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Study of bitopertin to improve sunlight tolerance in adults with erythropoietic protoporphyria or X-linked protoporphyria

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on two rare genetic conditions: Erythropoietic Protoporphyria (EPP) and X-Linked Protoporphyria (XLP). These disorders cause extreme sensitivity to sunlight, where exposure can lead to painful skin reactions. The study will test a medication called Bitopertin, given as a film-coated tablet that patients take by mouth.

The purpose of this research is to determine if Bitopertin can help patients spend more time in sunlight without experiencing pain and reduce certain harmful substances in their blood. The study will compare Bitopertin against a placebo to evaluate how well it works and how safe it is for patients with these conditions.

During the six-month study, participants will take either Bitopertin or placebo tablets daily. They will keep track of their time spent in sunlight and any skin reactions they experience. Regular blood tests will be performed to measure changes in blood components related to their condition. The study will monitor how well patients tolerate the medication and any side effects that may occur.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial screening period

    Your eligibility will be assessed based on medical criteria including EPP or XLP diagnosis confirmation through genetic testing or biochemical analysis.

    Basic health measurements will be taken, including body weight (minimum 32 kg for ages 12-17) or BMI (minimum 18.5 for adults).

    Laboratory tests will check your liver function and other health indicators.

    If applicable, you must complete a 2-month washout period from certain medications (afamelanotide and dersimelagon).

  2. Step 2

    Treatment period start

    You will receive either bitopertin tablets or placebo (inactive tablets that look identical).

    The treatment will continue for 6 months (24 weeks).

    You will need to take the medication orally as prescribed.

  3. Step 3

    Sun exposure monitoring

    You will keep a daily record of your sun exposure between 10:00 AM and 6:00 PM.

    You will note any phototoxic reactions (pain or discomfort caused by sun exposure).

    You will record when you first experience symptoms like burning, tingling, itching, or stinging during sun exposure.

  4. Step 4

    Medical monitoring

    Your blood will be tested to measure protoporphyrin IX (PPIX) levels.

    Any side effects or health changes will be monitored and recorded.

    Regular laboratory tests will be conducted to ensure your safety.

  5. Step 5

    Study completion

    Final assessments will be conducted after the 6-month treatment period.

    Your sun exposure tolerance and blood PPIX levels will be evaluated.

    All adverse events and laboratory results will be reviewed.

Who can join the trial?

10 criteria

  • Must be 12 years of age or older when consenting to participate in the study
  • Must have a confirmed diagnosis of EPP or XLP (rare genetic conditions affecting how the body processes substances called porphyrins) through genetic testing or blood analysis
  • Must maintain at least 85% compliance with completing a daily Sun Exposure Diary during the screening period
  • Must meet minimum weight requirements: - For ages 12-17: at least 32 kg - For ages 18 and above: body mass index of at least 18.5 kg/m²
  • Must not have used medications called afamelanotide or dersimelagon for at least 2 months before screening
  • Must have liver function tests within specified limits: - Liver enzymes less than 3 times the normal upper limit - Bilirubin less than 2 times the normal upper limit - Normal albumin levels
  • Must be willing to use effective birth control methods during the study and for 30 days after the last dose (applies to both males with partners who can become pregnant and females who can become pregnant)
  • Females who can become pregnant must have negative pregnancy tests during screening and before starting treatment
  • Must be able to understand study requirements and provide written informed consent
  • Must be able to follow all study procedures

Who cannot join the trial?

15 criteria

  • History of severe allergic reactions to medications or other substances
  • Pregnant women or those planning pregnancy during the study period
  • Currently breastfeeding mothers
  • Participation in another clinical trial within the past 30 days
  • Significant liver problems or abnormal liver function tests
  • Significant kidney problems or abnormal kidney function tests
  • Uncontrolled medical conditions like high blood pressure or diabetes
  • History of skin cancer or current suspicious skin lesions
  • Current use of medications that increase sensitivity to sunlight
  • Inability to follow study procedures or attend scheduled visits
  • History of substance abuse within the past year
  • Mental health conditions that could interfere with study participation
  • Major surgery planned during the study period
  • Blood disorders other than EPP or XLP
  • Current active infections or diseases that could affect study results
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Investigated drugs

Bitopertin is a medication being studied to help people with rare conditions called Erythropoietic Protoporphyria (EPP) and X-Linked Protoporphyria (XLP). These conditions make people extremely sensitive to sunlight, causing painful reactions when exposed to sun. The medication aims to increase patients' ability to tolerate sunlight without pain and reduce levels of a substance called protoporphyrin IX in their blood. It is taken as an oral medication that may help patients spend more time outdoors without experiencing painful symptoms.

What is already known about the treatment

Bitopertin - An investigational oral medication being studied in clinical trials for the treatment of Erythropoietic Protoporphyria (EPP) and X-Linked Protoporphyria (XLP), rare genetic conditions that cause severe pain and burning sensation when skin is exposed to sunlight. The drug works by modulating glycine transport at the molecular level, which may help reduce the accumulation of protoporphyrin IX in blood and skin, potentially increasing patients' tolerance to sunlight exposure. Currently undergoing controlled clinical trials to evaluate its efficacy, safety, and tolerability, bitopertin represents a novel therapeutic approach in the pharmacological class of glycine reuptake inhibitors.

Investigated diseases

  • Erythropoietic Protoporphyria (EPP)

    A rare genetic condition that causes extreme sensitivity to sunlight and visible light. People with EPP experience intense burning pain, tingling, and stinging when their skin is exposed to sunlight. The condition is caused by a build-up of protoporphyrin IX in the blood and tissues. Symptoms typically begin in early childhood and can significantly affect daily activities that involve exposure to light. The pain can persist for hours or days after sun exposure.

  • X-Linked Protoporphyria (XLP)

    A rare genetic disorder that causes severe sensitivity to sunlight, similar to EPP but with a different genetic cause. The condition results from mutations in a specific gene on the X chromosome, leading to increased levels of protoporphyrin IX in the blood. Affected individuals experience painful burning sensations when exposed to sunlight or bright light. Symptoms usually appear in early childhood and can significantly impact outdoor activities.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-520407-27-00Protocol codeDISC-1459-301Estimated enrolment150 patientsSponsorDisc Medicine Inc.

sourced from the EU Clinical Trials Register and site verification

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