Rectal AdenocarcinomaPhase 2NCT07292298
Phase 2 Single-Arm Rectal Cancer Brachytherapy for Patients With Low-Lying Residual Adenocarcinoma After Total Neoadjuvant Therapy to Improve Organ Preservation Rates
A Phase 2 study testing High Rare Dose Rectal Brachytherapy Boost in people with Rectal Adenocarcinoma and Rectal Cancer, run by University of Colorado, Denver at 3 sites in United States.
Trial summary
Rectal cancer patients who do not achieve a complete response to standard of care chemotherapy and radiation often require surgical resection as part of curative intent therapy. This study will evaluate whether additional "focal" radiation delivered internally (rectal brachytherapy) can provide complete responses and… Read more about this study
- Who is it for?
- Ages 18 to 100 years
- Conditions the study is for
- Rectal Adenocarcinoma, Rectal Cancer
- What is being tested?
- High Rare Dose Rectal Brachytherapy Boost
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 44 participants
- Where
- 3 sitesUnited States
- Study dates
- Nov 2026to Nov 2031
- 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 to 100 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Provision to sign and date the consent form.
- Stated willingness to comply with all study procedures and be available for the duration of the study.
- Adults (18-100 years old)
- ECOG 0-3
- Patients with MMR-proficient low-mid rectal adenocarcinoma cT1-4 N0-2 M0 who underwent total neoadjuvant therapy who have not achieved complete response (i.e. incomplete or near-complete) in the rectal primary tumor such that surgical resection, if offered presently or in the future, would be an APR or low LAR per colorectal surgeon expert opinion and central review at University of Colorado rectal tumor board. Tumor restaging will be 4-16 weeks following completion of total neoadjuvant therapy, and no sooner than 8 weeks if patients received chemotherapy followed by chemoradiation/short course radiation.
- Residual rectal disease must have its craniocaudal extent <4 cm with thickness <1.2 cm. Tumor must have <50% circumferential involvement. Residual disease must be above the dentate line and not involving the anal canal.
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- In patients with original cN1-2 disease, restaging CT and MRI after total neoadjuvant therapy must demonstrate at least near-complete response of the pelvic lymph nodes per NCCN criteria as evaluated by central review at University of Colorado rectal tumor board.
- Interval of time between completion of TNT and initiation of rectal brachytherapy must be between 4-16 weeks.
- Patients must be recovered from total neoadjuvant therapy and must not have significant rectal incontinence at time of screening.
- Received conventionally fractionated external beam chemoradiation between 45-56 Gy or short-course external beam radiation prescription of 25 Gy to rectal mucosa, in addition to systemic chemotherapy before or after radiation per National Comprehensive Cancer Network (NCCN) guidelines.
- Women of child-bearing potential must have a negative urine or serum pregnancy test within 14 days of HDR treatment.
- Men and women of reproductive potential who are sexually active must agree to follow instructions of contraception for the duration of the study and 6 months post-rectal brachytherapy completion.
- CBC at the time of screening must have platelets>50 10^9/L, Hemoglobin>8 g/dL and Absolute Neutrophil Count > 500 10^9/L
Who cannot join
- History of ulcerative colitis or Crohn's disease.
- Pelvic radiotherapy given prior to rectal cancer external beam radiation.
- Prior colorectal surgery in which anastomotic site is at or near HDR brachytherapy target.
- o Prior local excision is not an exclusion criterion.
- Uncontrolled intercurrent severe illness, including but not limited to, ongoing or active infection, symptomatic congestive heart failure, uncontrolled hypertension, unstable angina pectoris, cardiac arrhythmia, interstitial lung disease, serious chronic gastrointestinal conditions associated with diarrhea, or psychiatric illness/social situations that would limit compliance with study requirement, substantially increase risk of incurring AEs or compromise the ability of the patient to give written informed consent.
- Life expectancy <3 years per provider discretion.
