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Macular Telangiectasia Type 2 (MacTel)Phase 3SEErineNCT07342439

Study of Serine Supplementation to Protect Vision in MacTel

A Phase 3 study testing L-serine in people with Macular Telangiectasia Type 2 (MacTel), run by The Lowy Medical Research Institute Limited at 12 sites in 5 countries.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts
Official record
Search all trials

Trial summary

The goal of this clinical trial is to look at the efficacy and safety of giving oral serine (an amino acid) on the progression of structural and functional changes of the retina in people with MacTel type 2. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Macular Telangiectasia Type 2 (MacTel)
What is being tested?
L-serine
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
120 participants
Where
12 sitesin 5 countries
Study dates
Sep 2026to Feb 2030
Phase
Phase 3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Be able to read, comprehend, and agree to conditions as explained in the informed consent document and provide written informed consent;
  • Be at least 18 years of age;
  • Enrolled or enrolling in the Natural History Observation and Registry Study (NHOR) and confirmed with MacTel type 2 by the Reading Center in at least one eye*;
  • Participant has clear ocular media (both eyes) for sufficient image quality;
  • Participant must have steady fixation in the foveal or parafoveal area;
  • Female participants of childbearing potential must agree to use a highly effective method of contraception from the time consent is signed until six days after treatment discontinuation (this is due to a lack of safety data on use of L-serine in pregnant and breastfeeding women; and to allow for medication wash out post treatment discontinuation). Highly effective methods of contraception include:
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  • (i)Combined hormonal contraception associated with inhibition of ovulation, (ii) progesterone only hormonal contraception associated with inhibition of ovulation (iii) Intrauterine devices, (iv) surgical sterilization such as bilateral tubal occlusion or vasectomized partner or (v) true abstinence (refraining from heterosexual intercourse during the entire period associated with the study treatments, and the reliability of sexual abstinence is in line with the usual lifestyle of the subject)
  • Willing and able to comply with study protocol and follow-up visits
  • Agree to unconditional use of their donated samples, images and/or data;
  • Be able to fast for at least 10 hours prior to blood specimen collection;
  • Have a minimum area of total EZ loss of 0.16 mm2 in the study eye. The Reading Center will determine the exact size once images are uploaded.
  • Participant has a BCVA of better than or equal to 20/100 Snellen equivalent (>/= 50 letters) using Early Treatment Diabetic Retinopathy Study (ETDRS) charts at a starting distance of 4 meters in the study eye.

Who cannot join

  • Unable to undergo the study procedures or unavailable for follow up visits;
  • Unwilling to agree to blanket consent for use of the acquired data, including human biological specimens and images;
  • Participant is pregnant, breastfeeding or planning a pregnancy during the study time period;
  • Participant has taken serine or glycine supplements in the last 3 months;
  • Participant is currently taking or has been taking Fibrates such as fenofibrate, clofibrate, ciprofibrate, bezafibrate, gemfibrozil within the last 3 months;
  • Participant has known allergy or hypersensitivity to serine or rice;
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  • Participant is currently taking or has been taking tamoxifen, chloroquine (or hydroxychloroquine) and/or other retinotoxic substances; for a total period of 6 months
  • Participant has uncontrolled type 1 or type 2 diabetes (defined as an HbA1c level of 9% or higher at screening (with or without medication);
  • Participant has uncontrolled hypo- or hyperthyroidism, defined as TSH-levels of below 0.4mU/L or above 4.0mU/L at screening with or without treatment;
  • Participant is undergoing chemotherapy, radiation therapy or other treatments for active cancer;
  • Participant has significant kidney disease or an estimated glomerular filtration rate <50 ml/min/1.73m2 at screening;
  • Participant has an active and/ or chronic liver disease (including viral hepatitis, autoimmune liver disease, hemochromatosis, homozygous alpha1-antitrypsin deficiency and Wilson disease, primary biliary cirrhosis, primary sclerosing cholangitis) or poor liver function as estimated by transaminases (ALT/AST) or gamma glutamyl transferase (GGT) or alkaline phosphatase or bilirubin above 2xULN (upper limit of normal) at screening;
  • Participant is currently enrolled in another clinical treatment trial or participated in one within the last 30 days;
  • Participant has previously received a CNTF device ("Encelto"; either eye) or has intentions of receiving a CNTF device in either eye during the duration of this study;
  • Participant shows signs of retinal diseases other than MacTel (including central serous chorioretinopathy, severe non-proliferative or proliferative diabetic retinopathy, diabetic macular edema, age-related macular degeneration, preretinal membrane) that, in the judgment of the investigator, may confound the diagnosis, procedures or outcome of the study (either eye);
  • Participant has a diagnosis of uncontrolled glaucoma with intraocular pressure of >30 mm Hg (despite current pharmacological or non-pharmacological treatment; either eye);
  • Participant has evidence of pathologic myopia in either eye;
  • Participant has significant corneal or media opacities in either eye;
  • Participant has any of the following lens opacities: cortical opacity > standard 3, posterior subcapsular opacity > standard 2, or a nuclear opacity > standard 3 as measured on the Age-Related Eye Disease Study (AREDS) clinical lens grading system (either eye);
  • Participant has undergone lens removal in the previous 3 months or YAG laser within the last 4 weeks, in either eye;
  • Participant has a chronic requirement (eg, ≥ 4 weeks at a time) for ocular medications (vitamins, supplements and artificial tears are permitted) and/or has a diagnosed disease that, in the judgment of the examining physician, may be vision threatening or may affect the primary outcome in the study eye;
  • Participant has had previous ocular treatments that in the judgment of the investigator may complicate the evaluation of the central retina (including vitreo-retinal surgeries, central laser treatments, including central non-damaging retinal laser therapy (either eye); previous peripheral laser treatments or cryotherapy are NOT exclusionary;
  • Participant has ever received any periocular or intravitreal injections (including intravitreal anti-vascular endothelial growth factor (anti-VEGF), periocular or intravitreal corticosteroid injections) in the study eye OR participant has received any periocular or intravitreal injections in the fellow eye within the past 3 months
  • Participant has evidence of previously active or currently active intraretinal neovascularization or subretinal neovascularization (SRNV), in either eye; subretinal or sub-RPE fibrovascular proliferation or disciform scars (subretinal fibrosis) in either eye are exclusionary;
  • Participant has evidence of intraretinal hyperreflectivity** as evaluated by OCT in the study eye;
  • Participant has a full thickness macular hole (FTMH) within the foveal area (ETDRS field 1) with a diameter of >400um at its narrowest point and outer retinal atrophy in the study eye;
  • Amblyopia in the study eye; or
  • Participant is allergic to fluorescein dye, and the clinical site does not have an OCT-A
  • Participant has, in the opinion of the Investigator, any physical or mental condition that would increase the patient's risk of participation in the study or may interfere with the study procedures, evaluations and outcome assessments.

