Gut Microbiome in Colorectal Cancer

This is a pilot feasibility study designed to investigate the alterations in the gut microbiome that occur during the course of treatment for colorectal cancer (CRC). Three patient cohorts will be followed. Cohort A: patients treated with oral fluoropyrimidine CAP as part of standard of care (SOC) chemotherapy. Cohort B: patients treated with TAS-102 including those receiving it in combination with Y-90 radioembolization as part of a clinical trial. Cohort C: patients receiving CAP plus immunotherapy (pembrolizumab) and bevacizumab as part of a clinical trial. Investigators will replace participants as needed to ensure a minimum of 10 evaluable participants per cohort (or minimum total of 30 evaluable patients). Evaluable participants are defined as patients with two analyzable stool samples including a baseline sample and at least one on-treatment sample to be used in endpoint analysis

Inclusion criteria

• The patient has histologically proven colorectal adenocarcinoma
• The patient is starting treatment with oral fluoropyrimidine therapy: CAP or TAS-102 as SOC or on a clinical trial. This also includes those patients receiving treatment in the adjuvant setting or post-metastasectomy with no evidence of disease on imaging.
• Combination of oral fluoropyrimidine with other cancer-directed therapies, including oxaliplatin, bevacizumab, Y-90 radioembolization, or immunotherapy checkpoint inhibitors, is permitted.
• Combination of CAP with concurrent radiation is permitted, including patients undergoing radiotherapy to a rectal primary or a metastatic site.
• Male or female patient aged 18 years of age or older at the time of obtaining the signed and dated informed consent (no upper age limit).
• Be able to read and speak English.
• Be willing and able to provide written informed consent for the study

Exclusion criteria

• Patient has had prior chemotherapy, biologic or immunotherapy in the previous 2 weeks.
• Patient has completed a course of antibiotics longer than 2 weeks in preceding six months or a course of antibiotics of any duration in the 4 weeks prior to starting oral chemotherapy. Any patient who requires treatment with antibiotics during the study may be removed at the investigator's discretion.
• Known HIV positive.