Despite the extension of the original recruitment period, the target number of evaluable patients defined in the study protocol could not be reached and recruitment for the trial was stopped at that point of time.

This is a first-in-human, open label phase I study in ovarian cancer patients with primary disease eligible for standard-of-care treatment with neo-adjuvant chemotherapy, i.e. 3 cycles carboplatin/paclitaxel, interval surgery and 3 additional cycles carboplatin/paclitaxel. Eight doses of the W_ova1 vaccine will be administered prior and in combination with the (neo-)adjuvant chemotherapy to induce an anti-tumor immune response. Systemic immune responses are determined using peripheral blood mononuclear cells collected before, during and after vaccinations. Intratumoral accumulation of T-cells recognizing vaccine-encoded TAAs will be determined before vaccination in a tumor biopsy and after the 3 cycles of chemotherapy and the 5th vaccination using tumor tissue derived from interval surgery. [18F]FB-IL2 PET-CT will be used for the non-invasive assessment of T-cell activation and correlated to immunohistochemistry tumor tissue data from pre-treatment biopsy and interval debulking surgery

This is a first-in-human, open label phase I intra-patient dose escalation study (vaccination 1 and 2) in OC patients with primary disease eligible for SoC treatment with neo-adjuvant chemotherapy, i.e. 3 cycles carboplatin/paclitaxel, interval surgery and 3 additional cycles carboplatin/paclitaxel.

OC patients will be vaccinated prior and during (neo)-adjuvant chemotherapy with the W_ova1 vaccine, which includes 3 OC TAA RNAs. Vaccines will be administered by means of intravenous injection. A total of eight vaccinations will be administered with intra-patient dose escalation planned for the first two doses, i.e. the first vaccine will contain 50 µg total RNA and the subsequent seven vaccines will contain the target dose of 100 µg total RNA. Dose reductions/modifications to 50, 25 and 14.4 µg are allowed per protocol.

The first two vaccinations will be administered before the start of neo-adjuvant chemotherapy with 7 day time lag (+/- 2 days) between each vaccination. The subsequent 6 vaccinations are scheduled 15 days (+/- 3 days) after the start of each cycle of chemotherapy to avoid overlap with immune-suppressive corticosteroid premedication as well as with the direct effects of the chemotherapy. Patient evaluation will be performed before, during and after vaccination, including history, physical examination, ECOG performance status and toxicity scoring using NCI CTCAE 5.0 toxicity grades. Blood sample collection for bio monitoring by means of a vena puncture will occur before each vaccination. During the two-step dose escalation blood samples will also be collected 6 hours and 24 hours after vaccination. Blood samples will be analyzed for biochemistry, hematology and tumor marker CA-125.

To determine the systemic immune response (primary objective), PBMCs are obtained by venous blood collection at baseline (100 mL) and twice during study related treatment period (60 mL). In addition, three leukaphereses (or 100 mL blood draw alternatively) and four blood draws for ctDNA analysis are scheduled during the trial for each patient.

To determine the intratumoral immune response (secondary objective), tumor material will be collected before vaccination by an image-guided biopsy and during surgery (standard treatment).

The first [18F]FB-IL2 PET-CT (exploratory objective) will occur at baseline and the second [18F]FB-IL2 PET-CT as close to the surgery as possible. These study procedures are optional and patients can still participate in the trial without the [18F]FB-IL2 PET-CT.

In case of premature drop-out, patients will be asked to undergo the leukapheresis (or 100 mL blood draw alternatively) and if possible / feasible, additional tumor material sampling at time of the planned interval surgery.

Inclusion Criteria:

• Primary epithelial OC patients with measurable tumor lesions (determined by CT or MRI), who are intended to be treated with neo-adjuvant chemotherapy (carboplatin/paclitaxel), subsequent surgery and adjuvant chemotherapy
• Age ≥ 18 years
• Signed informed consent in accordance with institutional and regulatory guidelines
• Adequate access of the tumor for image-guided biopsy
• Adequate (according to the institutional standards) hematology, liver and kidney function to undergo chemotherapy with carboplatin and paclitaxel
• ECOG-performance status of 0 or 1 at screening
• Current BMI > 18.5 and no weight loss of >5% over the past month. Notably, weight loss due to drainage of ascites is not applicable.

Exclusion Criteria:

• History of a second malignancy except for curatively treated low-stage tumors with a histology that can be differentiated from the epithelial OC type
• History of an autoimmune disease, specifically HAV, HBV, HCV and HIV, or any other systemic intercurrent disease or condition that might affect the immunocompetence of the patient, or treatment with systemic highly immunosuppressive therapy (e.g. transplant recipients or patients who underwent a splenectomy)
• Use of systemic continuous corticosteroid therapy (e.g. prednisone i.v. or p.o. >7.5 mg / day).
• Pregnancy or breast feeding
• Participation in a trial with another investigational drug within 30 days prior to the enrolment in this trial
• Any condition that in the opinion of the investigator could interfere with the conduct of the trial.