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- Concurrent administration of any cytotoxic chemotherapy, immunotherapy, or other any targeted oncologic agent that would impact rectal cancer is not allowed during study protocol.
- If rectal cancer has been treated outside of standard total neoadjuvant therapy per NCCN guidelines, patients are ineligible for the trial. This includes if patients received external beam chemoradiation dose with prescription >56 Gy or short-course radiation to rectal mucosa prescription >30 Gy.
- Pregnant women.
Trial locations and contacts
3 sites in 1 country. Contact the study team or a site near you to ask about taking part.
United States3 sites, 3 recruiting
- Recruiting
University of Colorado Cancer Center
Aurora, Colorado, 80045
Radiation Therapy Group, 303-724-8822, RTClinicalResearch@olucdenver.onmicrosoft.com
David Binder, MD, PhD
- Not yet recruiting
Oregon Health and Sciences University
Portland, Oregon, 97239
- Not yet recruiting
University of Rochester Medical Center
Rochester, New York, 14642
About this study
Rectal cancer patients who do not achieve a complete response to standard of care chemotherapy and radiation often require surgical resection as part of curative intent therapy. This study will evaluate whether additional "focal" radiation delivered internally (rectal brachytherapy) can provide complete responses and thus spare the requirement for surgery.
The main questions are whether: 1) rectal brachytherapy is safe in this clinical treatment paradigm and if 2) rectal brachytherapy improves organ preservation (no need for surgery).
The trial involves an additional MRI pelvis and sigmoidoscopy with marker placement to define high-risk residual disease for radiation planning. Subsequently, 3 outpatient brachytherapy treatments are given on a weekly basis. If a patient achieves a complete response to brachytherapy, standard of care non-operative surveillance visits are conducted with study visits aligned during the first two years following brachytherapy.
Read the detailed description
Rectal cancer patients with incomplete responses following standard of care chemotherapy and radiation are offered surgery as part of curative intent regimens. Similarly, patients with near-complete responses following initial therapy may require future salvage surgery given high local recurrence risk in the rectum. The goal of this study is to determine whether additional "internal" focal radiation delivered by rectal brachytherapy can provide a complete tumor response, such that patients can avoid surgical intervention. While rectal brachytherapy efficacy, technique, and safety has been demonstrated in previous studies conducted in Europe and Canada, it has not been tested to "boost" responses following standard of care chemotherapy/radiation in the United States.
Specifically, rectal brachytherapy treatment requires placement of a multichannel cylinder into the rectum following local analgesia and oral medication to improve procedure tolerability. A balloon on the cylinder is inflated to displace rectum uninvolved with tumor away from the internal high-dose radiation source that travels through the cylinder channels abutting the tumor. 21 Gy cumulative dose over 3 weekly treatments is administered to the high-risk rectal mucosa at a depth aligning to tumor thickness. The cylinder will be immobilized in the rectum for up to 3 hours during each of the 3 brachytherapy sessions, with radiation treatment being less than 10 minutes following completion of planning.
If complete response is achieved, surveillance visits will be conducted with an almost identical protocol to patients who achieve complete response following standard of care radiation/chemotherapy.
- Conditions
- Rectal Adenocarcinoma, Rectal Cancer
- Being tested
- High Rare Dose Rectal Brachytherapy Boost
- Keywords
- Locally Advanced Rectal Cancer, Non-metastatic Rectal Cancer, Rectal Neoplasms
- Medical subject headings
- Rectal Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
High Rare Dose Rectal Brachytherapy BoostRadiation
HDR rectal brachytherapy boost using Iridium-192 delivered via an intracavitary applicator in three weekly fractions (total dose: 21 Gy) for patients with low-lying residual rectal adenocarcinoma following total neoadjuvant therapy.
| Study group | Role | What they receive |
|---|---|---|
| HDR Rectal Brachytherapy Boost | Experimental | The intervention consists of a boost using Iridium-192 delivered via an intracavitary applicator in three weekly fractions totaling 21 Gy. The goal is to improve organ preservation rates and avoid surgical resection (APR or low LAR). Treatment planning includes MRI, endoscopic clip placement, and CT simulation prior to each fraction. Receives: Radiation: High Rare Dose Rectal Brachytherapy Boost |
What is being measured
The primary outcome is the main question the study is designed to answer.
