Leuprolide

At a glance

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What is leuprolide?

Leuprolide is a synthetic nonapeptide — nine amino acids long — modeled on endogenous gonadotropin-releasing hormone (GnRH), the hypothalamic peptide that controls reproductive hormones throughout life. Two structural changes from the native sequence give leuprolide its therapeutic character: D-leucine at position 6 (instead of glycine) and an ethylamide replacing the C-terminal glycinamide. Together those modifications make leuprolide roughly 80 to 100 times more potent than native GnRH and dramatically more resistant to enzymatic breakdown.^[9]

It was first synthesized in the 1970s and FDA-approved in 1985 as Lupron for advanced prostate cancer, where it offered an alternative to surgical castration and to high-dose diethylstilbestrol (DES), the standard at the time. Subsequent development added depot formulations (1-month, 3-month, 4-month, and 6-month) and indications across a remarkable clinical breadth: endometriosis, uterine leiomyomata (fibroids — preoperative use), and central precocious puberty in children. Brand names today include Lupron Depot, Eligard, Fensolvi (pediatric CPP), Lupaneta Pack (with norethindrone add-back for endometriosis), and Camcevi (Foresee Pharma's prefilled depot).

Why this peptide matters in the broader landscape. Leuprolide is the prototype of an entire drug class. Almost every conversation about modern endocrine oncology, IVF protocol design, endometriosis pharmacology, and pediatric puberty suppression begins with leuprolide as the reference compound. Newer GnRH antagonists (elagolix, relugolix, cetrorelix) are typically positioned and priced relative to leuprolide. For many patients — especially women with endometriosis or fibroids, and parents of children with CPP — leuprolide is also where the conversation about peptide medicines becomes intensely personal.

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How it works

Leuprolide's pharmacology is one of the most elegant — and counterintuitive — examples of receptor biology in clinical medicine. It is a GnRH agonist, but the therapeutic effect comes from suppressing GnRH signaling. The trick is in how the pituitary GnRH receptor responds to continuous versus pulsatile stimulation.^[9]

In normal physiology, the hypothalamus releases GnRH in pulses every 60 to 120 minutes. Those pulses tell the pituitary to release LH and FSH, which in turn stimulate the ovaries or testes to make estrogen or testosterone. Leuprolide, given as a depot, provides continuous GnRH receptor stimulation. The receptor responds in two phases:

• Flare (first 7–14 days): an initial surge of LH, FSH, estrogen, and testosterone — the so-called testosterone or estrogen flare. In advanced prostate cancer this can transiently worsen bone pain or urinary obstruction, which is why an antiandrogen is often co-prescribed for the first few weeks.
• Downregulation (after ~2–4 weeks): the pituitary GnRH receptors internalize and desensitize. LH and FSH fall to castrate levels. Gonadal sex hormone production collapses to a postmenopausal- or postcastration-equivalent state and is maintained there as long as treatment continues.

The result is a reversible, drug-induced hypogonadal state — sometimes called "medical castration." This is what treats hormone-sensitive prostate cancer, calms estrogen-driven endometriosis and fibroids, and pauses the pubertal axis in children with CPP.

Detailed mechanism (for advanced readers)

Leuprolide acts at the GnRH receptor (GnRHR), a Gq-coupled GPCR on pituitary gonadotrope cells:

• Acute phase: binding triggers the canonical Gq–PLC–IP3/DAG–calcium pathway and stimulates LH and FSH synthesis and release. This is the "flare."
• Receptor downregulation: sustained occupancy drives GnRHR internalization, β-arrestin recruitment, and uncoupling from G-proteins. Within ~2–4 weeks, gonadotrope responsiveness is profoundly reduced.
• Sustained suppression: LH and FSH fall to castrate levels. In men, testosterone falls to ≤50 ng/dL (often ≤20 ng/dL). In women, estradiol falls to postmenopausal levels (typically <20 pg/mL).
• Reversibility: in adults, the axis recovers over weeks to months after the depot effect wears off. Recovery is more variable in pediatric patients, in patients with extended courses, and in older adults with prostate cancer.

