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Diabetic Macular EdemaPhase 2ANNCT05727891

Evaluation of Tonabersat for DME

A Phase 2 study testing Tonabersat in people with Diabetic Macular Edema, run by Jaeb Center for Health Research at 28 sites in United States.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This randomized clinical trial will evaluate the effect of tonabersat compared with placebo on central subfield thickness (CST) in eyes with center-involved diabetic macular edema (CI-DME) and good visual acuity. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Diabetic Macular Edema
What is being tested?
Tonabersat
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
128 participants
Where
28 sitesUnited States
Study dates
2 May 2023to Jan 2026
Phase
Phase 2
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

  • Adults with type 1 or 2 diabetes mellitus
  • At least one eye with:
  • Best corrected E-ETDRS visual acuity letter score ≥ 74 (i.e., 20/32 or better)
  • Ophthalmoscopic evidence of center-involved DME in study eye confirmed by central subfield thickness on spectral domain OCT
  • Zeiss Cirrus: ≥ 290 µm in females, ≥ 305 µm in males
  • Heidelberg Spectralis: ≥ 305 µm in females, ≥ 320 µm in males
  • Recruitment will be monitored with a goal to have equal proportions in the following categories above the CI-DME thresholds: <75 μm, 75 μm to <175 μm, ≥175 μm
  • Media clarity, pupillary dilation, and study participant cooperation sufficient for adequate OCT

Who cannot join

  • Macular edema is considered to be due to a cause other than DME
  • Major ocular surgery within prior 4 months, or anticipated after randomization
  • History of focal/grid laser or other ocular surgical, intravitreal, or peribulbar treatment for DR or DME within prior 1 year, and no more than 4 anti-VEGF injections within prior 3 years
  • Anticipated need to treat DME or DR during the first 6 months, or anticipated need for cataract surgery during study period
  • Any history of vitrectomy
  • Systemic anti-VEGF or pro-VEGF treatment within 12 months prior to randomization
  • History of chronic renal failure requiring dialysis or kidney transplant
  • History of moderate to severe hepatic impairment, including known liver function test (LFT) values > 3x's the upper limit of normal

Trial locations and contacts

28 sites in 1 country.

28 sites in 1 country

United States28 sites

  • Southeast Retina Center

    Augusta, Georgia, 30909

  • Elman Retina Group

    Baltimore, Maryland, 21237

  • Retina Consultants of Texas, PA

    Bellaire, Texas, 77401

  • Boston Medical Center Corporation

    Boston, Massachusetts, 02118

  • Joslin Diabetes Center

    Boston, Massachusetts, 02215

  • Verum Research LLC

    Eugene, Oregon, 97401

  • National Ophthalmic Research Institute

    Fort Myers, Florida, 33912

  • Hilton Head Retina Institute

    Hilton Head Island, South Carolina, 29926

  • Retina Associates of Southern California

    Huntington Beach, California, 92647

  • Midwest Eye Institute

    Indianapolis, Indiana, 46290

  • University of Florida- Jacksonville

    Jacksonville, Florida, 32209

  • Central Florida Retina Institute

    Lakeland, Florida, 33805

  • Florida Retina Consultants

    Lakeland, Florida, 33805

  • Retina-Vitreous Surgeons of Central NY, PC

    Liverpool, New York, 13088

  • Loma Linda University

    Loma Linda, California, 92354

  • Texas Retina Associates

    Lubbock, Texas, 79424

  • Illinois Retina Associates

    Oak Park, Illinois, 60304

  • East Bay Retina Consultants, Inc.

    Oakland, California, 94609

  • Southern California Desert Retina Consultants, Inc.

    Palm Desert, California, 92211

  • The Trustees of the University of Pennsylvania

    Philadelphia, Pennsylvania, 19104

  • Southeast Eye Institute, P.A. dba Eye Associates of Pinellas

    Pinellas Park, Florida, 33782

  • Mayo Clinic

    Rochester, Minnesota, 55905

  • Retinal Consultants of Texas

    San Antonio, Texas, 78240

  • Thomas Eye Group

    Sandy Springs, Georgia, 30328

  • Pittsburg Clinical Trial Consortium

    Sewickley, Pennsylvania, 15143

  • Retina Research Institute, LLC

    St Louis, Missouri, 63128

  • Macula Retina Vitreous Institute

    Torrance, California, 90503

  • Joseph E. Humble and Raymond Haik PTRS DBA Eye Assoc of Northeast Louisiana

    West Monroe, Louisiana, 71291

Other trials in United States

About this study

Official title: A Phase 2 Evaluation of Tonabersat for Diabetic Macular Edema (Protocol AN)

This randomized clinical trial will evaluate the effect of tonabersat compared with placebo on central subfield thickness (CST) in eyes with center-involved diabetic macular edema (CI-DME) and good visual acuity.

Read the detailed description

The primary objective is to assess the effects of tonabersat, an orally administered Connexin43 hemichannel inhibitor, on central subfield thickness (mean change) compared with placebo in eyes with CI-DME and good visual acuity at 6 months.

Exploratory objectives will evaluate biomarkers of kidney function for potential benefit. Furthermore, this phase 2 study is being conducted to determine whether the conduct of a phase 3 trial has merit and provide information on outcome measures needed to design a phase 3 trial.

Being tested
Tonabersat, Placebo

What participants receive

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

  • TonabersatDrug

    Two pills of Study Drug (80 mg tonabersat) is taken orally once daily. It is recommended the Study Drug be taken at bedtime. The first dose (two pills) will be taken at bedtime on the day the participant is randomized.

  • PlaceboOther

    Two pills of Study Drug (placebo) is taken orally once daily. It is recommended the Study Drug be taken at bedtime. The first dose (two pills) will be taken at bedtime on the day the participant is randomized.

Study groups in NCT05727891
Study groupRoleWhat they receive
PlaceboPlacebo comparatorNot described
Receives: Other: Placebo
Tonabersat (80 mg)Active comparatorNot described
Receives: Drug: Tonabersat

What is being measured

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

  1. Mean change in central subfield thickness

    Measured: 6 months

Secondary outcomes (4)

  1. Mean change in retinal volume from baseline

    Measured: 6 months

  2. Percentage of eyes central subfield thickness below optical coherence machine- and sex-specific threshold for DME and at least a 10% decrease from baseline

    Composite outcome, gender-specific spectral domain optical coherence tomography equivalent of 250 µm on Zeiss Stratus optical coherence tomography

    Measured: 6 months

  3. Mean change in visual acuity from baseline

    Measured: 6 months

  4. Percentage of eyes receiving other treatment for DME prior to the 6 month visit

    Measured: 6 months

Timeline

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

  1. First posted14 Feb 2023
  2. Study start2 May 2023
  3. Primary completion27 Jun 2025
  4. Study completionJan 2026 (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 2
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Model description
Randomized, double-masked, placebo-controlled clinical trial
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
128 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05727891
Sponsor's protocol ID
DRCR Protocol AN
Other IDs
UG1EY014231
Acronym
AN
Status last verified
Dec 2025
First submitted
6 Feb 2023
Last updated
11 Dec 2025
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 2 study testing Tonabersat in people with Diabetic Macular Edema, run by Jaeb Center for Health Research at 28 sites in United States.

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 8 inclusion and 8 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: under way, not looking for participants, as of the sponsor's last update on 11 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 28 sites in United States. 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 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

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?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Mean change in central subfield thickness (time frame: 6 months). 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 NCT05727891.

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 11 Dec 2025.

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