MRI-Guided Adaptive Radiotherapy for Limited Peritoneal Metastases (MARACAS Trial). (MARACAS)

May 12, 2026 updated by: Fondazione Policlinico Universitario Agostino Gemelli IRCCS

MARACAS: A Phase II Trial of MRI-guided Adaptive Stereotactic RAdiotherapy in oligometastatiC Patients With Peritoneal Spread.

This prospective phase II study evaluates the efficacy and safety of MRI-guided stereotactic body radiotherapy (MRIgSBRT) in patients with oligometastatic peritoneal carcinomatosis from gastrointestinal or gynecological tumors. Eligible patients with up to 5 MRI-visible peritoneal lesions and PCI ≤20 will be treated with MRIgSBRT using a hybrid MRI-linear accelerator with online adaptive planning and real-time tumor tracking.

The primary endpoint is radiologic response rate according to RECIST 1.1 criteria. Secondary endpoints include overall survival, progression-free survival, local control, chemotherapy-free survival, and treatment-related toxicity. The study aims to assess MRIgSBRT as a safe and non-invasive treatment option for selected patients with limited peritoneal metastatic disease.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Peritoneal carcinomatosis (PC) represents a frequent metastatic pattern in gastrointestinal and gynecological malignancies and is associated with poor prognosis and limited therapeutic options. Although cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) may improve outcomes in selected patients, many patients are not candidates for surgery because of recurrent disease, comorbidities, or poor performance status.

MRI-guided stereotactic body radiotherapy (MRIgSBRT) allows highly conformal radiation delivery with online adaptive planning and real-time tumor tracking, potentially improving treatment precision and sparing surrounding organs at risk in anatomically complex abdominal sites.

This prospective single-center phase II study will evaluate MRIgSBRT in patients with oligometastatic peritoneal carcinomatosis with up to 5 MRI-visible lesions and PCI ≤20. Treatment will be delivered using a hybrid MRI-linear accelerator with adaptive planning according to daily anatomical variations.

The primary endpoint is radiologic response rate according to RECIST 1.1 criteria. Secondary endpoints include overall survival, progression-free survival, local control, chemotherapy-free survival, and treatment-related toxicity assessed according to CTCAE v5.0.

Study Type

Interventional

Enrollment (Estimated)

34

Phase

  • Phase 2

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 Locations

  • Italy
      • Roma, Italy, 000168
        • Gemelli ART (Advanced Radiation Therapy)-Fondazione Policlinico Universitario Agostino Gemelli IRCCS
        • Contact:
        • Principal Investigator:
          • Luca Boldrini

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age ≥18 years
  • ECOG performance status 0-2
  • Life expectancy ≥6 months
  • Up to 5 MRI-visible peritoneal nodules
  • PCI ≤20
  • No prior radiotherapy in the same abdominal region within 6 months
  • Signed informed consent
  • History of prior CRS and/or HIPEC

Exclusion Criteria:

  • Diffuse peritoneal carcinomatosis
  • Psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule (those conditions should be discussed with the patient before registration in the trial)
  • Significant comorbidities (such as: severe cardiac or coagulative disease, moderate or severe
  • restrictive/obsiructive lung deficit, severe cognitive impairment, moderate and severe renal and hepatic impairment.
  • Pregnancy or breastfeeding
  • MRI contraindications (e.g., pacemaker, severe claustrophobia)

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: MRI-guided SBRT
Patients with oligometastatic peritoneal carcinomatosis will receive MRI-guided stereotactic body radiotherapy (MRIgSBRT) delivered with a hybrid MRI-linear accelerator using online adaptive planning and real-time tumor tracking. Treatment dose will range from 30 to 50 Gy in 5 fractions according to clinical judgment and organ-at-risk constraints.
Device: MRI-guided stereotactic body radiotherapy
Patients will receive MRI-guided stereotactic body radiotherapy (MRIgSBRT) delivered using a hybrid MRI-linear accelerator with online adaptive planning and real-time tumor tracking. Treatment will consist of 30-50 Gy delivered in 5 fractions according to clinical judgment, target characteristics, and organ-at-risk constraints. Daily adaptive replanning may be performed to account for anatomical changes and optimize dose delivery in patients with oligometastatic peritoneal carcinomatosis.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Radiological Response Rate (RR)
Time Frame: Up to 12 months after completion of MRIgSBRT
RR: The response rate will be calculated as the proportion of patients achieving a complete or partial radiological response out of the total number of evaluable patients according to RECIST 1.1 criteria
Up to 12 months after completion of MRIgSBRT

Collaborators and Investigators

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

Sponsor

Fondazione Policlinico Universitario Agostino Gemelli IRCCS

Investigators

  • Principal Investigator: Luca Boldrini, Fondazione Policlinico Universitario Agostino Gemelli IRCCS

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)

July 1, 2026

Primary Completion (Estimated)

July 1, 2029

Study Completion (Estimated)

July 1, 2032

Study Registration Dates

First Submitted

May 12, 2026

First Submitted That Met QC Criteria

May 12, 2026

First Posted (Actual)

May 18, 2026

Study Record Updates

Last Update Posted (Actual)

May 18, 2026

Last Update Submitted That Met QC Criteria

May 12, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 26983

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.

Yes

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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