Pathios Therapeutics

Pathios Therapeutics is an Oxford-based biopharmaceutical company pursuing a first-in-class approach to cancer immunotherapy. Founded in 2017 and headquartered at the Innovation Centre on Milton Park near Oxford, the company was built around a specific scientific insight: that GPR65, a proton-sensing G protein-coupled receptor activated by the acidic microenvironment characteristic of solid tumours, plays a key role in suppressing immune cells within the tumour and allowing cancers to evade attack. By developing drugs that block GPR65, Pathios aims to restore immune function inside tumours and unlock responses in patients who do not benefit from existing checkpoint inhibitor therapies.

The company's lead asset, PTT-4256, is a potent and selective oral small molecule inhibitor of GPR65, discovered entirely in-house. Its potential complementarity with PD-1/PD-L1 checkpoint inhibitors — the current standard of care in many solid tumour indications — attracted a strategic investment from Bristol-Myers Squibb, one of the world's leading cancer immunotherapy companies. Pathios entered the clinic with PTT-4256 in first-in-human trials in late 2024, a major milestone for a company that had spent its early years building conviction in a novel and scientifically complex target.

To date, Pathios has raised over $58 million, including Series A funding from Canaan Partners and Brandon Capital, and Series B participation from Bristol-Myers Squibb. The company has also received Innovate UK grant support. Its leadership team combines scientific depth, clinical development expertise, and operational experience in drug development across the US, UK, and Australia.