Goserelin
Also known as: Goserelin acetate, ICI-118630, Zoladex
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Summary
Goserelin is a synthetic decapeptide analogue of gonadotropin‑releasing hormone (GnRH) used to suppress ovarian estrogen production in premenopausal women with hormone‑receptor‑positive breast cancer. By creating a medically induced menopause, it enables the use of aromatase inhibitors, fulvestrant, or CDK4/6 inhibitors that otherwise require low estrogen levels. Goserelin is administered as a subcutaneous depot injection and is approved for clinical use in several countries.
Mechanism of Action
Goserelin binds to GnRH receptors on pituitary gonadotropes, initially stimulating a surge of luteinising hormone (LH) and follicle‑stimulating hormone (FSH). Continuous exposure then down‑regulates receptor expression, leading to profound suppression of LH and FSH release. The resulting decline in ovarian steroidogenesis reduces circulating estradiol to post‑menopausal levels, thereby limiting estrogen‑driven tumor growth in hormone‑sensitive breast cancers.
What the Research Shows
Clinical trials of advanced hormone‑receptor‑positive breast cancer have incorporated goserelin to achieve ovarian suppression in premenopausal participants. In the PALOMA‑3 phase III study, premenopausal women received goserelin alongside palbociclib + fulvestrant, contributing to a median progression‑free survival (PFS) of 9.2 months versus 3.8 months with fulvestrant alone. The MONALEESA‑7 trial used goserelin with a non‑steroidal aromatase inhibitor or tamoxifen plus ribociclib, showing overall survival of 58.7 months versus 48.0 months for control. The RIGHT Choice phase II trial combined goserelin with ribociclib + letrozole/anastrozole, achieving a median PFS of 21.8 months, superior to combination chemotherapy. In the adjuvant NATALEE study, goserelin was given to premenopausal women (and men) receiving ribociclib + aromatase inhibitor, contributing to a significant invasive disease‑free survival benefit. Across these studies, goserelin’s role was as an ovarian‑suppressive adjunct rather than a direct anticancer agent.
Reported Benefits
Goserelin provides reliable, reversible ovarian suppression, allowing the use of estrogen‑lowering therapies such as aromatase inhibitors, fulvestrant, and CDK4/6 inhibitors in premenopausal patients. In combination regimens, it has been associated with longer progression‑free and overall survival compared with endocrine therapy alone. Its depot formulation offers convenient dosing intervals, reducing the need for daily medication.
Limitations of the Evidence
Evidence for goserelin is confined to its use as part of combination therapy in hormone‑receptor‑positive breast cancer; no data demonstrate benefit as a monotherapy or in other cancers. Direct comparisons with alternative GnRH analogues are lacking, and long‑term outcomes beyond trial follow‑up remain uncertain. The abstracts do not address its efficacy in fertility preservation or non‑oncologic indications.
Safety Considerations
Goserelin induces a hypo‑estrogenic state, which can cause hot flashes, night sweats, vaginal dryness, mood changes, and loss of bone mineral density. Injection‑site reactions may occur. In the cited trials, most adverse events were attributed to accompanying agents (e.g., neutropenia from CDK4/6 inhibitors). Patients should be monitored for bone health and managed with calcium, vitamin D, or bisphosphonates as appropriate.
How It Is Administered
Goserelin is supplied as a subcutaneous depot injection (commonly 3.6 mg). The formulation provides sustained release, typically administered once every 28 days, though other dosing intervals have been evaluated in clinical studies. It is used as part of combination regimens for breast cancer and is not intended for self‑administration without medical supervision.
Routes of Administration
Goals & Uses
- Ovarian protection during chemotherapyOncology/fertilityModerate
- Prostate cancerOncologyHigh
- Endometrial thinning before ablationGynecologyModerate
- Prostate cancer treatmentOncologyHigh
- Precocious pubertyPediatric EndocrinologyModerate
- Breast cancer treatmentOncologyHigh
- Uterine fibroidsGynecologyModerate
- Uterine fibroids (leiomyomata)GynecologyHigh
- Breast cancerOncologyHigh
- Endometriosis managementGynecologyHigh
- EndometriosisGynecologyHigh
Contraindications
- Severe hypersensitivity to goserelin or excipientsImmunologicHigh
- Undiagnosed vaginal bleedingGynecologicalModerate
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- BreastfeedingPopulationHighPotential transfer into breast milk or insufficient safety data
- Hypersensitivity to GnRH analoguesAllergy/ImmunologyHigh
- Osteoporosis (severe pre-existing)Metabolic/boneModerate
Adverse Effects
- Injection site reactionsLocalCommon
- Hot flashesEndocrine / VasomotorCommon
- Cardiovascular events (e.g., myocardial infarction)CardiovascularRare
- Bone mineral density lossSkeletalUncommon
- Tumor flare (initial)OncologyUncommon
- Hot flashes/flushesVasomotorCommon
- Depression and mood changesPsychiatricUncommon
- Sexual dysfunction / decreased libidoEndocrine/sexualCommon
- Injection site reactionLocalCommonRedness, swelling, itching, bruising, or pain at the injection site
- Bone mineral density reductionMusculoskeletalCommon
- Decreased libido / erectile dysfunctionSexual / EndocrineCommon
Drug Interactions
- QT-prolonging drugsModerate
- CYP3A4 inhibitors (e.g., ketoconazole)Low
- Estrogen replacement therapyModerate
- Aromatase inhibitors (e.g., anastrozole, letrozole)Low
- Anti-androgens (e.g., bicalutamide, flutamide)Low
- Antidiabetic agents (insulin, oral hypoglycemics)Moderate
Population Constraints
- Pediatric patientsAgeRelative
- Patients with osteoporosis or high fracture riskMusculoskeletalRelative
- Patients with diabetes mellitusMetabolicRelative
- Elderly patientsAgeRelative
- Patients with cardiovascular diseaseComorbidityRelative
- Patients with urinary tract obstruction (prostate cancer)UrologicalRelative
Regulatory Status
- European UnionApprovedApproved: Prostate cancer, Breast cancer, Endometriosis, Uterine fibroids, Precocious pubertyEMA approval for same indications.
