An observational study in Quality of Life (QOL), Mismatch Repair Deficient Colorectal Cancer and Microsatellite Instability-High Colorectal Cancer, sponsored by University Hospital, Basel, Switzerland. Recruiting at 3 sites in Switzerland. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-18.
Sponsored by University Hospital, Basel, Switzerland · Observational
Among 90 studies in Colorectal Neoplasms with a site in Switzerland — 13 open to participants now, 18 under way, 4 of them phase 3. Colorectal Neoplasms · Switzerland.
Among the 90 studies in Colorectal Neoplasms with a site in Switzerland, this one is the 10th largest by planned enrollment of the 16 observational ones, is one of 2 that started in 2026, is one of 16 observational ones, reaches primary completion later than 17 of the 17 other live ones, and was the 90th registered.
6,541 studies on the registry are indexed under Colorectal Neoplasms; 1,667 are open to participants now.
This study's planned enrollment of 234 is close to the median of 250 across 1,440 observational studies indexed under Colorectal Neoplasms.
Browse Colorectal Neoplasms studies →13 of the 90 studies in Colorectal Neoplasms with a site in Switzerland are open now, in 12 countries. Each count lists the studies.
Of the 1,185 Colorectal Neoplasms studies recruiting now, 769 (65%) set no upper age limit and 265 (22%) stop at 75 or younger; 48 take children under 18; 123 take healthy volunteers.
This study: 18 Years and older · all sexes · no healthy volunteers.
The full table on the hub →90 studies; the count open now beside each. This study's row is marked.
First in 1993; this study’s year is marked. 2 started in 2026.
Median enrollment 160 across the 71 interventional studies, 378 across the 16 observational. Of the 63 that completed or were terminated, 19 (30%) have results posted.
45 of 90 have an industry lead sponsor. The 10 most frequent:
University Hospital, Basel, Switzerland is the lead sponsor of 990 studies on the registry; 189 are open to participants now.
University Hospital, Basel, Switzerland has 4 studies filed under Colorectal Neoplasms — fewer than ten, so there is no comparison to draw.
3 of the studies in Colorectal Neoplasms with a site in Switzerland that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT05748145Oncology Institute of Southern SwitzerlandMetronidazole as Preoperative Therapy in CRC / FusoMetro-001 | 2026-12-31 |
| NCT05176483ExelixisStudy of Zanzalintinib in Combination With Immuno-Oncology or Other Agents in Participants With Solid Tumors | 2027-01-31 |
| NCT05489211AstraZenecaStudy of Dato-DXd as Monotherapy and in Combination With Anti-cancer Agents in Patients With Advanced Solid Tumours (TROPION-PanTumor03) | 2027-10-01 |
Among the 90 studies in Colorectal Neoplasms with a site in Switzerland, from their registry updates:
This cohort study is divided into two parts:
Part A: Registry Cohort All patients with non-metastatic, MMRd/MSI-H colorectal cancers (and other gastrointestinal cancers for exploratory analysis) who have signed the general research consent will be included in a prospective registry. This includes patients who undergo primary surgical resection (+/- neoadjuvant/adjuvant therapy) or following immunotherapy, regardless of response.
Part A is a multicenter observational registry with both prospective and retrospective enrolment. Prospective enrolment includes eligible patients entered into the registry after activation of the study at the respective participating site. Retrospective enrolment includes eligible patients diagnosed on or after 1 January 2024 whose clinical data were generated prior to registry activation. Both prospectively and retrospectively enrolled patients contribute to the registry analyses.
Part B: Active Surveillance Cohort (Surveillance Study) A subset of patients from Part A who achieve a complete or near-complete response to ICI therapy, wish to avoid surgery, and are deemed appropriate for non-operative management by a multidisciplinary tumor board are offered inclusion in a phase II surveillance study (Part B). Patients enrolled in Part B will be analysed for the primary endpoint.
Background and Rationale: Mismatch repair-deficient (MMRd) or microsatellite instability-high (MSI-H) gastrointestinal (GI) cancers represent a distinct molecular subtype characterized by high tumor mutational burden and increased immunogenicity. Immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy in this population, with recent studies showing high rates of pathological complete response (pCR) when used in the neoadjuvant setting for non-metastatic GI cancers and colorectal cancers in particular. These results raise important questions about the necessity of surgical resection in patients who achieve complete clinical response (cCR) after ICI therapy.
Avoiding surgery in patients with complete response through an active surveillance approach could significantly reduce treatment-related morbidity and improve quality of life for selected patients. However, this strategy remains investigational and robust clinical evidence is lacking regarding its safety, long-term oncologic outcomes and appropriate selection criteria. Our study seeks to address this gap by evaluating response-guided, non-operative management in patients with non-metastatic MMRd/ MSI-H GI tumors treated primarily with immunotherapy.
Objectives: The primary objective of this study is to evaluate 2-year relapse-free survival (RFS) in patients with non-metastatic, mismatch repair-deficient (MMRd) or microsatellite instability-high (MSI-H) in patients with stage II/III colorectal cancer who achieve a complete or near-complete response following primary treatment with immune checkpoint inhibitors (ICIs) who enter Part B of the study (surveillance study).
