An observational study in Colorectal Cancer, Colorectal Cancer Metastatic and MSI-H Colorectal Cancer, sponsored by OncoAtlas LLC. Completed at 2 sites in Russia. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-06-27.
Sponsored by OncoAtlas LLC · Observational
Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. Microsatellite instability or mismatch repair deficiency occurs in 20% of CRC, and is predominantly found in non-metastatic tumors. The success of the CheckMate 142 and KEYNOTE-177 clinical trials has shifted the treatment paradigm of the MSI/dMMR CRC, which has led to the adoption of immune checkpoint inhibitors (ICI) by international treatment standards. However, despite the encouraging effects of ICI, up to 30% of patients are resistant to treatment and exhibit rapid disease progression shortly after starting ICI. On the other hand, around 30% of patients treated with ICI demonstrate prolonged responses to the treatment with a duration of response of over 40 months. Furthermore, for \~10% of patients, treatment with ICI results in pseudo-progression - a phenomenon of a short-term increase followed by the decrease of the tumor volume.
Currently, the mechanisms and biomarkers associated with the response or resistance to ICI in MSI-positive CRC are largely unknown. Select studies suggest that BRAF mutations (specifically, BRAF p.V600E) might negatively affect the patients' progression-free survival following ICI, however, these data are premature.
The primary hypothesis is that the clonal heterogeneity and the evolution of MSI status of MSI-positive CRC will play a role in the development of ICI treatment resistance. The primary objective of the study is to investigate the dynamics of MSI status in serial liquid biopsy samples from patients with MSI-positive tumors receiving ICI.
This is a multicenter observational trial designed to evaluate the dynamics of microsatellite instability and the genomic profiles of CRC during immune checkpoint inhibitor treatment.
Patients with MSI/dMMR-positive tumors who are candidates for the ICI treatment will be included in the study. MSI/dMMR positivity should be confirmed with polymerase chain reaction-based (PCR) assays, immunohistochemistry (IHC) or Next-generation sequencing (NGS). Treatment with any ICI will be allowed. Upon inclusion in the study, patients will be asked to provide the pre-treatment FFPE tumor and liquid biopsy (LB) samples along with LB samples on the 14th, 28th days of ICI, and at every control study. LB samples will be collected until treatment discontinuation.
The pre-treatment FFPE samples will be tested with an alternative routine method (PCR and/or IHC, depending on what method was used for initial testing), as well as with the Solo Atlas Pro NGS panel covering common cancer-related genes and short tandem repeats for MSI detection. All LB samples will be tested with the Solo Atlas Pro NGS panel. Dynamics of MSI and genomic profiles will be correlated with the treatment outcomes.
Disease response to study treatment will be evaluated by imaging methods. Response to treatment will be determined by RECIST v1.1.
2,457 studies on the registry are indexed under Colonic Neoplasms; 458 are open to participants now.
This study's enrollment of 30 is below the median of 227 across 555 observational studies indexed under Colonic Neoplasms.
Browse Colonic Neoplasms studies →This is the only study on the registry with OncoAtlas LLC as lead sponsor.
Compared within Colonic Neoplasms, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Colorectal Neoplasms. The counts are of registry records indexed under each term, refreshed daily. How we classify →
Patients with histologically confirmed colorectal cancer with microsatellite instability (MSI) or mismatch repair deficiency (dMMR)
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.
Exclusion Criteria:
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.
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.
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.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
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.
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.
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.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
RECIST
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Concordance of NGS and routine methods (PCR, IHC) for MSI analysis
Concordance will be calculated using Cohen's Kappa (κ)
Time frame: Through study completion, an average of 3 years
Concordance of MSI in tumor tissue and liquid biopsy (ctDNA)
Concordance will be calculated using Cohen's Kappa (κ)
Time frame: Through study completion, an average of 3 years
Qualitative and quantitative status of MSI in serial liquid biopsy (ctDNA) samples
Liquid biopsy samples will be collected prior to the start of ICI, on the 14th and 28th days of therapy and at every follow-up tumor scan
Time frame: Through study completion, an average of 3 years
Correlation of biomarkers with the treatment outcomes
Dynamics of biomarkers in serial liquid biopsy samples will be correlated with treatment outcomes. Response to treatment will be determined by RECIST v1.1.
Time frame: Through study completion, an average of 3 years
Evaluation of the ctDNA dynamics in the course of ICI in serial plasma samples
Dynamics of ctDNA in serial liquid biopsy samples will be correlated with treatment outcomes. Response to treatment will be determined by RECIST v1.1.
Time frame: Through study completion, an average of 3 years
Ran from Jun 2022 to primary completion in Sep 2024, 27 months.
Of 224 observational studies under Colonic Neoplasms, half reached primary completion within 50 months of starting (the median), counting those still running; a quarter within 24 and three quarters within 116. This study's 27 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Jun 2025. You cannot join it, but the record below documents what was studied.
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