Alethio Therapeutics closed an oversubscribed $90 million Series A to fund development of ATX-011, a first-in-class monoclonal antibody targeting G6B for essential thrombocythaemia (ET). The Oxford University spinout plans Phase I/IIa studies and aims to reach Phase III readiness by advancing IND-enabling work and first-in-patient data. ATX-011 is designed to lower platelet counts by enhancing platelet clearance via G6B, with Alethio also asserting the target’s presence on myeloproliferative neoplasm (MPN)-initiating stem cells. The company positions the program as a potential alternative to hydroxyurea, citing limitations in response rates and thrombotic events. Sofinnova Partners and RA Capital co-led the round, with Oxford Science Enterprises joining as a founding backer and Cancer Research Horizons and the University of Oxford providing additional support. The financing gives Alethio runway to convert a biology-driven hypothesis into early clinical evidence.