Oncoinvent, a clinical-stage radiopharmaceutical company, has announced that its Phase 2 clinical trial evaluating Radspherin for the treatment of peritoneal metastases arising from ovarian cancer has reached the halfway mark in patient enrollment.

The study has now enrolled 54 patients, representing 50 percent of the planned trial population. The company reported a significant acceleration in recruitment during 2026, with 11 patients enrolled in the first quarter and 17 additional patients recruited during the second quarter to date. The total enrollment of 28 patients so far this year has already exceeded the number of patients recruited throughout 2025.

To support the growing pace of enrollment, Oncoinvent has expanded its clinical network by activating four additional study sites in 2026. The trial is currently being conducted at ten hospitals across the United States, Spain, Norway, Belgium, the United Kingdom and Italy, with further site activations planned.

Radspherin is a receptor-independent alpha-emitting radiopharmaceutical designed to eliminate residual cancer cells in the abdominal cavity following surgery. The therapy delivers a single, highly localised dose of alpha radiation aimed at destroying microscopic cancer deposits that may remain after tumour removal.

The ongoing Phase 2 study is a randomised controlled trial assessing both the efficacy and safety of Radspherin in ovarian cancer patients with peritoneal metastases. Researchers are comparing progression-free survival in patients receiving Radspherin after complete surgical resection and pre-operative chemotherapy against patients receiving standard treatment comprising surgery and chemotherapy alone.

According to Oncoinvent, earlier clinical studies have demonstrated encouraging results. Phase 1 and Phase 1/2a trials showed that Radspherin was generally well tolerated, with no dose-limiting toxicities observed at the recommended dose of 7 MBq. Preliminary efficacy findings also indicated potential therapeutic benefits.

Results from the Phase 1 ovarian cancer study have been published in the journal Gynecologic Oncology, while findings from the Phase I/IIa colorectal cancer trial appeared in the Journal of Surgical Oncology and Frontiers in Medicine.

Oystein Soug, Chief Executive Officer of Oncoinvent, said reaching the 50 percent recruitment milestone reflects the dedication of investigators and clinical sites participating in the study. He added that the increased enrollment momentum strengthens the company’s ability to further assess Radspherin’s potential in a patient population with limited treatment options after surgery.

The company’s development strategy focuses initially on ovarian and colorectal cancers, where cancer cells often spread to the peritoneum—the membrane lining the abdominal cavity and surrounding abdominal organs. By targeting residual micrometastases after surgery, Oncoinvent aims to reduce disease recurrence and improve long-term outcomes for patients.