Cytospire Lands £61M to Revolutionize Cancer Immunotherapy

LONDON, UK – May 05, 2026 – UK-based biotech firm Cytospire Therapeutics has successfully closed an oversubscribed £61 million ($83 million) Series A financing round to advance a new class of cancer immunotherapies designed to be both safer and more effective than current options. The investment, led by specialist venture firm 4BIO Capital, will fuel the development of Cytospire’s pioneering pan-gamma delta T cell engagers, with its lead candidate, CYT X300, poised to enter clinical trials for hard-to-treat solid tumors.

The significant financing highlights surging investor confidence in a novel approach that aims to overcome the critical safety and efficacy hurdles that have limited the potential of conventional T cell therapies. The powerful syndicate includes new investors Servier Ventures, Sound Bioventures, the British Business Bank, and Criteria Bio Ventures, joining existing backers Abingworth and LifeArc Ventures in a strong endorsement of the UK's burgeoning life sciences sector.

A New Weapon in the Immune Arsenal

At the heart of Cytospire’s innovation is a fundamentally different way of harnessing the immune system to fight cancer. For years, immunotherapies known as CD3 T cell engagers have shown promise by redirecting a patient's T cells to attack tumors. However, their widespread use has been hampered by severe side effects, including life-threatening cytokine release syndrome (CRS) and damage to healthy tissues that also express the target protein.

Cytospire is sidestepping these challenges by focusing on a unique and powerful subset of immune cells: gamma delta (γδ) T cells. Unlike conventional T cells, γδ T cells possess an innate ability to distinguish between cancerous and healthy cells, even when both express the same target antigen. They do this by recognizing stress signals that are uniquely present on malignant cells, acting as a natural safety switch.

The company's platform engineers multispecific antibodies that act as a bridge, binding to a tumor cell on one end and activating the body’s entire fleet of γδ T cells on the other. This "pan-gamma delta" approach engages all subtypes of these specialized immune cells, including those residing in tissues near the tumor and those circulating in the blood. This strategy is designed to mount a broader, more robust anti-tumor assault, particularly within the complex microenvironment of solid tumors where other therapies often fail to penetrate effectively.

"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," said Natalie Mount, Chief Executive Officer of Cytospire Therapeutics. "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."

Targeting Hard-to-Treat Solid Tumors

The newly secured funds will be primarily directed toward advancing Cytospire's lead program, CYT X300, through final preclinical studies, GMP manufacturing, and into a first-in-human clinical trial. CYT X300 targets the epidermal growth factor receptor (EGFR), a well-validated protein that is overexpressed in a variety of solid tumors, including colorectal, head and neck, and non-small cell lung cancers (NSCLC).

While several drugs targeting EGFR already exist, their effectiveness is often limited by acquired resistance and significant toxicities, as EGFR is also present on healthy skin and gut cells. Cytospire’s technology aims to solve this long-standing problem. By leveraging the inherent selectivity of γδ T cells, CYT X300 is designed to kill only the EGFR-positive cancer cells, while sparing healthy cells. Preclinical studies, including in non-human primates, have already indicated a favorable safety profile, free from the severe toxicities that have plagued EGFR-targeting CD3 engagers.

This offers new hope for large patient populations. The market for EGFR-positive NSCLC alone is projected to exceed $32 billion by 2032, yet the development of resistance to current tyrosine kinase inhibitors (TKIs) remains a major clinical challenge. Similarly, in head and neck and colorectal cancers, existing anti-EGFR therapies offer only modest benefits for specific patient subgroups. CYT X300 could provide a vital new treatment option for patients who have exhausted current therapies or cannot tolerate their side effects.

A Vote of Confidence in UK Biotech

The oversubscribed nature of the financing and the caliber of the investor syndicate represent a major validation of Cytospire's platform and its experienced leadership team. The round was led by 4BIO Capital, a firm specializing in advanced therapies, which has backed Cytospire since its seed stage.

"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 a 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."

The participation of the British Business Bank underscores a national strategic interest in nurturing high-potential domestic life sciences companies and cementing the UK's position as a global biotech hub. The inclusion of corporate venture arms like Servier Ventures, alongside specialist international funds, further signals broad market recognition of the technology's disruptive potential. This diverse support system provides not just capital, but also a network of strategic expertise to guide Cytospire as it transitions into a clinical-stage company.

The company is led by CEO Natalie Mount and CTO Mark Uden, a team with a proven track record in the gamma delta T cell space, having previously led two companies, GammaDelta Therapeutics and Adaptate Biotherapeutics, to successful acquisitions by Takeda. This history of scientific and commercial success provides a strong foundation of credibility as Cytospire prepares to take its innovative science from the lab to patients in need. The financing announced today provides the necessary runway to achieve this critical milestone.