Blocking tryptophan breakdown in rectal cancer

Targeting Tryptophan Metabolism in Rectal Cancer

['FUNDING_R01'] · WASHINGTON UNIVERSITY · NIH-11161439

This project tests whether adding a drug that blocks tryptophan metabolism (an IDO1 inhibitor) to short-course radiation helps people with locally advanced rectal cancer have stronger tumor responses.

Quick facts

Phase['FUNDING_R01']
Study typeNih_funding
SexAll
SponsorWASHINGTON UNIVERSITY (nih funded)
Locations1 site (SAINT LOUIS, UNITED STATES)
Trial IDNIH-11161439 on ClinicalTrials.gov

What this research studies

I have locally advanced rectal cancer and my care team uses short-course radiation before surgery. Researchers found radiation makes tumors increase an enzyme called IDO1 that breaks down tryptophan and weakens the immune response. They plan to give an IDO1-blocking drug (epacadostat) with radiation, using patient tumor samples, lab models, and previous early-phase dosing work to see if tumors shrink more and die off faster. The team will also study how blocking tryptophan metabolism affects tumor survival pathways and the immune environment.

Who could benefit from this research

Good fit: Ideal candidates are people with locally advanced rectal cancer receiving neoadjuvant short-course radiation who meet safety criteria for an IDO1 inhibitor.

Not a fit: People with very early-stage disease, those who cannot undergo radiation, or whose tumors do not rely on IDO1-driven resistance are unlikely to benefit.

Why it matters

Potential benefit: If successful, combining an IDO1 inhibitor with radiation could raise complete response rates and reduce the need for extensive surgery or recurrence.

How similar studies have performed: Preclinical models and a Phase I dose-escalation of epacadostat showed tumor-sensitizing effects, but larger clinical trials of IDO1 inhibitors in other cancer settings have had mixed results.

Where this research is happening

SAINT LOUIS, 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: Cancer Center

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.