Combining SBRT with Relugolix for Prostate Cancer Treatment

The SUGAR Study: (SBRT and Ultrashort GnRH Antagonist-Relugolix) for Clinicogenomic Unfavorable Intermediate Risk Prostate Cancer

Phase 2 Interventional Yale University · NCT06111781

This study is testing if combining a type of radiation therapy with a new oral medication can help men with certain prostate cancer types achieve better treatment results while keeping their sexual and hormonal functions healthier.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment60 (estimated)
Ages18 Years and up
SexMale
SponsorYale University Academic / other
Drugs / interventionsradiation
Locations3 sites (New Haven, Connecticut and 2 other locations)
Trial IDNCT06111781 on ClinicalTrials.gov

What this trial studies

This clinical trial evaluates the effectiveness and toxicity of combining stereotactic body radiotherapy (SBRT) with the oral androgen deprivation therapy Relugolix in men with unfavorable intermediate risk prostate cancer. Participants will be randomly assigned to receive either SBRT alone or SBRT with Relugolix. The study aims to determine if the combination treatment leads to a superior rate of achieving a low PSA level and minimizes declines in sexual and hormonal function compared to historical data. The trial focuses on men aged 18 and older with specific Gleason scores and PSA levels.

Who should consider this trial

Good fit: Ideal candidates are men aged 18 and older with a confirmed diagnosis of adenocarcinoma of the prostate and specific Gleason scores and PSA levels.

Not a fit: Patients who have undergone testosterone suppressing therapy or do not meet the specified Gleason score and PSA criteria may not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could improve treatment outcomes and reduce side effects for men with intermediate risk prostate cancer.

How similar studies have performed: While there is ongoing research in this area, the combination of SBRT with Relugolix represents a novel approach that has not been extensively tested in prior studies.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Provision of signed and dated informed consent form
2. Stated willingness to comply with all study procedures and availability for the duration of the study
3. Has histologically or cytologically confirmed diagnosis of adenocarcinoma of the prostate
4. 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.
5. Has a serum testosterone at the Screening visit of \>100 ng/dL
6. Has a serum PSA concentration at the Screening visit of \> 0.2 ng/mL
7. 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).
8. 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
9. Agreement to adhere to Lifestyle Considerations (see section 5.3) throughout study duration
10. 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.
11. Decipher GC score of 0.6 or higher or higher indicating high genomic risk for most recent biopsy
12. Documented prostate volume (by MRI or ultrasound within 120 days or physician attestation within 120 days) \<= 80 cc

Exclusion Criteria:

1. Current use of medications that cause QT prolongation
2. Known allergic reactions to relugolix
3. Treatment with another investigational drug or other intervention for prostate cancer within 30 days of enrollment
4. Ulcerative colitis or other inflammatory bowel disease history
5. Connective tissue disease such as lupus, scleroderma, or dermatomyositis
6. GNRH antagonist therapy or SBRT to the prostate are medically contraindicated or not tolerated
7. History of long QT syndrome documented in the medical record
8. The following ECG abnormalities are excluded:

   1. Q-wave infarction unless identified 6 or more months before the Screening Visit
   2. 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
   3. Congenital long QT syndromeQ
9. History of surgical castration
10. Prior treatment for prostate cancer with surgery or prostate directed radiotherapy

Where this trial is running

New Haven, Connecticut and 2 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Prostate Cancer
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.