Trial locations and contacts

12 sites in 5 countries. Contact the study team or a site near you to ask about taking part.

12 sites in 5 countries

United States4 sites

  • University of Michigan, Kellogg Eye Center

    Ann Arbor, Michigan, 48105

    Maddie Study Coordinator, 734-936-0138, maboss@med.umich.edu

    Courtney Study Coordinator, 734-936-9798, cosoto@med.umich.edu

  • Retina Associates Of Cleveland, Inc.

    Cleveland, Ohio, 44122

    Diane Study Coordinator, 216-831-5704 ext. 244, dew@retina-assoc.com

    LAWRENCE SINGERMAN, MD

  • Hamilton Glaucoma Center- UCSD

    La Jolla, California, 92093

    Veronica Study Coordinator, 858-822-1896, vrubio@health.ucsd.edu

    Chrisopher Toomey, MD, PhD

  • University of Utah Health Care, Moran Eye Center

    Salt Lake City, Utah, 84132

    Barbara Study Coordinator, 801-581-6459, barbarahart@hsc.utah.edu

    Kimberley Study Coordinator, 858-584-6265, Kimberley.wegner@hsc.utah.edu

Other trials in United States

Germany3 sites

  • University of Bonn

    Bonn, 53127

    Kristin Raming, MD, 49-228-287-5647, Kristin.Raming@ukbonn.de

    Kristina Pfau, MD

  • University of Freiburg, Department of Ophthalmology

    Freiburg im Breisgau, 79106

    Wiebke Study Coordinator, 49-761-270-40231, Wiebke.hoch@uniklinik-freiburg.de

    Christine Study Coordinator, 49-761-270-40237, christine.kremer@uniklinik-freiburg.de

  • St. Franziskus Hospital

    Münster, 48145

    Elke Study Coordinator, 0251-935-2758, elke.attenberger@uveitis-zentrum.de

    Clemens Lange, MD

Other trials in Germany

Australia2 sites

  • Cerulea- RVEEH

    Melbourne, Victoria, 3002

    Carla Study Coordinator, MD, 61-3-9959-0081, cabbott@cera.org.au

    Robyn Guymer, MD

  • Save Sight Institute

    Sydney, New South Wales, 2000

    Emily Study Coordinator, 61-2-9382-7309, emily.luu@sydney.edu.au

    Elisa Cornish, MD

Other trials in Australia

United Kingdom2 sites

  • Moorfields Eye Hospital

    London, EC1V 2PD

    Rabiah Study Coordinator, 02072533411, rabiah.abbassaud@nhs.net

    Cathy Egan, MD

  • Oxford Eye Hospital

    Oxford, OX3 9DU

    Alexina Study Coordinator, 01865 231053, alexina.fantato@ouh.nhs.uk

    Samantha de Silva, MD

Other trials in United Kingdom

Netherlands1 site

  • Radboud University Medical Center

    Nijmegen, 6525GA

    Asha Study Coordinator, 24-36-13212, asha.kalisingh@radboudumc.nl

    Suzanne Yzer, MD

Other trials in Netherlands

About this study

Official title: Phase 3 Study of Serine Supplementation to Protect Vision in MacTel

