At a Glance
- Company: Mestag Therapeutics
- Location: Cambridge, UK
- Deal value: 40 million USD growth financing (>95 million USD committed to date)
- Focus area: FAP‑targeted LTβR agonist bispecific MST‑0312 for solid tumours; fibroblast immunology platform
- Next steps: Phase 1 STARLYS trial in solid tumours starting mid‑2026; ongoing inflammatory disease programmes
What happened?
Mestag Therapeutics has closed a 40 million USD (around £30.1 million) financing round backed by its existing investor syndicate. The proceeds will fund the first‑in‑human Phase 1 STARLYS trial of lead asset MST‑0312 in patients with solid tumours, with study initiation planned for mid‑2026, and will also support broader platform and inflammatory disease pipeline work.
Why does it matter?
MST‑0312 is designed to remodel the tumour microenvironment by inducing tertiary lymphoid structures (TLS) and high endothelial venules (HEV), features that correlate with better survival and improved responses to immunotherapy in multiple cancer types. If this approach translates clinically, it could help turn “cold” tumours into immune‑responsive lesions and act as a potentiator for checkpoint inhibitors and other immuno‑oncology drugs.
Who’s behind it?
Mestag is a fibroblast‑immunology‑focused biotech founded and backed by investors including SV Health Investors, Johnson & Johnson Innovation, Forbion, GV and Northpond Ventures. The company has also built a fibroblast‑immune “RAFT” discovery platform and has an ongoing research collaboration with Merck & Co. (MSD) in inflammatory disease, underscoring pharma interest in its stromal‑targeted biology.
How was it achieved?
MST‑0312 is a FAP‑targeted bispecific antibody that agonises lymphotoxin‑β receptor (LTβR) on stromal cells, with the goal of driving TLS and HEV formation and recruiting and activating lymphocytes within tumours. Preclinical data show robust, dose‑dependent anti‑tumour activity as monotherapy, including in low‑antigen “cold” tumours, supporting progression into the STARLYS Phase 1 trial across lung, skin, bladder, breast and colorectal cancers that express fibroblast activation protein.
What’s next?
The Phase 1 STARLYS study will evaluate safety, pharmacokinetics and early signs of activity for MST‑0312 in solid tumours, while generating translational data on TLS/HEV induction and immune remodelling. In parallel, Mestag plans to advance additional fibroblast‑directed programmes in oncology and inflammatory disease, leveraging the new capital and recently appointed clinical development leaders to build a broader pipeline if MST‑0312’s mechanism is validated in humans.