Observational Study of Adults and Adolescents With Erythropoietic Protoporphyria (EPP) and X-linked Porphyria (XLP) (stEPP)

April 28, 2026 updated by: Portal Therapeutics, Inc.

Prospective Clinical Assessment Study in Adolescents and Adults With Erythropoietic Protoporphyria (EPP) and X-Linked Porphyria (XLP) (STEPP)

The purpose of this study is to collect information about the effects of EPP/XLP in adults and adolescents. This is an observational study in which participants will not receive any treatment. Study details include:

  • The study duration will be up to 6 months for each participant.
  • After Screening, participants will have a Baseline (Day 1) visit and return for visits every 4 weeks through 24 weeks.
  • Assessments to evaluate EPP/XLP will include clinical laboratory tests, physical exams, vital signs measurement, blood draws for PPIX concentration, reporting of EPP/XLP-related symptoms (including completion of a daily diary), light dosimetry.

Study Overview

Status

Recruiting

Conditions

Study Type

Observational

Enrollment (Estimated)

50

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Belgium
      • Leuven, Belgium
  • Canada
  • France
      • Bordeaux, France
        • Not yet recruiting
        • Centre Hospitalier Universitaire de Bordeaux - Hopital Saint - Andre
        • Contact:
      • Paris, France
        • Not yet recruiting
        • AP-HP Hopital Bichat - Claude Bernard
        • Contact:
  • Italy
      • Milan, Italy
        • Not yet recruiting
        • Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico di Milano
        • Contact:
      • Modena, Italy
        • Not yet recruiting
        • Azienda Ospedaliero-Universitaria di Modena
        • Contact:
  • Norway
      • Bergen, Norway
        • Not yet recruiting
        • Haukeland University Hospital
        • Contact:
  • Spain
      • Madrid, Spain
        • Recruiting
        • Hospital Universitario 12 de Octubre
        • Contact:
      • Valencia, Spain
        • Not yet recruiting
        • Consorcio Hospital General Universitario de Valencia
        • Contact:
  • Turkey (Türkiye)
      • Ankara, Turkey (Türkiye)
        • Not yet recruiting
        • Gazi University Faculty of Medicine
        • Contact:
  • United Kingdom
      • Cardiff, United Kingdom
        • Recruiting
        • University Hospital of Wales
        • Contact:
      • Dundee, United Kingdom
      • London, United Kingdom
      • Manchester, United Kingdom
  • United States
    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Recruiting
        • Massachusetts General Hospital
        • Contact:
    • New York
      • New York, New York, United States, 10029
        • Recruiting
        • Mount Sinai School of Medicine
        • Contact:
    • North Carolina
      • Wake Forest, North Carolina, United States, 27587
        • Recruiting
        • Wake Forest University Baptist Health - Dept of Gastroenterology
        • Contact:
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19121
    • Texas
      • Houston, Texas, United States, 77030
        • Recruiting
        • University of Texas Health - Ertan Digestive Disease Center
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

The study design and key inclusion criteria are focused on EPP/XLP and are inclusive of all potential participants, including those from underrepresented racial and ethnic populations. The sites and countries selected have diverse populations and the potential to enroll diverse participants.

Description

Inclusion Criteria:

  1. Aged 12 years and older.

  2. Confirmed diagnosis of EPP or XLP as follows:

    1. Genetic confirmation of EPP (FECH mutation with reduced ferrochelatase activity) OR
    2. Genetic confirmation of XLP (ALAS2 gain-of-function mutation) OR
    3. Elevated free PPIX levels in RBCs consistent with EPP/XLP, supported by clinical and/or family history.
  3. Currently has symptoms of EPP/XLP.
  4. History of consistent, non-painful prodrome within approximately 45 minutes of sunlight exposure and prior to phototoxic attacks, as self-reported by the participant.
  5. Willing and able to wear a light dosimetry device during the study.
  6. Willing and able to complete a daily diary of EPP/XLP symptoms.
  7. Willing and able to keep skin sites chosen for provocative sunlight exposure testing covered by opaque material when outside or exposed to potentially triggering light beginning 2 days prior to testing.
  8. Willing and able to provide informed consent and/or assent for the study.
  9. Study participants and LAR (as appropriate) are willing and able to comply with study visits and study procedures.

