Ethyreal Bio has emerged from stealth with $101M in financing to advance ETHY-001, a potentially best-in-class anti-TSHR monoclonal antibody for Graves’ disease (GD) and thyroid eye disease (TED). The Cambridge, Mass.–based company is developing precision therapies for thyroid diseases with high unmet need and plans to begin first-in-human clinical trials of ETHY-001 in the second half of 2026. The financing includes a Series A co-led by Atlas Venture and Medicxi Ventures with participation from Nandi Life Sciences and Checkpoint Capital, and a Series B led by Avoro Capital with continued support from all Series A investors. Preclinical data for ETHY-001 will be presented in an oral session at the Endocrine Society’s ENDO 2026 meeting in Chicago on June 15.
ETHY-001 is designed to block autoantibody-mediated activation of the thyroid stimulating hormone receptor (TSHR), the shared pathogenic driver of both GD and TED, with the goal of comprehensively halting disease activity. The antibody is formulated for patient-friendly low-volume subcutaneous administration, with plans for an autoinjector, and incorporates half-life extension technology intended to support infrequent dosing and durable disease control. Ethyreal’s leadership believes this mechanism-driven approach can address both hyperthyroidism associated with GD and the ophthalmic manifestations of TED in a single therapy, an area where current treatments typically address only one condition or the other.
Chief Executive Officer Niranjan Kameswaran, Ph.D., said GD and TED are prevalent, debilitating conditions that frequently co-exist in the same patient, yet existing therapies for GD do not prevent or treat TED and TED-directed treatments do not tackle GD-related hyperthyroidism. He noted that ETHY-001 is designed to target the underlying autoimmune driver by blocking pathogenic stimulating autoantibodies to TSHR, with the aim of improving outcomes across both diseases. Kameswaran added that, with a purpose-built team and strong investor backing, the company is focused on rapid, disciplined execution to move ETHY‑001 into the clinic in the second half of 2026.
Board Chairman Simon Read, Ph.D., said Ethyreal has assembled an accomplished management team and seasoned Board of Directors with the scientific, clinical and company-building experience to translate compelling biology into transformative medicines. He highlighted ETHY-001’s differentiated profile and its potential to treat two closely related, debilitating conditions as a unique value proposition, and noted the company’s “healthy capital position” and rapid progress since inception. Ethyreal’s leadership team includes Kameswaran as CEO, Jessica Stromme as chief development officer, Kelly Foster, Ph.D., as senior vice president of translational medicine, and Stephen Huang, M.D., as senior vice president of clinical development.
The Board of Directors comprises independent and investor representatives, including Read as chairman; Mark Chin, partner and head of Avoro Ventures; Michael Gladstone, partner at Atlas Venture; Jernej Godec, Ph.D., principal at Atlas Venture; Kameswaran; Karen Smith, M.D., Ph.D., M.B.A., L.L.M., as an independent director; and Nick Williams, M.Pharm, Ph.D., partner at Medicxi Ventures. Read said the Board has strong conviction in Ethyreal’s ability to execute with focus and urgency and to establish itself as the leading company in GD and TED.
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