Structural pharmacology:

• D-Leu at position 6 prevents cleavage at the central peptide bond by GnRH-degrading endopeptidases.
• C-terminal ethylamide blocks aminopeptidase action and increases receptor affinity.
• Together these modifications produce ~80–100x the potency of native GnRH and a half-life suitable for depot dosing every 1–6 months.

How leuprolide compares to related compounds:

• vs. Kisspeptin: Kisspeptin acts upstream of GnRH on hypothalamic neurons. Leuprolide bypasses kisspeptin and the hypothalamus entirely by acting directly on the pituitary.
• vs. GnRH antagonists (degarelix, relugolix, elagolix, cetrorelix): Antagonists block the GnRH receptor directly, producing immediate suppression with no flare. Leuprolide is an agonist that achieves the same end-state via downregulation, with an initial flare.
• vs. Surgical castration / oophorectomy: Leuprolide produces an equivalent endocrine state pharmacologically, with the major advantage of reversibility.

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What the research says

Leuprolide has one of the deepest clinical evidence bases of any peptide medicine — four decades of randomized trials across four FDA-approved indications. The honest gap in that record is not efficacy. It is the long-term, post-treatment safety experience reported by patients themselves, which controlled studies have not adequately characterized.

Research timeline

Leuprolide's clinical history spans from the launch of modern endocrine oncology to today's GnRH-antagonist era:

Endometriosis evidence

The pivotal endometriosis trial — Dlugi 1990 — was a small but well-designed double-blind, placebo-controlled study (n=63) demonstrating that monthly depot leuprolide significantly reduced pelvic pain, dysmenorrhea, and laparoscopically scored disease over six months.^[3] It supported the FDA approval and became one of the most-cited endometriosis trials of its era.

The longer-term picture is dominated by the add-back era. Leuprolide produces a postmenopausal endocrine state, with predictable consequences: hot flashes, vaginal dryness, mood changes, and bone mineral density loss. Hornstein's 1998 trial (n=201, 12 months) demonstrated that adding low-dose norethindrone acetate (with or without conjugated estrogens) preserved efficacy on pelvic pain while dramatically reducing the bone and vasomotor side-effect burden.^[4] This is the regimen marketed today as Lupaneta Pack.

Newer oral GnRH antagonists (elagolix, relugolix combination therapy) now offer comparable efficacy with finer dose control and a more favorable BMD profile at lower doses.^[7][8] For many patients, leuprolide is no longer first-line but remains a depot option — particularly when adherence to daily oral therapy is a concern.

Prostate cancer evidence

Leuprolide's prostate cancer evidence is the deepest in the entire GnRH-modulator class. The Leuprolide Study Group (NEJM 1984) randomized 199 men with previously untreated metastatic prostate cancer to leuprolide or DES.^[1] Objective response rates and survival were equivalent. Leuprolide produced fewer cardiovascular events, no gynecomastia, and a substantially better tolerability profile. That trial defined the modern GnRH-agonist standard.

Crawford 1989 (n=603) tested combined androgen blockade — leuprolide plus flutamide vs leuprolide alone — and demonstrated meaningful improvements in progression-free and overall survival.^[2] That trial entrenched leuprolide as the backbone of androgen deprivation therapy for the next three decades.

The 2020 HERO trial (Shore et al.) introduced oral relugolix as a credible GnRH-antagonist alternative, achieving castrate testosterone faster (no flare) and with fewer major adverse cardiovascular events than depot leuprolide.^[13] Leuprolide remains widely used — depot dosing is operationally simpler than daily oral therapy — but it is no longer the only option, and the cardiovascular comparison is one prescribers and patients increasingly weigh.

Central precocious puberty

Depot leuprolide is the global standard of care for central precocious puberty (CPP). The Carel 2009 international consensus endorsed GnRH analogs (with leuprolide as the most commonly used agent) as effective for suppressing pubertal progression and improving predicted adult height.^[6] Long-acting formulations — Fensolvi 6-month depot is the most prominent today — have made treatment substantially more practical for children and families.

The pediatric prescribing label carries warnings for psychiatric events, seizure, and pseudotumor cerebri (rare but documented).^[10] The 2009 consensus explicitly flagged long-term post-treatment outcomes — bone, growth, and possibly other systems — as an area where evidence was still emerging. That framing is, in many respects, still accurate in 2026. Patient and parent advocacy groups have pushed for more rigorous long-term follow-up than the published literature has so far provided.

