Alethio Therapeutics closed an oversubscribed $90 million Series A to fund development of its lead antibody program, ATX-011, targeting G6B in essential thrombocythemia (ET). The University of Oxford spinout plans to move ATX-011 through Phase I/IIa studies and aims for Phase III readiness. ATX-011 is designed to lower platelet counts by boosting platelet clearance, and Alethio says G6B expression is present on ET-relevant cellular populations while sparing healthy ones. The company positions the antibody as a targeted alternative in ET, where treatment options remain limited and response rates with hydroxyurea are variable. The financing is intended to complete IND-enabling work and generate first-in-patient data, with investors including Sofinnova Partners and RA Capital as co-leads, plus participation from Oxford Science Enterprises and Cancer Research Horizons. For rare blood disorder development, the round highlights continued capital flow into mechanism-defined programs where existing standard-of-care therapy is described as blunt and slow to work.