Pseudovax – a Cancer Vaccine Targeting Mutated Gnas Combined with Immune Checkpoint Inhibition for Patients with Pseudomyxoma Peritonei

Overview

Sponsor-declared trial summary

Key facts

Sponsor

Oslo University Hospital HF

Participant type

Patients

Age range

18-64 years, 65+ years

Gender

Male and Female

Therapeutic area

Diseases [C] - Neoplasms [C04], Diseases [C] - Pathological Conditions, Signs and Symptoms [C23]

Trial duration

1 Sep 2025 → ongoing

Decision date (initial)

2025-09-01

Transition trial

No

Low-intervention

No

Rare-disease indication

Yes

Vulnerable population

No

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Safety, Efficacy, Therapy

To assess safety and tolerability of sequential treatment with Pseudovax/GM-CSF and tislelizumab in order to measure immune activation following study treatment.

Secondary objectives 1

1. To assess preliminary efficacy of the study treatment

Conditions and MedDRA coding

Pseudomyxoma Peritonei

Regulatory references

Scientific advice from competent authorities

Norwegian Medical Products Agency

Plan to share IPD

No

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 10

1. 1. The subject is ≥ 18 years of age on the day of signing the informed consent form, able to provide written informed consent and can understand and agree to comply with the requirements of the study and the schedule of assessments.
2. 2. Confirmed diagnosis of recurrent or non-resectable PMP with no other available treatment options that are expected to be efficacious.
3. 3. The subject’s tumor must carry a mutation in the GNAS oncogene*
4. 4. Subjects must have peritoneal tumor distribution at screening that, in the opinion of the Investigator, is suitable for repeat biopsies: Up to 3 biopsies of target tissue are planned for subjects that complete the study.
5. 5. Adequate organ, bone marrow, liver, and renal function at screening, including: a). Absolute neutrophil count: ≥ 1,5 x10^9/L. b). Platelets: ≥ 100 x10^9/L. c). Hemoglobin: ≥ 9 x10^9/L. d). Creatinine ≤ 1,5 upper limit normal (ULN) OR measured/calculated GFR ≥60 mL/min. e). Albumin ≥ 30 g/L. f). Total bilirubin ≤ 1,5 ULN. g). ASAT and ALAT ≤ 3 ULN. h). International Normalized Ratio (INR) ≤ 1,5 ULN and Activated Partial Thromboplastin Time (TT) ≤ 1,5 ULN unless subject is receiving anticoagulant therapy.
6. 6. ECOG performance status of 0 or 1.
7. 7. Life expectancy of >6 months, at the time of signing the informed consent.
8. 8. Women of childbearing potential must have a negative serum pregnancy test within 48 hours of the first study intervention, and must not be breast-feeding.
9. 8a). a. Female participant: i. Unless documented not to have childbearing potential: Subject is willing to use contraceptive measures for the duration of the study, and ≥ 6 months after the last dose of IMP, as prescribed by the protocol (according to the applicable guidance: CTFG, 2020). The Investigator should counsel women of childbearing potential of the importance of pregnancy prevention. ii. Women of childbearing potential must have a negative serum pregnancy test within 48 hours of the first study intervention.
10. 8b). b. Male subject: Sexually active males must be willing to use a condom during sex for the duration of the study and for ≥ 6 months after the last dose of IMP. Males must also be willing to abstain from donating sperm during the same period.

