VYNE Therapeutics and Yarrow Bioscience Announce Merger Agreement (Form 8-K)

VYNE Therapeutics and Yarrow Bioscience Announce Merger Agreement

New York, NY United States -December 17, 2025 -VYNE Therapeutics Inc. (Nasdaq: VYNE) ("VYNE") and Yarrow Bioscience, Inc. ("Yarrow") today announced that they have entered into a definitive merger agreement pursuant to which the companies will combine in an all-stock transaction (the "Merger"). Upon completion of the Merger, the combined company expects to operate as Yarrow Bioscience, Inc. and trade on Nasdaq under the ticker symbol "YARW". Following completion of the Merger, the combined company plans to focus on advancing YB-101 (also known as GS-098), a clinical-stage, potentially first-in-class TSHR antibody for the treatment of GD and TED.

In support of the Merger, a syndicate of industry-leading healthcare investors led by RTW Investments and OrbiMed Advisors, with participation from Janus Henderson Investors, venBio Partners, Logos Capital, LifeSci Venture Partners and Perceptive Advisors, has committed to pre-closing financings in Yarrow totaling approximately $200.0 million in cash proceeds.

The combined company's cash balance at closing is expected to fund operations into 2028, including the advancement of the combined company's lead program YB-101, into a Phase 1b/2b trial in patients with GD, which is expected to be conducted in the United States and other territories. Phase 1b data is expected in the second half of 2027. In parallel, a Phase 1 trial, which is being conducted by licensing partner GenSci, is evaluating the safety and efficacy of YB-101 in patients with TED in China.

Prior to closing, VYNE expects to declare a cash dividend to pre-Merger VYNE stockholders to distribute excess net cash, which is expected to be approximately $14.5 to $16.5 million.

"We are excited about this merger, which establishes Yarrow on a strong foundation to advance YB-101 for patients living with Graves' disease and thyroid eye disease," said Rebecca Frey, Pharm.D., President and Chief Executive Officer of Yarrow. "Autoimmune thyroid disorders represent areas of significant unmet need, and we believe YB-101 has the potential to deliver meaningful clinical benefit through its highly targeted TSHR-directed mechanism of action. Together with an exceptional leadership team and the support of a premier group of life sciences investors, Yarrow is well positioned to deliver on our mission to transform treatment options in this field."

"Over the last several months, VYNE has evaluated a wide range of options to maximize stockholder value, including an assessment of our internal pipeline, financing opportunities and strategic alternatives," said David Domzalski, President and Chief Executive Officer of VYNE. "We believe this merger provides our stockholders a compelling opportunity to realize both short- and long-term value creation through a cash dividend and the continued advancement of Yarrow's potential breakthrough therapies for the treatment of thyroid autoimmune diseases."

About YB-101

YB-101 (also known as GS-098) is a clinical-stage, humanized monoclonal antibody targeting the thyroid-stimulating hormone receptor (TSHR). The antibody is designed to rapidly and efficiently block the pathogenic activity of thyroid-stimulating autoantibodies that drive disease progression in Graves' disease (GD) and thyroid eye disease (TED). By binding selectively to the TSH receptor and blocking autoantibody-induced receptor activation, YB-101 directly inhibits the biological pathway responsible for hyperthyroidism and orbitopathy. This novel and targeted approach represents a potential breakthrough for patients who are inadequately controlled with first-line therapies and remain at high risk for complications of GD and TED. While existing IGF-1R-directed therapies have demonstrated clinical benefit in TED, their broad receptor expression has been associated with treatment-limiting adverse events in certain patients. YB-101 targets the thyroid-stimulating hormone receptor, a key disease-driving pathway with more restricted tissue expression, and is designed to directly inhibit pathogenic autoantibody activity. This targeted approach has the potential to address an important unmet need for therapies with differentiated risk-benefit profiles. Earlier this week, Yarrow executed an exclusive license agreement with Shanghai Scizeng Medical Technology Co., Ltd, an affiliate of GenSci, to obtain global ex-China rights to develop GS-098 in GD and TED.

About the Proposed Transactions

Under the terms of the merger agreement, the pre-Merger VYNE stockholders are expected to own approximately 3% of the combined company, and the pre-Merger Yarrow stockholders (inclusive of those investors participating in the financings described above) are expected to own approximately 97% of the combined company, which is subject to adjustment in accordance with the definitive merger agreement.

The Merger has received unanimous approval by the boards of directors of both companies and is expected to close in the second quarter of 2026, subject to certain closing conditions, including, among other things, approval by the stockholders of each company, the effectiveness of a registration statement on Form S-4 to be filed with the U.S. Securities and Exchange Commission (the "SEC") to register the securities to be issued in connection with the Merger and the satisfaction of other customary closing conditions.

The combined company will be named "Yarrow Bioscience, Inc." and be led by Rebecca Frey, Yarrow's Chief Executive Officer and a member of Yarrow's board of directors. Yarrow's board at closing will also include Mona Ashiya, Ph.D., General Partner, OrbiMed Advisors. In addition, Lori Payton, Ph.D. is joining Yarrow's management team as Chief Development Officer.

Advisory and Legal Counsel

Gibson, Dunn & Crutcher LLP is serving as legal counsel to Yarrow, while Wedbush Securities Inc. is serving as exclusive strategic financial advisor. Cooley LLP is serving as legal counsel to VYNE and LifeSci Capital is serving as exclusive financial advisor.

Conference Call Details

Yarrow and VYNE plan to hold a joint conference call on December 17, 2025 at 8:30 AM EDT to discuss the Merger in more detail. To join the webcast, please register here: https://viavid.webcasts.com/starthere.jsp?ei=1746336&tp_key=e5c90dda9d. A replay of the webcast can be accessed following the call by visiting www.vynetherapeutics.com.

About Yarrow Bioscience, Inc.

Yarrow Bioscience is a clinical-stage biotechnology company focused on developing transformative therapies for autoimmune thyroid diseases. The company's lead candidate, YB-101, is a humanized monoclonal antibody targeting the thyroid-stimulating hormone receptor (TSHR) for the treatment of Graves' disease and thyroid eye disease. Yarrow is headquartered in New York, NY, and is backed by leading healthcare investors, including RTW Investments.

For more information, please visit www.yarrowbioscience.com.

About VYNE Therapeutics Inc.

VYNE is a clinical-stage biopharmaceutical company focused on developing differentiated therapies to treat inflammatory and immune-mediated conditions with high unmet need. VYNE's unique and proprietary BET inhibitors, which comprise its InhiBET™ platform, are designed to overcome limitations of early generation BET inhibitors by leveraging alternative routes of administration and enhanced selectivity.

For more information, please visit www.vynetherapeutics.com.