, co-led by Neal Shore, enrolled 1,199 men with metastatic CRPC who had progressed after docetaxel. Enzalutamide reduced the risk of death by 37% compared with placebo (HR 0.63, p<0.001) and improved median overall survival from 13.6 to 18.4 months. This 2012 NEJM publication (cited over 4,500 times) established enzalutamide as a standard second-line option after chemotherapy.

The PROSPER trial (NEJM 2018) studied enzalutamide in nonmetastatic CRPC — men whose PSA was rising rapidly despite castrate testosterone but who had no detectable metastases on conventional imaging. Enzalutamide reduced the risk of metastasis or death by 71% compared with placebo, extending metastasis-free survival from 14.7 to 36.6 months.

The ARCHES trial (JCO 2019) randomized 1,150 men with metastatic hormone-sensitive prostate cancer to ADT plus enzalutamide versus ADT plus placebo. Enzalutamide significantly reduced radiographic progression or death (HR 0.39, p<0.001) across subgroups including low-volume and high-volume metastatic disease.

Key enzalutamide side effects: Fatigue (33%), hypertension (14%), hot flashes (13%), falls (6%), seizure risk (0.5% — contraindicated in patients with prior seizure history or CNS lesions).

Abiraterone: the CYP17 inhibitor approach

Abiraterone blocks the enzyme CYP17A1, which is required for androgen synthesis in the adrenal glands, testes, and prostate tumor cells themselves. Unlike enzalutamide (which blocks the receptor), abiraterone reduces the ligand — the androgens that fuel the receptor.

Abiraterone must be given with prednisone (10 mg/day) because CYP17A1 inhibition leads to mineralocorticoid excess. This steroid requirement distinguishes it clinically from the pure AR antagonists, and can complicate management in patients with diabetes, osteoporosis, or immune-mediated conditions.

Key trials: COU-AA-301 and COU-AA-302 established abiraterone in post- and pre-chemo mCRPC. The LATITUDE trial showed that adding abiraterone to ADT in newly metastatic high-risk HSPC significantly improved overall survival (HR 0.62).

Key abiraterone side effects: Fluid retention (28%), hypokalemia (17%), hypertension (22%), hepatotoxicity (requires liver function monitoring), fatigue, steroid-related effects from prednisone.

Darolutamide: lower CNS penetration, favorable tolerability

Darolutamide's distinct chemical structure results in minimal blood-brain barrier penetration compared with enzalutamide and apalutamide, which may explain its lower rates of CNS side effects (fatigue, falls, cognitive impairment). The ARAMIS trial — co-led by Neal Shore — showed darolutamide extended metastasis-free survival from 18.4 to 40.4 months in nmCRPC (HR 0.41, p<0.001) with a side effect profile not statistically different from placebo.

Key darolutamide advantage: Approved for use in mHSPC in combination with docetaxel (ARASENS trial) and has fewer drug-drug interactions than enzalutamide, which matters for older patients on multiple medications.

When BRCA mutations change the treatment decision: PARP inhibitors

The PROfound trial, co-led by Neal Shore, enrolled men with mCRPC who had progressed on abiraterone or enzalutamide and had alterations in homologous recombination repair genes (BRCA1/2, ATM, and others). Olaparib (a PARP inhibitor) significantly prolonged radiographic progression-free survival compared with physician's choice of enzalutamide or abiraterone (HR 0.34 for the BRCA1/2 cohort, p<0.001). Overall survival was significantly improved in the BRCA1/2 subgroup.

This means that genomic testing (tumor or germline) for BRCA1/2 mutations is now a standard part of mCRPC management, and men who progress on an ARPI and carry a BRCA mutation should discuss olaparib or rucaparib with their oncologist.

Bone health during long-term ADT

Paul Sieber's denosumab trial enrolled 1,432 men with nmCRPC and found that denosumab — a RANK-L inhibitor — extended bone-metastasis-free survival by 4.2 months compared with placebo (29.5 vs. 25.2 months, HR 0.85, p=0.028) and delayed time to bone metastasis. Long-term ADT causes bone mineral density loss, increasing fracture risk. Current guidelines recommend calcium plus vitamin D, weight-bearing exercise, DEXA bone density scanning at baseline, and bisphosphonate or denosumab therapy for men with osteoporosis or high fracture risk.

Questions to ask your doctor

• What stage of prostate cancer do I have — hormone-sensitive, nonmetastatic castration-resistant, or metastatic castration-resistant — and which drug class is appropriate for my stage?
• Has my tumor been tested for BRCA1/2 or other DNA repair mutations that would make me eligible for a PARP inhibitor?
• What is my PSA doubling time, and does it influence which ARPI to use first?
• Are there drug-drug interactions with my current medications that favor darolutamide over enzalutamide?
• Should I be started on bone protective therapy alongside my hormonal treatment?
• Has my tumor been tested with a genomic classifier (Decipher) to guide intensity of treatment?

The bottom line

The choice between enzalutamide, abiraterone, darolutamide, and apalutamide is not purely interchangeable — each has distinct mechanisms, side effect profiles, drug interactions, and optimal disease-stage indications. Randomized trial data from the AFFIRM, PROSPER, ARCHES, and ARAMIS trials demonstrate that ARPIs improve survival at every stage of advanced prostate cancer from hormone-sensitive through castration-resistant disease. Men whose cancer progresses on an ARPI should undergo genomic testing for BRCA mutations — because PARP inhibitors like olaparib offer meaningful additional survival benefit in that molecular subgroup.