Alethio Therapeutics, an Oxford University spinout, has raised $90 million in a Series A to advance its lead program for essential thrombocythemia, a rare myeloproliferative neoplasm. The company emerged from stealth about a year ago and is positioning its antibody asset to address a group of conditions where durable disease control remains challenging. The financing underscores investor appetite for early-stage rare hematology targets, particularly antibodies that can be differentiated by depth of response and potential durability. Alethio is using the capital to drive clinical development and supporting translational work through key milestones. The round also signals a renewed focus on myeloproliferative neoplasms as biotech investors continue to broaden rare disease portfolios beyond single-disease, single-biomarker bets.