Rebecca Frey
executive
Thank you, Dave, for the introduction. On behalf of Yarrow, I want to thank you and the entire VYNE team for your partnership as we embark on this exciting transaction.
Today, we are thrilled to introduce Yarrow Bioscience and announce our planned merger with VYNE Therapeutics. At Yarrow, we are driven to develop safe and effective therapies to address unmet needs in thyroid autoimmune diseases, which produce serious, chronic and debilitating clinical sequelae. To that end, we are building a deeply experienced team of global drug developers and have in-licensed an asset with transformative clinical potential.
Our company is focused on bringing a clinical stage, potentially first-in-class TSHR antibody therapeutic to market for the treatment of both Graves' disease and thyroid eye disease or TED. Graves' disease and TED represent areas of significant unmet need for targeted therapeutics, particularly in patients who are inadequately treated with first-line therapies.
We recently in-licensed YB-101, also known as GS-098, a humanized monoclonal antibody targeting TSHR from Changchun GeneScience Pharmaceutical Company Limited, or GenSci. GenSci is currently developing YB-101 for the treatment of Graves' disease and TED in China. Through this collaboration, Yarrow has obtained global ex-China rights to develop YB-101 for both indications. YB-101 is a selective antibody to TSHR that has demonstrated promising efficacy results in preclinical models of Graves' disease and TED. This investigational product candidate is administered in a convenient subcutaneous injection and possesses a long half-life.
YB-101 is currently being evaluated in an ongoing Phase I clinical trial in TED by our partner, GenSci in China. Data from the single ascending dose portion of this trial in TED patients is expected in the first half of 2026. In parallel with GenSci's Phase I TED trial, Yarrow intends to initiate a combined Phase Ib/IIb trial of YB-101 in patients with Graves' disease in the United States and other territories in the first half of 2026.
Graves' disease is a common endocrine disease affecting an estimated 1% of the United States population. Among patients with Graves, an estimated 30% to 50% will also go on to develop TED. The current mainstay of treatment is antithyroid drugs or ATDs, which inhibit thyroid hormone synthesis.
However, ATDs are associated with dose-limiting toxicities, including hepatitis and agranulocytosis and not all patients achieve adequate disease control on ATDs. In Graves' disease, studies have shown that after 1 year, 25% or more of patients who receive first-line treatment with ATDs remain inadequately controlled and that even more patients may be refractory after 2 years.
When patients with Graves' disease cannot be adequately controlled with ATDs, their only options are tissue ablative interventions such as radioactive iodine or surgery to remove the thyroid, which both have significant safety risks. Similarly, in TED, patients are initially treated with glucocorticoids. If adequate response is not achieved, they may be treated with teprotumumab, an antibody targeting the IGF-1 receptor.
Teprotumumab is effective at improving the signs and symptoms of TED. However, it is associated with dose-limiting toxicities, including hearing impairment and hyperglycemia. It also does not directly inhibit the activity of autoantibodies at the TSH receptor. Currently, there are no approved therapies that can treat both Graves' hyperthyroidism and TED. And we believe that an easy-to-administer TSHR antibody with a favorable risk-benefit profile could become the preferred treatment for patients who are not adequately controlled on first-line therapies.
TSHR blockade directly addresses the main driver of both diseases. Both Graves disease and TED are polyclonal diseases in which autoantibodies attack and overstimulate the TSH receptor in the thyroid gland or in the eye. This overstimulation leads to hyperthyroidism and in TED oridopathy. Based on this well-characterized disease biology, TSHR is a rational target to treat both diseases because it is the final effector site regardless of autoantibody type or titer.
Recent publications of clinical trials evaluating this approach have shown that competitively blocking TSHR with a therapeutic antibody can rapidly reverse hyperthyroidism and improve signs and symptoms in patients with Graves' disease and TED. The differentiated target product profile of our TSHR antibody is a convenient subcutaneous therapy that we believe will deliver rapid and efficient reversal of hyperthyroidism along with meaningful improvement of extrahyroidal symptoms.
These effects are expected to be sustained over 4-week or longer dosing intervals, and it is expected that this benefit can be achieved with a favorable risk-benefit profile. This approach may offer a potentially rapid-acting, highly beneficial and convenient treatment option for patients with Graves' disease and TED. It represents a potential breakthrough for patients who are not adequately controlled with first-line therapies.
We believe this approach has a strong value proposition and that the addressable market across both indications represents a substantial global commercial opportunity. In conclusion, we are excited to advance YB-101 globally through our partnership with GenSci and through the planned merger with VYNE. In support of our bold vision for YB-101, we are delighted to welcome an industry-leading investor syndicate to fund our clinical progress in both indications. We look forward to working together with the VYNE team in the months ahead to prepare for the successful completion of this merger.
With that, I will conclude my remarks and hand the call back to the operator. Thank you for joining the call.