The SUGAR Study; SBRT and Relugolix) for Prostate Cancer

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

• Age18 Years to no maximum
• SexMale
• Healthy volunteersNo

You may be able to join if

• Provision of signed and dated informed consent form
• Stated willingness to comply with all study procedures and availability for the duration of the study
• Has histologically or cytologically confirmed diagnosis of adenocarcinoma of the prostate
• Born assigned to Male gender, age 18 and above. Female identifying transgender or gender fluid are allowed on study provided they have not undergone testosterone suppressing therapy and were born with a prostate.
• Has a serum testosterone at the Screening visit of >100 ng/dL
• Has a serum PSA concentration at the Screening visit of > 0.2 ng/mL
• Able to swallow pills and take medication orally (no documented inability to eat solids and swallow pills) and be willing to adhere to the daily regimen of medication (if assigned to the experimental arm).
• For patients of reproductive potential: use of condoms or other methods (including abstinence) to ensure effective contraception with partner during radiotherapy and through 4 months after the last dose of the study drug or radiotherapy
• Agreement to adhere to Lifestyle Considerations (see section 5.3) throughout study duration
• Clinical favorable intermediate risk prostate cancer: Gleason score must be Gleason 3+4 with a PSA < 20 ng/mL, or Gleason 6 (3+3) and PSA > 10 ng/mL and < 20 ng mL.
• Decipher GC score of 0.6 or higher or higher indicating high genomic risk for most recent biopsy
• Documented prostate volume (by MRI or ultrasound within 120 days or physician attestation within 120 days) <= 80 cc

You cannot join if

• Current use of medications that cause QT prolongation
• Known allergic reactions to relugolix
• Treatment with another investigational drug or other intervention for prostate cancer within 30 days of enrollment
• Ulcerative colitis or other inflammatory bowel disease history
• Connective tissue disease such as lupus, scleroderma, or dermatomyositis
• GNRH antagonist therapy or SBRT to the prostate are medically contraindicated or not tolerated
• History of long QT syndrome documented in the medical record
• The following ECG abnormalities are excluded:
• Q-wave infarction unless identified 6 or more months before the Screening Visit
• QT interval corrected for heart rate (QTc) > 470 msec. If the QTc is prolonged in a patient with a pacemaker, the patient may be enrolled in the study upon discussion with the study PI
• Congenital long QT syndromeQ
• History of surgical castration
• Prior treatment for prostate cancer with surgery or prostate directed radiotherapy

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

relugolix. An orally available, non-peptide gonadotropin-releasing hormone (GnRH or luteinizing hormone-releasing hormone (LHRH)) antagonist, with potential antineoplastic activity. Relugolix competitively binds to and blocks the GnRH receptor in the anterior pituitary gland, which both prevents GnRH binding to the GnRH receptor and inhibits the secretion and release of both luteinizing hormone (LH) and follicle stimulating hormone (FSH). In males, the inhibition of LH secretion prevents the release of testosterone from Leydig cells in the testes. Since testosterone is required to sustain prostate growth, reducing testosterone levels may inhibit hormone-dependent prostate cancer cell proliferation. NCI Drug Dictionary

Treatments listed in the registry

• Relugolix 120 MG [Orgovyx] (Drug): ORGOVYX will be initiated with a loading dose of 360 mg on the first day and continue treatment with a 120 mg dose taken orally once daily at approximately the same time each day. Total length of treatment will be 30 days.
• SBRT standard of care radiotherapy treatment (Radiation): SBRT is a standard-of-care radiotherapy treatment for intermediate-risk prostate cancer.

Randomized · Parallel · masking: None

As the registry describes them. Requirements to join, such as a tissue sample, are in the eligibility list above even when on-study procedures are optional. Ask the study team which steps apply to you.

• questionnaires: Part of the study plan
• radiation: Part of the study plan

Main goals

• Proportion of participants that attain PSA nadir (up to 2 years post treatment)

Other goals

• Change in Quality of life assessment using the EPIC-26 survey

Planned enrollment: 60 (estimated).

• Yale Cancer Center, New Haven, Connecticut
• Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
• Memorial Sloan Kettering Cancer Center, New York, New York
• University of Washington, Seattle, Washington

Site status as of Oct 30, 2026. Check the live record before contacting a site.

• ClinicalTrials.gov NCT06111781
• NCI Drug Dictionary: C114498

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Sep 13, 2026. Public record; not medical advice.