An observational study in Metastatic Colorectal Cancer (CRC), sponsored by Barretos Cancer Hospital. Active, not recruiting at 1 site in Brazil. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-04.
Sponsored by Barretos Cancer Hospital · Observational
This retrospective observational cohort study investigates the association between the intratumoral burden of the bacterium Fusobacterium nucleatum (Fn) and the efficacy of anti-EGFR targeted therapies (cetuximab or panitumumab) in patients with RAS wild-type metastatic colorectal cancer (mCRC). Bacterial quantification will be performed using droplet digital polymerase chain reaction (ddPCR) on formalin-fixed, paraffin-embedded (FFPE) tissue samples, comprising an estimated cohort of 500 patients.
RAS wild-type colorectal cancer is frequently treated with anti-EGFR monoclonal antibodies; however, primary and acquired resistance rates remain a major limitation to clinical outcomes. Recent evidence suggests that Fusobacterium nucleatum colonization acts as a resistance factor to conventional chemotherapy through the induction of autophagy. This project aims to address the current scientific gap regarding the impact of this bacterium on the response to EGFR inhibitors. The study includes absolute quantification of bacterial 16S ribosomal RNA by droplet digital polymerase chain reaction (ddPCR) and its association with clinicopathological variables, overall survival, progression-free survival, and molecular profile (BRAF, TP53, PIK3CA, and MSI). Additionally, in an exploratory approach, the study will perform a comparative investigation of microbial colonization dynamics between primary tumor sites and their corresponding metastatic lesions using paired tissue samples.
6,541 studies on the registry are indexed under Colorectal Neoplasms; 1,667 are open to participants now.
This study's planned enrollment of 500 is above the median of 250 across 1,440 observational studies indexed under Colorectal Neoplasms.
Browse Colorectal Neoplasms studies →Barretos Cancer Hospital is the lead sponsor of 49 studies on the registry; 5 are open to participants now.
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The study population consists of patients diagnosed with metastatic (Stage IV) colorectal adenocarcinoma who received at least one cycle of anti-EGFR therapy (Cetuximab or Panitumumab) between January 2016 and December 2022 at the Hospital de Amor (Barretos, SP, Brazil). Eligible patients must have formalin-fixed paraffin-embedded (FFPE) tumor tissue samples available in the institutional biobank for molecular analysis. Patients with primary tumors outside the colon or rectum, non-adenocarcinoma histology, or with activating mutations in KRAS, NRAS, or BRAF (unless anti-EGFR was used in combination with BRAF inhibitors) 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.
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.
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.
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
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.
Line of therapy
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients with intratumoral Fusobacterium nucleatum burden above the median.
Patients with intratumoral Fusobacterium nucleatum burden less than or equal to the median, or with undetectable infection
Objective Response Rate (ORR)
Proportion of patients who achieved complete or partial response as assessed according to standardized RECIST 1.1 criteria.
Time frame: From the date of first anti-EGFR administration until disease progression, assessed up to 186 months
Overall Survival (OS)
Time elapsed from diagnosis to death from any cause
Time frame: From the date of initial anti-EGFR therapy administration to the date of death from any cause, with a maximum follow-up assessment of up to 186 months.
Progression-Free Survival (PFS).
Time elapsed from treatment initiation (for each line of therapy) to radiological disease progression or death.
Time frame: From the date of initial anti-EGFR therapy administration to the date of first documented radiological disease progression, with a maximum follow-up assessment of up to 186 months
F. nucleatum Load by Tumor Topography and Paired Metastases, Assessed by ddPCR
Analyses will be stratified according to the location of the primary tumor (right-sided colon, left-sided colon, and rectum). In paired samples, the Fusobacterium nucleatum burden will be compared between biopsies from the primary tumor and the corresponding metastatic lesion.
Time frame: Up to 186 months.
Survival Outcomes by Treatment Line (Kaplan-Meier)
Survival distributions are estimated using the Kaplan-Meier method to evaluate the variation in clinical outcomes (OS and PFS) stratified according to the treatment line in which anti-EGFR therapy was administered (first-line versus subsequent lines)
Time frame: From the date of initial anti-EGFR therapy administration, with a maximum follow-up assessment of up to 186 months
OS and PFS Stratified by Age (Kaplan-Meier Method)
Association between the predictive value of Fusobacterium nucleatum and age at diagnosis (early-onset colorectal cancer, \<50 years, versus late-onset colorectal cancer, ≥50 years).
Time frame: From the date of initial anti-EGFR therapy administration, with a maximum follow-up assessment of up to 186 months
OS and PFS Stratified by Antibiotic Use (Kaplan-Meier Method)
Impact of systemic antibiotic therapy administered during anti-EGFR treatment on OS and PFS, adjusted for baseline intratumoral Fusobacterium nucleatum burden.
Time frame: "From the date of initial anti-EGFR therapy administration, with a maximum follow-up assessment of up to 186 months
F. nucleatum Load by Tumor Mutational Profile, Assessed by ddPCR
Independent predictive correlation between Fusobacterium nucleatum burden and the tumor mutational profile (BRAF, PIK3CA, TP53) as well as microsatellite instability (MSI)
Time frame: Up to 186 months
This study is active, not recruiting, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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Barretos Cancer Hospital