4BIO Capital leads oversubscribed £61 million ($83m) Series A financing of Cytospire Therapeutics

·       4BIO Capital joined by new investors Servier Ventures, Sound Bioventures, British Business Bank and Criteria Bio Ventures, supported by existing investors Abingworth and LifeArc Ventures

·       Cytospire’s novel pan-gamma T cell engagers offer a compelling solution to the efficacy and safety challenges faced by conventional T cell engagers

·       New financing will accelerate Cytospire’s pipeline in solid and liquid tumours, including advancement of lead program, CYT X300 targeting EGFR-positive cancers, to clinical proof-of-concept

London, United Kingdom, 5 May 2026 - 4BIO Capital, a specialist biotech venture firm transforming innovative technologies into breakthrough precision therapies, today announces that its portfolio company, Cytospire Therapeutics (‘Cytospire’), a UK based biotech developing differentiated multispecific immune cell engager antibodies designed to enhance and direct the activity of the body’s own immune system, has closed an oversubscribed £61 million ($83 million) Series A financing supported by a strong syndicate of new and existing biotech investors.

Cytospire will use the proceeds to advance its pipeline of first-in-class pan-gamma delta T cell engagers, including its lead programme, CYT X300, which is currently being advanced through IND-enabling preclinical studies and GMP manufacturing. A first-in-human clinical study is being planned to evaluate CYT X300 as a treatment for EGFR-positive solid tumours, such as colorectal, head and neck and non-small cell lung cancers.

The round was led by 4BIO Capital, with significant investment from new syndicate members Servier Ventures, British Business Bank, Sound Bioventures and Criteria Bio Ventures, as well as from existing investors Abingworth, which originally seeded Cytospire, and LifeArc Ventures. Modi Ventures, Medical Incubator Japan and Pathway Bioventures also join the round as new investors. 

“Cytospire brings together exceptional science with a highly experienced management team with a strong track record of delivery and we are delighted to lead this round,” commented Owen Smith, Partner at 4BIO Capital and Board Member at Cytospire. “The company is developing a differentiated approach to cancer immunotherapy, supported by early data, and is now focused on translating that into the clinic. This is 4BIO's investment thesis in action, and we are proud to back the team as CYT X300 moves towards first in human studies.”

“We are excited to write the next chapter of Cytospire’s story with this fantastic group of specialist investors. I would like to thank the 4BIO team for their continued support that has been instrumental as Cytospire has progressed,” said Natalie Mount, Chief Executive Officer of Cytospire Therapeutics. “Immune cell engagers are an important type of cancer immunotherapy, but we know that there are significant limitations from both an efficacy and safety perspective with conventional CD3 T cell engagers. We are building on the growing body of translational and clinical data showing gamma delta T cells are critical components of the anti-cancer immune response, with biology ideally suited to novel cell engagers. The significant fundraise that we are announcing today reflects the quality of our team and our science, and the huge potential of our pan-gamma delta T cell engagers.”

Cytospire’s pan-gamma delta T cell engagers are uniquely engineered to target all gamma delta T cells rather than specific subtypes. Through this approach, Cytospire seeks to overcome patient heterogeneity and generate broader, more effective anti‑tumour immune responses through the activation of both tissue/tumour resident and blood resident effector cells.