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

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

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Prostate Cancer; Localized Prostate Carcinoma
• Intervention / Treatment: Radiation: Microboost SBRT; Radiation: Whole gland de-escalation 30 Gy; Radiation: Whole gland de-escalation 35 Gy

• Study Type: Interventional
• Enrollment (Estimated): 58
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Jonathan Lischalk, MD; Phone Number: 2026879194; Email: jonathan.w.lischalk@gunet.georgetown.edu

Study Locations

• United States
  • District of Columbia
    • Washington D.C., District of Columbia, United States, 20007
      • Lombardi Comprehensive Cancer Center, Georgetown University
      • Contact: TBD TBD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Patients age 18 or older.
2. Patients with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2
3. Patients with histologically confirmed adenocarcinoma of the prostate who have not received prior pelvic radiation therapy or prostatectomy.

4. 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
5. 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.

6. 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.
7. Genitourinary function with a baseline score ≤20 as defined by any pre-treatment IPSS questionnaire.
8. 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.

9. 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
   • The WHO's Life Tables by country: https://apps.who.int/gho/data/view.main.60000?lang=en
   • The Memorial Sloan Kettering Male Life Expectancy tool: https://www.mskcc.org/nomograms/prostate
   • If using a life expectancy table, life expectancy should be adjusted using the clinician's assessment of overall health as follows: best quartile of health - add 50%; worst quartile of health - subtract 50%; and middle two quartiles of health - no adjustment. See the NCCN Prostate Cancer Guidelines for more information.

10. Patients who agree to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures, and agree to refrain from donating sperm, as defined below:

    • With a female partner of childbearing potential who is not pregnant, men who are not surgically sterile must remain abstinent or use a condom plus an additional contraceptive method, which together result in a failure rate of < 1% per year, during the treatment period and for 1 year after treatment per local and institutional guidelines. Men must refrain from donating sperm during this same period.
    • With a pregnant female partner, men must remain abstinent or use a condom during the treatment period per local and institutional guidelines to avoid potential exposure to the embryo.
    • The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or post-ovulation methods) and withdrawal are not adequate methods of contraception.
11. Patients who are able to give informed consent.

Exclusion Criteria:

1. Patients with evidence of disease Grade Group 4 (GG4) or higher.
2. Patients with PSA >20 ng/mL.
3. Patients with evidence of clinical stage T3a+ or gross extracapsular extension on the diagnostic MRI.
4. Patients who received prior or concurrent androgen deprivation therapy for prostate cancer.
5. Patients with more than 4 disease foci identifiable on MRI.
6. Patients with evidence of metastatic disease on imaging (e.g., bone scan, PSMA PET scan, or MRI/CT scan).

7. 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.
8. Patients with an I-PSS score >20 as defined by any pre-treatment IPSS questionnaire.
9. 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.
10. Patients with a prior history of severe urethral stricture.
11. Patients with a prior history of pelvic irradiation.
12. Patients unable to meet dosimetric constraints
13. Patients with a prior history of non-cutaneous solid malignancy within the last 5 years.
14. Patients with a history of active and uncontrolled inflammatory bowel disease.
15. Patients who are unable to comply with follow-up visits and treatment plans.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Arm 1- Low Risk; Patients enrolled to arm 1 will have low risk prostate cancer without Grade Group 2-3 (GG2-3) outside of the microboost target(s). Patients in arm 1 will receive microboost SBRT at a dose of 45 Gy delivered in 5 fractions in up to 4 MRI-defined lesions plus whole gland de-escalation at a dose of 30 Gy delivered in 5 fractions.	Radiation: Microboost SBRT; Microboost SBRT at a dose of 45 Gy for 5 fractions; Radiation: Whole gland de-escalation 30 Gy; Whole gland de-escalation at a dose of 30 Gy delivered in 5 fractions.
Experimental: Arm 2- Intermidiate Risk; Patients enrolled to arm 2 will have intermidiate risk prostate cancer with grade group 2-3 disease outside of the microboost target(s). Patients in arm 2 will receive microboost SBRT at a dose of 45 Gy delivered in 5 fractions in up to 4 MRI-defined lesions plus whole gland de-escalation at a dose of 35 Gy delivered in 5 fractions.	Radiation: Microboost SBRT; Microboost SBRT at a dose of 45 Gy for 5 fractions; Radiation: Whole gland de-escalation 35 Gy; Whole gland de-escalation at a dose of 35 Gy delivered in 5 fractions