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What the evidence shows

People encounter leuprolide through different doors — a prostate cancer diagnosis, an endometriosis flare, a fibroid surgery referral, a pediatric endocrinology visit, an IVF protocol, or a deep-dive into the patient-advocacy literature. Here is what the published research actually supports across those different lenses:

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Safety & side effects

Expected pharmacologic effects

Leuprolide produces a hypogonadal endocrine state. Most of its common side effects are direct, predictable consequences of estrogen or testosterone suppression rather than off-target toxicity:^[9]

• Hot flashes and vasomotor symptoms (~60–80% across indications)
• Decreased libido and erectile or arousal difficulties
• Bone mineral density loss (clinically significant with treatment beyond ~6 months without add-back)
• Mood changes — irritability, depression, emotional lability
• Vaginal dryness and atrophic changes (women)
• Gynecomastia, hot flashes, fatigue (men with prostate cancer)
• Injection-site reactions with depot formulations (typically mild)
• Initial flare — transient symptom worsening in the first 1–2 weeks of treatment for prostate cancer patients (often co-managed with a short course of antiandrogen)

Metabolic effects

Long-term androgen deprivation in men with prostate cancer is associated with increased risk of insulin resistance, type 2 diabetes, dyslipidemia, weight gain, and cardiovascular events. The prescribing information for adult formulations carries warnings around these effects, and the HERO trial of relugolix vs leuprolide highlighted a meaningfully different cardiovascular event profile favoring the antagonist.^[13][9]

Pediatric-specific safety

Pediatric leuprolide labeling (Fensolvi and others) carries specific warnings:^[10]

• Psychiatric events — emotional lability, depression, suicidal ideation. Children and parents should be counselled to monitor and report.
• Seizure — reported in children with and without prior seizure history or risk factors. Mechanism is incompletely understood.
• Pseudotumor cerebri (idiopathic intracranial hypertension) — rare but documented. Headache, visual changes, papilledema warrant evaluation.

Patient-reported post-treatment symptoms — what we know and don't know

This is the part of leuprolide's safety story that is hardest to write honestly. We will try.

A substantial number of patients — across endometriosis, prostate cancer, and pediatric CPP populations — have reported persistent symptoms in the months to years after discontinuing leuprolide that they attribute to the drug. Common patient-reported categories include:

• Persistent joint and bone pain, sometimes severe
• Cognitive complaints — memory, word-finding, concentration
• Mood changes, depression, anxiety
• Autonomic symptoms — temperature dysregulation, heart-rate variability
• Persistent fatigue
• Vision changes
• For some pediatric CPP patients followed into adulthood: complaints about bone, joint, and other systems

These reports show up in FAERS, in patient advocacy communities, in litigation, and in lay-press coverage.^[11]

What we do not have, in 2026, is a robust body of controlled, long-term follow-up studies that adequately characterize whether these patient-reported syndromes represent:

• A distinct, drug-attributable post-treatment syndrome,
• Prolonged or incomplete recovery from the hypogonadal state,
• Unmasking or worsening of an underlying condition,
• Or a heterogeneous mix that requires careful subgrouping to study.

Contraindications and precautions

Contraindications (varies by formulation; refer to prescribing information):

• Known hypersensitivity to leuprolide or to any component of the formulation
• Pregnancy and breastfeeding (Category X — known fetal harm)
• Undiagnosed abnormal vaginal bleeding (in adult women's indications)

Key precautions:

• Monitor BMD, especially with treatment beyond ~6 months and in patients with risk factors for osteoporosis
• Monitor mood, particularly in pediatric patients and those with prior psychiatric history
• In prostate cancer: monitor cardiovascular risk and glycemic status
• Initial flare — consider antiandrogen co-administration in patients with high disease burden
• Pediatric: monitor for seizures, psychiatric events, signs of pseudotumor cerebri

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How people use it

Leuprolide is used almost exclusively as a depot injection — daily subcutaneous formulations exist but are uncommon in current practice. Depot dosing intervals range from 1 month to 6 months depending on formulation and indication.

