Yarrow Bioscience Completes Merger with VYNE Therapeutics and Secures Approximately $200 Million to Advance First-in-Class Autoimmune Thyroid Disease Program
Yarrow Bioscience, Inc., a clinical-stage biotechnology company dedicated to developing innovative therapies for autoimmune thyroid diseases, has announced the successful completion of its merger with VYNE Therapeutics Inc., marking a significant milestone in the company’s evolution. Simultaneously, Yarrow finalized previously announced private financing transactions totaling approximately $200 million, providing substantial financial resources to support the continued development of its lead investigational therapy, YB-101, and its broader strategic objectives.
Following the completion of the transaction, the combined organization will operate under the name Yarrow Bioscience, Inc., with its common stock expected to begin trading on the Nasdaq Capital Market under the ticker symbol “YARW.” The merger creates a well-capitalized biotechnology company focused exclusively on advancing therapies for autoimmune thyroid disorders, particularly Graves’ disease (GD) and thyroid eye disease (TED), two conditions that continue to present significant unmet medical needs despite currently available treatment options.
The completion of the merger, together with the successful financing, establishes a strong foundation for Yarrow as it advances multiple clinical development programs and prepares for several important milestones over the next several years.
Establishing a Company Focused on Autoimmune Thyroid Diseases
Autoimmune thyroid diseases affect millions of individuals worldwide and remain among the most common autoimmune disorders. Graves’ disease occurs when the immune system mistakenly produces antibodies that overstimulate the thyroid-stimulating hormone receptor (TSHR), causing excessive thyroid hormone production, or hyperthyroidism. In many patients, the same autoimmune process also affects tissues surrounding the eyes, leading to thyroid eye disease, a debilitating condition characterized by inflammation, eye protrusion, pain, double vision, and, in severe cases, vision impairment.
Although several treatment options exist for both Graves’ disease and thyroid eye disease, many therapies focus primarily on symptom management rather than directly targeting the underlying autoimmune mechanism responsible for disease progression. Current treatment strategies often include anti-thyroid medications, radioactive iodine therapy, surgery, corticosteroids, and biologic therapies, each associated with varying levels of effectiveness and potential adverse effects.
Yarrow’s scientific strategy centers on developing therapies that directly interrupt the biological drivers of these diseases rather than simply addressing downstream symptoms.
YB-101: A Potential First-in-Class Anti-TSHR Therapy
At the center of Yarrow’s development portfolio is YB-101, an investigational monoclonal antibody designed to block the thyroid-stimulating hormone receptor (TSHR).
Unlike existing therapies that target individual manifestations of Graves’ disease or thyroid eye disease, YB-101 aims to directly interfere with the receptor responsible for initiating the autoimmune cascade in both conditions.
By preventing disease-causing autoantibodies from activating TSHR, the therapy is intended to halt disease progression at its source. Because TSHR is expressed both in thyroid tissue and in orbital tissues surrounding the eyes, investigators believe a single targeted therapy could potentially address both Graves’ disease and thyroid eye disease simultaneously.
If successful, YB-101 could represent a fundamentally different treatment approach capable of providing broader disease control while potentially improving both efficacy and safety compared with currently available treatment options.
Designed for Patient Convenience
Beyond its novel mechanism of action, YB-101 has also been developed with patient convenience in mind.
The investigational antibody is designed for subcutaneous administration, allowing treatment to be delivered through relatively simple injections rather than more complex intravenous infusions.
The company also envisions infrequent dosing intervals and potential future availability through an autoinjector device, which could improve patient adherence and enhance overall treatment convenience.
Such features may become increasingly important for patients managing chronic autoimmune diseases requiring long-term therapy.
Ongoing Phase 2 Clinical Development
Yarrow has already initiated patient dosing in a Phase 2a/2b clinical trial evaluating YB-101 in adults diagnosed with Graves’ disease, including patients who also have concurrent thyroid eye disease.
