Ovarian, fallopian tube, or primary peritoneal cancer, collectively referred to as ovarian cancer, remains the deadliest type of gynaecological cancer. The most common and aggressive form is called high-grade serous ovarian cancer.

The main purpose of this study is to understand whether an experimental study vaccine, CryptiVax-1001, is safe when administered to patients with high-grade serous ovarian cancer (HGSOC). The study vaccine is a cancer vaccine, which aims to delay or possibly prevent the cancer from coming back. However, as this is the first study of the vaccine in patients, the primary purpose of this study is to assess the safety of the study vaccine.

Following surgery and platinum-based chemotherapy participants may enter the trial and receive CryptiVax-1001 as an explorative maintenance therapy.

The main purposes of this study are therefore to:

• assess how well the study vaccine is tolerated and identify any side effects.
• analyse the study vaccine's capacity to activate your immune system

The study will test escalating dose levels of CryptiVax-1001 based on the safety evaluations to estimate appropriate future dose levels for CryptiVax-1001.

The OVACT study is the First in Human clinical evaluation of Cryptivax-1001 in patients with advanced high-grade serous or predominantly serous ovarian, fallopian tube, or primary peritoneal cancer, following optimal debulking surgery (R0 or R1 after either IDS or PDS), and no recurrence or progression after completion of platinum-based chemotherapy. This phase I/Ib dose escalation and expansion study will assess safety, tolerability, and immunogenicity in a population where there is a high unmet need and no clearly effective maintenance therapy options. By focusing on the BRCAwt/HRP subgroup, the study addresses the majority of patients who currently lack access to biologically-matched maintenance strategies.

The study consist of 2 parts - a dose escalation part and an optional dose expansion part

Inclusion Criteria:

• Able to comprehend and are willing to sign the ICF and willing to follow the study procedures
• Female, aged 18 years of age or older at the time of informed consent.
• Histologically confirmed diagnosis of epithelial ovarian, fallopian tube, or primary peritoneal carcinoma of high-grade serous histology or other high-grade predominantly serous subtypes
• The FIGO 2014 stage III or IV disease at initial diagnosis.
• Underwent optimal PDS or IDS with residual disease ≤1 cm (R0 or R1 resection)
• Completed first-line platinum-based chemotherapy (minimum 4 cycles of carboplatin and paclitaxel, or equivalent, received in either neoadjuvant or adjuvant, or both settings).
• In the presence of measurable target lesion, achieved CR or PR per investigator assessment based on RECIST 1.1 after completion of chemotherapy. In the absence of measurable target lesion, no new lesion or overt progression per investigator assessment based on RECIST 1.1 after completion of chemotherapy.
• A minimum of 4 weeks from screening since the last dose of first-line platinum-based chemotherapy but not more than 12 weeks from screening since the last dose of first-line platinum-based chemotherapy.
• No evidence of radiologic or clinical progression between the end of chemotherapy and baseline screening.
• Known BRCAwt status.
• HRP confirmed
• No prior, current, or planned treatment with bevacizumab or PARPi in the first-line maintenance setting.
• ECOG performance status of 0 or 1.
• Adequate haematologic and organ function
• Negative pregnancy test for WOCBP.
• HLA type matching Cryptivax-1001

Exclusion Criteria:

• Non-epithelial or low malignant potential ovarian tumours
• Presence of uncontrolled ascites or pleural effusion requiring drainage within 4 weeks of screening.
• Concurrent malignancy or history of another malignancy within the past 3 years except for malignancies with a negligible risk of metastasis or death
• Active autoimmune disease requiring systemic immunosuppression
• Uncontrolled intercurrent illness that, in the opinion of the investigator, would compromise participant safety or interfere with study assessments
• History of anaphylactic reaction to mRNA-LNP therapies.
• Previous treatment with any cancer vaccine, checkpoint inhibitor, or adoptive cellular immunotherapy.
• Administration of any vaccine within 30 days prior to first dosing.
• Participation in a clinical study involving administration of an IMP (new chemical entity) in the past 90 days or 5 half-lives of that drug (if known) prior to first dosing, whichever is longer.