Approved indications and typical regimens

• Advanced prostate cancer: depot leuprolide (e.g., Lupron Depot, Eligard, Camcevi) at 1-, 3-, 4-, or 6-month intervals. Often combined with an oral antiandrogen for the first 2–4 weeks to manage flare, and increasingly combined with novel hormonal agents (abiraterone, enzalutamide) per current guidelines.
• Endometriosis: monthly or 3-month depot leuprolide, typically for 6 months. Lupaneta Pack adds daily oral norethindrone acetate to mitigate BMD loss and vasomotor symptoms; this is the standard approach for treatment courses beyond 3–6 months.
• Uterine leiomyomata (fibroids): preoperative use, typically 3 months (sometimes longer) before myomectomy or hysterectomy. Goal is volume reduction and anemia correction.
• Central precocious puberty: depot leuprolide (Fensolvi 6-month depot is most common today) until the appropriate age for puberty to resume. Ongoing endocrinology monitoring required.
• IVF — long agonist protocol: daily subcutaneous leuprolide in the luteal phase prior to controlled ovarian stimulation. Largely displaced by GnRH antagonist protocols in modern practice but retained for specific patient subgroups.

About off-label and unconventional use

Leuprolide is not commonly used outside its approved indications, and we do not encourage off-label exploration. The mechanism (medical castration) makes leuprolide categorically different from a wellness or body-composition peptide. Any use should be in collaboration with a clinician who can evaluate appropriateness, monitor BMD, mood, and metabolic parameters, and discuss the long-term unknowns honestly.

If you plan to reconstitute peptides for any approved use, see our reconstitution guide for safety-first preparation principles.

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Legal & regulatory status

As of April 2026:

FDA status

Leuprolide acetate has been FDA-approved since 1985. Currently approved indications include:^[9][10]

1. Advanced prostate cancer (palliative)
2. Endometriosis (with or without norethindrone add-back; Lupaneta Pack is the combination product)
3. Uterine leiomyomata (preoperative anemia and volume reduction)
4. Central precocious puberty in pediatric patients

Multiple depot formulations exist — 1-month, 3-month, 4-month, and 6-month — under brand names including Lupron Depot (AbbVie), Eligard (Tolmar), Fensolvi (Tolmar; pediatric CPP), Lupaneta Pack (AbbVie; with norethindrone add-back), and Camcevi (Foresee Pharma). Generic leuprolide acetate has been available since approximately 2017.

Boxed and labeled warnings vary by formulation. The pediatric CPP labels include warnings for seizure, pseudotumor cerebri, and psychiatric events. The prostate cancer labels include warnings for cardiovascular events, hyperglycemia, and increased risk of diabetes.

WADA / USADA status

Leuprolide is prohibited in male athletes only under WADA Section S2 (Gonadotropins, GnRH, and their releasing factors). It is not prohibited in female athletes, though use in performance contexts would be highly unusual given its pharmacology. Therapeutic Use Exemption is possible.^[12]

International status

Leuprolide is approved across the EU, UK, Canada, Japan, Australia, and most major markets — typically marketed as leuprorelin outside the US. It is used worldwide as a standard-of-care agent for hormone-sensitive prostate cancer, endometriosis, fibroids, and central precocious puberty. Generic and biosimilar competition has expanded access in many markets.

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How leuprolide compares

The clearest way to understand leuprolide's current place is to compare it with the GnRH antagonists that have come to challenge it across multiple indications:

The trade-offs between leuprolide and the newer oral antagonists are substantive:

• Onset and flare: GnRH antagonists produce immediate suppression with no testosterone or estrogen flare. Leuprolide takes 2–4 weeks and produces an initial flare that requires co-management for prostate cancer.
• Dosing logistics: Leuprolide is a depot — one injection every 1 to 6 months. Antagonists are daily oral medications, which means more reliable steady-state suppression but greater dependence on daily adherence.
• BMD and side effects: Antagonist regimens can be dose-titrated to balance suppression against bone loss; depot leuprolide produces a fixed-magnitude effect over its dosing interval.
• Cardiovascular profile (men with prostate cancer): The HERO trial demonstrated reduced major adverse cardiovascular events with relugolix vs leuprolide, which has shifted prescribing in patients with cardiovascular risk factors.^[13]
• Cost and access: Leuprolide is generic and broadly accessible. Antagonists are newer, branded, and substantially more expensive in many markets.

