Observational Study of Adults and Adolescents With Erythropoietic Protoporphyria (EPP) and X-linked Porphyria (XLP)
Prospective Clinical Assessment Study in Adolescents and Adults With Erythropoietic Protoporphyria (EPP) and X-Linked Porphyria (XLP) (STEPP)
Portal Therapeutics, Inc.
50 participants
Apr 30, 2026
OBSERVATIONAL
Conditions
Summary
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.
Eligibility
Inclusion Criteria12
- Aged 12 years and older.
- Confirmed diagnosis of EPP or XLP as follows:
- Genetic confirmation of EPP (FECH mutation with reduced ferrochelatase activity) OR
- Genetic confirmation of XLP (ALAS2 gain-of-function mutation) OR
- Elevated free PPIX levels in RBCs consistent with EPP/XLP, supported by clinical and/or family history.
- Currently has symptoms of EPP/XLP.
- History of consistent, non-painful prodrome within approximately 45 minutes of sunlight exposure and prior to phototoxic attacks, as self-reported by the participant.
- Willing and able to wear a light dosimetry device during the study.
- Willing and able to complete a daily diary of EPP/XLP symptoms.
- 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.
- Willing and able to provide informed consent and/or assent for the study.
- Study participants and LAR (as appropriate) are willing and able to comply with study visits and study procedures.
Exclusion Criteria4
- Diagnosis of another porphyria or another photodermatosis that may confound the characterization of EPP/XLP.
- 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.
- 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).
- Concurrent or anticipated participation in an interventional clinical trial during the study period.
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Locations(19)
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NCT07567131