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of acute grade 2 or higher genitourinary toxicity	Safety of the microboost technique will be determined based on the incidence of acute grade 2 or higher genitourinary adverse events (AEs). AEs will be assessed and graded according to the current version of the Common Terminology Criteria for Adverse Events (CTCAE) or severity grade when CTCAE grading does not exist. Grade 1 to 5 will be used to characterize the severity of the AE. If CTCAE grading does not exist for an AE, the severity of mild, moderate, severe, life-threatening and death due to the AE, corresponding respectively to Grades 1 - 5, will be used.	during treatment through 90 days after radiation treatment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of acute grade 2 or higher gastrointestinal (GI) toxicity	The incidence of acute grade 2 or higher gastrointestinal AEs will be assessed and graded according to the current version of the Common Terminology Criteria for Adverse Events (CTCAE) or severity grade when CTCAE grading does not exist. Grade 1 to 5 will be used to characterize the severity of the AE. If CTCAE grading does not exist for an AE, the severity of mild, moderate, severe, life-threatening and death due to the AE, corresponding respectively to Grades 1 - 5, will be used.	Up to 5 years
Incidence of late grade 2 or higher genitourinary (GU) or gastrointestinal (GI) toxicity	The incidence of late grade 2 or higher genitourinary or gastrointestinal AEs will be assessed and graded according to the current version of the Common Terminology Criteria for Adverse Events (CTCAE) or severity grade when CTCAE grading does not exist. Grade 1 to 5 will be used to characterize the severity of the AE. If CTCAE grading does not exist for an AE, the severity of mild, moderate, severe, life-threatening and death due to the AE, corresponding respectively to Grades 1 - 5, will be used.	Up to 5 years
Incidence of late grade 3 or higher genitourinary or gastrointestinal toxicity	The cumulative incidence of late grade 3 or higher genitourinary or gastrointestinal AEs will be assessed and graded according to the current version of the Common Terminology Criteria for Adverse Events (CTCAE) or severity grade when CTCAE grading does not exist. Grade 1 to 5 will be used to characterize the severity of the AE. If CTCAE grading does not exist for an AE, the severity of mild, moderate, severe, life-threatening and death due to the AE, corresponding respectively to Grades 1 - 5, will be used	Up to 5 years
PSA (Prostate-specific antigen) nadir	PSA nadir is defined as the lowest PSA achieved at the time of follow up as determined by the treating physician. The PSA nadir will be determined by denoting the lowest value by 2- and 5-years of follow up.	at 2 years and 5 years
Biochemical failure (BF)	Biochemical failure is defined as a PSA rise of at least 2.0 n/g/mL above the patient's PSA nadir following radiation treatment by the Phoenix definition and as determined by the treating physician.	at 2 years and 5 years
Biochemical failure free survival (BFFS)	Biochemical failure free survival (BFFS) is defined as the length of time from radiation completion to the first documented evidence of biochemical failure of prostate cancer or death, whichever occurs first. Patients who are alive and free from biochemical failure will be censored at the date of last follow-up for BFFS.	up to 5 years
Disease-free survival (DFS)	Defined as the length of time from radiation completion to the first evidence of biochemical or clinical recurrence of prostate cancer or death, whichever occurs first. Patients who are alive and free from disease recurrence will be censored at the date of last follow-up for DFS.	up to 5 years
Patient-reported QoL (Quality of life) outcomes- Expanded Prostate Index Composite (EPIC)-26	Patient-reported QoL as measured by EPIC-26 questionnaire which measures health related quality of life. Scores range from 0 to 100 with higher scores indicating a better quality of life. The EPIC-26 instrument includes sub-scales like urinary function, bowel habits, and sexual function, which will be used to measure the changes in the GU (Genitourinary), GI (gastrointestinal), and sexual domains, respectively.	up to 5 years
Patient-reported QoL outcomes- International Prostate Symptom Score (I-PSS)	The I-PSS is based on the answers to 7 questions concerning Urinary symptoms. Scores range from 0 to 35, with 0 being asymptomatic to 35 being very symptomatic.	up to 5 years
Patient-reported QoL outcomes- International Index of Erectile Dysfunction (IIEF-5)	The IIEF-5 is a 5 question questionnaire which evaluates erectile dysfunction. Scores range from 5 to 25, 5-7 being severe erectile dysfunction and 22-25 being no erectile dysfunction.	up to 5 years
Patient-reported QoL outcomes- Health Questionnaire (EQ-5D-5L)	EQ-5D-5L questionnaire will have participants evaluate their quality of life across 5 Dimensions including Mobility, Self-care, Usual activities, Pain/discomfort, Anxiety/depression. Index scores range from -0.59 to 1, where 1 is the best possible health state.	up to 5 years

Collaborators and Investigators

• Sponsor: Georgetown University

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): January 1, 2028
• Study Completion (Estimated): January 1, 2035

Study Registration Dates

• First Submitted: May 28, 2026
• First Submitted That Met QC Criteria: June 8, 2026
• First Posted (Actual): June 12, 2026

Study Record Updates

• Last Update Posted (Actual): June 12, 2026
• Last Update Submitted That Met QC Criteria: June 8, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Localized prostate cancer
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Prostatic Neoplasms
• Other Study ID Numbers: STUDY00009733

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No