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Efficacy and Safety of Intravitreal MK-8748 Compared with Aflibercept in Adults with Diabetic Macular Edema

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What is this trial about?

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

Diabetic macular edema is a condition where fluid builds up in the central part of the retina in people with diabetes, causing vision to become blurry or distorted. The study compares two medicines that are injected directly into the eye (intravitreal). One medicine is a new experimental drug called MK-8748, which is a type of laboratory‑made protein that targets signals that cause blood vessels to leak. The other medicine is an already approved drug called aflibercept, which also works by blocking similar signals.

The aim of the study is to find out whether MK-8748 works as well as or better than aflibercept in improving vision. Participants will receive a series of eye injections over about a year, with regular visits to check safety and how the eyes are responding. Vision will be measured using a standard eye chart test that records the number of letters a person can read (ETDRS letters), reported as a change in Best-Corrected Visual Acuity (BCVA) from the start of the study.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and Randomization

    After giving informed consent, you are assigned at random to receive either MK-8748 or aflibercept for the treatment of diabetic macular edema (DME).

    The assignment is kept unknown to you and the study staff who assess outcomes, ensuring a double‑masked design.

  2. Step 2

    Baseline Assessments

    A series of eye examinations are performed, including measurement of best‑corrected visual acuity (the sharpest vision you can achieve with glasses or contacts) using the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart.

    Imaging of the retina is done to document the extent of swelling caused by DME.

  3. Step 3

    First Intravitreal Injection

    You receive an intravitreal injection (a tiny amount of medication placed directly into the eye).

    If you are in the MK-8748 group, the injection contains a solution for injection of the study drug; if you are in the aflibercept group, the injection contains 2 mg of aflibercept.

    The injection is performed under sterile conditions by a qualified ophthalmologist.

  4. Step 4

    Monthly Follow‑Up Visits and Injections

    You return to the clinic approximately every four weeks (weeks 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, and 52).

    At each visit, your visual acuity is measured again, and the eye is examined for safety and effectiveness.

    An additional intravitreal injection of the same medication you received at the first visit is administered according to the study schedule.

  5. Step 5

    Mid‑Study Assessment

    At week 48, a detailed assessment of your visual acuity is performed. This measurement is one of the two values used to determine the primary outcome of the study.

  6. Step 6

    End‑of‑Year Assessment and Study Completion

    At week 52, a final set of examinations is carried out, including another visual acuity test and safety checks.

    The results from week 48 and week 52 are averaged to evaluate the change in vision from the start of the study.

    After the week‑52 visit, no further study‑specific procedures are required.

Who can join the trial?

6 criteria

  • You must have either Type 1 diabetes or Type 2 diabetes, and your recent blood‑sugar test called hemoglobin A1c (HbA1c) must be 12% or lower (this test shows how well your blood sugar has been controlled over the past few months).
  • You must have a loss of vision in the eye being studied that the doctor believes is mainly caused by diabetic macular edema (DME) (swelling in the central part of the retina due to diabetes).
  • If you have never been treated for DME before (called treatment‑naïve), your DME diagnosis must have been made within the last 9 months before the screening visit.
  • If you have received treatment for DME before, the first treatment must have been given no more than 3 years before the screening visit.
  • You can be either male or female.
  • You must be an adult (generally age 18 years or older).

Who cannot join the trial?

9 criteria

  • Has had renal failure (kidneys not working properly) that needed a renal transplant (kidney transplant), hemodialysis (machine that cleans blood), or peritoneal dialysis (fluid‑based blood cleaning), or is expected to need dialysis during the study.
  • Has a history of stroke (a “brain attack” where blood flow stops) or myocardial infarction (a heart attack) within the past 180 days (about 6 months) before the first dose.
  • Has newly diagnosed or previously untreated diabetes mellitus (high blood sugar disease) and started oral pills or injectable medicines to lower sugar within the past 3 months (about 90 days) before the first dose.
  • Has had cataract surgery (operation to remove a cloudy lens) and/or minimally invasive glaucoma surgery (small procedure to lower eye pressure) in the study eye within the past 90 days.
  • Has received treatment for cataract‑surgery complications using steroids (anti‑inflammatory medicines) or a YAG laser capsulotomy (laser to clear cloudiness after cataract surgery) in the study eye within the past 90 days.
  • Has advanced (severe) or uncontrolled glaucoma (eye disease with high pressure that can damage the optic nerve) in the study eye.
  • Has any history of retinal detachment (the light‑sensing layer of the eye pulling away) or has had treatment or surgery for it in the study eye.
  • Has an active retinal disease (any problem affecting the retina) in the study eye that is not the condition being studied.
  • Has uncontrolled blood pressure (high blood pressure that is not under control) at the screening visit.
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Investigated drugs

  • MK-8748

    is a laboratory‑made antibody that targets two proteins involved in eye blood‑vessel problems: the receptor for angiopoietin‑1 and vascular endothelial growth factor‑A (VEGF‑A). By blocking these signals, the drug aims to reduce swelling and fluid leakage in the retina of people with diabetic macular edema. In the study it is given as a sterile solution that is injected directly into the eye.

  • Aflibercept

    is a medicine that works by binding to VEGF and related growth factors, stopping them from stimulating abnormal blood‑vessel growth and leakage in the retina. It is used to treat diabetic macular edema and is administered as an injection into the eye. The trial compares its effects with those of MK‑8748.

What is already known about the treatment

  • MK-8748

    This investigational drug is given as a sterile solution for injection directly into the eye (intravitreal injection). It is currently in Phase 3 clinical trials and not yet approved for routine medical use. The medication is being studied for the treatment of diabetic macular edema, a condition that causes swelling in the central part of the retina. It works by attaching to the angiopoietin‑1 receptor and to vascular endothelial growth factor‑A, blocking signals that make blood vessels leak, and it is classified as a recombinant fusion protein with anti‑angiogenic activity.

  • Aflibercept

    Aflibercept is administered as a sterile solution for intravitreal injection, typically 2 mg per dose. It is an approved medicine that has been widely used for several years in eye care. The drug is indicated for diabetic macular edema as well as other retinal diseases that cause fluid buildup. It acts by binding to VEGF‑A, VEGF‑B and placental growth factor, preventing these proteins from stimulating abnormal blood vessel growth, and it is classified as a VEGF‑trap biologic agent.

Investigated diseases

Diabetic macular edema - Diabetic macular edema is a condition in which fluid builds up in the central part of the retina (the macula) due to leakage from damaged blood vessels caused by diabetes. The swelling can cause the retina to thicken and distort vision. Over time, the fluid may increase, leading to a gradual loss of sharp central vision. The condition often progresses slowly, with changes that can be detected during eye examinations. If left unchecked, the swelling can become more extensive and affect daily activities such as reading and recognizing faces.
Trial detailsLast updated 13 Nov 2026
Age18+ yearsPhasePhase IIITrial ID2026-526790-42-01Protocol codeMK-8748-004Estimated enrolment824 patientsSponsorMerck Sharp & Dohme LLC

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