Ovarian Cancer Treatment With a Liposome Formulated mRNA Vaccine in Combination With (Neo-)Adjuvant Chemotherapy

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.