The proposed proof-of concept trial aims at determining the effectiveness of metronidazole in decreasing the Fusobacterium nucleatum load in tissues and possibly on its detrimental effects on tumor cells and tumor microenvironment.
Colorectal cancer (CRC) is among the most frequent tumor types and is a leading cause of cancer-related death worldwide. Surgery represents the first therapeutic option, whereas advanced cases are usually treated by established chemotherapy protocols, yet with variable response rates. Mechanisms underlying unresponsiveness are still largely unclear. Recently, the gut microbiota, consisting of trillions of microorganisms, which populate the gastrointestinal tract, has also been implicated in chemo-resistance. Defined bacterial species have been reported to be associated with CRC. In particular, Fusobacterium nucleatum (F.n.), a commensal bacterium of the oral cavity, is enriched in CRC tissues and its abundance appears to be associated with reduced patient survival. In experimental models F.n. promotes CRC cell proliferation and reduces tumor responsiveness to 5-fluorouracil (5-FU). Furthermore, it suppresses tumor infiltration by immune cells associated with improved prognosis. Administration of metronidazole effectively reduces F.n. load and overall tumor growth in animal models. However, its efficacy in reducing F.n. loads in human CRC has not been verified so far. The proposed proof-of concept trial aims at determining the effectiveness of metronidazole in decreasing the F.n. load in tissues and possibly on its detrimental effects on tumor cells and tumor microenvironment.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
OTHER
Masking
NONE
Enrollment
40
Metronidazole will be administered per os at 500 mg x 3/day, for 10 days prior to surgery.
Oncology Institute of Southern Switzerland
Bellinzona, Canton Ticino, Switzerland
RECRUITINGImpact of metronidazole on F.n. loads in CRC tissues.
F.n. load assessed by qRT-PCR analysis in excised tumor tissues upon antibiotic treatment, as compared to corresponding diagnostic biopsies prior to treatment.
Time frame: 12 (+ 3) days after surgery
Potential effects of metronidazole on the expression of immune cell markers in CRC tissue samples
Expression of multiple immune cell markers will be assessed in tissue samples by immunohistochemistry and immunofluorescence. Number of positive cells/mm2 will be evaluated.
Time frame: 12 (+ 3) days after surgery
Potential effects of metronidazole on the expression of autophagy markers in CRC tissue samples
Expression of multiple autophagy signaling elements will be assessed in tissue samples by immunohistochemistry and immunofluorescence. Number of positive cells/mm2 will be evaluated.
Time frame: 12 (+ 3) days after surgery
Potential effects of metronidazole on microbiome
Differences in community diversity and/or abundance of specific bacterial taxa between the tumor-associated microbiome prior to or after antibiotic treatment.
Time frame: 12 (+ 3) days after surgery
Potential effects of metronidazole on the intestinal metabolic profile
Measurement of changes in the biosynthesis pathways of intestinal bacteria by comparing the gut metabolic profile before and after antibiotic treatment. Fold changes in the abundance of bacterial metabolites will be evaluated.
Time frame: 12 (+ 3) days after surgery
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