Organ preservation (no surgical requirement) of the rectum associated with complete clinical response
As evaluated by standard of care sigmoidoscopy and MRI
Measured: 2 years following study treatment
Secondary outcomes (4)
Locoregional recurrence free survival
As defined by CT and MRI pelvis
Measured: 2 years following study treatment
Distant metastatic free survivial
As assessed by CT c/a/p
Measured: 2 years following study treatment
Overall survival
Overall survival
Measured: 2 years following study treatment
Bowel function
As assessed by LARS (low anterior resection syndrome) questionnaire
Measured: 2 years following study treatment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Dec 2025
- Study startNov 2026 (estimated)
- Primary completionNov 2030 (estimated)
- Study completionNov 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Rectal AdenocarcinomaStudies of the same condition, open and under way.
- More trials run by University of Colorado, DenverThe 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
- 44 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Colorado, Denver
- Sponsor type
- University, hospital or other
- Collaborators
- Cancer League of Colorado
- Responsible party
- Sponsor
- Investigators
- David Binder, Principal investigator, University of Colorado, Denver
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07292298
- Sponsor's protocol ID
- 25-1202.cc
- Status last verified
- Apr 2026
- First submitted
- 5 Dec 2025
- Last updated
- 2 Sep 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Phase 2 Single-Arm Rectal Cancer Brachytherapy for Patients With Low-Lying Residual Adenocarcinoma After Total Neoadjuvant Therapy to Improve Organ Preservation Rates
- ClinicalTrials.gov ID
- NCT07292298
- Acronym / sponsor ID
- 25-1202.cc
- Conditions
- Rectal Adenocarcinoma, Rectal Cancer
- Keywords
- Locally Advanced Rectal Cancer, Non-metastatic Rectal Cancer, Rectal Neoplasms
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 44 participants (estimated)
- Lead sponsor
- University of Colorado, DenverUniversity, hospital or other
- Collaborators
- Cancer League of Colorado
- Study start
- Nov 2026 (estimated)
- Primary completion
- Nov 2030 (estimated)
- Study completion
- Nov 2031 (estimated)
- First posted
- 18 Dec 2025 (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.
Rectal cancer patients who do not achieve a complete response to standard of care chemotherapy and radiation often require surgical resection as part of curative intent therapy. This study will evaluate whether additional "focal" radiation delivered internally (rectal brachytherapy) can provide complete responses and thus spare the requirement for surgery.
The main questions are whether: 1) rectal brachytherapy is safe in this clinical treatment paradigm and if 2) rectal brachytherapy improves organ preservation (no need for surgery).
The trial involves an additional MRI pelvis and sigmoidoscopy with marker placement to define high-risk residual disease for radiation planning. Subsequently, 3 outpatient brachytherapy treatments are given on a weekly basis. If a patient achieves a complete response to brachytherapy, standard of care non-operative surveillance visits are conducted with study visits aligned during the first two years following brachytherapy.
Detailed description
Rectal cancer patients with incomplete responses following standard of care chemotherapy and radiation are offered surgery as part of curative intent regimens. Similarly, patients with near-complete responses following initial therapy may require future salvage surgery given high local recurrence risk in the rectum. The goal of this study is to determine whether additional "internal" focal radiation delivered by rectal brachytherapy can provide a complete tumor response, such that patients can avoid surgical intervention. While rectal brachytherapy efficacy, technique, and safety has been demonstrated in previous studies conducted in Europe and Canada, it has not been tested to "boost" responses following standard of care chemotherapy/radiation in the United States.