The goal of this clinical trial is to look at the efficacy and safety of giving oral serine (an amino acid) on the progression of structural and functional changes of the retina in people with MacTel type 2. The main questions it aims to answer are:

  • Does serine slow the progression of MacTel?
  • Is long-term serine supplementation safe in people with MacTel? Researchers will compare serine to a placebo (a look-alike substance that contains no drug) to see if serine works to slow the progression of MacTel.
Read more

Participants will:

  • Take serine or a placebo twice a day for 24 months
  • Visit the clinic once every 6 months for eye exam, eye imaging and blood tests
  • Keep a diary of their symptoms, missed doses, and changes in medications
Read the detailed description

Macular telangiectasia type 2 (MacTel) is a bilateral, slowly progressive retinal neurodegenerative disease characterized by photoreceptor loss, vascular abnormalities, and gradual decline in visual function.

Alterations in serine metabolism and the accumulation of toxic deoxysphingolipids have been implicated in the pathophysiology of MacTel. Oral serine supplementation has been proposed as a potential approach to modify this metabolic pathway and reduce the formation of potentially neurotoxic metabolites.

This study is a randomized, double-masked, placebo-controlled, parallel-group clinical trial designed to evaluate the effect of oral serine supplementation on disease progression in participants with macular telangiectasia type 2.

Participants will undergo a screening evaluation to determine eligibility. Eligible participants will be adults aged 18 years or older with a confirmed diagnosis of MacTel through the Natural History Observation Registry (NHOR) study. Participants must meet all eligibility criteria. Eligibility and assignment of the study eye will be determined by review of the images taken at screening. If both eyes are eligible, both eyes may be included as study eyes. A minimum of 110 participants will complete the study.

At the baseline visit, participants will be randomized in a 1:1 ratio to receive either oral serine or placebo. Randomization will be stratified by diabetes status to ensure balanced distribution of participants with and without type 2 diabetes between treatment groups. Participants, investigators, study staff, and outcome assessors will remain masked to treatment assignment throughout the study.

Participants will receive their assigned study treatment for 24 months. In-person study visits will occur every 6 months, with telephone contacts between visits to assess treatment compliance and adverse events. Retinal structure, visual function, and participant safety will be monitored throughout the 24-month treatment period. A follow-up telephone contact will occur approximately 4 weeks after discontinuation of study treatment.

Data will be collected on both eyes of each participant; however, only eyes designated as study eyes and meeting eligibility criteria will be included in the primary efficacy analysis.

The primary objective of the study is to evaluate the effect of serine supplementation compared with placebo on the progression of photoreceptor loss in MacTel. Secondary objectives include the effect of serine supplementation on further structural retinal changes and visual function as well as the assessment of safety and tolerability of long-term oral serine supplementation in this population.

Being tested
L-serine, Placebo
Keywords
Serine, MacTel

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • L-serineDrug

    L-serine powder administered twice daily

  • PlaceboOther

    Placebo powder administered twice daily

Study groups in NCT07342439
Study groupRoleWhat they receive
L-serineExperimentalParticipant receives oral L-serine
Receives: Drug: L-serine
PlaceboPlacebo comparatorParticipant receives placebo
Receives: Other: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. EZ loss

    Mean rate of change in the total area of EZ loss (IS/OS; macular photoreceptor loss) from Baseline (BL) through Month 24 (M24), as assessed using SD-OCT in the study eye(s).

    Measured: Baseline through Month 24

Secondary outcomes (23)

  1. EZ loss at different time points

    Mean rate of change in the area of EZ loss (IS/OS; macular photoreceptor loss) from BL through Month 12 (M12) in the study eye(s) and through M12 and M24 in the fellow eye, as assessed using SD-OCT

    Measured: Baseline through Month 12 and 24

  2. Changes in Disease Severity

    Changes in disease severity (stages, according to Chew et al) in study eye(s), and fellow eye, from BL to M24

    Measured: Baseline through Month 24

  3. Retinal Sensitivity Loss

    Mean change in retinal sensitivity loss as measured by Macular Integrity Assessment (MAIA) from BL to M24 in study eye(s), and fellow eye

