Clinical Trial to Observe the Effects of Tamoxifen on Testosterone Recovery in Medically Castrated Prostate Cancer Patients

NCT07535905 | Not Yet Recruiting Phase 2

• 1 other identifier: 25-5742
• Study Type: interventional
• Target: 96
• Locations: 1 country
• Sites: 1

Brief Summary

Androgen deprivation therapy (ADT) is a cornerstone therapy in the treatment of curable prostate cancer (PCa). However, ADT often leads to a protracted testosterone recovery period in most men or absence of complete recovery in 10-25% of cases. The hypogonadal state has significant psychosocial and physical side effects. Therefore, limiting ADT effect's duration beyond the prescribed castration period is very compelling to patients and providers alike. Tamoxifen, a well-established selective estrogen receptor modulator, offers a novel and cost-effective approach to accelerate testosterone recovery in men with secondary hypogonadism. This project addresses a critical gap in global cancer care by evaluating Tamoxifen as a viable solution for reducing the burden of delayed testosterone recovery and its associated side effects, particularly in resource-limited settings.

Conditions

Hypogonadism; Prostate Cancer

Outcome Measures

Primary Outcomes (1)

• Normal Testosterone Recovery

  Proportion of participants with normal testosterone levels (i.e. total testosterone \> 7.7nmol/L \[222 ng/dL\])

  6 months after starting intervention

Secondary Outcomes (11)

• Disease Control

  From enrollment to 2 years after starting treatment

• Patient-Reported Toxicities

  From enrollment to 2 years after starting treatment

• Non-Castrated Testosterone Recovery

  From enrollment to 2 years after starting treatment

• Time to Testosterone Recovery

  From enrollment to 2 years after starting treatment

• Urinary Function (Patient-Reported Quality of Life)

  From enrollment to 2 years after starting treatment

Study Arms (2)

Non-Experimental Intervention: Observation

NO INTERVENTION

Participant will not receive intervention after treatment with ADT. Per routine care, participant will undergo observation for testosterone recovery

Experimental Intervention: Tamoxifen

EXPERIMENTAL

Participant will take 2 tamoxifen pills by mouth, every day, for a total of 40 mg each day. The duration of tamoxifen treatment will depend on the duration of the participant's previous ADT treatment. If the participant received ADT treatment for 6 months, they will receive daily Tamoxifen for 3 months. If the participant received ADT treatment for 18-36 months, they will receive daily Tamoxifen for 6 months.

Drug: Tamoxifen

Interventions

Tamoxifen DRUG

Selective estrogen receptor modulator, oral tablet

Experimental Intervention: Tamoxifen

Eligibility Criteria

• Age: 18 Years+
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• At least 18 years of age;
• Ability to understand the purposes and risks of the trial and has signed a written informed consent form. Have a diagnosis of prostate cancer;
• Patient received ADT for a duration of either 6 or 18-36 months as part of the curative intent treatment. Curative intent prostate cancer patients who completed ADT and have had no further ADT for the length of the last ADT injection depot formulation (e.g., if the last ADT injection depot formulation is for 3 months, the patient must have no ADT for 3 months after last injection)
• Have effectively castrated testosterone (\< 1.7 nmol/L \[50 ng/dL\]) within 6 weeks of enrollment;
• ECOG Performance status 0-2

You may not qualify if:

• Harbouring certain CYP2D6 alleles (i.e. CYP2D6\*4) or from the chronic use of a CYP2D6 inhibitor(s);
• History of blood clots (venous thromboembolism or pulmonary embolism);
• History of stroke or transient ischemic attack (TIA);
• Reduced liver function within last 120 days prior to enrolment, defined as follows:
• Total Bilirubin: 1.5 \> upper limit of normal (ULN) (For Gilbert's syndrome, if total bilirubin is \<1.5 x ULN, measure direct and indirect bilirubin. If direct bilirubin is greater than 1.5 x ULN, participant is ineligible;
• AST(SGOT) and ALT(SGPT): \> 2.5x ULN;
• Or other liver disease as deemed ineligible by the investigator
• Baseline QT/QTc \> 500ms;
• Active therapy with selective serotonin reuptake inhibitor (SSRI) antidepressants (e.g. paroxetine, a known CYP2D6 inhibitor);
• Active therapy with coumarin-type anticoagulants;
• Active therapy with cytotoxic agents;
• Active therapy with aromatase inhibitors;
• Other invasive malignancy within the last 5 years, other than squamous or basal cell carcinoma of the skin;
• Treatment with a non-approved or experimental drug during the 3 months before informed consent;
• Patients known to have one of the following hereditary illnesses; galactose- intolerance, Lapp lactase deficiency or glucose-galactose malabsorption;

Sponsors & Collaborators

• University Health Network, Toronto: lead

Study Sites (1)

University Health Network - Princess Margaret Cancer Center

Toronto, Ontario, M5G 2M9, Canada

Location

MeSH Terms

Conditions

Hypogonadism; Prostatic Neoplasms

Interventions

Tamoxifen

Condition Hierarchy (Ancestors)

Gonadal Disorders; Endocrine System Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Genital Diseases; Urogenital Diseases; Prostatic Diseases; Male Urogenital Diseases

Intervention Hierarchy (Ancestors)

Stilbenes; Benzylidene Compounds; Benzene Derivatives; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals

Central Study Contacts

Alejandro Berlin, MD

CONTACT

416-946-4501; alejandro.berlin@uhn.ca

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 27, 2026
• First Posted: April 17, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): October 1, 2030
• Study Completion (Estimated): October 1, 2030
• Last Updated: April 17, 2026

Record last verified: 2026-04

Locations

CA (1)