Oslo, Norway, 8 December 2025 - Oncoinvent, a clinical stage,
radiopharmaceutical company developing innovative treatments for solid cancers,
today announced the publication of 12-month data from its Phase 1 study of
patients with platinum-sensitive recurrent ovarian cancer and peritoneal
carcinomatosis. The results from the first patients have been published in the
respected peer-reviewed journal Gynecologic Oncology, under the title: "First
experience with intraperitoneal 224Ra-labeled microparticles after cytoreductive
surgery in patients with peritoneal recurrence of platinum-sensitive epithelial
ovarian
cancer (https://www.sciencedirect.com/science/article/pii/S0090825825011023)."

"We are proud to announce that our article has been published in Gynecologic
Oncology. This recognition underscores the importance of our research and
validates our ongoing efforts. As our phase 2 study progresses in patients with
peritoneal metastasis from ovarian cancer, we remain fully committed to
advancing new treatment options to address this urgent medical need," said Kari
Myren, Chief Medical Officer at Oncoinvent.

The primary objectives of the phase 1 study were to evaluate the safety and
tolerability of the alpha emitting therapy using [224]Ra-labeled microparticles
(Radspherin®)[ ]and to determine the recommended dose for subsequent clinical
development. Initial experiences indicate that all dose levels were well
tolerated, no dose limiting toxicity was observed during dose escalation and the
highest dose of 7 MBq was selected as the recommended dose for the expansion
phase.  Alongside the now published  12-month data, Oncoinvent has also released
topline 24-month follow-up data for the phase 1
study (https://www.oncoinvent.com/press-release/oncoinvent-reports-positive
-final-data-from-phase-1-trial-of-radspherin-to-treat-ovarian-cancer/) in
ovarian cancer patients.

A randomized controlled phase 2 study is ongoing to evaluate the efficacy and
safety of Radspherin® in patients with peritoneal metastasis from ovarian
cancer. The primary aim is to compare progression-free survival (PFS) between
two groups: those who receive Radspherin® following complete surgical resection
after pre-operative chemotherapy, and those treated with pre-operative
chemotherapy and surgery alone. Further details can be found at
clinicaltrials.gov (https://clinicaltrials.gov/study/NCT06504147).

For further information, please contact:
Øystein Soug, Chief Executive Officer
Email: soug@oncoinvent.com

Renate Birkeli, Director Investor Relations
Email: birkeli@onconinvent.com

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

About Oncoinvent

Oncoinvent is a clinical-stage biotechnology company developing novel
radiopharmaceutical therapies against cancer. The lead product candidate,
Radspherin®, uses the alpha-emitting radionuclide radium-224, directly targeting
micro-metastases post-surgery, harnessing the benefits of modern
radiopharmaceuticals without the complexities of biological targeting.
Oncoinvent is investigating the safety and efficacy of Radspherin® in a clinical
development program in two indications. One Phase 1 trial and one Phase 1/2a
trial have been completed and one randomized Phase 2 trial is currently ongoing
in the US, UK and Europe. Early clinical efficacy data are highly encouraging,
and no serious toxicity or safety concerns have been reported to date. The
Oncoinvent team consists of approx. 40 employees and runs a state-of-the-art
manufacturing facility to produce drug products for clinical trials in Nydalen,
Oslo. Oncoinvent is listed on the Oslo Stock Exchange.

About Radspherin

Radspherin® is an investigational radiopharmaceutical designed for the local
treatment of cancer that has spread to body cavities. It consists of calcium
carbonate microparticles containing the radioactive material radium-224. The
mode of action is the decay of radium-224 emitting alpha-particles, a highly
potent form of ionizing radiation. Radspherin® is investigated in clinical
studies to treat peritoneal carcinomatoses from ovarian and colorectal cancer
and it is administered intraperitoneally after surgical resection with removal
of all macroscopic tumors.

Forward-Looking Statements

All statements other than statements of historical facts contained in this press
release are forward-looking statements and are not a representation that
Oncoinvent's plans, estimates, or expectations will be achieved. These forward
-looking statements represent Oncoinvent's expectations as of the date of this
press release, and Oncoinvent disclaims any obligation to update the forward
-looking statements. These forward-looking statements are subject to known and
unknown risks and uncertainties that may cause actual results to differ
materially, including with respect to whether the results of clinical or other
studies will support the use of our product offerings, the impact of results of
such studies, our expectations of the reliability, accuracy and performance of
our tests, or of the benefits of our tests and product offerings to patients,
providers and payers.