Company: StimOxyGen
Location: Northern Ireland
Founders: Dr. Sian Farrell, Dr. Tony McHale and Dr. Les Russell.
Written by: Lucy Ahern
Edited by: Caroline Babisz & Natasha Barrow
Up to 90% of solid tumours are hypoxic, meaning they are starved of oxygen. This poses a major challenge for cancer treatment. Radiotherapy, one of the most common frontline cancer therapies, relies on the conversion of oxygen to reactive oxygen species (ROS) that damage cancer cells’ DNA. Without sufficient oxygen, radiotherapy is far less effective [1].
StimOxyGen, a biotech startup based in Northern Ireland, are addressing this with their injectable, oxygen-releasing nanoparticles, designed to temporarily reoxygenate solid tumours. At the heart of their innovation is SGEN-33, a therapeutic that delivers short, targeted bursts of oxygen directly into hypoxic solid tumours, increasing the efficacy of radiotherapy.
"We can boost the effects of radiotherapy by up to 300%" said Dr. Sian Farrell, CEO of StimOxyGen, at the SEC summit 2025.
Tumour hypoxia also plays a role in immunosuppression, meaning that low oxygen helps tumours to hide from the immune system [2]. This is especially critical in pancreatic cancer, which is often both hypoxic and immunosuppressed, making it a particularly aggressive and treatment-resistant form of cancer [3]. SGEN-33 has shown early promise in re-sensitising tumours to currently available therapies.
StimOxyGen was spun out of Ulster University in March 2021. Dr Sian Farrell was closely involved in the early development of the oxygen-releasing nanoparticle technology during her PhD and went on to lead its commercialisation alongside co-founders Dr. Tony McHale and Dr. Les Russell.
This technology originally focused on photodynamic therapy, a light-activated treatment [4] with limited market potential. StimOxyGen were supported by ICURe, a commercialisation programme supporting early career scientists, where they had extensive conversations with industry, clinicians, and academics (including collaborators at the University of Oxford) and they recognised an unmet need in radiotherapy.
This pivot unlocked a vastly larger market and therapeutic impact. Since then, StimOxyGen have steadily gained momentum and secured a £1.5m seed round in early 2024 led by DSW Ventures.
StimOxyGen have a clear pipeline for expansion. With radiotherapy as their initial clinical application, the team are currently scaling up manufacturing, preparing for GLP toxicology studies, and beginning discussions with the US FDA with the goal of undergoing clinical trials in the US. Beyond radiotherapy, StimOxyGen have promising preclinical data supporting expansion into SGEN-33’s potential to enhance a range of other cancer treatments.
StimOxyGen are currently expanding the team and are seeking exceptional scientists to join them in their journey. They will be fundraising for their next round (series A) mid 2026.
Want to see StimOxyGen's technology in action? Watch the video here.
1. Harrison, L. B., Chadha, M., Hill, R. J., Hu, K. & Shasha, D. Impact of Tumor Hypoxia and Anemia on Radiation Therapy Outcomes. The Oncologist 7,492–508 (2002).
2. Fu, Z., Mowday, A. M., Smaill, J. B., Hermans, I. F. & Patterson, A. V. Tumour Hypoxia-Mediated Immunosuppression: Mechanisms and Therapeutic Approaches toImprove Cancer Immunotherapy. Cells 10, 1006 (2021).
3. Sadozai, H. et al. High hypoxia status in pancreatic cancer is associated with multiple hallmarks of an immunosuppressive tumor microenvironment. Front.Immunol. 15, 1360629 (2024).
4. Photodynamic therapy (PDT). nhs.ukhttps://www.nhs.uk/tests-and-treatments/photodynamic-therapy/ (2017).
5. DSWVentures - Regional Investments, Global Vision - Early-Stage VC. https://dsw.vc.
6. StimOxyGen - Oxygen-Generating Nanoparticles for Enhanced Treatment of Cancer. (2020).
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