MRI-based Focal Intraprostatic Simultaneous Integrated Boost (SIB) Intensification With De-escalated Adaptive-risk SBRT for Patients With Low to Intermediate Risk Prostate Cancer

Recruiting now · Phase 2

Conditions studied: Prostate Cancer, Localized Prostate Carcinoma

In brief

The goal of this clinical trial is to determine the safety of stereotactic body radiation therapy (SBRT) microboost technique in patients with low to intermediate risk prostate cancer. The main question it aims to answer is: Is microboost SBRT with whole gland de-escalation both safe and effective in managing patients with low to intermediate-risk prostate cancer while maintaining acceptable toxicity levels? All patients will receive microboost SBRT at a dose of 45 Gy delivered in 5 fractions in up to 4 MRI-defined lesions. Patients (Arm 1) with highest grade disease in the microboost target lesion in the absence of GG2-3 beyond the microboost target (only GG1 disease can be present outside of the microboost region) will receive whole gland de-escalation at a dose of 30 Gy delivered in 5 fractions. Patients (Arm 2) with highest grade disease outside of the target lesion will receive whole gland de-escalation at a dose of 35 Gy delivered in 5 fractions. Participants will be treated every other day over a two week period and then follow up after radiation treament for up to 5 years. Participants will be asked to complete questionnaires and provide blood and urine samples for research purposes.

Key facts

Study ID

NCT07644598

Run by

Georgetown University

People needed

58

Starts

2026-09-01

Expected to finish

2035-01-01

Last updated by the study team

2026-08-04

Who can join

Age: 18 and older. Sex: male. Healthy volunteers: not accepted.

You may qualify if…

• Patients age 18 or older.
• Patients with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2
• Patients with histologically confirmed adenocarcinoma of the prostate who have not received prior pelvic radiation therapy or prostatectomy.
• Patients with low to intermediate risk group defined by the NCCN (National Comprehensive Cancer Network) guidelines as follows:
• Low risk prostate cancer:
• cT1-cT2a (AJCC; 8TH edition, 2017)
• Grade Group 1 (GG1)
• PSA <10 ng/mL
• Intermediate risk prostate cancer:
• cT2b-cT2c (AJCC; 8TH edition, 2017)
• Grade Group 2 (GG2) or Grade Group 3 (GG3)
• PSA 10-20 ng/mL
• Patients with unfavorable intermediate risk prostate cancer defined by the NCCN guidelines are recommended to undergo a PSMA (Prostate-Specific Membrane Antigen) PET, then the PSMA PET must show localized disease.
• Patients must have preferably undergone a standard of care pretreatment MRI fusion biopsy* to identify visible intraprostatic lesions and confirm the absence of regional or distant metastatic disease, with criteria as follows:
• Ability to undergo an MRI fusion biopsy;
• Prostate size <100 cc on any diagnostic MRI;
• Presence of a visible prostatic lesion:
• PIRADS (Prostate Imaging-Reporting and Data System) 4+ lesion, and/or
• PIRADS 3 lesion with evidence of grade group 2-3
• Less than or equal to 4 lesions in total allowed;
• Lesion may contact the capsular edge, "possible" extracapsular extension (ECE) permitted; *MRI fusion biopsy is preferred but if the positive core is in the same region as the target on the MRI based on a systemic biopsy, the patient can be included.
• Genitourinary function with a baseline score ≤20 as defined by any pre-treatment IPSS questionnaire.
• Patients are mandated to get a fiducial placement. Optional proper rectal spacer placement is recommended as determined by the treating radiation oncologist based upon whether there is overt rectal wall invasion from the hydrogel spacer or if there is minimal to no separation of the prostate-rectal interface measured at the prostate mid-gland.
• Patients with a life expectancy of greater than 5 years as assessment by the investigator. Life expectancy can be estimated using any 1 of the following tools:
• The Social Security Administration tables: https://www.ssa.gov/OACT/STATS/table4c6.html

You may not qualify if…

• Patients with evidence of disease Grade Group 4 (GG4) or higher.
• Patients with PSA >20 ng/mL.
• Patients with evidence of clinical stage T3a+ or gross extracapsular extension on the diagnostic MRI.
• Patients who received prior or concurrent androgen deprivation therapy for prostate cancer.
• Patients with more than 4 disease foci identifiable on MRI.
• Patients with evidence of metastatic disease on imaging (e.g., bone scan, PSMA PET scan, or MRI/CT scan).
• Patients with ineligibility to undergo an MRI due to:
• The presence of a cardiac pacemaker, defibrillator, or other implanted metallic or electronic device which is considered MRI unsafe;
• Severe claustrophobia;
• Inability to lie flat for the duration of the study;
• Metallic implant or device in the pelvis that might distort the local magnetic field and compromise quality of MRI;
• Any other reason as determined by the investigator or treating physician.
• Patients with an I-PSS score >20 as defined by any pre-treatment IPSS questionnaire.
• Patients with a prior history of transurethral resection of the prostate, TURP, Urolift, or other similar trans-urethral LUTS management procedure within the last 6 months.
• Patients with a prior history of severe urethral stricture.
• Patients with a prior history of pelvic irradiation.
• Patients unable to meet dosimetric constraints
• Patients with a prior history of non-cutaneous solid malignancy within the last 5 years.
• Patients with a history of active and uncontrolled inflammatory bowel disease.
• Patients who are unable to comply with follow-up visits and treatment plans.

Where it is running

• Lombardi Comprehensive Cancer Center, Georgetown University — Washington D.C., District of Columbia, United States (enrolling)

Full record on ClinicalTrials.gov

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