Cytospire Therapeutics, a UK-based developer of multispecific antibodies that engage all subsets of gamma delta T cells, has raised £61M ($83M) in an oversubscribed Series A funding round led by 4BIO Capital. The CYT X platform powers candidates like lead asset CYT X300, an EGFR x pan-γδ T cell engager designed for solid tumors such as colorectal, head and neck, and NSCLC. The proceeds will fund IND-enabling studies, GMP manufacturing, and the first-in-human trial for CYT X300 expected in 2027.
Gamma Delta Investors Double Down
The raise arrives as investors pour capital into gamma delta T cell therapies. Lava Therapeutics has secured $204M total funding for its Vγ9Vδ2-focused bispecifics now in Phase 1, while Adicet Bio raised $389M for allogeneic gamma delta CAR-T programs in clinical trials per PitchBook data. Cytospire's pan-γδ approach, activating both blood- and tissue-resident cells including Vδ1, Vδ2, and Vδ3 subsets, targets limitations in subset-specific competitors. This broader activation promises better efficacy against patient heterogeneity in solid tumors.
CD3 Engagers Hit Solid Tumor Wall
Conventional CD3 T cell engagers excel in liquid tumors but falter in solids due to high cytokine release syndrome (CRS), poor tumor penetration, and on-target off-tumor toxicity. EGFR-positive tumors like colorectal cancer resist these therapies despite validated targets. Gamma delta T cells offer innate tumor discrimination without MHC restriction, reducing CRS risks shown in preclinical non-human primate studies. Current solutions leave 90% of solid tumor patients without effective options.
Pan-Gamma Delta Sweeps All Subsets
Cytospire's CYT X engagers bind a proprietary pan-γδ epitope, recruiting all gamma delta subsets for potent killing with minimal cytokines. Unlike Lava's circulating Vγ9Vδ2 focus or Adicet and IN8bio's cell therapies requiring manufacturing, Cytospire delivers off-the-shelf antibodies with IgG-like pharmacokinetics. Lead CYT X300 pairs EGFR targeting with pan-γδ activation, unlocking tumors resistant to CD3 bispecifics. The pipeline extends to heme malignancies (CYT X600), other solids (CYT X400), and autoimmunity (CYT X500).
As CEO Natalie Mount noted:
“What we want to achieve with the engager is to provide something in a biologic format which is very familiar to big pharma and has the ability to be scaled to be widely available to large numbers of patients.”
Oversubscribed Syndicate Signals Conviction
4BIO Capital led the round with participation from Servier Ventures in its debut investment, Abingworth, British Business Bank, and others including Sound Bioventures and LifeArc Ventures. This syndicate reflects strategic validation for Cytospire's biology, tech, and team. Owen Smith of 4BIO highlighted the build-up of conviction over two years.
As Owen Smith, Partner at 4BIO Capital, stated:
“The Series A reflects two years of conviction building… Cytospire has all three [tech, biology, team].”
Gamma Delta Therapies Eye Billions
The gamma delta T cell cancer therapy market stands at $318M in 2024, projected to reach $4.9B by 2030 at 32.6% CAGR, driven by solid tumor needs. Another estimate pegs it at $2.5B with 19% CAGR. Over 30 gamma delta programs advance in trials, though none commercialized yet. Bispecific T cell engagers overall expand into solids post-blood cancer approvals.
Team Delivers Repeat Takeda Exits
Co-founder and CEO Natalie Mount led prior ventures Adaptate Biotherapeutics and GammaDelta Therapeutics, both acquired by Takeda. This track record in gamma delta innovation de-risks Cytospire's platform. CSO James Legg presents preclinical CYT X300 data at AACR 2026.
Clinic Plans Accelerate Pipeline
Funding advances CYT X300 through IND-enabling studies toward a 2027 first-in-human trial in EGFR+ solid tumors. The company also progresses CYT X600 for hematologic cancers and explores autoimmune applications with CYT X500. Preclinical collaborations like with Humanitas bolster data for clinical proof-of-concept.