For most patients the decision is now genuinely clinical — informed by indication, comorbidities, adherence reality, and cost — rather than a default to leuprolide because it was the only option. That is a healthy evolution of the field.

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Common exaggerations to watch for

Leuprolide attracts overstatement from both directions — clinicians and marketing material that downplay risks, and patient communities and legal advertising that catastrophize them. Both deserve a careful eye:

Overclaims of efficacy or safety:

• "Leuprolide is a curative treatment for endometriosis or fibroids." False. Leuprolide manages symptoms during treatment. Endometriosis pain typically returns after discontinuation; fibroids regrow within months. Leuprolide is a powerful symptom-suppressor and a useful surgical bridge, not a cure.
• "Side effects are mild and easily managed." Misleading. Hot flashes, BMD loss, mood changes, and the metabolic effects of androgen deprivation are real and meaningful for most patients on leuprolide. Add-back therapy helps, but quality-of-life impact is substantial.
• "Leuprolide is safer than newer GnRH antagonists." Not supported, particularly in advanced prostate cancer where the HERO trial showed reduced cardiovascular events with relugolix.

Overclaims of harm:

• "Leuprolide will destroy your life." Overstated. For many patients across all four approved indications, leuprolide is well-tolerated for the duration of treatment and produces durable benefit. The serious patient-reported post-treatment concerns are real and underdocumented, but they are not universal — and presenting them as inevitable does a disservice to patients facing genuine treatment decisions for serious conditions.
• "All long-term effects are permanent." Not supported. BMD recovers in most adult patients after discontinuation. The persistent symptoms that some patients report exist and warrant investigation, but framing every leuprolide effect as irreversible is not consistent with the evidence we have.
• "Leuprolide causes [specific severe outcome] in everyone." Watch for absolutist claims in either direction. The honest position is that leuprolide has a well-characterized acute and short-term safety profile, and an inadequately characterized long-term post-treatment profile. Both halves of that statement matter.

The brand we are trying to build is one where the same writer who tells you a peptide is genuinely effective will also tell you, plainly, where the evidence is thinner than its prescribers admit. Leuprolide is the test case for that voice.

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Related content

Peptide

Kisspeptin Profile

The upstream master regulator of the HPG axis that leuprolide acts on. Kisspeptin drives endogenous GnRH release; leuprolide overrides that pulse with continuous receptor stimulation. The natural pairing for understanding leuprolide's biology.

Peptide

PT-141 Profile

A melanocortin agonist for sexual function. Often discussed alongside leuprolide because androgen and estrogen suppression can blunt libido — an expected pharmacologic effect that PT-141 acts on through a different pathway.

Guide

What Are Peptides? — A Plain-Language Guide

Background on peptide therapeutics — useful context for understanding how a 9-amino-acid analog like leuprolide can produce such profound, body-wide endocrine effects.

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References

1. [1]

   The Leuprolide Study Group. “Leuprolide versus diethylstilbestrol for metastatic prostate cancer.” N Engl J Med. 1984. 311(20):1281-1286 DOI PubMedRCT

   First major multicenter RCT of leuprolide. Demonstrated equivalent oncologic efficacy to DES with substantially fewer cardiovascular events. Foundational evidence for the entire GnRH-agonist class.

2. [2]

   Crawford ED, Eisenberger MA, McLeod DG, Spaulding JT, Benson R, Dorr FA, et al.. “A controlled trial of leuprolide with and without flutamide in prostatic carcinoma.” N Engl J Med. 1989. 321(7):419-424 DOI PubMedRCT

   Pivotal combined androgen blockade trial. Established the role of leuprolide as a backbone of ADT and influenced standard of care for advanced prostate cancer.

3. [3]

   Dlugi AM, Miller JD, Knittle J. “Lupron depot (leuprolide acetate for depot suspension) in the treatment of endometriosis: a randomized, placebo-controlled, double-blind study.” Fertil Steril. 1990. 54(3):419-427 DOI PubMedRCT

   Pivotal Phase 3 trial supporting the endometriosis indication. Small but well-designed double-blind placebo-controlled study.

