Gut bacteria boosts cancer drug? early trial hints at possibility

NCT ID NCT03595683

Terminated Disease control Sponsor: University of Chicago Source: ClinicalTrials.gov ↗

First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study tested whether taking a pill containing gut bacteria (EDP1503) could help the immunotherapy drug pembrolizumab (Keytruda) work better in people with advanced melanoma. The trial included two groups: those who had never received anti-PD1 therapy and those whose cancer had stopped responding to it. Only 8 people enrolled before the study was stopped early, so the results are very limited.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: pembrolizumab (Keytruda) and EDP1503 (a gut bacteria pill)
What this could lead to: If it works, this could point toward a way to make standard immunotherapy more effective for advanced melanoma by using gut bacteria.
What could go wrong: This was a very small, early-phase study that was terminated early, so results are limited. It is unclear if the combination is safe or effective, and it may not work for everyone.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

melanoma metastatic melanoma

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

MELANOMA MELANOMA (SKIN)

Contacts and locations

Locations

University of Chicago Medical Center

Chicago, Illinois, 60637, United States

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