Pembrolizumab for Patients with Localised dMMR Colon Cancer: Neoadjuvant and Organ-Sparing Treatment Study

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What is this study about?

This clinical trial is being done in people with localised dMMR colon cancer, a type of colon cancer that is found in one area of the body and has a problem in the system that helps repair DNA damage. The treatment used in the study is pembrolizumab, given by vein as an infusion. The purpose of the study is to see whether this treatment can shrink or clear the cancer enough to avoid or reduce the need for surgery.

At the start, pembrolizumab is given over a period of time, with regular medical checks during treatment. After treatment, the cancer is checked again with tests such as a CT scan, which is a special X-ray picture of the body, and an endoscopy, which is a thin tube test used to look inside the bowel. Based on these results, some people may go on to surgery, while others may be monitored closely without immediate surgery. The study also follows health over time to learn about possible side effects, recovery, and general well-being.

1 study treatment period

After joining the study, you receive pembrolizumab as an intravenous infusion, which means it is given into a vein.

The dose is 400 mg each time.

The medicine is given once every 6 weeks.

This treatment continues for up to 6 months.

2 response check after treatment

After the pembrolizumab treatment ends, your response to treatment is checked.

This check includes an endoscopy, which is a test that looks inside the bowel using a thin tube with a camera.

It also includes a ct scan, which is an imaging test used to look for spread of disease.

The main question at this point is whether there is a complete clinical response, meaning no visible local disease on endoscopy and no spread of disease on ct imaging.

3 after the response check

After the response check, the next stage depends on the study plan for your care.

The study records whether you have surgery, continue without surgery, or follow another planned path in the trial.

The study also follows your health over time to record survival, return of disease, treatment side effects, and quality of life.

4 follow-up after treatment

Your condition is followed for a long period after treatment ends.

The study tracks outcomes up to 36 months after joining the study for survival and disease return.

Side effects from pembrolizumab are tracked for 12 months after the medicine is given.

If you have surgery, surgery-related problems are tracked for 90 days after the operation.

If you have endoscopy, endoscopy-related problems are tracked for 7 days after the procedure.

If surgery is done, recovery is also checked on day 0, day 2, and day 14 after surgery.

Quality of life is checked before, during, and after treatment at 3, 6, 12, 24, and 60 months after treatment.

Physical function and fitness tests are also repeated at enrolment, after each cycle of immunotherapy, and 3 months after definitive treatment.

Who Can Join the Study?

Age 18 years or older.
Written informed consent, meaning the patient must sign a form showing they understand the study and agree to take part.
Clinical UICC stage I to III colon adenocarcinoma, meaning the cancer is in the colon and is at an early to locally advanced stage, but not stage IV. Adenocarcinoma means a cancer that starts in gland-like cells lining the colon.
dMMR colon cancer, meaning the cancer has mismatch repair deficiency and does not fix DNA mistakes normally.
Planned elective surgery with curative intent, meaning surgery is already planned and the goal is to remove the cancer and try to cure it.

Who Cannot Join the Study?

Patients who are considered not suitable for surgery by the multidisciplinary team (MDT), which means a group of specialists who review the case together.
Patients who need emergency surgery because the tumor is blocking the bowel and causing an obstruction.
Patients who cannot receive pembrolizumab, based on the study doctor’s judgment. A contraindication means a reason a treatment should not be given because it may be unsafe.
Patients with any serious or uncontrolled medical problem, including another cancer, if it could raise the risk of taking part in the study or receiving the drug.
Patients who have a colonic stent, which is a small tube placed in the colon to help keep it open.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Bispebjerg Hospital	Copenhagen	Denmark

Other Sites

Site Name	City	Country
Odense University Hospital	Odense	Denmark
Slagelse Hospital	Slagelse	Denmark
Sygehus Lillebaelt Vejle Sygehus	Vejle	Denmark
Aalborg University Hospital	Aalborg	Denmark
Rigshospitalet	Copenhagen	Denmark
Region Midtjylland	Randers	Denmark
Zealand University Hospital	Koege	Denmark
Hrnlav Hlghjczk	Herlev	Denmark
Autbcr Usigprxrgc Hzyjfdum	Aarhus	Denmark
Rfpigr Mmctplbjyhy	Herning	Denmark
Hiowufzk Hoyeshjf	Hvidovre	Denmark

Trial status

Country	Status	Recruitment Start
Denmark	Not yet recruiting	06.04.2026

Trial locations

Investigated drugs:

Pembrolizumab

pembrolizumab: This is an immunotherapy medicine given through a vein. It helps the body’s immune system recognize and attack cancer cells. In this trial, it is being used before surgery or other local treatment to see whether it can shrink or even remove the visible signs of colon cancer, with the goal of helping some patients avoid more extensive surgery if they respond very well.

Investigated diseases:

Colon cancer

Localized mismatch repair deficient colon cancer – A form of colon cancer in which the tumor is limited to the colon and shows deficient DNA repair, a change that can allow cancer cells to grow and spread more easily. It usually develops from abnormal growth in the lining of the colon and may remain confined to one area for a time before extending deeper into the bowel wall or nearby tissues. As it progresses, it can enlarge locally and, in some cases, spread to nearby lymph nodes or other parts of the body.

Trial ID:

2026-525214-62-00

NCT ID:

NCT07409844

Trial Phase:

Therapeutic exploratory (Phase II)

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Pembrolizumab for Patients with Localised dMMR Colon Cancer: Neoadjuvant and Organ-Sparing Treatment Study

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?