Vascular Optimized Radiotherapy Tuned to Critical Structures for Erectile Function Using High-Precision X-Ray Treatment (VORTEX)

December 17, 2025 updated by: Jonsson Comprehensive Cancer Center

With people living longer after being treated for prostate cancer, quality of life has become a concern when considering the treatment plan. Sometimes after radiation therapy, patients may experience problems that affect the urinary and bowel systems, along with sexual function.

Stereotactic body radiotherapy (SBRT) is a type of radiation technique that delivers five high doses of radiation. At University of California at Los Angeles (UCLA), we have the option to administer SBRT in both our CT-guided and MRI-guided radiation machines.

This trial aims to determine the most effective method for protecting the nerves and blood vessels essential for erectile function, utilizing a technique known as neurovascular sparing.

This technique uses images (i.e., MRI) to map the neurovascular bundles of nerves and blood vessels, which are crucial for erectile function. "Adapting" the radiotherapy treatment for each of these five treatment sessions could enable a more precise delivery of your radiation treatment that is customized based on your internal anatomy immediately before the treatment starts. This is also a standard and low-risk intervention used in many different types of cancer. However, it is a very labor-intensive and time-consuming procedure that requires a team of experts to work together before each of your radiotherapy sessions. We are unsure if the increased complexity associated with this adaptive treatment reduces side effects.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
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.

Detailed Description

The mechanism implicated in sexual function decline following radiotherapy involves injury to vascular structures surrounding the prostate which are critical for normal erectile function, namely the corpora cavernosa, internal pudendal arteries, and neurovascular bundles. These structures are all in close proximity to the prostate gland and are often included at least partially within the planning target volume margin of treatment plans. As noted above, these planning target volume (PTV) expansions were historically large due to the need to ensure adequate coverage of the target volume to achieve disease control although this likely came at the cost of higher rates of treatment-related toxicity. With enhanced technology for target visualization and intra-fraction motion management, it is technically feasible to reduce margins and spare surrounding normal tissue from receiving the full prescription dose while still treating the target volume with high confidence.

Beyond reducing the isometric PTV expansion due to increased precision in radiation delivery with modern techniques, however, it is now technically feasible to crop out these sensitive Organs-at-risk (OARs) from the final PTV volume in order to further spare them from receiving excess dose. This process, referred to as neurovascular-sparing (NV-sparing), involves the fusion of an MRI and/or MR angiogram to standard radiation planning images to allow accurate contouring of the internal pudendal arteries and neurovascular bundles so that these can be intentionally spared. Daily online adaptive replanning may also play a role in ensuring appropriate coverage of the target volume and sparing of OARs as intended by the treatment plan. To date, no investigations have reported on the clinical or dosimetric outcomes of patients treated with an NV approach in conjunction with these other methods. Furthermore, specific dose constraints for these structures are largely unknown due to the lack of empiric evidence to guide selection.

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.
200

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.
  • Phase 3

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

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90045
        • Recruiting
        • University of California at Los Angeles
        • Principal Investigator:
          • Amar Kishan, MD
        • Contact:
        • Contact:

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:

  1. Age ≥ 18.
  2. Histologically confirmed, clinically localized adenocarcinoma of the prostate.

  3. Staging workup as recommended by the National Comprehensive Cancer Network (NCCN) on the basis of risk grouping.

    a. Advanced imaging studies (i.e. prostate-specific membrane antigen [PSMA] positron emission tomography [PET]/CT and fluciclovine PET/CT scan) can supplant a bone scan if performed first.

  4. No evidence of metastatic disease in lymph nodes above the bifurcation of the renal arteries, or in bones or visceral organs (nodal disease identified on a PSMA PET/CT scan below the bifurcation of the renal arteries is allowable).
  5. Eastern Cooperative Oncology Group (ECOG) performance status ≤2.
  6. Ability to undergo magnetic resonance angiography (MRA) of the pelvis.
  7. No indication for urgent or emergent radiation.
  8. Written informed consent obtained from participant or participant's legal representative and ability for participant to comply with the requirements of the study.

Exclusion Criteria:

  1. Patients with neuroendocrine or small cell carcinoma of the prostate.
  2. Patients with any evidence of distant metastases except that evidence of lymphadenopathy below the level of the renal arteries can be deemed locoregional per the discretion of the investigator.
  3. Evidence of intraprostatic lesion by biopsy, MRI, or PSMA PET/CT within the middle third, or both lateral thirds of the prostate gland.
  4. History of whole-gland cryosurgery, high-intensity focused ultrasound (HIFU), brachytherapy, or other ablative treatments of the whole prostate.
  5. Prior pelvic radiotherapy.
  6. History of Crohn's disease, ulcerative colitis, or ataxia telangiectasia.
  7. Penile prosthesis or implant present prior to treatment.

