Patients With Metastasized Prostate Cancer Whose Prostate-specific Antigen-level (PSA) Remains >0,2 ng/ml After Six Months of Dual Antihormonal Therapy Will Receive Radiotherapy to the Prostate and Radiotherapy to Refractory Metastases (RIALTO)

June 8, 2026 updated by: University Hospital Tuebingen

RIALTO: Radiotherapy in Primarily Metastasized Prostate Cancer - Image-guided Local AbLaTion of Prostate and Oligoresidual Disease

The goal of this clinical trial is to learn if radiotherapy to the prostate and PET-positive (positron emission tomography) metastasis will lead to radiological response on PSMA-PET (prostate specific membrane antigen-PET). Patients who receive combined androgen deprivation therapy for de novo metastasized prostate cancer and show an incomplete PSA-response (>0,2 ng/ml after six months) and exhibit at least four bone metastases on PET-imaging at this time point (without metastases to organs) can take part in this study.

The main questions it aims to answer are:

• Does radiotherapy to the prostate and PET-positive metastases lead to a radiological response one year after radiotherapy? Researchers will analyze PET-imaging prior to radiotherapy to the prostate and metastases and one yeare thereafter.

Participants will:

  • Continue taking combined androgen-deprivation therapy
  • Receive a total of three PSMA-PET/CT scans
  • Receive radiotherapy to the prostate and PET-positive metastases
  • Visit the clinic every three months for 36 months
  • Complete quality of life questionnaires at every visit

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
27

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

  • Name: Maximilian Niyazi, MD, Prof. Dr. Dipl.-Phys.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Prostate adenocarcinoma
  • de novo metastasized prostate cancer (at least 4 osseous metastases +/- lymphonodal metastases)
  • first-line combined antihormonal therapy (ADT + ARPI) for six months
  • PSA > 0,2 ng/ml after six months of combined ADT/ARPI therapy
  • multimetastasized disease stage without visceral metastases on imaging at first diagnosis (PET, CT, or bone scan)
  • <16 osseous/lymphnodal metastases on response assessment imaging (PSMA-PET/CT) after six months of combined antihormonal therapy

Exclusion Criteria:

  • neuroendocrine histology
  • visceral metastases (M1c)
  • prior radiotherapy to the pelvis
  • PSA < 0,2 ng/ml after 6 months of combined antihormonal therapy
  • prior prostatectomy
  • contraindication against PSMA-PET/CT and/or radiotherapy to the prostate/metastases
  • HIFU or TUR-P within 6 months of study treatment
  • other active malignancy two years prior to study inclusion (except skin cancer in remission)
  • relevant GU/GI condition (active fistula or other)
  • known tumor predisposition syndrome

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Radiotherapy to the prostate and PSMA-PET/CT guided radiotherapy of refractory metastases
Radiotherapy to the prostate and refractory metastases on PSMA-PET/CT
Radiation: Radiotherapy to the prostate and to PSMA-PET positive metastases
Patients will receive radiotherapy to the prostate and to PSMA-PET postivie Metastases

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Radiological Progression-Free Survival
Time Frame: 12 months after radiotherapy of metastases
Radiological Progression-Free Survival as determined on PSMA-PET/CT according to RECIP criteria, defined as 30% response in PSA-volume
12 months after radiotherapy of metastases

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Lesion-specific response on imaging
Time Frame: 12 months after radiotherapy to metastases
12 months after radiotherapy to metastases
Prostate specific antigen (PSA)
Time Frame: up to 36 months after radiotherapy to the prostate
Prostate specific antigen
up to 36 months after radiotherapy to the prostate
Objective response rate
Time Frame: 12 months after radiotherapy to metastases
12 months after radiotherapy to metastases
Time to next systemic therapy
Time Frame: up to 36 months after radiotherapy to the prostate
up to 36 months after radiotherapy to the prostate
Overall survival
Time Frame: up to 36 months after radiotherapy to the prostate
up to 36 months after radiotherapy to the prostate
Failure-free survival
Time Frame: up to 36 months after radiotherapy to the prostate
up to 36 months after radiotherapy to the prostate
Progression-free survival
Time Frame: up to 36 months after radiotherapy to the prostate
up to 36 months after radiotherapy to the prostate
Metastasis-free survival
Time Frame: up to 36 months after radiotherapy to the prostate
up to 36 months after radiotherapy to the prostate
Prostate-cancer specific survival
Time Frame: up to 36 months after radiotherapy to the prostate
up to 36 months after radiotherapy to the prostate

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Quality of life questionnaires
Time Frame: up to 36 months after radiotherapy of the prostate
EORTC QLQ-C30 Prostate
up to 36 months after radiotherapy of the prostate
Organ-specific side effects
Time Frame: up to 36 months after radiotherapy of the prostate
CTCAEv5
up to 36 months after radiotherapy of the prostate
Organ function
Time Frame: up to 36 months after radiotherapy of the prostate
IPS-Score
up to 36 months after radiotherapy of the prostate
Choice of next systemic therapy
Time Frame: up to 36 months after radiotherapy to the prostate
Documentation of systemic treatment in case of progression
up to 36 months after radiotherapy to the prostate
Reason for change in systemic therapy
Time Frame: up to 36 months after radiotherapy to the prostate
Documentation in case of change in systemic therapy
up to 36 months after radiotherapy to the prostate
Quality of Life questionnaire
Time Frame: up to 36 months after end of radiotherapy of the prostate
QLQ-PR25
up to 36 months after end of radiotherapy of the prostate
Quality of life questionnaire
Time Frame: up to 36 months after radiotherapy to the prostate
EQ-D5
up to 36 months after radiotherapy to the prostate
Organ-specific side effects
Time Frame: up to 36 months after end of radiotherapy
RTOG questionnaire
up to 36 months after end of radiotherapy
Organ function
Time Frame: up to 36 months after radiotherapy to the prostate
ICIQScore
up to 36 months after radiotherapy to the prostate
Organ-specific function
Time Frame: up to 36 months after radiotherapy to the prostate
NCI-PRO-CTCAE
up to 36 months after radiotherapy to the prostate
Organ-specific function
Time Frame: up to 36 months after radiotherapy to the prostate
IIEF
up to 36 months after radiotherapy to the prostate

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University Hospital Tuebingen

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Ludwig-Maximilians - University of Munich
University Hospital Freiburg
University Hospital Dresden
University Hospital Augsburg
Uniklinikum Giessen und Marburg

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Elgin Hoffmann, MD, Department of Radiation Oncology, University Hospital Tübingen

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
July 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
February 1, 2031

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
June 1, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 8, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 12, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 12, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 8, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 430/2025BO1
  • DRKS00038018 (Registry Identifier: Deutsches Register Klinischer Studien (German clinical trial registry))

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Depending on national data security legislation for sharing individual data, providing IPD might not be permitted without explicit consent by the patients enrolled in this study.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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