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A study of Pseudovax, molgramostim and tislelizumab combination therapy for patients with pseudomyxoma peritonei cancer

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

This clinical trial focuses on treating patients with Pseudomyxoma Peritonei, a rare type of cancer that primarily affects the abdominal cavity. The study will test a combination of three medications: Pseudovax (a cancer vaccine), Tislelizumab (a medication that helps the immune system fight cancer cells), and Molgramostim (a substance that stimulates the production of white blood cells).

The purpose of this study is to evaluate how safe and well-tolerated these medications are when given in sequence, and to measure how they activate the immune system. Pseudovax will be given as an injection under the skin, while Tislelizumab will be administered through an intravenous infusion (directly into a vein). Molgramostim will also be given as an injection under the skin.

The treatment period will last several months, during which participants will receive regular doses of these medications. Throughout the study, doctors will monitor the participants' health and measure how their immune system responds to the treatment. They will also track how long participants remain free from disease progression.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment phase

    You will receive Pseudovax, a cancer vaccine, through an injection under the skin

    Together with the vaccine, you will receive molgramostim (also known as GM-CSF) through an injection under the skin to help boost your immune system

  2. Step 2

    Secondary treatment phase

    You will receive tislelizumab through an intravenous infusion (delivered directly into your bloodstream)

    This medication helps your immune system fight cancer cells

  3. Step 3

    Monitoring and assessment

    Your doctor will monitor your health throughout the treatment period

    Blood samples will be taken to check your immune system response

    Up to three tissue samples (biopsies) will be collected during the study to evaluate treatment effectiveness

    Regular checks of your organ function, including liver, kidney, and blood tests will be performed

  4. Step 4

    Follow-up period

    After completing treatment, you will need to continue using appropriate birth control methods for 6 months after the last dose

    Your health status will be monitored to track how long you remain free from disease progression

    The total duration of the study is expected to continue until October 30, 2029

Who can join the trial?

15 criteria

  • Must be at least 18 years old and able to provide written informed consent
  • Must have a confirmed diagnosis of recurrent or non-resectable PMP (a type of cancer that spreads in the abdomen) with no other available treatment options
  • Must have a tumor with a specific genetic change called GNAS mutation
  • Must have tumors that are suitable for taking up to 3 tissue samples (biopsies)
  • Must have adequate organ function, including:
    • Sufficient blood cell counts
    • Normal kidney function
    • Normal liver function
    • Normal blood clotting
    • Must have good physical ability (ECOG performance status of 0 or 1, meaning able to perform most daily activities)
    • Must have a life expectancy of more than 6 months
    • For women who can become pregnant:
      • Must have a negative pregnancy test within 48 hours before starting the study
      • Must not be breastfeeding
      • Must use effective contraception during the study and for 6 months after
      • For men:
        • Must use condoms during sexual activity throughout the study and for 6 months after
        • Must not donate sperm during this period

Who cannot join the trial?

14 criteria

  • Age under 18 years or over 65 years
  • Previous treatment with tislelizumab (a type of immunotherapy drug)
  • Known allergic reactions to any of the study medications
  • Active or chronic infections, including hepatitis B, hepatitis C, or HIV
  • Presence of other types of cancer in the last 5 years
  • Severe heart conditions or uncontrolled high blood pressure
  • Significant liver problems or abnormal liver function tests
  • Severe kidney disease requiring dialysis
  • Autoimmune diseases (conditions where the immune system attacks healthy cells)
  • Pregnancy or breastfeeding
  • Mental conditions that could interfere with following study procedures
  • Use of medications that suppress the immune system
  • Participation in other clinical trials within the last 30 days
  • Any condition that, in the opinion of the study doctor, makes participation unsafe
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Investigated drugs

  • Pseudovax

    is an experimental cancer vaccine designed to target specific mutations in cancer cells, particularly those with GNAS mutations found in patients with pseudomyxoma peritonei, a rare type of cancer. The vaccine works by training the immune system to recognize and attack these cancer cells.

  • GM-CSF

    (Granulocyte-Macrophage Colony-Stimulating Factor) is a protein that helps stimulate the immune system. It is used in combination with the vaccine to enhance the body's immune response against cancer cells.

  • Tislelizumab

    is an immune checkpoint inhibitor that helps the immune system fight cancer. It works by blocking a protein that normally prevents immune cells from attacking cancer cells, allowing the body's natural defenses to work more effectively against the disease.

What is already known about the treatment

  • Tislelizumab

    An innovative immunotherapy medication administered through intravenous infusion, belonging to the class of PD-1 inhibitors (immune checkpoint inhibitors). This monoclonal antibody works by blocking the PD-1 pathway, which helps the immune system recognize and attack cancer cells more effectively, particularly in the treatment of Pseudomyxoma Peritonei. The drug is currently undergoing clinical trials to evaluate its efficacy when combined with cancer vaccines, showing promising results in enhancing the body's immune response against cancer cells.

  • GM-CSF (Sargramostim)

    A protein-based medication administered via subcutaneous injection that stimulates the production and function of white blood cells, particularly granulocytes and macrophages. As a granulocyte-macrophage colony-stimulating factor, it plays a crucial role in enhancing immune response and is often used in combination with cancer vaccines to boost their effectiveness. In clinical trials, it is being studied as an adjuvant therapy to improve immune response in patients with Pseudomyxoma Peritonei.

  • Pseudovax

    An investigational cancer vaccine specifically designed to target mutations in the GNAS gene, which is commonly altered in Pseudomyxoma Peritonei. The vaccine is administered through injection and works by training the immune system to recognize and attack cancer cells carrying specific GNAS mutations. Currently in clinical trials, it is being studied in combination with immune checkpoint inhibitors to potentially enhance the overall anti-tumor immune response.

Investigated diseases

Pseudomyxoma Peritonei - A rare condition characterized by the accumulation of mucin-producing tumor cells in the abdominal cavity. The disease typically begins in the appendix and spreads throughout the peritoneum, causing a buildup of mucus-like material. As it progresses, the jelly-like substance gradually fills the abdominal cavity, putting pressure on digestive organs. The condition develops slowly over time, with patients initially experiencing gradual abdominal enlargement and digestive changes. Some patients may feel increasing abdominal pressure and changes in bowel habits as the condition advances.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase ITrial ID2024-517047-30-01Protocol codePseudovax 1Estimated enrolment10 patientsSponsorOslo University Hospital HF

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