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: Treatment
  • Allocation: Randomized
  • Interventional Model: Single Group Assignment
  • Masking: Single

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.
Active Comparator: Arm 1 non-adaptive SBRT
Patients undergo MRI or CT-guided SBRT without daily plan adaptation once every other day or on consecutive days if necessary, for a total of 5 treatments over 18 days in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo MRI and CT during screening and blood sample collection throughout the trial.
Radiation: Neurovascular sparing stereotactic body radiation therapy
Use of adaptive radiotherapy
Experimental: Arm 2 Neurovascular sparing stereotactic body radiation therapy
Patients undergo MRI or CT-guided SBRT with daily plan adaptation once every other day or on consecutive days if necessary, for a total of 5 treatments over 18 days in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo MRI and CT during screening and blood sample collection throughout the trial.
Radiation: Neurovascular sparing stereotactic body radiation therapy
Use of adaptive radiotherapy

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
Expanded Prostate Cancer Index Composite (EPIC-26) sexual function Questionnaire
Time Frame: 24 months
The primary endpoint is clinically relevant (≥24 point) decline in EPIC-26 sexual function domain scores at 24 months following treatment in patients randomized to NV-sparing SBRT relative to patients randomized to conventional SBRT without explicit NV-sparing.
24 months

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
Clinically relevant acute change in International Prostate Symptom Score (I-PSS) domain of EPIC-26.
Time Frame: From initiation to 90 days post treatment
Clinically relevant acute changes (from initiation to within 90 days after completion of SBRT) in IPSS of EPIC-26 patient-reported QOL. The International Prostate Symptom Score (I-PSS) is based on answers to seven questions concerning urinary symptoms and one question concerning quality of life. Answers are assigned points from 0 to 5. The total score range is from 0 -35. 0 indicating no symptoms to 35 indicating extremely symptomatic.
From initiation to 90 days post treatment
Clinically relevant acute change in Sexual Health Inventory for Men (SHIM) domain of EPIC-26.
Time Frame: From initiation to 90 days post treatment
Clinically relevant acute changes (from initiation to within 90 days after completion of SBRT) in SHIM domain of EPIC-26 patient-reported QOL. The SHIM score range is from 5 to 25. Higher score indicates better erectile function.
From initiation to 90 days post treatment
Clinically relevant chronic changes in IPSS, of EPIC-26.
Time Frame: From initiation to 90 days post treatment
Clinically relevant chronic changes (from initiation to within 90 days after completion of SBRT) in IPSS domain of EPIC-26 patient-reported QOL
From initiation to 90 days post treatment
Clinically relevant chronic changes in SHIM, of EPIC-26.
Time Frame: From initiation to 90 days post treatment
Clinically relevant chronic changes (from initiation to within 90 days after completion of SBRT) in SHIM domain of EPIC-26 patient-reported QOL
From initiation to 90 days post treatment
Gastric ulcer (GU) or Gastriointestinal (GI) toxicity
Time Frame: From initiation to 90 days post treatment
Incidence of GU or GI toxicity of at least grade 2 by the physician-reported CTCAE criteria.
From initiation to 90 days post treatment
prostate specific antigen (PSA) completed response at 2 years
Time Frame: From initiation to 90 days post treatment
PSA completed response at 2 years, defined as proportion of patients with PSA <20% of the pre-SBRT PSA.
From initiation to 90 days post treatment
Biochemical Recurrence-Free Survival rate
Time Frame: From initiation to 90 days post treatment
Biochemical Recurrence-Free Survival rates at 5 years, where biochemical recurrence is defined as serum PSA levels 2 ng/mL higher than the post-treatment PSA nadir.
From initiation to 90 days post treatment

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.
Jonsson Comprehensive Cancer Center

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.
Viewray Inc.

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: Amar Kishan, MD, UCLA / Jonsson Comprehensive Cancer Center

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 (Actual)

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.
December 16, 2025

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.
December 16, 2035

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.
December 16, 2036

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).
December 16, 2025

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.
December 17, 2025

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.
December 19, 2025

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.
December 19, 2025

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.
December 17, 2025

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.
December 1, 2025

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.
  • 25-2129

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

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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