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Evaluating dostarlimab for resectable colon cancer

A Phase 3, Open-Label, Randomized Study of Perioperative Dostarlimab Monotherapy Versus Standard of Care in Participants With Untreated T4N0 or Stage III dMMR/MSI-H Resectable Colon Cancer

PHASE3 · GlaxoSmithKline · NCT05855200

This study is testing if adding a new immunotherapy called dostarlimab to standard chemotherapy can help people with certain types of resectable colon cancer do better.

Quick facts

PhasePHASE3
Study typeInterventional
Enrollment892 (estimated)
Ages18 Years and up
SexAll
SponsorGlaxoSmithKline (industry)
Drugs / interventionsdostarlimab, chemotherapy, immunotherapy, radiation
Locations266 sites (Tucson, Arizona and 265 other locations)
Trial IDNCT05855200 on ClinicalTrials.gov

What this trial studies

This study aims to assess the effectiveness of perioperative dostarlimab compared to standard care in patients with untreated T4N0 or Stage III resectable colon cancer that exhibits defective mismatch repair or high microsatellite instability. Participants will receive dostarlimab alongside standard chemotherapy regimens, CAPEOX or FOLFOX, to determine if this immunotherapy can improve outcomes. The study focuses on patients with specific tumor characteristics and aims to provide a new treatment option for this patient population.

Who should consider this trial

Good fit: Ideal candidates are individuals with untreated, resectable T4N0 or Stage III colon adenocarcinoma that is dMMR or MSI-H.

Not a fit: Patients with distant metastatic disease or those who have previously received treatment for colon cancer are unlikely to benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could offer a new effective option for patients with a specific type of colon cancer, potentially improving their prognosis.

How similar studies have performed: Other studies have shown promising results with immunotherapy approaches in similar cancer types, indicating potential for success in this novel application.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Has untreated pathologically confirmed colon adenocarcinoma
* Has resectable colon adenocarcinoma defined as clinically T4N0 or Stage III
* Has radiologically evaluable disease
* Has a tumor demonstrating the presence of either dMMR status or MSI-H

Exclusion Criteria:

* Has distant metastatic disease.
* Has received prior medical therapy (chemotherapy, immunotherapy, biologic, or targeted therapy), radiation therapy or surgery for management of the current diagnosis of colon cancer
* Has a tumor that, in the investigator's judgment is causing symptomatic bowel obstruction or otherwise requires urgent/emergent surgery at the time of screening. Participants with a history of colonic obstruction are eligible after obstruction is relieved by a diverting stoma (defunctioning ileostomy or colostomy). Patients with a history of colonic obstruction in the context of current colon cancer diagnosis and treated with colonic stents are not eligible.
* Has undergone any major surgical procedure, open biopsy, or experienced significant traumatic injury within 28 days prior to randomization
* Has any history of interstitial lung disease or pneumonitis and/or history of radiation induced enteritis.
* Has cirrhosis or current unstable liver or biliary disease per investigator assessment defined by the presence of ascites, encephalopathy, coagulopathy, hypoalbuminemia, esophageal/gastric varices, or persistent jaundice
* Has a history of allogenic stem cell transplantation or organ transplantation
* Is receiving any other anticancer or experimental therapy. No other experimental therapies (including but not limited to chemotherapy, radiation, hormonal treatment, antibody therapy, immunotherapy, gene therapy, vaccine therapy, or other experimental drugs) of any kind are permitted while the participant is receiving study intervention
* Is pregnant, breastfeeding, or expecting to conceive children within the projected duration of the study
* Has a history of severe allergic and/or anaphylactic reactions to chimeric, human or humanized antibodies, fusion proteins, or known allergies to dostarlimab, or its excipients, or any components of FOLFOX or CAPEOX

Where this trial is running

Tucson, Arizona and 265 other locations

+216 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Colonic Neoplasms, Neoplasms, Colon, JEMPERLI, Dostarlimab, dostarlimab-gxly, TSR-042, GSK4057190A, FOLFOX

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.