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A Phase 2a Study Evaluating the Efficacy and Safety of MK-8690 in Adults with Moderately to Severely Active Ulcerative Colitis

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What is this trial about?

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

The trial focuses on adults who have moderate to severe ulcerative colitis, a condition that causes long‑lasting inflammation and ulcers in the colon, leading to frequent diarrhea, abdominal pain, and bleeding. Participants will receive either the investigational medicine MK-8690, given as a subcutaneous injection, or a placebo. The purpose of the study is to evaluate the efficacy and safety of MK-8690 compared with placebo in this patient group.

During the study, volunteers will attend regular clinic visits over about 12 weeks. At each visit, doctors will check how the disease is doing using a scoring system called the Modified Mayo Score, which looks at symptoms, a visual exam of the colon (called an endoscopic exam), and lab results. A “clinical remission” means the person’s symptoms have become minimal or disappeared, while a “clinical response” means the symptoms have improved but may not be completely gone. An “endoscopic improvement” indicates that the lining of the colon looks better when viewed with a camera, and “histologic” improvement means that tissue samples show less inflammation under a microscope. Safety will be monitored by recording any side effects and noting if anyone stops the treatment because of them.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and consent

    After joining the study, a written consent form is signed to confirm understanding of the trial requirements.

    Baseline health information and medical history are recorded.

  2. Step 2

    Baseline assessments

    Initial examinations include physical measurements, laboratory tests, and endoscopic evaluation of the colon.

    The modified mayo score, which measures ulcerative colitis activity, is calculated.

  3. Step 3

    Randomization to treatment group

    Participants are assigned, by a computer system, to receive either mk-8690 or a placebo without knowing which one is administered.

    The assignment is double‑blind, meaning neither the participant nor the study staff knows the group assignment.

  4. Step 4

    Medication administration

    The study drug is given by subcutaneous injection, which means the medication is injected into the tissue under the skin.

    The injection contains a solution with a concentration of 00 % (v/v) of mk-8690 for participants in the active group; the placebo injection contains no active substance.

    The specific schedule (how often the injection is given) and the total duration are defined by the study protocol and continue until the assessment at week 12.

  5. Step 5

    Regular study visits and monitoring

    Participants attend scheduled clinic visits for safety checks, laboratory tests, and symptom review.

    Any adverse events, which are unwanted medical occurrences, are recorded at each visit.

    The study staff may perform additional endoscopic examinations as required by the protocol.

  6. Step 6

    Mid‑study assessment (optional)

    If the protocol includes an interim evaluation, participants may undergo a brief assessment of disease activity before the final visit.

  7. Step 7

    Final assessment at week 12

    At the end of the 12‑week treatment period, a comprehensive evaluation is performed.

    The primary outcome is the proportion of participants achieving clinical remission according to the modified mayo score.

    Secondary outcomes include clinical response, endoscopic improvement, and safety measures such as adverse events.

  8. Step 8

    Study completion and follow‑up

    After the final assessment, participants may have a post‑study follow‑up visit to ensure continued safety.

    Study medication is discontinued, and participants receive standard medical care as directed by their own physicians.

Who can join the trial?

7 criteria

  • You must have ulcerative colitis (a long‑lasting inflammation of the colon) for at least three months before the study begins.
  • Your ulcerative colitis must be moderately to severely active, meaning you have noticeable symptoms and inflammation.
  • You must weigh at least 40 kg (about 88 pounds).
  • You need to meet at least one of these conditions: you did not get enough benefit from one or more standard ulcerative colitis medicines (inadequate response), the medicines stopped working for you (loss of response), you need steroids on a regular basis (corticosteroid dependence), or you cannot tolerate one or more standard medicines.
  • You must be taking one of the study’s specified drugs during the trial and keep the dose steady as required.
  • Both male and female participants are allowed.
  • You must be in one of the age groups included in the study (the trial includes children and adults as defined by the study).

Who cannot join the trial?

13 criteria

  • You have Crohn’s disease, indeterminate colitis, or other types of colitis or intestinal inflammation that could make it hard to see how the study drug works.
  • You have had cancer (except fully treated non‑melanoma skin cancers or early‑stage cervical cancer that was completely removed) and have been cancer‑free for less than 5 years, or you have ever had colorectal cancer.
  • You have current or past evidence of definite abnormal cells in the colon (colonic dysplasia) except low‑grade dysplasia that was completely removed.
  • You had a major surgery (a surgery that required general anesthesia) within the last 3 months, or you are planning to have such a surgery during the study.
  • You are taking any medication that the study protocol says is not allowed.
  • You have a severe, rapidly worsening inflammation of the colon (fulminant colitis) or a dangerous swelling of the colon called toxic megacolon.
  • Your ulcerative colitis is limited only to the rectum.
  • You need, or will soon need, a colostomy (an opening of the colon to the skin) or an ileostomy (an opening of the small intestine to the skin).
  • You have already had a total removal of the colon and rectum (total proctocolectomy) or part of your colon removed (partial colectomy).
  • You were hospitalized because your ulcerative colitis got worse within the two weeks before screening.
  • You have any active infection, such as a symptom‑causing infection that is not fully treated, a long‑lasting infection that needs ongoing antibiotics, or a recent infection where you finished IV or oral antibiotics too soon.
  • You are known to be infected with hepatitis B virus, hepatitis C virus, or human immunodeficiency virus (HIV).
  • You have active tuberculosis (TB) or meet the study’s criteria for excluding someone with TB.
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Investigated drugs

MK-8690 is an experimental medication being studied for its ability to treat ulcerative colitis, a condition that causes inflammation and ulcers in the colon. In this trial, participants receive the drug as a subcutaneous injection, meaning it is given under the skin. The medication is supplied as a concentrate that is mixed with a liquid before injection. Researchers are testing whether MK-8690 can help patients achieve clinical remission, which means that the signs and symptoms of ulcerative colitis become minimal or disappear after 12 weeks of treatment.

What is already known about the treatment

  • MK-8690

    This medication is given as a subcutaneous injection using a concentrate that is mixed with liquid before use. It is currently an investigational drug being studied in a Phase 2a trial and has not received market approval. The study is testing it as a possible treatment for moderately to severely active ulcerative colitis. It is thought to work by blocking certain inflammatory signals that drive the disease, and it is classified as an experimental anti‑inflammatory biologic.

  • Placebo for MK-8690

    The placebo is administered in the same way as the test drug, by subcutaneous injection of a solution that contains no active ingredient. It is not a therapeutic product, but is used in the trial to compare the effects of the real drug. It has no intended medical use and therefore has no mechanism of action. It is classified simply as a placebo control.

Investigated diseases

Ulcerative colitis - Ulcerative colitis is a chronic condition that causes inflammation and ulcer formation in the lining of the large intestine. It typically begins with mild swelling and may develop into more extensive irritation that spreads along the colon. Over time, the affected areas can become red, bleed, and produce excess mucus. The disease often progresses in episodes, with periods of increased symptoms followed by quieter phases. As the inflammation continues, the colon wall may become thinner and less flexible.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-523479-49-00Protocol codeMK-8690-002Estimated enrolment106 patientsSponsorMerck Sharp & Dohme LLC

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