Ethyreal Bio

Ethyreal Bio is a clinical-stage biotechnology company focused on developing precision therapies for thyroid diseases. The company emerged from stealth on June 10, 2026, securing $101 million through two financing rounds. The Series A was co-led by Atlas Venture and Medicxi Ventures, with participation from Nandi Life Sciences and Checkpoint Capital. The Series B was led by Avoro Capital, which was joined by all the Series A investors. The company is headquartered in Cambridge, Massachusetts. The leadership team includes Chief Executive Officer Niranjan Kameswaran, Ph.D., who was previously an Entrepreneur-in-Residence at Atlas Venture and held senior roles at Kala Pharmaceuticals and Civitas Therapeutics. The board is chaired by Simon Read, Ph.D., an independent director. Ethyreal Bio's core business revolves around its lead asset, ETHY-001, a monoclonal antibody designed to block the thyroid-stimulating hormone receptor (TSHR). This receptor is the shared pathogenic driver of both Graves' disease (GD) and thyroid eye disease (TED). By targeting the underlying cause, ETHY-001 has the potential to be a single, mechanism-driven therapy for both conditions, which often coexist but are typically treated separately. Graves' disease is a common cause of hyperthyroidism, while thyroid eye disease is a debilitating orbital condition that can affect a significant portion of Graves' patients. ETHY-001 is formulated for convenient, low-volume subcutaneous administration via a planned autoinjector. It also incorporates half-life extension technology to allow for infrequent dosing. Preclinical data presented in June 2026 demonstrated that ETHY-001 completely blocks autoantibody-mediated TSHR activation and shows a differentiated activity profile compared to other treatments. The company plans to initiate first-in-human clinical trials in the second half of 2026. Keywords:Monoclonal antibody, thyroid stimulating hormone receptor, TSHR, Graves' disease, thyroid eye disease, autoimmune disease, ETHY-001, subcutaneous administration, Niranjan Kameswaran, Atlas Venture, Medicxi Ventures, Avoro Capital, clinical-stage biotech, hyperthyroidism, endocrinology, orbital fibroblasts, half-life extension, autoinjector, TSHR antagonist, biopharmaceutical