Mestag Therapeutics raises £30.1m to test FAP-targeted bispecific remodelling tumour environment
This article covers Mestag Therapeutics, a Cambridge biotech startup, which has closed a growth funding round of £30.1m ($40m), bringing total committed capital to £71.4m. The financing will fund its Phase 1 STARLYS study of MST-0312 and support ongoing platform and inflammatory disease programmes focused on fibroblast immunology.
Mestag Therapeutics, a Cambridge biotech startup, has closed a growth funding round of £30.1m ($40m), bringing total committed capital to £71.4m. The money will bankroll the company’s Phase 1 STARLYS study of MST-0312 — a FAP-targeted bispecific antibody aimed at remodelling the tumour microenvironment — and support ongoing platform and inflammatory disease work. The round matters because it pairs experienced drug developers with corporate and specialist life science investors as Mestag prepares to enter the clinic.
Why it matters
Mestag is advancing an approach that targets fibroblast immunology to change immune architecture inside solid tumours. If MST-0312 can reliably induce tertiary lymphoid structures and high endothelial venules, it could improve responses to existing immunotherapies in tumours that are often resistant today. The financing and the hires that accompany it suggest investors are willing to back more complex, biology-driven strategies beyond checkpoint inhibition.
The deal also reflects continued interest from biotech investors and corporate venture capital in first-in-human programmes that address the tumour microenvironment, a growing subtheme in oncology investing.
Inside the product
MST-0312 is described by the company as a FAP-targeted bispecific antibody that engages lymphotoxin-β receptor (LTBR) to induce tertiary lymphoid structures (TLS) and high endothelial venules (HEV) within tumours. Clinical and translational studies have repeatedly found correlations between the presence of TLS or HEV and improved patient survival and better responses to therapy, which is why inducing those structures is an attractive therapeutic hypothesis.
The STARLYS study is planned to start mid-2026 and will be a Phase 1 trial in cancer patients. Beyond MST-0312, Mestag’s platform work focuses on fibroblast-directed biology with programs in both oncology and inflammatory disease, positioning the company to develop multiple antibodies if the initial mechanism translates clinically.
Who are the investors?
The £30.1m financing was announced with backing from a syndicate that includes SV Health Investors, Johnson & Johnson (via Johnson & Johnson Innovation – JJDC, Inc.), Forbion, GV (formerly Google Ventures) and Northpond Ventures. The round increases Mestag’s total committed funding to £71.4m (more than $95m).
Investor rationale given in the announcement centres on supporting the STARLYS clinical trial and the company’s broader platform work in fibroblast immunology. The presence of a strategic corporate investor in JJDC signals pharma-level interest in the modality, while the mix of specialist life science firms provides both sector expertise and development experience.
If you're researching potential backers in this space:
- Explore our list of biotech venture capital firms in the UK
- Browse our directory of biotech angel investors in the UK
Founder perspective
In the announcement, Susan Hill, PhD, Chief Executive Officer of Mestag Therapeutics, said:
We are thrilled to welcome Lindsey and Pascal to the team at this exciting time as we progress our groundbreaking program MST-0312 into the STARLYS clinical trial. We thank our exceptional investor syndicate for their unwavering support of our mission to develop impactful new antibody therapeutics for patients with cancer and inflammatory disease. Lindsey’s extensive experience leading global development, medical affairs and regulatory affairs across multiple programs, including regulatory approval, will be instrumental in shaping the advancement of our clinical programs. Additionally, we welcome Pascal, with his breadth and depth of expertise in cancer and inflammatory disease, to drive our development activities, including our innovative pipeline and platform uniquely focused on fibroblast immunology.
Mestag has also expanded its leadership team. Lindsey Rolfe joins as Chief Medical Officer; she has led global development and regulatory activities at companies including Clovis Oncology, where she helped secure marketing approvals for the PARP inhibitor Rubraca in ovarian and prostate cancer. Pascal Merchiers, Chief Development Officer, brings more than 25 years of discovery and preclinical development experience, including stints at Oncurious and Tusk Therapeutics, the latter acquired by Roche in 2018 for £570.5m. Both hires add late-stage development and regulatory know-how that the company will need as it opens its first-in-human study.
The bigger picture
The round highlights two wider trends in the UK and European biotech ecosystem: growing appetite for clinical-stage investments in novel immuno-oncology mechanisms and continued participation from corporate venture arms alongside specialist life science funds. Cambridge remains a hub for such activity, and Mestag’s ability to recruit senior drug development executives underlines the region’s deep talent pool.
As the STARLYS trial begins, investors and observers will be watching whether fibroblast-focused approaches can deliver the kind of translational readouts that justify broader deployment in combination with existing therapies. The outcome will influence not only Mestag’s trajectory but investor enthusiasm for similar tumour microenvironment strategies across the UK and Europe.
They've invested in Mestag Therapeutics
Get to know these biotech investors
| Investor | Sector | Stage | Activity | Team | Connect |
|---|---|---|---|---|---|
 SV Health Investors | 7 investments investments | 6 contacts contacts | |||
 Johnson & Johnson Innovation – JJDC | 2 investments investments | more info | |||
 Forbion | 15 investments investments | more info | |||
 GV (formerly Google Ventures) | 1 investment investment | more info | |||
 Northpond Ventures | 2 investments investments | more info | |||
Google Ventures | 21 investments investments | 14 contacts contacts |
Click here for a full list of 7,526+ startup investors in the UK