Specifically, rectal brachytherapy treatment requires placement of a multichannel cylinder into the rectum following local analgesia and oral medication to improve procedure tolerability. A balloon on the cylinder is inflated to displace rectum uninvolved with tumor away from the internal high-dose radiation source that travels through the cylinder channels abutting the tumor. 21 Gy cumulative dose over 3 weekly treatments is administered to the high-risk rectal mucosa at a depth aligning to tumor thickness. The cylinder will be immobilized in the rectum for up to 3 hours during each of the 3 brachytherapy sessions, with radiation treatment being less than 10 minutes following completion of planning.
If complete response is achieved, surveillance visits will be conducted with an almost identical protocol to patients who achieve complete response following standard of care radiation/chemotherapy.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| HDR Rectal Brachytherapy Boost | Experimental | Radiation: High Rare Dose Rectal Brachytherapy BoostThe intervention consists of a boost using Iridium-192 delivered via an intracavitary applicator in three weekly fractions totaling 21 Gy. The goal is to improve organ preservation rates and avoid surgical resection (APR or low LAR). Treatment planning includes MRI, endoscopic clip placement, and CT simulation prior to each fraction. |
Who may qualify
- Ages
- 18 to 100 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (13 listed)
- Provision to sign and date the consent form.
- Stated willingness to comply with all study procedures and be available for the duration of the study.
- Adults (18-100 years old)
- ECOG 0-3
- Patients with MMR-proficient low-mid rectal adenocarcinoma cT1-4 N0-2 M0 who underwent total neoadjuvant therapy who have not achieved complete response (i.e. incomplete or near-complete) in the rectal primary tumor such that surgical resection, if offered presently or in the future, would be an APR or low LAR per colorectal surgeon expert opinion and central review at University of Colorado rectal tumor board. Tumor restaging will be 4-16 weeks following completion of total neoadjuvant therapy, and no sooner than 8 weeks if patients received chemotherapy followed by chemoradiation/short course radiation.
Key exclusion criteria (9 listed)
- History of ulcerative colitis or Crohn's disease.
- Pelvic radiotherapy given prior to rectal cancer external beam radiation.
- Prior colorectal surgery in which anastomotic site is at or near HDR brachytherapy target.
- o Prior local excision is not an exclusion criterion.
- Uncontrolled intercurrent severe illness, including but not limited to, ongoing or active infection, symptomatic congestive heart failure, uncontrolled hypertension, unstable angina pectoris, cardiac arrhythmia, interstitial lung disease, serious chronic gastrointestinal conditions associated with diarrhea, or psychiatric illness/social situations that would limit compliance with study requirement, substantially increase risk of incurring AEs or compromise the ability of the patient to give written informed consent.
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 |
|---|---|---|
| High Rare Dose Rectal Brachytherapy BoostHDR rectal brachytherapy boost using Iridium-192 delivered via an intracavitary applicator in three weekly fractions (total dose: 21 Gy) for patients with low-lying residual rectal adenocarcinoma following total neoadjuvant therapy. | Radiation | HDR Rectal Brachytherapy Boost |
Primary outcome
Organ preservation (no surgical requirement) of the rectum associated with complete clinical response
Time frame: 2 years following study treatment
As evaluated by standard of care sigmoidoscopy and MRI
4 secondary outcomes
Locoregional recurrence free survival
Time frame: 2 years following study treatment
Distant metastatic free survivial
Time frame: 2 years following study treatment
Overall survival
Time frame: 2 years following study treatment
Bowel function
Time frame: 2 years following study treatment
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 2 Sep 2026.
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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.
David Binder principal investigator
University of Colorado, Denver
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing High Rare Dose Rectal Brachytherapy Boost in people with Rectal Adenocarcinoma and Rectal Cancer, run by University of Colorado, Denver at 3 sites in United States.
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 13 inclusion and 9 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 2 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in United States. 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 Radiation Therapy Group (303-724-8822, RTClinicalResearch@olucdenver.onmicrosoft.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Organ preservation (no surgical requirement) of the rectum associated with complete clinical response (time frame: 2 years following study treatment). 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 2 Sep 2026.