Single-Dose Image-Guided Radiotherapy With Urethral Sparing and DIL Boost for Intermediate-Risk Prostate Cancer (PROSINT II)

Summary

This prospective single-arm phase II study evaluates the safety, feasibility, quality-of-life effects, PSA kinetics, imaging response, and clinical outcomes of definitive ultra-high dose single-fraction external beam radiation therapy in patients with biopsy-proven NCCN intermediate-risk localized adenocarcinoma of the prostate.

All eligible patients receive image-guided volumetric modulated arc radiotherapy with urethral sparing and organ-motion mitigation. Treatment consists of 24 Gy in one fraction to the whole prostate gland and proximal seminal vesicles. Patients with NCCN unfavorable intermediate-risk disease and an imaging-defined dominant intraprostatic lesion may receive a PSMA PET/CT-guided simultaneous integrated boost to the dominant intraprostatic lesion in sequential dose-escalation cohorts, up to 30 Gy, while maintaining protocol-defined organ-at-risk constraints.

A rectal balloon with air filling is used for prostate target immobilization and anatomical reproducibility, and a urethral catheter loaded with beacon transponders is used to identify the urethra, support urethral sparing, and enable online target tracking. Toxicity is assessed using CTCAE v4.0, and patient-reported outcomes are assessed using EPIC-26, IPSS, and IIEF questionnaires. PSA is measured at protocol-defined follow-up visits. Multiparametric MRI is performed at baseline and at 12 and 24 months after treatment. Participants are followed for a minimum of 5 years.

Conditions

• Prostate Cancer

Interventions

RADIATION

IGRT-VMAT / SDRT 24 Gy in 1 fraction

PSMA PET/CT-guided dominant intraprostatic lesion simultaneous integrated boost

DEVICE

Rectal balloon with air filling

A rectal balloon with air filling will be used for prostate target immobilization and anatomical reproducibility.

DEVICE

Urethral catheter loaded with beacon transponders

A urethral catheter loaded with beacon transponders will be used to ensure set-up reproducibility and online target tracking.

DIAGNOSTIC_TEST

PSMA PET/CT for DIL definition and/or staging where protocol-required

PSMA PET/CT for DIL definition

DIAGNOSTIC_TEST

Planning MRI for organ at risk and target definition

Planning MRI for organ at risk and target definition. mpMRI will also be used to aid DIL definition in conjunction with PSMA-PET/CT

Sponsors & Collaborators

• Fundacao Champalimaud

  lead OTHER

Principal Investigators

• Carlo Greco, MD · Fundacao Champalimaud

Study Design

Allocation

NA

Purpose

TREATMENT

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Sex

MALE

Healthy Volunteers

No

Timeline & Regulatory

Start

2019-06-01

Primary Completion

2026-12-31

Completion

2030-12-31

Countries

• Portugal

Study Locations