Connecticut-based Yarrow Bioscience, Inc. (Nasdaq: YARW) has closed its reverse merger with VYNE Therapeutics and simultaneously initiated dosing in a Phase IIa/IIb trial of YB-101, an anti-TSHR monoclonal antibody targeting both Graves' disease and thyroid eye disease. The combined US company begins trading on the Nasdaq Capital Market under the ticker YARW on July 28, 2026. The transaction used VYNE, a Nasdaq-listed shell, as the public vehicle for Yarrow, which retains its name and pipeline as the surviving entity. Unlike currently approved TED therapies that target IGF-1R, YB-101 directly blocks TSHR, the initiating autoantigen in Graves' disease, potentially allowing treatment of both hyperthyroidism and thyroid eye disease with a single antibody.
Pre-closing private placements totaling approximately USD 200 million funded the transaction, led by RTW Investments with participation from OrbiMed, Janus Henderson Investors, venBio Partners, Logos Capital, LifeSci Venture Partners, and Perceptive Advisors. Legacy VYNE stockholders received a special cash dividend of USD 17.3 million (approximately USD 0.40 per share), distributed on July 23, 2026. Yarrow's cash is expected to fund operations into 2028.
YB-101 is a subcutaneous anti-thyroid stimulating hormone receptor (TSHR) monoclonal antibody designed to block the autoantibody-driven TSHR signaling that drives both Graves' disease thyroid dysfunction and the orbital inflammation characteristic of TED. The Phase IIa/IIb trial (NCT07682896) is a randomized, placebo-controlled study enrolling 32 patients across four cohorts in Part 1, evaluating safety, pharmacokinetics, pharmacodynamics, and efficacy through 24 weeks, with Phase IIa data expected in H2 2027. YB-101 has received FDA Fast Track Designation. China-based Changchun GeneScience Pharmaceutical Co., Ltd. (GenSci) holds a license to develop YB-101 (also designated GenSci-098) in China, where a Phase I single and multiple ascending dose trial in TED patients demonstrated dose-dependent proof-of-mechanism and a favorable safety profile in the single ascending dose cohort; MAD data are also expected in H2 2027.