The study is designed to evaluate the therapy’s safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical efficacy across multiple patient populations.
The company expects to report data from the Phase 2a portion of the study during the second half of 2027.
Positive results from this trial could support advancement into larger late-stage clinical studies and further strengthen the therapeutic potential of YB-101.
FDA Fast Track Designation
Recognizing the potential significance of YB-101, the U.S. Food and Drug Administration has granted the investigational therapy Fast Track Designation.
Fast Track status is intended to facilitate the development and regulatory review of therapies addressing serious medical conditions while meeting unmet clinical needs.
The designation may allow for more frequent communication with FDA reviewers and potentially expedite future regulatory interactions as development progresses.
Parallel Development Program in China
While Yarrow advances YB-101 globally, its licensing partner, Changchun GeneScience Pharmaceutical Co., Ltd. (GenSci), is independently developing the therapy within China under the name GenSci-098.
GenSci currently has multiple Phase 1 clinical studies underway evaluating the antibody in both thyroid eye disease and Graves’ disease.
The ongoing development program includes:
- A Phase 1 single ascending dose (SAD) and multiple ascending dose (MAD) trial in patients with thyroid eye disease.
- A Phase 1 single ascending dose study in patients with Graves’ disease.
The Chinese clinical program has already produced encouraging early findings.
Promising Early Clinical Results
According to Yarrow, results from the completed single ascending dose portion of GenSci’s thyroid eye disease study demonstrated rapid, dose-dependent biological activity consistent with the therapy’s intended mechanism of action.
Investigators also observed preliminary evidence suggesting potential clinical responses among treated patients.
Importantly, YB-101 demonstrated a favorable safety profile, with no clinically meaningful differences in adverse events compared with placebo during the single ascending dose portion of the study.
These positive safety findings supported progression into the multiple ascending dose phase of the Chinese study while also providing confidence for initiation of Yarrow’s Phase 2 clinical trial in the United States.
Data from GenSci’s ongoing multiple ascending dose trial are expected during the second half of 2027 and may contribute valuable information supporting future global development decisions.
Leadership Highlights Long-Term Opportunity
Rebecca V. Frey, PharmD, President and Chief Executive Officer of Yarrow Bioscience, described the completion of the merger as the beginning of an important new chapter for the company.
She emphasized that YB-101 represents a potentially first-in-class therapy capable of addressing two significant autoimmune diseases through a single biological target.
According to Dr. Frey, currently available treatments often fail to directly interrupt the disease-driving TSHR signaling pathway and may expose patients to significant toxicities or incomplete disease control.
By directly blocking TSHR activation, YB-101 has the potential to fundamentally alter disease progression while offering improved clinical outcomes for both Graves’ disease and thyroid eye disease.
She also highlighted the company’s strong financial position, noting that the newly completed financing provides operational funding into 2028 and supports multiple anticipated clinical milestones.
Experienced Leadership Team
Yarrow begins this next phase with an executive leadership team possessing extensive experience in biotechnology, clinical development, drug commercialization, and corporate strategy.
The executive management team includes:
- Rebecca V. Frey, PharmD – President and Chief Executive Officer
- Rachael Alford, PhD – Chief Operating Officer
- Lori Payton, PhD – Chief Development Officer
- Steve Ryder, MD – Chief Medical Officer
- Tyler Zeronda – Chief Financial Officer
Together, the leadership team brings decades of expertise in advancing innovative medicines from early research through regulatory approval and commercialization.
Board of Directors Strengthens Corporate Governance
The company’s Board of Directors includes experienced biotechnology executives, investors, and corporate leaders with backgrounds spanning drug development, finance, governance, and strategic growth.
Board members include:
- Bill Lundberg, MD, Board Chair and former Chief Executive Officer of Merus
- Rebecca V. Frey, PharmD
- Mona Ashiya, PhD, General Partner at OrbiMed
- Steve Hoerter, Chairman and Chief Executive Officer of MBX Biosciences
- Peter Silverman, JD, former Chief Operating Officer and General Counsel at Merus
- Bill White, Chief Financial Officer and Head of Corporate Development at Avere
The board is expected to guide Yarrow through its clinical expansion while maintaining disciplined financial management and long-term shareholder value creation.