- United StatesApprovedApproved: Prostate cancer, Breast cancer, Endometriosis, Uterine fibroids, Precocious pubertyFDA‑approved as Zoladex.
- United KingdomApprovedApproved: Prostate cancer, Breast cancer, Endometriosis, Uterine fibroids, Precocious pubertyMHRA approval.
FDA‑approved (1991) for prostate cancer and later for breast cancer, endometriosis, and other indications. EMA and other agencies have similar approvals.
Evidence & Sources
- Journal ArticleModerateTurner NC, et al.2015-01-01T00:00:00.000000Z
- Journal ArticleModerateLu YS, et al.2022-01-01T00:00:00.000000Z
- Journal ArticleModerateLu YS, et al.2024-01-01T00:00:00.000000Z
- Journal ArticleModerateHortobagyi GN, et al.2025-01-01T00:00:00.000000Z
- Journal ArticleModerateTripathy D, et al.2018-01-01T00:00:00.000000Z
- Journal ArticleModerateSlamon D, et al.2024-01-01T00:00:00.000000Z
Frequently Asked Questions
Why is goserelin needed for premenopausal breast cancer patients?
Premenopausal ovaries produce estrogen, which can fuel hormone‑receptor‑positive tumors. Goserelin suppresses ovarian estrogen production, creating a post‑menopausal hormonal environment that allows aromatase inhibitors, fulvestrant, or CDK4/6 inhibitors to work effectively.
How long does the ovarian suppression last after an injection?
A single depot injection maintains gonadotropin suppression for about four weeks, keeping estradiol at post‑menopausal levels throughout that period. Continuous monthly dosing is required to sustain suppression.
Can goserelin affect fertility?
Yes, the drug temporarily halts ovarian function, which can impair fertility while treatment continues. Normal ovarian activity typically resumes after discontinuation, but patients desiring future pregnancy should discuss fertility preservation before starting therapy.
Is goserelin safe for long‑term use?
Long‑term use is generally well tolerated, but chronic hypo‑estrogenism can lead to bone density loss, cardiovascular changes, and menopausal symptoms. Regular monitoring and supportive measures, such as bone‑protective agents, are recommended.
Are there any drug interactions with goserelin?
The abstracts report no pharmacokinetic interactions between goserelin and CDK4/6 inhibitors or aromatase inhibitors. However, clinicians should assess each patient’s full medication list, as other drugs may influence hormone levels or bone health.
What is Goserelin?
Goserelin is a synthetic decapeptide analogue of gonadotropin‑releasing hormone (GnRH) used to suppress ovarian estrogen production in premenopausal women with hormone‑receptor‑positive breast cancer. By creating a medically induced menopause, it enables the use of aromatase inhibitors, fulvestrant, or CDK4/6 inhibitors that otherwise require low estrogen levels. Goserelin is administered as a subcutaneous depot injection and is approved for clinical use in several countries.
What is Goserelin used for?
Goserelin is educationally associated with: Ovarian protection during chemotherapy, Prostate cancer, Endometrial thinning before ablation, Prostate cancer treatment, Precocious puberty, Breast cancer treatment, Uterine fibroids, Uterine fibroids (leiomyomata), Breast cancer, Endometriosis management, Endometriosis. Educational only — not medical advice.
How is Goserelin administered?
Recorded routes of administration: Intramuscular, Subcutaneous.
What are the potential side effects of Goserelin?
Reported adverse effects include: Injection site reactions, Hot flashes, Cardiovascular events (e.g., myocardial infarction), Bone mineral density loss, Tumor flare (initial), Hot flashes/flushes, Depression and mood changes, Sexual dysfunction / decreased libido, Injection site reaction, Bone mineral density reduction, Decreased libido / erectile dysfunction. This list is not exhaustive — consult a qualified clinician.
Who should avoid Goserelin?
Recorded contraindications: Severe hypersensitivity to goserelin or excipients, Undiagnosed vaginal bleeding, Pregnancy, Breastfeeding, Hypersensitivity to GnRH analogues, Osteoporosis (severe pre-existing). Consult a qualified clinician before use.