Rectal CancerPhase 2MARSNCT07337876
Organ Preservation in Rectal Cancer by Dose Escalated MR Guided Adaptive Radiotherapy
A Phase 2 study testing Dose escalated radiotherapy using a 1.5 T MR-Linac in people with Rectal Cancer, run by University Hospital Tuebingen at 1 site in Germany.
Trial summary
This study is testing whether radiation delivered with MRI guidance using a so-called MR-linac in distal rectal cancer can result in a high rate of organ preservation. Patients will receive radiotherapy together with standard chemotherapy. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Rectal Cancer
- What is being tested?
- Dose escalated radiotherapy using a 1.5 T MR-Linac
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 100 participants
- Where
- 1 siteGermany
- Study dates
- 7 Jan 2026to Jan 2029
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients with histologically confirmed diagnosis of rectal cancer localized between dentate line and 12 cm from the anocutaneous line
- Any MRI staged rectal cancer meeting the following criteria
- cT1-cT3 and
- cN0 -cN1 and
- cM0
- Inclusion of UICC Stage I tumors only if unsuitable for endoscopic resection or if primary surgery would require permanent colostomy or deep anastomosis with expected poor organ function.
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- Tumor affects less than 70% of the rectal circumference.
- Maximum longitudinal extension of the tumor less than 8 cm on MRI
- MR-Staging requirements: High-resolution, thin-sliced (i.e.
- ≤3mm) magnetic resonance imaging (MRI) of the pelvis.
- Cross-sectional imaging of the abdomen and chest to exclude distant metastases.
- Aged at least 18 years. No upper age limit.
- WHO/ECOG Performance Status ≤ 1
- Adequate hematological, hepatic, renal and metabolic function parameters
- Informed consent of the patient
Who cannot join
- Lower border of the tumor localised more than 12 cm from the anocutaneous line as measured by rigid rectoscopy
- Distant metastases
- Preexisting fecal incontinence for solid stool
- Prior antineoplastic therapy for rectal cancer
- Prior radiotherapy of the pelvic region
- Subject pregnant or breast feeding, or planning to become pregnant within 6 months after the end of treatment.
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- Subject (male or female) is not willing to use highly effective methods of contraception (per institutional standard) during treatment and for 6 months (male or female) after the end of treatment (adequate: oral contraceptives, intrauterine device or barrier method in conjunction with spermicidal jelly).
- Other concomitant antineoplastic therapy
- Serious concurrent diseases, including neurologic or psychiatric disorders (incl. dementia and uncontrolled seizures), active,uncontrolled infections, active, disseminated coagulation disorder
- Other primary tumors with an estimated life expectancy of less than three years
- Contraindications for treatment with 5-Fluorouracil or Capecitabine
- Psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule (these conditions should be discussed with the patient before registration in the trial).
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Germany1 site, 1 recruiting
- Recruiting
University Hospital Tübingen
Tübingen, Baden-Wurttemberg, 72074
About this study
This study is testing whether radiation delivered with MRI guidance using a so-called MR-linac in distal rectal cancer can result in a high rate of organ preservation. Patients will receive radiotherapy together with standard chemotherapy.
- Conditions
- Rectal Cancer
- Being tested
- Dose escalated radiotherapy using a 1.5 T MR-Linac
- Keywords
- organ preservation
- Medical subject headings
- Rectal Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dose escalated radiotherapy using a 1.5 T MR-LinacRadiation
Dose escalated radiotherapy using a 1.5 T MR-Linac is given to the primary tumor and affected lymph nodes in an online adaptive manner
| Study group | Role | What they receive |
|---|---|---|
| MR guided dose escalated radiotherapy | Experimental | A dose of 65 Gy is delivered to the primary tumor and affected lymph nodes. Receives: Radiation: Dose escalated radiotherapy using a 1.5 T MR-Linac |
What is being measured
The primary outcome is the main question the study is designed to answer.
Two year TME-free survival
Patients alive and without TME-surgery
Measured: Two years from the start of radiotherapy
Secondary outcomes (1)
Clincal complete response rate
Patients who have no evidence of residual tumor on MRI and rectoscopy
Measured: three months after the end of radiotherapy
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Jan 2026
- Study start7 Jan 2026
- Primary completionJan 2029 (estimated)
- Study completionJan 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Rectal CancerStudies of the same condition, open and under way.
- More trials run by University Hospital TuebingenThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 100 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University Hospital Tuebingen
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dr. Cihan Gani, University Hospital Tuebingen
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07337876
- Sponsor's protocol ID
- 311/2025BO1
- Acronym
- MARS
- Status last verified
- Feb 2026
- First submitted
- 1 Jan 2026
- Last updated
- 17 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Data will be shared if a sound scientific proposal if provided.
Study at a glance
From the registry record, last updated by the sponsor on 17 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Organ Preservation in Rectal Cancer by Dose Escalated MR Guided Adaptive Radiotherapy
- ClinicalTrials.gov ID
- NCT07337876
- Acronym / sponsor ID
- MARS / 311/2025BO1
- Conditions
- Rectal Cancer
- Keywords
- organ preservation
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- University Hospital TuebingenUniversity, hospital or other
- Study start
- 7 Jan 2026 (actual)
- Primary completion
- Jan 2029 (estimated)
- Study completion
- Jan 2029 (estimated)
- First posted
- 13 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is testing whether radiation delivered with MRI guidance using a so-called MR-linac in distal rectal cancer can result in a high rate of organ preservation. Patients will receive radiotherapy together with standard chemotherapy.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| MR guided dose escalated radiotherapy | Experimental | Radiation: Dose escalated radiotherapy using a 1.5 T MR-LinacA dose of 65 Gy is delivered to the primary tumor and affected lymph nodes. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (15 listed)
- Patients with histologically confirmed diagnosis of rectal cancer localized between dentate line and 12 cm from the anocutaneous line
- Any MRI staged rectal cancer meeting the following criteria
- cT1-cT3 and
- cN0 -cN1 and
- cM0
Key exclusion criteria (12 listed)
- Lower border of the tumor localised more than 12 cm from the anocutaneous line as measured by rigid rectoscopy
- Distant metastases
- Preexisting fecal incontinence for solid stool
- Prior antineoplastic therapy for rectal cancer
- Prior radiotherapy of the pelvic region
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Dose escalated radiotherapy using a 1.5 T MR-LinacDose escalated radiotherapy using a 1.5 T MR-Linac is given to the primary tumor and affected lymph nodes in an online adaptive manner | Radiation | MR guided dose escalated radiotherapy |
Primary outcome
Two year TME-free survival
Time frame: Two years from the start of radiotherapy
Patients alive and without TME-surgery
1 secondary outcome
Clincal complete response rate
Time frame: three months after the end of radiotherapy
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Feb 2026.
- Individual participant dataSharing planned: Undecided. Data will be shared if a sound scientific proposal if provided.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Dose escalated radiotherapy using a 1.5 T MR-Linac in people with Rectal Cancer, run by University Hospital Tuebingen at 1 site in Germany.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 15 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 17 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Germany. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Cihan Gani, MD (+4970712982165, cihan.gani@med.uni-tuebingen.de), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Two year TME-free survival (time frame: Two years from the start of radiotherapy). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Feb 2026.