Exclusion Criteria:

  1. Diagnosis of another porphyria or another photodermatosis that may confound the characterization of EPP/XLP.
  2. Has a clinically significant disease or condition that, at the discretion of the Investigator or Sponsor, would interfere with the evaluation of EPP/XLP or study participation, or would make study participation not in the best interest of the participant.
  3. Is taking, or has taken within 60 days of Day 1, any medication, vitamin, or supplement that alters sensitivity to light exposure (eg, afamelanotide, melanotan, beta carotene, dersimelagon, or bitopertin).
  4. Concurrent or anticipated participation in an interventional clinical trial during the study period.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Plasma Protoporphyrin IX (PPIX) Levels Over Time
Time Frame: Screening; Baseline; Weeks 4, 8, 12, 16, 20, 24
Plasma protoporphyrin IX (PPIX) concentrations measured at specified study visits.
Screening; Baseline; Weeks 4, 8, 12, 16, 20, 24
Clinical History of Phototoxic Symptoms and Prodrome Timing
Time Frame: Screening, Baseline, Weeks 4, 8, 12, 16, 20, 24
Medical history of EPP/XLP symptoms, including time to onset of prodromal sensations and occurrence of phototoxic reactions.
Screening, Baseline, Weeks 4, 8, 12, 16, 20, 24
Skin Damage Manifestations
Time Frame: Screening, Baseline, Weeks 4, 8, 12, 16, 20, 24
Skin damage manifestations associated with EPP/XLP, including swelling, erythema, and chronic skin changes.
Screening, Baseline, Weeks 4, 8, 12, 16, 20, 24
Light Exposure and Phototoxic Reaction Data From Daily Diary
Time Frame: Screening, Baseline, Weeks 4, 8, 12, 16, 20, 24
Daily recorded light exposure (including time spent outdoors), light dosimetry measurements, and occurrence of phototoxic reactions as captured in participant diaries.
Screening, Baseline, Weeks 4, 8, 12, 16, 20, 24
Sunlight Exposure Required to Induce Prodromal Symptoms
Time Frame: Baseline and Weeks 4, 8, 12, 16, 20
Amount of sunlight exposure associated with onset of prodromal symptoms, along with corresponding plasma protoporphyrin IX (PPIX) levels.
Baseline and Weeks 4, 8, 12, 16, 20

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Liver Function Test Results
Time Frame: Baseline and Weeks 4, 8, 12, 16, 20, 24
Blood levels of liver function parameters (e.g., alanine aminotransferase [ALT], aspartate aminotransferase [AST], bilirubin) and corresponding plasma protoporphyrin IX (PPIX) levels.
Baseline and Weeks 4, 8, 12, 16, 20, 24

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Portal Therapeutics, Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

April 30, 2026

Primary Completion (Estimated)

March 1, 2027

Study Completion (Estimated)

April 1, 2027

Study Registration Dates

First Submitted

April 15, 2026

First Submitted That Met QC Criteria

April 28, 2026

First Posted (Actual)

May 5, 2026

Study Record Updates

Last Update Posted (Actual)

May 5, 2026

Last Update Submitted That Met QC Criteria

April 28, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • PORT-77-001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

What may be shared:

De-identified individual participant data (no direct identifiers)

Who can access it:

Qualified researchers with a scientifically sound research proposal

Conditions for access:

Submission and approval of a research proposal Execution of a data sharing agreement (DSA) Compliance with privacy regulations (e.g., GDPR, HIPAA as applicable)

How it will be shared:

Through a secure data access process managed by the sponsor or designated data-sharing platform

Timing:

Typically after study completion and/or publication of primary results

Purpose:

To support further research on EPP and XLP while protecting participant confidentiality

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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