Method: Eligible patients may receive immune checkpoint inhibitor (ICI) therapy as the primary treatment for mismatch repair-deficient (MMRd) or microsatellite instability-high (MSI-H), locally advanced, non-metastatic gastrointestinal cancer according to local practice. Treatment regimens include PD-(L)1 monotherapy (e.g., pembrolizumab, atezolizumab) or combination ICI therapy (e.g., nivolumab plus ipilimumab), administered at the discretion of the treating oncologist for up to 6 months (in case of near complete response ICI may be continued up to a total of 12 months following multidisciplinary evaluation).
Patients who do not achieve a complete or near-complete clinical response-or who are not eligible or not willing to undergo non-operative management-proceed to standard oncological surgery (with or without neo-/adjuvant systemic therapy), in accordance with clinical guidelines. Postoperatively, they receive routine oncological follow-up per institutional standards and remain in registry cohort (Part A).
Patients who demonstrate a complete or near-complete clinical response to ICI and are considered eligible for non-surgical management (based on multidisciplinary evaluation), enter an intensified surveillance program in lieu of immediate surgery (Part B).
The active surveillance includes Clinical assessments, Cross-sectional imaging (e.g., CT or MRI) , Endoscopic evaluations at defined intervals and Facultative ctDNA testing 6 months after completion of immunotherapy (Part B)
The study population includes adult patients with non-metastatic MSI-H/MMRd gastrointestinal cancers, specifically colorectal (colon and rectal) cancer as well as gastro-oesophageal and gastric adenocarcinoma. Eligible participants must have achieved a complete or near-complete clinical response following immune checkpoint inhibitor therapy, with no radiologic, endoscopic, or histologic evidence of residual disease at the time of response assessment. Patients are enrolled into a structured active surveillance program instead of undergoing immediate surgical resection. Individuals with metastatic disease, insufficient response to immunotherapy or contraindications to surveillance procedures are excluded.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Part A and Part B:
Part B only:
Clinical parameters (e.g., normalization of tumor markers, absence of symptoms **)
Note: in case of near complete response up to a total of 12 months of ICI is allowed following multidisciplinary team (MDT) discussion. After diagnosis of a near-complete response, tumor reassessments should be performed every 3 months up to a total treatment period of 12 months. If a complete tumor response is observed within the 12-month period, it should be recorded as the best overall response.
Exclusion Criteria:
Part B only:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
PD-1, PD-L1 and checkpoint inhibitors
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants with mismatch repair-deficient (MMRd) or microsatellite instability-high (MSI-H) stage II/III gastrointestinal cancer who achieve a complete or near-complete response after immune checkpoint inhibitor (ICI) therapy enter a structured active surveillance program instead of undergoing immediate surgery. Surveillance includes scheduled radiologic imaging, endoscopic evaluation, clinical assessment, and biomarker monitoring to detect relapse early and allow timely salvage treatment.
Other: Active surveillance after complete response to immunotherapy in MMRd GI cancers
Patients that receive an operation to remove the primary tumour after completion of immunecheckpoint therapy for MSI high colorectal cancer (resp. other MSI high GI cancer).
Other: Stand of Care
Eligible patients may receive immune checkpoint inhibitor (ICI) therapy as the primary treatment for mismatch repair-deficient (MMRd) or microsatellite instability-high (MSI-H), locally advanced, non-metastatic gastrointestinal cancer according to local practice. In case of near complete response ICI may be continued up to a total of 12 months following multidisciplinary evaluation. Part A includes all patients with stage II or III colorectal cancer (esophageal adenocarcinoma, gastric cancer will be allowed as well) confirmed as MMRd/MSI-H. Patients are enrolled regardless of treatment strategy, including those receiving immune checkpoint inhibitor (ICI) therapy or primary surgery. A subset of patients from Part A who achieve a complete or near-complete response to ICI therapy, wish to avoid surgery, and are deemed appropriate for non-operative management by a multidisciplinary tumor board are offered inclusion in a phase II active surveillance protocol (Part B).
Also known as: watch and wait
Patients in the Standard of care Arm (Arm A) will receive a resection of the primary tumour after completion of the immunecheckpoint inhibition therapy.
Relapse-Free Survival (RFS)
The proportion of patients with colorectal cancers who remain free from local, regional, or distant recurrence at 24 months after achieving a complete or near-complete clinical response to immune checkpoint inhibitor therapy and undergoing active surveillance. Recurrence is defined as radiologic, endoscopic, or histologic evidence of tumor regrowth requiring salvage surgery or systemic treatment.
Time frame: 24 months
Relapse-Free Survival - other GI Cancers
applied to patients with non-metastatic MMRd/MSI-H gastroesophageal or other GI cancers entering active surveillance.
Time frame: 24 months
Clinical Complete Response (cCR) Rate
Proportion of patients achieving clinical complete response, near-complete response, partial response, stable disease, or progressive disease following ICI therapy, assessed by radiologic, endoscopic, clinical criteria, and biopsy results.
Time frame: 12 months
Plan to share: No
No publications or documents are linked to this record.
Started Sep 2026 (actual). Primary completion is estimated for Aug 2033, 83 months after the start.
Of 528 non-industry observational studies under Colorectal Neoplasms, half reached primary completion within 56 months of starting (the median), counting those still running; a quarter within 27 and three quarters within 132. This study's planned 83 months is above that.
Counting every sponsor, half of 645 studies reached it within 51 months; a quarter within 27 and three quarters within 104.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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University Hospital, Basel, Switzerland →