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Safety and Efficacy of MK-1045 with Tocilizumab in Patients with CLL/SLL

Verified siteRegistered drugNo placebo
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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 people with chronic lymphocytic leukemia, a type of B‑cell cancer that starts in the blood and bone marrow. The investigational medicine being tested is called MK-1045, which is given as a liquid that is infused into a vein. This medication is studied by itself, without combining it with other cancer drugs.

The main goal is to see how safe the drug is and whether it can shrink the cancer, measured by the objective response rate. Participants will receive the infusion at regular intervals and will be monitored for side effects such as dose‑limiting toxicity—a reaction that would stop the dose from being increased—and any adverse event, which means any unwanted health problem that occurs during the study. The study lasts for several months, during which doctors will check the participants’ health, collect blood samples, and evaluate how the disease responds to the treatment.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline Assessments

    After you join the study, you will undergo baseline assessments that include a review of your medical history, physical examination, laboratory tests, and any imaging required to document your condition.

    These assessments establish a starting point for evaluating the safety and effectiveness of the study medication.

  2. Step 2

    First Infusion of MK-1045

    You will receive MK-1045 as an intravenous infusion. The formulation is a solution for infusion with a concentration of 0% volume/volume as specified in the study protocol.

    The infusion is administered by qualified staff in a clinical setting. The exact schedule (e.g., weekly, bi‑weekly) is defined by the study protocol and will be followed throughout the trial.

  3. Step 3

    Administration of Background Medication Tocilizumab

    In addition to MK-1045, you may receive tocilizumab as a background medication. The dose is 0 mg per kilogram of body weight, administered according to the protocol.

    Tocilizumab is a medication that helps modulate the immune system and is used in the study to support the primary treatment.

  4. Step 4

    Regular Safety Monitoring Visits

    During the study, you will attend regular visits for safety monitoring. At each visit, laboratory tests and physical examinations will be performed to check for any adverse events (undesired medical occurrences).

    You will be asked to report any new symptoms or changes in your health at these visits.

  5. Step 5

    Evaluation of Treatment Response

    Your response to the study medication will be evaluated using the International Workshop on Chronic Lymphocytic Leukemia (iwCLL) criteria from 2018. This assessment determines the objective response rate, which measures how well the cancer responds to treatment.

    Response evaluations are performed by an independent review committee to ensure unbiased assessment.

  6. Step 6

    Continuation of Treatment Cycles

    You will continue to receive the scheduled infusions of MK-1045 (and tocilizumab, if applicable) for the duration defined by the study protocol, unless you experience a severe adverse event or the investigator decides to discontinue treatment for safety reasons.

  7. Step 7

    Final Study Visit

    At the end of the study period, you will attend a final visit that includes a complete set of assessments similar to the baseline visit. This final evaluation records the overall safety, tolerability, and efficacy outcomes of the treatment.

Who can join the trial?

7 criteria

  • Have a confirmed diagnosis of chronic lymphocytic leukemia (CLL) or small lymphocytic leukemia (SLL) that has returned or not responded to previous treatments; “confirmed” means doctors have examined tissue under a microscope.
  • The cancer cells must show the protein called CD19 on their surface.
  • If you are living with HIV, the infection must be well‑controlled with medicines known as antiretroviral therapy.
  • If you test positive for the hepatitis B surface antigen (HBsAg), the amount of hepatitis B virus in your blood (viral load) must be undetectable.
  • If you have a history of hepatitis C, the amount of hepatitis C virus in your blood (viral load) must be undetectable.
  • Both men and women are eligible to participate.
  • You must be within the age range required by the study (generally adult participants).

Who cannot join the trial?

10 criteria

  • Has a history of serious cardiovascular (heart and blood vessel) or cerebrovascular (brain blood vessel) disease.
  • Has been diagnosed with Richter Transformation, an aggressive form of lymphoma that can develop from CLL.
  • Has a past or current disease of the central nervous system (brain or spinal cord).
  • Is infected with HIV and has a history of Kaposi’s sarcoma (a type of skin cancer) or Multicentric Castleman’s Disease (a condition causing enlarged lymph nodes).
  • Has a diagnosis of immunodeficiency, meaning the immune system does not work properly.
  • Has another malignancy (cancer) that is getting worse or needed active treatment within the past two years.
  • Has an active autoimmune disease (the body’s immune system attacks its own tissues) that required medication in the past two years and is not related to the leukemia.
  • Has any active acute or chronic graft versus host disease (GvHD) that requires medication, which is when donated immune cells attack the body.
  • Has an active infection that needs medication.
  • Has not fully recovered from major surgery or still has complications from surgery.
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Investigated drugs

  • MK-1045

    is an experimental medicine being studied for the first time in people with certain blood cancers, such as chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). In this trial it is given as a liquid that is infused into a vein. The main goal is to see if the drug is safe, how well patients can tolerate it, and whether it can shrink or control the cancer.

  • Tocilizumab

    is a medication that is already approved for other conditions and works by blocking a protein called interleukin‑6, which can cause inflammation. In this study it is used as a background treatment, meaning participants may receive it alongside the investigational drug to help manage immune‑related side effects or other health issues while the safety and effectiveness of MK‑1045 are being evaluated.

What is already known about the treatment

  • MK-1045

    MK-1045 is given as an intravenous solution for infusion, where the medicine is mixed into a fluid and delivered through a vein. It is currently an investigational drug being studied in a Phase 2 clinical trial and is not yet approved for general medical use. The trial is testing MK-1045 as a single treatment for people with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). It works by targeting a specific molecular pathway that helps cancer cells grow, and it is classified as an experimental small‑molecule therapy.

  • TOCILIZUMAB

    Tocilizumab is administered by intravenous infusion, where the drug is slowly injected into a vein. It is an approved medication that has been widely studied and is used to treat conditions like rheumatoid arthritis and cytokine release syndrome. In this study it is used as background therapy for patients with CLL/SLL. Tocilizumab blocks the body’s interleukin‑6 (IL‑6) receptor, reducing inflammation, and it is classified as a biologic monoclonal antibody immunosuppressant.

Investigated diseases

Chronic lymphocytic leukemia / small lymphocytic lymphoma - A cancer of mature B‑cells that usually starts in the blood and bone marrow (chronic lymphocytic leukemia) and can also appear as solid tumors in lymph nodes (small lymphocytic lymphoma). The disease often progresses slowly, with an increase in abnormal lymphocytes over time. As the abnormal cells multiply, they may accumulate in the bone marrow, spleen, and other organs, gradually impairing normal blood cell production. Patients may notice enlarged lymph nodes, fatigue, or a higher risk of infections as the condition advances.
Trial detailsLast updated 17 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-522242-49-00Protocol codeMK-1045-006Estimated enrolment118 patientsSponsorMerck Sharp & Dohme LLC

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