Oncoinvent to Present Positive 24-month Follow-up Data from Phase 1 Ovarian Cancer Study of Radspherin® at ESGO 2026

• 9 of 10 patients at the highest dose remained free from peritoneal recurrence at 24 months at the recommended dose

Oslo, Norway, 17 February 2026 – Oncoinvent, a biotech developing a receptor-independent alpha radiopharmaceutical to eradicate cancer cells in the abdominal cavity after surgery with a single, targeted dose, today announced that it will present final 24‑month results from its RAD-18-001 Phase 1 study of Radspherin® after cytoreductive surgery in patients with platinum‑sensitive epithelial ovarian cancer and peritoneal recurrence at the European Society of Gynaecological Oncology (ESGO) 2026 Congress, taking place in Copenhagen, Denmark, from 26-28 February 2026.

Radspherin® is an intraperitoneal alpha-emitting therapy (²²⁴Ra-labeled microparticles), targeting remaining cancer cells while sparing healthy tissue within the peritoneal cavity to address microscopic residual disease following cytoreductive surgery, to prevent recurrence and enhance long-term patient outcomes.

The poster presentation, titled ‘Safety and efficacy results from a phase 1 study of intraperitoneal alpha-emitting radium-224 labelled microparticles after cytoreductive surgery in patients with peritoneal recurrence of platinum-sensitive epithelial ovarian cancer,’ will share final 24-month data from the Phase 1 study detailing:

• 21 patients enrolled across dose levels with a favourable safety profile and no dose‑limiting toxicities observed
• No grade ≥3 adverse events considered related to Radspherin®
• Recommended dose selected at 7 MBq following dose escalation
• Durable local disease control signal at 24 months: only 1 of 10 patients treated at the recommended dose experienced peritoneal recurrence

“We are pleased to present our Phase 1 data at the ESGO 27th Annual Meeting, an important forum for sharing findings with the international gynecologic oncology community. These encouraging data reflect the collaborative efforts of the study team and the potential of Radspherin® to address a patient population with high risk of peritoneal recurrence and poor prognosis,” said Yun Wang, MD, PhD, Department for Cancer Surgery, Section for Gynecological Oncology, The Norwegian Radium Hospital, Oslo University Hospital, principal investigator in the RAD-18-001 trial. Chief Medical Offer Kari Myren at Oncoinvent added, “We remain committed to advancing Radspherin® in the Phase 2 trial and to further evaluating its potential to benefit patients with ovarian cancer.”

Details of the presentation are as follows:

Poster title: Safety and efficacy results from a phase 1 study of intraperitoneal alpha-emitting radium-224 labelled microparticles after cytoreductive surgery in patients with peritoneal recurrence of platinum-sensitive epithelial ovarian cancer
Presenter: Yun Wang, Department of Surgical Oncology Section of Gynaecological Cancer, Norwegian Radium Hospital, Oslo University Hospital
Authors: Y. Wang¹, E. Van Nieuwenhuysen², L. Chiva³, E. Chacon⁴, M-E. Revheim^1,5, CM. Deroose², L. Sancho³, JJ. Rosales Castillo⁴, A-K. Aksnes⁶, K. Myren⁶, I. Vergote², ?S. Bruland^1,5
Session title: Poster walk
Session date and time: 27 February 2026, 17:20-18:20 CET
Location: Exhibition
Abstract ID: 938

Abstracts are available on the ESGO program guide here, and the poster once presented will be available on Oncoinvent’s website here.

¹ The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway

² University Hospital Leuven and KU Leuven, Leuven, Belgium

³ Cl?nica Universidad de Navarra, Madrid, Spain

⁴ Cl?nica Universidad de Navarra, Pamplona, Spain

⁵ University of Oslo, Oslo, Norway

⁶ Oncoinvent Solutions AS, Oslo, Norway