Dosing begins in phase 2a/2b trial of YB-101 after Yarrow Bioscience closes merger with VYNE Therapeutics

Yarrow Bioscience announced in a press release that it closed its merger with VYNE Therapeutics and dosing of patients began in a phase 2a/b trial (NCT07682896) of Graves’ disease (GD) and thyroid eye disease (TED). YB-101 has received Fast Track Designation from the FDA.

YB-101 is described as a potential first-in-class anti-thyroid stimulating hormone receptor (TSHR) monoclonal antibody that targets TSHR, a shared autoantibody target in GD and TED, YB-101 is administered subcutaneously, which, according to the company, may lessen the treatment burden. The treatment is designed to directly disrupt the central mechanism of both diseases.

The company claims that YB-101 has the potential to rapidly arrest the disease process and provide improved efficacy and safety versus the current standard of care and other mechanisms in development.

Phase 2a/b trial

In the phase 2a/b trial, patients with GD, with or without concurrent TED, will be evaluated. Data from the phase 2a portion of the trial are expected to be released in the second half of 2027.

The phase 2a trial is a randomized, blinded, placebo-controlled, proof-of-concept study that includes 32 patients across four cohorts to assess safety, pharmacokinetics, pharmacodynamics, and efficacy through 24 weeks. The study endpoints include the percentage euthyroid and off anti-thyroid drugs, plus orbitopathy measures in the patients with TED.

The phase 2b segment will investigate dosing efficacy in about 200 patients based on the part 1 results. This segment is expected to begin in the first half of 2028, according to the press release.

Yarrow’s licensing partner, Changchun GeneScience Pharmaceutical Co., is currently developing YB-101, also known as GenSci-098, to treat GD and TED in China. Changchun GeneScience Pharmaceutical Co. is evaluating YB-101 in ongoing phase 1 single ascending dose (SAD) and multiple ascending dose (MAD) trials in patients with TED and a phase 1 SAD trial in patients with GD in China.

The company reported that in the SAD portion of the TED trial, “YB-101 demonstrated a rapid, dose-dependent proof-of-mechanism and showed evidence of clinical responses in TED with a favorable safety profile. There were no clinically meaningful safety differences versus placebo in the SAD segment. These safety data supported the initiation of the MAD portion of the trial in China, and the initiation of the company’s phase 2a/2b trial in patients with GD.” The MAD data from the Changchun GeneScience Pharmaceutical Co.’s phase 1 TED trial are expected in the second half of 2027 and will determine the future development plans for YB-101 in the treatment of TED globally.

Rebecca V. Frey, PharmD, President and Chief Executive Officer of Yarrow, said, “Current treatments for GD and TED are limited, and many carry serious toxicities or fail to directly address disease-driving TSHR signaling. YB-101 offers an entirely new treatment approach through TSHR blockade, which we believe is the most direct way to disrupt the underlying disease process and has the potential to meaningfully improve outcomes for patients living with GD and TED. We look forward to executing across our development program and advancing our mission to bring transformative therapies to patients.”