How gut bacteria change common chemotherapy drugs

Metabolism of cancer chemotherapeutics by the human gut microbiome

['FUNDING_R01'] · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · NIH-11212154

This work looks at whether gut bacteria alter how fluoropyrimidine drugs like 5-FU and capecitabine work or cause side effects for people treated for colorectal cancer.

Quick facts

Phase['FUNDING_R01']
Study typeNih_funding
SexAll
SponsorUNIVERSITY OF CALIFORNIA, SAN FRANCISCO (nih funded)
Locations1 site (SAN FRANCISCO, UNITED STATES)
Trial IDNIH-11212154 on ClinicalTrials.gov

What this research studies

Researchers will examine how human gut bacteria and the genes they carry chemically modify 5-fluorouracil (5-FU) and its prodrug capecitabine using lab-based biochemical tests. They will introduce defined human gut microbes into germ-free (gnotobiotic) mice and use mice bearing human tumor grafts to measure drug levels, tumor response, and toxicity. The team will identify the specific bacterial species and enzymes responsible, with a focus on the Anaerostipes genus suggested by preliminary data. Results aim to link bacterial metabolism to differences in drug absorption and effectiveness.

Who could benefit from this research

Good fit: People with colorectal cancer receiving or about to receive 5-FU or capecitabine are the patients most likely to benefit from the findings.

Not a fit: Patients whose cancers are not treated with fluoropyrimidines or whose care is unrelated to gut microbiome effects are unlikely to get direct benefit from this work.

Why it matters

Potential benefit: If successful, this work could help predict who will respond to fluoropyrimidine chemotherapy and lead to microbiome-based strategies to reduce side effects and improve effectiveness.

How similar studies have performed: Some prior human and animal studies have linked gut bacteria to chemotherapy effects, but detailed mechanistic and preclinical mouse data remain limited, so this work builds on suggestive preliminary findings.

Where this research is happening

SAN FRANCISCO, UNITED STATES

Researchers

About this research

  1. This is an active NIH-funded research project — typically early-stage science, not a clinical trial accepting patient enrollment.
  2. Some NIH-funded labs run parallel clinical studies or seek volunteers for related work. To check, contact the principal investigator or institution listed above.
  3. For full project details, budget, and progress reports, visit the official NIH RePORTER page below.

View on NIH RePORTER →

Conditions: Anti-Cancer Agents

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.