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British Business Bank invests £12m in Cytospire Therapeutics

Press release 05 May 2026

The British Business Bank has invested £12 million in Cytospire Therapeutics (Cytospire), a UK based biotech company, as part of a £61 million ($83m) Series A financing round.

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

Cytospire develops differentiated multispecific immune cell engager antibodies designed to enhance and direct the activity of the body’s own immune system. Cytospire will use the proceeds of the round 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.

In connection with the financing, Carmine Circelli, Investment Director, British Business Bank has been appointed to Cytospire’s Board of Directors.

Charlotte Lawrence, Managing Director of Direct Equity at British Business Bank, said:

Immune engagers are poised to become a foundational pillar of oncology, and the UK’s biotech ecosystem is well positioned to deliver them. Our investment in Cytospire provides the crucial capital needed to advance the efficacy and safety of these complex biologics, helping to maintain the UK’s global edge and reinforcing the Bank’s commitment to supporting innovative life sciences platforms with break-out potential.

Carmine Circelli, Investment Director, British Business Bank, said:

Cytospire is developing a highly differentiated approach to immune cell engagers, targeting multiple subtypes of gamma delta T cells to unlock effective cancer immunotherapies. The team combines deep scientific expertise with strong experience of developing multispecific antibodies, and their lead programme has the potential to address a significant unmet medical need.

Natalie Mount, Chief Executive Officer of Cytospire Therapeutics, said:

We are excited to write the next chapter of Cytospire’s story with this fantastic group of specialist investors. 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.

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Notes to editors

About the British Business Bank 

The British Business Bank is the UK government’s economic development bank. Established in November 2014, its mission is to drive economic growth by helping smaller businesses get the finance they need to start, scale and stay in the UK. In doing so, we help capture the economic value of innovation for the UK and create jobs and prosperity for people across the country.  

The British Business Bank’s core programmes support £23bn 1  of finance to almost 64,000 2  smaller businesses. 

British Business Bank plc is a public limited company registered in England and Wales, registration number 08616013, registered office at Steel City House, West Street, Sheffield, S1 2GQ. It is a development bank wholly owned by HM Government. British Business Bank plc and its subsidiaries are not banking institutions and do not operate as such. With the exception of BBB Investment Services Limited they are not authorised or regulated by the Prudential Regulation Authority or the Financial Conduct Authority. BBB Investment Services Limited is authorised and regulated by the Financial Conduct Authority. A complete legal structure chart for the group can be found at british-business-bank.co.uk.  

British Patient Capital Limited is registered in England and Wales with company number 11271076, and registered office at Steel City House, West Street, Sheffield, S1 2GQ. British Patient Capital makes commitments and invests on its own behalf and on behalf of third-party investors whose investments British Patient Capital manages. 

The transaction described above does not constitute or imply any endorsement, warranty or recommendation by the UK government, the British Business Bank plc, its subsidiaries or any other party in respect of Cytospire Therapeutics or its products or services.

About Cytospire Therapeutics

Cytospire is developing an innovative portfolio of differentiated multispecific engager antibodies to enhance and direct the activity of innate and adaptive effector immune cells.  Our core technology allows binding and activation of both tissue/tumour and blood resident gamma delta T cells. This opens a path to safer and more efficacious targeting of well-validated antigens that are intractable to CD3 T cell engagers due to toxicity. There are broad opportunities for Cytospire’s gamma delta T cell engagers in solid and haematological malignancies, as well as in autoimmune disease. 

Based in London, UK, Cytospire Therapeutics is backed by a strong syndicate of life science investors including Abingworth, 4BIO Capital, Servier Ventures, British Business Bank, Sound Bioventures, LifeArc Ventures and Criteria Bio Ventures.

For more information, visit cytospire.com

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