    Measured: Baseline through Month 24

  4. Reading Speed

    Mean change in monocular and binocular reading speed assessed using International Reading Speed Texts (IReST) cards from BL through M24 in the study eye(s), and fellow eye

    Measured: Baseline through Month 24

  5. Contrast Sensitivity

    Mean change in monocular contrast sensitivity from BL to M24 in the study eye(s) and fellow eye as assessed by Pelli-Robson contrast sensitivity charts

    Measured: Baseline through Month 24

  6. Low Luminance Visual Acuity

    Mean change in monocular low luminance visual acuity (LLVA) scores from BL to M24 in the study eye(s) and fellow eye as assessed by ETDRS charts

    Measured: Baseline through Month 24

  7. Low Luminance Deficit

    Mean change in low luminance deficit (LLVA - BCVA) from BL to M24 in the study eye(s) and fellow eye

    Measured: Baseline through Month 24

  8. Best Corrected Visual Acuity

    Mean change in monocular best-corrected visual acuity (BCVA) scores from BL to M24 in the study eye(s) and fellow eye as assessed by Early Treatment Diabetic Retinopathy Study (ETDRS) charts

    Measured: Baseline through Month 24

  9. Corneal Nerve fiber Density

    Mean change in corneal nerve fiber and branch density (biomarkers of peripheral nerve health) from BL to M6, M12, M18 and M24 in the study eye(s) and fellow eye

    Measured: Baseline through Month 6, 12, 18 and 24

  10. HbA1c

    Mean change in HbA1c from BL to M12 and M24

    Measured: Baseline through Months 12 and 24

  11. BMI

    Mean change in BMI (weight and height will be combined to report BMI in kg/m^2) from BL to M12 and M24

    Measured: Baseline through Months 12 and 24

  12. Serum Metabolites

    Mean changes in fasted serum metabolite values from BL to M12 and M24

    Measured: Baseline through Months 12 and 24

  13. MacTel Metabolic Signature

    Mean changes in composite serum metabolic score measuring the global "MacTel Metabolic signature" from BL to M12 and M24

    Measured: Baseline through Months 12 and 24

  14. NEI VFQ-25

    Mean change in NEI VFQ-25 scores from BL to M12 and M24

    Measured: Baseline through Month 12 and 24

  15. VILL-33

    Mean change in VILL-33 scores from BL to M12 and M24

    Measured: Baseline through Months 12 and 24

  16. TEAEs and SAEs

    Incidence of treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), and ocular TEAEs and SAEs

    Measured: Baseline through Month 24

  17. ETDRS Letter Score

    Number of study eyes, fellow eyes with >= 15 letter loss (ETDRS letter score), >= 10 letter loss and >= 5 letter loss from BL to M24

    Measured: Baseline through Month 24

  18. Neovascularization

    Total number of study eyes, fellow eyes showing a de novo development of neovascularization from BL to M24

    Measured: Baseline through Month 24

  19. Outer Retinal Hyper-Reflectivity

    Total number of study eyes, fellow eyes showing a de novo development of outer retinal hyper-reflectivity from BL to M24

    Measured: Baseline through Month 24

  20. Hip to waist ratio

    Mean change in hip-to-waist ratio from BL to M12 and M24

    Measured: Baseline through Months 12 and 24

  21. Lipid Levels

    Mean change in Lipid Levels from BL to M12 and M24

    Measured: Baseline through Months 12 and 24

  22. Corneal Nerve Fiber Length

    Mean change in corneal nerve fiber length (biomarker of peripheral nerve health) from BL to M6, M12, M18 and M24 in the study eye(s) and fellow eye

    Measured: Baseline through Months 6, 12, 18 and 24

  23. Corneal Nerve Fiber Tortuosity

    Mean change in corneal nerve fiber tortuosity (biomarker of peripheral nerve health) from BL to M6, M12, M18 and M24 in the study eye(s) and fellow eye

    Measured: Baseline through Months 6, 12, 18 and 24

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted15 Jan 2026
  2. Study startSep 2026 (estimated)
  3. Primary completionNov 2029 (estimated)
  4. Study completionFeb 2030 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Model description
masked, two-arm, parallel-group, randomized, placebo-controlled trial
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
120 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07342439
Sponsor's protocol ID
2026-001
Acronym
SEErine
Status last verified
Jan 2026
First submitted
7 Jan 2026
Last updated
15 Jan 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing L-serine in people with Macular Telangiectasia Type 2 (MacTel), run by The Lowy Medical Research Institute Limited at 12 sites in 5 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 12 inclusion and 29 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: opening soon, as of the sponsor's last update on 15 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 12 sites in United States, Germany, Australia, United Kingdom, Netherlands. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

EZ loss (time frame: Baseline through Month 24). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07342439.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Jan 2026.

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