4. [4]

   Hornstein MD, Surrey ES, Weisberg GW, Casino LA, Lupron Add-Back Study Group. “Leuprolide acetate depot and hormonal add-back in endometriosis: a 12-month study.” Obstet Gynecol. 1998. 91(1):16-24 DOI PubMedRCT

   Established the efficacy and BMD-protective effect of norethindrone add-back for prolonged leuprolide therapy. Basis for the Lupaneta Pack regimen and modern long-term endometriosis use.

5. [5]

   Friedman AJ, Hoffman DI, Comite F, Browneller RW, Miller JD. “Treatment of leiomyomata uteri with leuprolide acetate depot: a double-blind, placebo-controlled, multicenter study.” Obstet Gynecol. 1991. 77(5):720-725 PubMedRCT

   Pivotal RCT for the uterine fibroid indication. Demonstrated significant short-term volume reduction and anemia correction supporting preoperative use.

6. [6]

   Carel JC, Eugster EA, Rogol A, Ghizzoni L, Palmert MR, et al.. “Consensus statement on the use of gonadotropin-releasing hormone analogs in children.” Pediatrics. 2009. 123(4):e752-e762 DOI PubMedReview

   International consensus statement endorsing depot GnRH analogs (including leuprolide) as standard of care for CPP. Discusses efficacy and known and uncertain long-term effects.

7. [7]

   Taylor HS, Giudice LC, Lessey BA, Abrao MS, Kotarski J, Archer DF, et al.. “Treatment of endometriosis-associated pain with elagolix, an oral GnRH antagonist.” N Engl J Med. 2017. 377(1):28-40 DOI PubMedRCT

   Two replicate Phase 3 trials (Elaris EM-I and EM-II) of the oral GnRH antagonist elagolix. Important comparator showing that oral antagonists are challenging leuprolide's first-line role in endometriosis.

8. [8]

   Carr B, Dmowski WP, O'Brien C, Jiang P, Burke J, Jimenez R, et al.. “Elagolix, an oral GnRH antagonist, versus subcutaneous depot leuprolide for endometriosis-associated pain.” Reprod Sci. 2014. 21(11):1341-1351 DOI PubMedRCT

   Comparative trial of elagolix vs depot leuprolide for endometriosis pain. Established that oral antagonists could match leuprolide on key efficacy endpoints with a different side-effect profile.

9. [9]

   AbbVie Inc. (prescribing information). “LUPRON DEPOT (leuprolide acetate for depot suspension) — Full Prescribing Information.” 2024. Link

   Current FDA-approved Lupron Depot prescribing label. Definitive source for adult dosing, contraindications, and adverse event rates across approved indications.

10. [10]

    Tolmar Pharmaceuticals (prescribing information). “FENSOLVI (leuprolide acetate) for injectable suspension — Full Prescribing Information (pediatric CPP).” 2023. Link

    Current FDA-approved pediatric CPP label. Documents pediatric-specific warnings including seizure, pseudotumor cerebri, and psychiatric events, and the boxed monitoring recommendations.

11. [11]

    U.S. Food and Drug Administration. “FDA Adverse Event Reporting System (FAERS) Public Dashboard — leuprolide acetate.” 2026. LinkSafety study

    Public FAERS dashboard for leuprolide acetate adverse events. Reflects spontaneous reports — useful as a signal of patient-reported concerns but not a controlled epidemiologic study.

12. [12]

    World Anti-Doping Agency. “The World Anti-Doping Code International Standard — Prohibited List 2026.” 2026. Link

    Leuprolide is prohibited in male athletes only under Section S2 (Gonadotropins, GnRH, and their releasing factors).

13. [13]

    Shore ND, Saad F, Cookson MS, George DJ, Saltzstein DR, Tutrone R, et al.. “Oral relugolix for androgen-deprivation therapy in advanced prostate cancer (HERO trial).” N Engl J Med. 2020. 382(23):2187-2196 DOI PubMedRCT

    HERO trial — established oral relugolix as a GnRH antagonist alternative to leuprolide in advanced prostate cancer with reduced major adverse cardiovascular events. Important comparator context.

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