Trial results for the Phase 2 study (NCT03595683) investigating pembrolizumab and EDP1503 in participants with advanced melanoma were posted on ClinicalTrials.gov on 2025-12-08. The study was terminated and reported 0 participants achieving a response in both the anti-PD1 naive and anti-PD1 refractory cohorts.
Background
The study aimed to determine if orally administered EDP1503 could enhance the response to standard immunotherapy treatment with pembrolizumab in participants diagnosed with advanced melanoma.
Trial design
The Phase 2 study (NCT03595683) was titled "Pembrolizumab and EDP1503 in Advanced Melanoma" and was terminated. It enrolled 8 participants with melanoma. The study investigated the combination of pembrolizumab and EDP1503, with an initial EDP1503 run-in period followed by administration of both drugs. Participants were divided into two cohorts: anti-PD1 naive and anti-PD1 refractory. Mandatory biopsies were required before starting study treatment and after two weeks of EDP1503 dosing.
Key results
The trial results reported on ClinicalTrials.gov included the following measurements:
- For "Response Rate":
- In Cohort 1: Anti-PD1 Naive, the number of participants with a response was 0.
- In Cohort 2: Anti-PD1 Refractory, the number of participants with a response was 0.
- For "Progression Free Survival (PFS)":
- In Cohort 1: Anti-PD1 Naive, the median PFS was 8.6 months (Standard Error: 0.5).
- In Cohort 2: Anti-PD1 Refractory, the median PFS was 2.7 months (Standard Error: 0.7).
- Regarding "Number of Participants With EPD1503 Related Adverse Events During the Run in Period":
- In Cohort 1: Anti-PD1 Naive, 0 participants experienced such events.
- In Cohort 2: Anti-PD1 Refractory, 0 participants experienced such events.
- Regarding "Number of Participants With Treatment Related Adverse Events During Combination Therapy":
- In Cohort 1: Anti-PD1 Naive, 1 participant experienced such events.
- In Cohort 2: Anti-PD1 Refractory, 0 participants experienced such events.
What this means
The termination of this Phase 2 study and the reported lack of responses in both cohorts suggest that the combination of pembrolizumab and EDP1503 did not demonstrate the desired efficacy in participants with advanced melanoma under the study conditions. While Progression Free Survival data was collected, the absence of responses indicates that the primary objective of enhancing immunotherapy response was not met. The low number of participants experiencing adverse events during the run-in and combination therapy periods suggests a generally tolerable safety profile for the limited number of participants enrolled.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT03595683, titled "Pembrolizumab and EDP1503 in Advanced Melanoma," were posted on 2025-12-08 on clinicaltrials.gov.