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

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What is this study about?

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.

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 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 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 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 Study?

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 Study?

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

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Oslo Universitetssykehus HF	Oslo	Norway

Other Sites

No sites found in this category

Trial status

Country	Status	Recruitment Start
Norway	Recruiting	01.09.2025

Trial locations

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.

Investigated diseases:

Pseudomyxoma peritonei

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 ID:

2024-517047-30-01

Protocol code:

Pseudovax 1

Trial Phase:

Human Pharmacology (Phase I) – First administration to humans

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