Trial Outcomes & Findings for Pembrolizumab and EDP1503 in Advanced Melanoma (NCT NCT03595683)

NCT ID: NCT03595683

Last Updated: 2025-12-08

Results Overview

For Cohort 1, based on deep response (\>80% tumor reduction). Assessed by standard RECIST criteria for Cohort 2 (complete + partial response).

• Recruitment status: TERMINATED
• Study phase: PHASE2
• Target enrollment: 8 participants
• Primary outcome timeframe: 2 years
• Results posted on: 2025-12-08

Participant Flow

Between 2018 and 2020 a total of 10 patients signed study consent from two sites. Two patients failed screening and the remaining 8 enrolled and underwent study treatment. Study was closed early due to EDP1503 no longer being manufactured.

Participant milestones

Measure	Cohort 1: Anti-PD1 Naive Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Overall Study STARTED	3	5
Overall Study Run-in Phase	3	5
Overall Study Combination Phase	0	1
Overall Study COMPLETED	0	1
Overall Study NOT COMPLETED	3	4

Reasons for withdrawal

Measure	Cohort 1: Anti-PD1 Naive Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Overall Study Adverse Event	1	0
Overall Study Pursue alternative therapy	1	1
Overall Study Progressive disease	1	3

Baseline Characteristics

Pembrolizumab and EDP1503 in Advanced Melanoma

Baseline characteristics by cohort

Measure	Cohort 1: Anti-PD1 Naive n=3 Participants Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory n=5 Participants Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Total n=8 Participants Total of all reporting groups
Age, Continuous	70 years n=37 Participants	59 years n=37 Participants	63 years n=74 Participants
Sex: Female, Male Female	2 Participants n=37 Participants	4 Participants n=37 Participants	6 Participants n=74 Participants
Sex: Female, Male Male	1 Participants n=37 Participants	1 Participants n=37 Participants	2 Participants n=74 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	0 Participants n=37 Participants	0 Participants n=37 Participants	0 Participants n=74 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	1 Participants n=37 Participants	3 Participants n=37 Participants	4 Participants n=74 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	2 Participants n=37 Participants	2 Participants n=37 Participants	4 Participants n=74 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=37 Participants	0 Participants n=37 Participants	0 Participants n=74 Participants
Race (NIH/OMB) Asian	0 Participants n=37 Participants	0 Participants n=37 Participants	0 Participants n=74 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=37 Participants	0 Participants n=37 Participants	0 Participants n=74 Participants
Race (NIH/OMB) Black or African American	0 Participants n=37 Participants	0 Participants n=37 Participants	0 Participants n=74 Participants
Race (NIH/OMB) White	3 Participants n=37 Participants	5 Participants n=37 Participants	8 Participants n=74 Participants
Race (NIH/OMB) More than one race	0 Participants n=37 Participants	0 Participants n=37 Participants	0 Participants n=74 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=37 Participants	0 Participants n=37 Participants	0 Participants n=74 Participants
Region of Enrollment United States	3 participants n=37 Participants	5 participants n=37 Participants	8 participants n=74 Participants

PRIMARY outcome

Timeframe: 2 years

For Cohort 1, based on deep response (>80% tumor reduction). Assessed by standard RECIST criteria for Cohort 2 (complete + partial response).

Outcome measures

Measure	Cohort 1: Anti-PD1 Naive n=3 Participants Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory n=5 Participants Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Response Rate	0 Participants	0 Participants

PRIMARY outcome

Timeframe: 2 weeks

Assessed by CTCAE v4.0, grade 3 or higher

Outcome measures

Measure	Cohort 1: Anti-PD1 Naive n=3 Participants Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory n=5 Participants Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Number of Participants With EPD1503 Related Adverse Events During the Run in Period	0 Participants	0 Participants

SECONDARY outcome

Timeframe: 2 years

Time from first dose of either drug until disease progression or death from any cause. Surviving subjects without progression will be censored as of the date of the last negative examination. Estimated using the Kaplan-Meier method

Outcome measures

Measure	Cohort 1: Anti-PD1 Naive n=3 Participants Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory n=5 Participants Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Progression Free Survival (PFS)	8.6 months Standard Error 0.5	2.7 months Standard Error 0.7

SECONDARY outcome

Timeframe: 2 years

Assessed by CTCAE v4.0, grade 3 or higher

Outcome measures

Measure	Cohort 1: Anti-PD1 Naive n=3 Participants Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory n=5 Participants Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Number of Participants With Treatment Related Adverse Events During Combination Therapy	1 Participants	0 Participants

Adverse Events

Cohort 1: Anti-PD1 Naive

Serious events: 1 serious events

Other events: 3 other events

Deaths: 1 deaths

Cohort 2: Anti-PD1 Refractory

Serious events: 1 serious events

Other events: 3 other events

Deaths: 3 deaths

Serious adverse events

Measure	Cohort 1: Anti-PD1 Naive n=3 participants at risk Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory n=5 participants at risk Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Infections and infestations Sepsis	0.00% 0/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	20.0% 1/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Gastrointestinal disorders Pancreatitis	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Investigations Lipase increased	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
General disorders Fatigue	0.00% 0/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	20.0% 1/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Metabolism and nutrition disorders Dehydration	0.00% 0/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	20.0% 1/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.

Other adverse events

Measure	Cohort 1: Anti-PD1 Naive n=3 participants at risk Participants that have not received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).	Cohort 2: Anti-PD1 Refractory n=5 participants at risk Participants that have received prior anti-PD1 therapy for their cancer will be enrolled to this arm. Pembrolizumab: 200 mg given by intravenous (IV) infusion once every 3 weeks. EDP1503: Taken by mouth twice daily. Each capsule will contain ≥ 7.5x10\^10 colony-forming units (CFU).
Skin and subcutaneous tissue disorders Rash	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	40.0% 2/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
General disorders Fatigue	100.0% 3/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Skin and subcutaneous tissue disorders Pruritus	0.00% 0/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	40.0% 2/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Gastrointestinal disorders Abdominal pain	0.00% 0/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	20.0% 1/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Musculoskeletal and connective tissue disorders Arthralgia	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Vascular disorders Hot flashes	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Nervous system disorders Peripheral sensory neuropathy	0.00% 0/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	20.0% 1/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Investigations Alanine aminotransferase increased	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Metabolism and nutrition disorders Hypocalcemia	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	20.0% 1/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Metabolism and nutrition disorders Hypokalemia	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Investigations Platelet count decreased	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Investigations Serum amylase increased	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Investigations Elevated TSH	33.3% 1/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	0.00% 0/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.
Injury, poisoning and procedural complications Bruising	0.00% 0/3 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.	20.0% 1/5 • 2 years All serious adverse events are reported and other adverse events related to treatment were collected and reported here.

Additional Information

Dr. Randy Sweis

University of Chicago

Phone: 773-834-3094

Email: rsweis@uchicago.edu

Results disclosure agreements

• Principal investigator is a sponsor employee
• Publication restrictions are in place