Phase II Study of Neoadjuvant Dostarlimab in Patients With Untreated T3-4N0-2 or Stage III pMMR/MSS Resectable Colon Cancer

Dostarlimab belongs to a class of drugs called PD-1 inhibitors that use your own immune system to treat cancer (immunotherapy). It is designed to stop cancer from growing by helping your immune system recognize and fight the cancer. This investigational medicinal product (IMP) has been approved by the Belgian authorities, but not for the treatment of colon cancer. It is known that a small number of patients with pMMR/MSS colon cancer may have significant response to medication of this type (immunotherapy) depending on each person's biology. Trial intervention for all patients will be neo-adjuvant dostarlimab 500 mg IV, given alone by intravenous infusion. Two administrations of dostarlimab are foreseen, at three weeks interval, before surgery for your colon cancer. It has not yet been proven that this treatment can cure, improve or stabilise your disease or condition. The study aims to investigate specific molecular changes in tumour and blood after dostarlimab monotherapy administered and before surgery which could be associated with improved response to conventional treatment in some patients. If you decide to participate, as the duration of treatment with dostarlimab is 6 weeks, surgery may be slightly delayed compared to patients that are not treated with dostarlimab and go directly for surgery. It remains uncertain if this is beneficial in your personal situation but some patients might experience significant response. The risks have been carefully assessed and the potential benefits for some patients are considered important and justify undertaking the treatment. Subsequent therapy after surgery remains at the discretion of the treating physician. The duration of a patient on trial will last up to 4 months from the first dose of dostarlimab and afterwards 2 years of follow up is applicable.

NCT Number	NCT06830239
Lead Sponsor	Universitaire Ziekenhuizen KU Leuven
Conditions	Colon Cancer Stage III
Enrollment	10 participants
Start Date	2025-04-03
Primary Completion	2027-12 (estimated)
Study Completion	2028-12 (estimated)
Updated on ClinicalTrials.gov	2026-02-12