Oncoinvent announces publication of normal tissue dosimetry results in Journal of Nuclear Medicine

· Clinical dosimetry results from Phase 1 studies of Radspherin[®] in ovarian and colorectal cancer demonstrate absorbed doses to normal organs well below values associated with toxicity risks · The results are consistent with the favorable safety profile observed to date and support the further development of Radspherin[®] for treatment of peritoneal metastases

Oslo, Norway, 11 August 2026 - Oncoinvent, a biotech company developing a receptor-independent alpha radiopharmaceutical to eradicate cancer cells in the abdominal cavity after surgery with a single, targeted dose, today announces the publication of clinical dosimetry data for Radspherin[®] in the Journal of Nuclear Medicine (https://jnm.snmjournals.org/), one of the leading peer -reviewed journals in the field.

The publication, titled "Normal Tissue Dosimetry of Intraperitoneal Radium-224 -Microparticle Therapy: Data from First-in-Human Studies in Patients with Peritoneal Metastases (https://jnm.snmjournals.org/content/early/2026/08/06/jnumed.125.2719 2 5)", reports results from nine patients enrolled in the dosimetry cohorts of the Phase 1 Radspherin[®] studies in ovarian and colorectal cancer. Positive final data from these studies, previously reported by Oncoinvent, demonstrated a favorable safety profile and encouraging efficacy signals.

"In early-phase clinical studies, dosimetry is essential to understand how radiation exposure relates to potential toxicity and identify potential dose -limiting tissues," said Caroline Stokke, senior author of the publication, Head of Nuclear Medicine Physics at Oslo University Hospital and Chair of the European Association of Nuclear Medicine Dosimetry Committee. "This work also reflects the methodological complexity of dosimetry for alpha therapies, where imaging cannot always be directly applied. To address these challenges, we were able to use a combination approach, also including blood sampling and biokinetic modeling, to estimate normal tissue radiation exposure and provide a basis for evaluating safety."

The dosimetry study, conducted at The Norwegian Radium Hospital, part of Oslo University Hospital, evaluated how radiation from Radspherin[®] is distributed to normal tissues following treatment. Results showed that absorbed radiation doses to normal organs were below levels commonly associated with risks for complications, including for organs typically regarded as activity-limiting such as the kidneys and red bone marrow.

"We are pleased to report the results from the outstanding work performed together with Oslo University Hospital published in the prestigious Journal of Nuclear Medicine," said Kari Myren, Chief Medical Officer at Oncoinvent. "Unintended radiation exposure to normal organs, especially for the kidneys and red bone marrow, frequently represents a limitation for obtaining therapeutic doses of radiopharmaceuticals. Our results indicate very low radiation exposure to healthy organs after treatment, which is consistent with the favorable safety profile observed in our clinical trials and supports the further development of Radspherin[®] to provide hope for patients for whom very limited treatment options exist."

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For further information, please contact:

Oystein Soug, Chief Executive Officer Email: IR@oncoinvent.com

Optimum Strategic Communications Zoe Bolt, Elena Bates, Katherine Bliss +44 (0) 203 882 9621 oncoinvent@optimumcomms.com

About Oncoinvent

Oncoinvent is developing Radspherin[®], a receptor-independent alpha radiation therapy that leverages the unique anatomy of the abdominal cavity to destroy residual micrometastases using a single, highly localized dose of alpha radiation. The initial clinical focus is treatment of ovarian and colorectal cancer patients after surgical removal of the primary tumor and visible metastases in the peritoneum, the thin membrane lining the abdominal cavity and covering the abdominal organs.

This radiopharmaceutical is designed to prevent or delay recurrence in the peritoneal cavity, keeping patients disease-free for longer than the current standard of care and thereby also impacting overall survival. It is broadly applicable to any cancer that spreads to the peritoneum, e.g. ovarian, colorectal, and gastric cancers. Radspherin[®] stands out for its simplicity, excellent safety profile, and seamless integration into existing surgical workflows. Oncoinvent's product is easy to use, avoids systemic delivery and significant toxicity. It is also differentiated in being simple to manufacture, scalable, and supply de-risked.

Data from two trials in ovarian (phase 1) and colorectal (phase 1/2a) cancers, are highly promising, showing an excellent safety profile and meaningful signals of efficacy. Interim data from an ongoing, randomized, controlled phase 2 ovarian cancer trial is expected in 2026. With cost-effective manufacturing, blockbuster potential, active pharma partnership momentum, plus strong endorsements from leading experts, Oncoinvent is built for scale and commercial success, and is set to become the new standard for post-surgical cancer care. The Company was founded by the originators of Algeta and Xofigo (acquired by Bayer).

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