Oncoinvent to Present Four Posters at the 34th Annual Congress of the European Association of Nuclear Medicine

Oncoinvent AS, a clinical stage company advancing a pipeline of radiopharmaceutical products across a variety of solid cancers, will present new preclinical data supporting the future clinical development of Radspherin^®, a novel alpha-emitting radioactive microsphere suspension designed for treatment of metastatic cancers in body cavities, in four digital presentations at the 34^th Annual Congress of the European Association of Nuclear Medicine (EANM).

"We are thrilled to present these data at EANM, furthering our confidence in the potential of alpha-emitting radioactive particles for the treatment of metastatic cancers in body cavities," said Jan A. Alfheim, Chief Executive Officer of Oncoinvent. "These data demonstrate that Radspherin^® has potentially robust and retained biodistribution in body cavities, and give us important insights into the safety of clinical doses. We look forward to the continued clinical development of Radspherin^® in colorectal and ovarian cancer patients suffering from peritoneal carcinomatosis."

Synergy of ²²⁴Ra-labeled microparticles and chemotherapy in a murine ovarian cancer model
Presenting Author: Roxanne Wouters
Abstract Number: OP-0108

This preclinical study aimed to evaluate the effects of combining ²²⁴Ra-CaCO₃-MP, radium-224-labeled calcium carbonate microparticles, with either first line chemotherapy for ovarian cancer, carboplatin-paclitaxel, or second line chemotherapy, carboplatin-pegylated liposomal doxorubicin (PLD), in an ovarian cancer model. Ovarian cancer mouse models were treated with ²²⁴Ra-CaCO₃-MP (5 mg, 14-22 kBq/animal) one day following tumor cell inoculation. Additionally, ²²⁴Ra-CaCO₃-MP treatment was combined with either carboplatin (100 mg/kg)-paclitaxel (10 mg/kg) on day 14, 21 or 28, or carboplatin (80 mg/kg)-PLD (1.6 mg/kg) on day 14.

Key results:

• As a single treatment, ²²⁴Ra-CaCO₃-MP delayed the onset of malignant ascites development compared to control.
• When ²²⁴Ra-CaCO₃-MP was administered in combination with carboplatin-PLD, survival was significantly prolonged compared to mice that received carboplatin-PLD alone.

Synergy when treating ovarian cancer cell lines with Radium-224 and PARP inhibitors
Presenting Author: Marion Masitsa Malenge
Abstract Number: EPS-064

This study evaluated the potential of combining radium-224 (²²⁴Ra), an alpha-emitter with 3.6 days half-life with the PARP inhibitors olaparib and niraparib to inhibit growth of ovarian cancer cell-lines. The effect of ²²⁴Ra in combination with olaparib and in combination with niraparib were evaluated in two human non-BRCA-mutated ovarian cancer cell-lines, ES-2 and SKOV-3. Cells were simultaneously treated with ²²⁴Ra and PARP inhibitors at escalating concentrations, and cell proliferation was measured 72, 96 and 120 hours after initiation of treatment.

Key results:

• The combination index (CI) between both evaluated cell-lines was heterogenous across the tested range depending on the PARP inhibitor used in the combination, the concentrations of the combined drugs and the timepoint of assessment.
• Combination treatment with PARP inhibitors and ²⁴⁴Ra was seen to be synergistic.

Biodistribution and dosimetry after intraperitoneal injection of ²²⁴Ra-labeled microparticles in rats
Presenting Author: Sara Westrøm
Abstract Number: EP-118

The presentation highlights the ex vivo biodistribution ²²⁴Ra-CaCO₃-MP in preclinical models. In addition, dosimetry was calculated and extrapolated to the absorbed doses to human. ²²⁴Ra-CaCO₃-MP (89 kBq/animal, 30 mg CaCO₃) or vehicle was administered to preclinical rat models intraperitoneal. Ex vivo biodistribution was assessed at time points ranging from 2 to 336 hours post injection. For dosimetry calculations, the cumulated activity was determined by linear interpolation between the measured values. The dosimetry results were extrapolated to humans and scaling with relative biologically effectiveness (RBE) factors was performed.

Key results:

• The majority of ²²⁴Ra was retained after intraperitoneal administration of ²²⁴Ra-CaCO₃-MP.
• Analyses of clinical pathology showed no treatment-related adverse effects, apart from a transient depression of neutrophils.
• Dosimetry demonstrated that based on the low absorbed doses for all tissues, administration of up to 7 MBq ²²⁴Ra-CaCO₃-MP, the maximum activity in ongoing Phase 1 studies, is deemed safe.

Dose response of ²¹²Pb-labeled calcium carbonate microparticles in mice with intraperitoneal ovarian cancer
Presenting Author: Ruth Gong Li
Abstract Number: OP-0111

This study evaluated the intraperitoneal retention and biodistribution of ²¹²Pb-CaCO₃ microparticles in mouse models of ovarian cancer. Mice received a single intraperitoneal injection of either 2-5mg with doses ranging from 57-390 kBq ²¹²Pb-CaCO₃ microparticles, or vehicle.

Key results:

• Calcium carbonate microparticles can be labeled with ²¹²Pb in an easy, fast and efficient process; no chelator or co-precipitants are necessary.
• ²¹²Pb-CaCO₃ microparticles were retained in the peritoneal cavity.
• The increased survival of mice with tumors that were treated with ²¹²Pb-CaCO₃ was dose-dependent and significant for all evaluated doses.

About Oncoinvent
Oncoinvent AS is a clinical stage company developing innovative radiopharmaceutical technology that delivers precise, alpha-emitting particles across solid cancers. By leveraging internal manufacturing and supply chain capabilities to enable a clinical supply of radioisotopes, the company is advancing a pipeline of novel products that use alpha particles, a higher Linear Energy Transfer (LET) form of radiation, that can potentially eradicate cancer cells. Oncoinvent's lead candidate, Radspherin^®, is designed for treatment of metastatic cancers in body cavities, and its versatility allows it to be deployed for the treatment of a variety of cancer indications. Radspherin^® is in two ongoing Phase 1 studies to treat peritoneal carcinomatosis from both ovarian cancer and colorectal cancer.