Exclusion criteria 25

1. 1. Patient has Eastern Cooperative Oncology Group performance status 2 or worse.
2. 10. Diagnosis of immunodeficiency.
3. 11. History of interstitial lung disease, non-infectious pneumonitis or uncontrolled diseases including pulmonary fibrosis, acute lung diseases, etc.
4. 12. Severe chronic or active infections requiring systemic antibacterial, antifungal or antiviral therapy, including tuberculosis infection, etc.
5. 2. Blood transfusion or growth factor support ≤ 14 days before sample collection at screening.
6. 3. Active malignancy the past 3 years except for the specific cancer under investigation in this study and any locally recurring cancer that has been treated curatively (e.g., resected basal or squamous cell skin cancer, superficial bladder cancer, carcinoma in situ of the cervix or breast)
7. 4. Enrollment in another interventional trial that, in the opinion of the Investigator, could influence the outcome of this study.
8. 5. Subject has within the last 30 days received any other interventional therapy that, in the opinion of the Investigator, could influence the outcome of this study.
9. 6. Pregnancy or lactating female.
10. 7. Known active hepatitis B or C, or is known to be HIV-positive.
11. 8. Any condition that required systemic treatment with either corticosteroids (> 10 mg daily of prednisone or equivalent) or other immunosuppressive medication ≤ 14 days before the first dose of IMP. Note: Subjects who are currently or have previously been on any of the following steroid regimens are not excluded: Adrenal replacement steroid (dose ≤ 10 mg daily of prednisone or equivalent); Topical, ocular, intra-articular, intranasal, or inhaled corticosteroid with minimal systemic absorption; Short course (≤ 7 days) of corticosteroid prescribed prophylactically (eg, for contrast dye allergy) or for the treatment of a non-autoimmune condition (eg, delayed-type hypersensitivity reaction caused by contact allergen).
12. 9. Active autoimmune diseases or history of autoimmune diseases that may relapse. Note: Subjects with the following diseases are not excluded and may proceed to further screening, controlled Type I diabetes, hypothyroidism (provided it is managed with hormone replacement therapy only), controlled celiac disease skin diseases not requiring systemic treatment (eg, vitiligo, psoriasis, alopecia), any other disease that is not expected to recur in the absence of external triggering factors.
13. 13. Severe infections within 4 weeks before first dose of IMP, including but not limited to hospitalization for complications of infection, bacteremia, or severe pneumonia.
14. 14. Therapeutic oral or intravenous antibiotics within 2 weeks before first dose of IMP
15. 15. Any major surgical procedure requiring general anesthesia ≤ 28 days before first dose of IMP.
16. 16. Prior allogeneic stem cell transplantation or organ transplantation
17. 17. Cardiac chest pain, defined as moderate pain that limits instrumental activities of daily living, ≤ 28 days before first dose of IMP.
18. 18. Pulmonary embolism ≤ 28 days before first dose of IMP.
19. 19. History of acute myocardial infarction ≤ 6 months before first dose of IMP.
20. 20. History of heart failure meeting New York Heart Association (NYHA) Classification III or IV (Appendix 6) ≤ 6 months before first dose of IMP.
21. 21. Subject has had any event of ventricular arrhythmia ≥ Grade 2 in severity ≤ 6 months before first dose of IMP.
22. 22. Severe hypersensitivity (≥grade 3) to chemotherapy, any other biologic drug or the contents or preservatives of any of the study drugs.
23. 23. History of cerebrovascular accident ≤ 6 months before first dose of IMP.
24. 24. Subject has underlying medical conditions (including laboratory abnormalities) or alcohol or drug abuse or dependence that, will be unfavorable for the administration of study drug or affect the explanation of drug toxicity or AEs or result in insufficient or might impair compliance with study conduct.
25. 25. Any reason why, in the opinion of the investigator, the patient should not participate.

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 2

1. Incidence (rate) of IMP-related adverse events
2. T cell responses against the vaccine peptide in blood samples and skin

Secondary endpoints 1

1. Progression-free survival, measured as the number of months from date of first treatment until disease progression or death from any cause

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 4

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

Oslo University Hospital HF

Sponsor organisation

Oslo University Hospital HF

Address

Taarnbygget, Kirkeveien 166 Kirkeveien 166

City

Oslo

Postcode

0450

Country

Norway

Scientific contact point

Organisation

Oslo University Hospital HF

Contact name

Geir Olav Hjortland

Public contact point

Organisation

Oslo University Hospital HF

Contact name

Geir Olav Hjortland

Locations

1 EU/EEA country · 1 investigational sites

By country

Investigational sites

Country notifications

Trial-start, recruitment-start, end and early-termination notifications submitted per Member State

Results and documents

Annex IV summary of results, Annex V layperson summary, and all documents registered in CTIS for this trial

Documents 8 files

Public protocol annexes, IB summaries, regulatory submissions and post-authorisation documents registered in CTIS.

Application history

2 submissions — initial application plus substantial / non-substantial modifications