Successful Financing Supports Long-Term Growth
Alongside the merger, Yarrow completed private financing transactions generating approximately $200 million in gross proceeds.
The financing attracted participation from several well-known healthcare investment firms, including:
- RTW Investments
- OrbiMed
- Janus Henderson Investors
- venBio Partners
- Logos Capital
- LifeSci Venture Partners
- Perceptive Advisors
The company expects these funds to support operations into 2028, providing sufficient capital to advance YB-101 through key clinical milestones without immediate financing requirements.
Merger Structure and Share Conversion
As part of the merger agreement, existing Yarrow common shares were converted into 0.7171 shares of the combined company’s common stock after accounting for VYNE’s previously completed 1-for-50 reverse stock split, which became effective on July 24, 2026.
The reverse stock split consolidated every 50 outstanding VYNE shares into one share before completion of the merger.
Following completion of both transactions, the combined company adopted a new CUSIP number and now has approximately 2.8 million issued and outstanding common shares, representing approximately 33.6 million fully diluted shares, or roughly 28.6 million fully diluted shares excluding equity incentive plans and awards.
Special Dividend Distributed Before Closing
Prior to completing the merger, VYNE also distributed its previously announced $17.3 million special cash dividend to eligible shareholders and warrant holders.
The dividend amounted to approximately $0.40242 per share, based on outstanding shares and equivalents as of the established record date.
Importantly, the dividend distribution remained unaffected by the reverse stock split.
The completion of the merger with VYNE Therapeutics and the successful $200 million financing significantly strengthen Yarrow Bioscience’s ability to pursue its long-term vision of transforming treatment for autoimmune thyroid diseases. With a differentiated lead candidate targeting the central disease mechanism underlying both Graves’ disease and thyroid eye disease, a growing body of encouraging clinical data, ongoing development programs in both the United States and China, and financial resources expected to support operations into 2028, the company is well positioned for its next stage of growth.
Over the coming years, Yarrow’s primary focus will remain on advancing YB-101 through clinical development, generating pivotal efficacy and safety data, expanding its understanding of TSHR-targeted therapy, and ultimately working toward delivering a first-in-class treatment option capable of improving outcomes for patients living with these challenging autoimmune conditions.
About the Phase 2a/2b Clinical Trial of YB-101 in Patients with GD, with or without TED
The Phase 2a/2b clinical trial (NCT07682896) is a randomized, blinded, placebo-controlled two-part trial evaluating YB-101 in patients with GD, with or without concurrent TED. The Phase 2a (Part 1) is a proof-of-concept trial of YB-101 versus placebo aiming to enroll 32 patients across four cohorts. The trial will evaluate safety, pharmacokinetics (“PK”), pharmacodynamics (“PD”), and efficacy endpoints through 24 weeks, including the percentage of patients that are euthyroid and off of anti-thyroid drugs, as well as relevant measures of orbitopathy in patients with concurrent TED. Data from the Phase 2a portion are expected in 2H 2027.
Part 2 is expected to be conducted as a Phase 2b dose-finding trial and enroll approximately 200 patients. The selection of doses and dosing intervals for Part 2 is expected to be informed by the safety, efficacy, PK, and PD data generated in Part 1 (Phase 2a). The Phase 2b is anticipated to commence in 1H 2028.
About Yarrow Bioscience
Yarrow Bioscience, Inc. is a clinical-stage biotechnology company focused on developing transformative therapies for autoimmune thyroid diseases. The Company is developing YB-101, a potentially first-in-class anti-thyroid stimulating hormone receptor (“TSHR”) monoclonal antibody designed to directly and rapidly disrupt the central mechanism of both GD and TED.